Assessment of hepatocellular carcinoma by contrast-enhanced ultrasound with perfluorobutane microbubbles: comparison with dynamic CT

Objective

The aim of this study was to evaluate tumour vascularity and Kupffer cell imaging in hepatocellular carcinoma (HCC) using contrast-enhanced ultrasonography (CEUS) with Sonazoid (perfluorobutane) and to compare performance with dynamic CT.

Methods

We studied 118 nodules in 88 patients with HCC. HCC was diagnosed as a hyperenhancement lesion in the arterial phase with washout in the portal phase on dynamic CT or by percutaneous biopsy. We observed tumour vascularity at the early vascular phase (10–30 s after contrast injection) and Kupffer imaging at the post-vascular phase (after 10 min).

Results

Detection of vascularity at the early vascular phase was 88% in nodules that were found to be hypervascular on dynamic CT and 28% in hypo-/isovascular nodules; the detection of local recurrence nodules was 92%. The detection of vascularity was significantly lower in nodules >9 cm deep than in those ≤9 cm deep, but was not affected by tumour size. The detection of tumours at the post-vascular phase on CEUS was 83% in nodules with low density in the portal phase on dynamic CT and 82% in nodules with isodensity. The rate did not depend on the severity of underlying liver disease; rates decreased in nodules deeper than 9 cm, those smaller than 2 cm in diameter and in iso-enhancing nodules at the early vascular phase of CEUS.

Conclusion

CEUS with Sonazoid is a useful tool for assessing the vascularity of HCC and is equal to that of dynamic CT; however, the detectability of HCC vascularity is affected by location.The development of imaging modalities has facilitated the detection and accurate diagnosis of hepatocellular carcinoma (HCC). Assessment of tumour vascularity and for the presence of Kupffer cells are important in differential diagnosis, the choice of treatment and for assessment of the therapeutic response. HCC tumour vascularity has been evaluated extensively using various imaging modalities, including colour or power Doppler ultrasonography [1,2], angiography, dynamic CT [3], CT during angiography [4,5] and MRI [3]. Dynamic helical CT is minimally invasive and provides information regarding arterial or portal supplies by scanning at different time intervals following an injection of contrast agent. Therefore, dynamic CT is the standard modality used in clinical assessment of tumour vascularity. Assessment of Kupffer cells is possible using superparamagnetic iron oxide (SPIO)-enhanced MRI [6,7]. The presence of Kupffer cells indicates normal or benign liver tissue, whereas the absence of Kupffer cells indicates non-liver tissue such as malignant neoplasms. Thus, evaluation of the presence of Kupffer cells is useful in the differential diagnosis of focal liver lesions.Microbubble contrast agents are available for clinical use with ultrasound. Levovist (Schering AG, Berlin, Germany) is a first-generation contrast agent widely used to characterise focal liver lesions [8-12]. The advent of Sonazoid, a second-generation contrast agent (perfluorobutane; Diichi Sankyo, Tokyo, Japan), enables low mechanical index continuous real-time imaging and Kupffer imaging [13-15]. Therefore, contrast-enhanced ultrasound (CEUS) using Sonazoid could potentially offer high-quality, detailed vascular information and clearer Kupffer imaging. The aim of the present study was to compare CEUS using Sonazoid with dynamic CT in the assessment and characterisation of HCC.     

Assessment of early treatment response after CT-guided radiofrequency ablation of unresectable lung tumours by diffusion-weighted MRI: a pilot study

The aim of this study was to evaluate prospectively the early treatment response after CT-guided radiofrequency ablation (RFA) of unresectable lung tumours by MRI including diffusion-weighted imaging (DWI). The study protocol was approved by the ethics committee of our hospital and signed consent was obtained from each patient. We studied 17 patients with 20 lung lesions (13 men and 4 women; mean age, 69±9.8 years; mean tumour size, 20.8±9.0 mm) who underwent RFA using a LeVeen electrode between November 2006 and January 2008. MRI was performed on a 1.5T unit before and 3 days after ablation. We compared changes in the apparent diffusion coefficient (ADC) on DWI and response evaluation based on subsequent follow-up CT. 14 of the 20 treatment sessions showed no local progression on follow-up CT, whereas 6 treatment sessions showed local progression (range, 3–17 months; mean, 6 months). For the no-progression group, the ADC pre- and post-RFA were 1.15±0.31 × 10⁻³ mm² s⁻¹ and 1.49±0.24 × 10⁻³ mm² s⁻¹, respectively, while the respective ADC values for those that showed local progression were 1.05±0.27 × 10⁻³ mm² s⁻¹ and 1.24±0.20 × 10⁻³ mm² s⁻¹. The ADC of the ablated lesion was significantly higher than before the procedure (p<0.05). There was a significant difference in the ADC post-RFA between no-progression and local progression groups (p<0.05). Our prospective pilot study showed that the ADC without local progression was significantly higher than with local progression after RFA, suggesting that the ADC can predict the response to RFA for lung tumours.After the first report in 2000 [1], lung radiofrequency ablation (RFA) is now considered effective in the treatment of lung cancer, which is traditionally considered unresectable owing to compromised pulmonary function or advanced age. In general, complications associated with lung RFA are minimal, and favourable local control has been reported in a number of studies of tumours with a diameter of 30 mm or less [1–5]. However, only a limited number of studies have been published regarding the treatment outcome after lung RFA [6–10]. In this process, a layer of normal lung tissue surrounding the tumour is also ablated as a safety margin. Inevitably, the ablated lesion depicted on a CT scan immediately after the procedure is larger than the original tumour mass. However, this region of increased density shrinks with time, but follow-up CT may still show the ablated lesion being as big as, or larger than, the tumour size before the procedure [6, 7]. Thus, radiologists sometimes encounter difficulty in distinguishing scarred tissue from a tumour residue/local progression when the size of the lesion remains the same. Accurate assessment of RFA outcome would have important consequences, as recurrent tumours can be treated again if detected at an early stage. Different modalities of early-stage follow-up examination, such as contrast-enhanced CT [8] and fluorodeoxyglucose positron emission tomography (FDG–PET), have been of great interest and their usefulness has been reported by several groups [9, 10]. Another approach — MR diffusion-weighted imaging (DWI) — which is based on the measurement of motion of water molecules, has also been reported as a non-invasive evaluation modality [11–19]. In this method, the apparent diffusion coefficient (ADC) represents the water content and distribution, the cellular density and the cell membrane integrity, suggesting the potential usefulness of an ADC map for estimating tumour viability. Indeed, DWI has been successfully used to assess the efficacy of radiotherapy [11, 12], chemotherapy [13–15] and transcatheter arterial embolisation [16, 17]. To our knowledge, only two studies have reported the use of DWI to evaluate the therapeutic outcome of RFA [18, 19]. A previous study reported that the ADC value of an ablated rabbit tumour model (VX2 tumour) was significantly higher than that of untreated tumours, and that FDG uptake on micro-PET for small animals with ablated tumours was significantly lower than for untreated tumours. These results indicate that DWI at 2 days and FDG–PET at 3 days after RFA are both potentially feasible modalities for monitoring the early effects of the procedure [19]. In this study, we calculated the ADC in tumour lesions before and after clinical lung RFA and examined the usefulness of DWI in the early detection of tumour response to RFA.     

MRI features of serous oligocystic adenoma of the pancreas: differentiation from mucinous cystic neoplasm of the pancreas

Objectives

The purpose of this study was to describe the MRI features of the benign pancreatic neoplasm serous oligocystic adenoma (SOA) that differ from those of mucinous cystic neoplasm (MCN), a neoplasm with the potential for malignant degeneration.

Methods

Seven patients with SOA (seven women; mean age 36.6 years) and eight patients with MCN (eight women: mean age 39.9 years) were included. Several imaging features were reviewed: mass size, location, shape, wall thickness, cyst configuration (Type I, unilocular; Type II, multiple clustered cyst; Type III, cyst with internal septation) and signal intensity of the lesion with heterogeneity.

Results

SOA lesions were smaller (3.4 cm) than those of MCN (9.3 cm) (p=0.023). The commonest lesion shape was lobulated (85.7%) for SOA, but oval (50.0%) or lobulated (37.5%) for MCN (p=0.015). The most common cyst configuration was Type II (85.7%) for SOA and Type III (75.0%) for MCN (p=0.008). Heterogeneity of each locule in T₁ weighted images was visible in all cases of MCN, but in no case for SOA (p=0.004).

Conclusion

SOA could be differentiated from MCN by identifying the imaging features of lobulated contour with multiple clustered cyst configurations and homogeneity of each locule in T₁ weighted MR images.Serous oligocystic adenoma (SOA) is a recently described rare, benign pancreatic neoplasm and a morphological variant of serous microcystic adenoma, because it contains six or fewer cysts and the cysts are large (>2 cm) [1,2]. Pathologically, SOA is a benign pancreatic neoplasm composed of a few relatively large cysts uniformly lined with glycogen-rich cuboidal epithelial cells [3]. According to the World Health Organization classification, SOA is a subgroup of pancreatic serous cystic tumours and the term SOA is a synonym for macrocystic serous cystadenoma [3,4].The CT and MRI features of SOA of the pancreas are documented [2]. On CT and MRI, SOA typically appears as a small unilocular or bilocular cyst (<5 cm) with a thin wall (<2 mm) that lacks mural nodules or calcifications [2]. Because the cystic spaces are >2 cm, SOA images can be mistaken for mucinous cystic neoplasm (MCN), pseudocyst or intraductal papillary mucinous tumour [2,5-7]. It is very difficult to differentiate SOA from MCN by clinical and radiological features [2,6,8,9]. SOA does not require resection unless it causes symptoms, but MCN should be resected because of a potential for malignant degeneration [5,7,8]. Endoscopic ultrasound and cyst fluid aspiration have a role in distinguishing mucinous and serous lesions, but it is an invasive procedure with a risk of complications such as pancreatitis [10]. Therefore, it is clinically valuable to determine characteristic imaging findings that can distinguish SOA from MCN.Recently, Kim et al [6] and Cohen-Scali et al [5] described characteristic CT findings that can be used to differentiate SOA from MCN. MRI can demonstrate septa within a lesion with greater sensitivity than CT; therefore, MRI provides a better evaluation of tissue characteristics than CT [1,11]. However, few studies have described the MRI features of SOA [1,2]. The purpose of this study was to describe the differences in the MRI features of SOA and MCN in the pancreas.     

Prognostic factors associated with a subchondral insufficiency fracture of the femoral head

Objective

The aim of this study was to identify the risk factors associated with the prognosis of a subchondral insufficiency fracture of the femoral head (SIF).

Methods

Between June 2002 and July 2009, 25 patients diagnosed with SIF were included in this study. Sequential radiographs were evaluated for the progression of collapse. Clinical profiles, including age, body mass index, follow-up period and Singh’s index, were documented. The morphological characteristics of the low-intensity band on T₁ weighted MRI were also examined with regards to four factors: band length, band thickness, the length of the weight-bearing portion and the band length ratio (defined as the proportion of the band length to the weight-bearing portion of the femoral head in the slice through the femoral head centre).

Results

Radiographically, a progression of collapse was observed in 15 of 25 (60.0%) patients. The band length in patients with progression of collapse [22.5 mm; 95% confidence interval (CI) 17.7, 27.3] was significantly larger than in patients without a progression of collapse (13.4 mm; 95% CI 7.6, 19.3; p<0.05). The band length ratio in patients with progression of collapse (59.8%; 95% CI 50.8, 68.9) was also significantly higher than in patients without a progression of collapse (40.9%; 95% CI 29.8, 52.0; p<0.05). No significant differences were present in the other values.

Conclusion

These results indicate that the band length and the band length ratio might be predictive for the progression of collapse in SIF.Subchondral insufficiency fractures of the femoral head (SIF) often occur in osteoporotic elderly patients [1-9]. Patients usually suffer from acute hip pain without any obvious antecedent trauma. Radiologically, a subchondral fracture is seen primarily in the superolateral portion of the femoral head [4,5,10]. T₁ weighted MRI reveal a very low-intensity band in the subchondral area of the femoral head, which tends to be irregular, disconnected and convex to the articular surface [2,4,5,7,9,11]. This low-intensity band in SIF was histologically proven to correspond with the fracture line and associated repair tissue [5,9]. Some cases of SIF resolve after conservative treatment [5,11-14]; other cases progress until collapse, thereby requiring surgical treatment [4-10,15]. The prognosis of SIF patients remains unclear.The current study investigated the risk factors that influence the prognosis of SIF based on the progression to collapse.     

Combining diffusion-weighted MRI with Gd-EOB-DTPA-enhanced MRI improves the detection of colorectal liver metastases

Objectives

To compare the diagnostic accuracy of gadolinium-ethoxybenzyl-diethylenetriaminepentaacetic acid (Gd-EOB-DTPA)-enhanced MRI, diffusion-weighted MRI (DW-MRI) and a combination of both techniques for the detection of colorectal hepatic metastases.

Methods

72 patients with suspected colorectal liver metastases underwent Gd-EOB-DTPA MRI and DW-MRI. Images were retrospectively reviewed with unenhanced T₁ and T₂ weighted images as Gd-EOB-DTPA image set, DW-MRI image set and combined image set by two independent radiologists. Each lesion detected was scored for size, location and likelihood of metastasis, and compared with surgery and follow-up imaging. Diagnostic accuracy was compared using receiver operating characteristics and interobserver agreement by kappa statistics.

Results

417 lesions (310 metastases, 107 benign) were found in 72 patients. For both readers, diagnostic accuracy using the combined image set was higher [area under the curve (Az) = 0.96, 0.97] than Gd-EOB-DTPA image set (Az = 0.86, 0.89) or DW-MRI image set (Az = 0.93, 0.92). Using combined image set improved identification of liver metastases compared with Gd-EOB-DTPA image set (p<0.001) or DW-MRI image set (p<0.001). There was very good interobserver agreement for lesion classification (κ = 0.81–0.88).

Conclusions

Combining DW-MRI with Gd-EOB-DTPA-enhanced T₁ weighted MRI significantly improved the detection of colorectal liver metastases.In patients with colorectal cancer, accurate assessment of the size, location and segmental distribution of liver metastases on a per-lesion basis is critical for treatment planning [1]. Accurate depiction of the size and distribution of liver metastases helps the selection of patients to undergo radical surgery [2,3] or minimally invasive therapy, such as radiofrequency ablation (RFA) [4], chemo-embolisation or radio-embolisation [5].The image contrast in diffusion-weighted MRI (DW-MRI) is based on differences in the mobility of water between tissues [6]. In tumour tissues, such as liver metastases, water mobility is often more impeded compared with normal parenchyma. Hence, metastases appear to have high signal intensity on DW-MRI, facilitating their detection.Compared with conventional T₂ weighted imaging, DW-MRI has been found to be superior for lesion detection in the liver [7-9]. When compared with contrast-enhanced MRI, DW-MRI had a higher diagnostic accuracy compared with superparamagnetic iron oxide (SPIO)-enhanced MRI [10] and similar diagnostic accuracy compared with gadolinium contrast-enhanced imaging [11] for detecting colorectal liver metastases. DW-MRI has also been found to be more sensitive than fluorodeoxyglucose (¹⁸FDG) positron emission tomography (PET) CT [12] for the same clinical indication. In another study, combining DW-MRI with T₁ weighted imaging after liver-specific contrast medium mangafodipir trisodium (MnDPDP) administration improved the diagnostic accuracy of colorectal liver metastases detection compared with either technique alone [13].Gadolinium-ethoxybenzyl-diethylenetriaminepentaacetic acid (Gd-EOB-DTPA; Eovist or Primovist; Bayer Schering Pharma, Berlin, Germany) is a relatively new hepatocyte-selective MR contrast medium that has been shown to be useful detecting liver metastases measuring <1 cm in diameter [14,15]. Delayed T₁ weighted imaging in the hepatocellular phase of contrast enhancement at 20 min to several hours after contrast administration demonstrates metastases as T₁ hypointense lesions against the avidly enhancing liver parenchyma.Both DW-MRI and Gd-EOB-DTPA-enhanced MRI are useful for the detection of liver metastases [7,8,14-16]. One study performed at 3 T compared the diagnostic performance of the two techniques for the identification of small (<2 cm) liver metastases [17]. Another study at 1.5 T independently compared the diagnostic performance of DW-MRI, dynamic phase MRI and hepatobiliary phase Gd-EOB-DTPA-enhanced MRI [18]. However, the possible incremental value of combining DW-MRI with Gd-EOB-DTPA-enhanced MRI for detecting colorectal metastases has not been reported. Hence, the aim of this study was to compare the diagnostic accuracy of Gd-EOB-DTPA-enhanced MRI, DW-MRI and a combination of both techniques for the detection of colorectal hepatic metastases.     

Pulmonary tuberculosis associated with the reversed halo sign on high-resolution CT

We describe the case of a 32-year-old woman with pulmonary tuberculosis in whom a high-resolution CT scan demonstrated the reversed halo sign. The diagnosis of tuberculosis was made by lung biopsy and the detection of acid-fast bacilli in the sputum smear and culture. Follow-up assessment revealed a significant improvement in the lesions.The reversed halo sign is observed on high-resolution CT (HRCT) as a focal round area of ground-glass attenuation surrounded by a crescent or ring of consolidation [1, 2]. It was first described as being relatively specific for cryptogenic organising pneumonia [1], but was later observed in several other infectious [3–5] and non-infectious [6, 7] diseases.We report a case of a 32-year-old patient with tuberculosis who exhibited the reversed halo sign on chest CT. To our knowledge, this sign has not been previously described in an adult with pulmonary tuberculosis.     

Miliary tuberculosis: a comparison of CT findings in HIV-seropositive and HIV-seronegative patients

The aim of this study was to determine the differences in CT findings of miliary tuberculosis in patients with and without HIV infection. Two radiologists reviewed retrospectively the CT findings of 15 HIV-seropositive and 14 HIV-seronegative patients with miliary tuberculosis. The decisions on the findings were reached by consensus. Statistical analysis was performed using the χ² test, Mann–Whitney U-test and Fisher''s exact test. All of the HIV-seropositive and -seronegative patients had small nodules and micronodules distributed randomly throughout both lungs. HIV-seropositive patients had a higher prevalence of interlobular septal thickening (p = 0.017), necrotic lymph nodes (p = 0.005) and extrathoracic involvement (p = 0.040). The seropositive patients had a lower prevalence of large nodules (p = 0.031). In conclusion, recognition of the differences in the radiological findings between HIV-seropositive and -seronegative patients may help in the establishment of an earlier diagnosis of immune status in patients with miliary tuberculosis.Miliary tuberculosis (TB), which results from lympho-haematogenous dissemination of Mycobacterium tuberculosis, is a complication of both primary and post-primary TB [1, 2]. This disease results in the formation of small discrete foci of granulomatous tissue, which are uniformly distributed throughout the lung [3].An increase in TB incidence, including miliary TB, has been associated with infection by human immunodeficiency virus (HIV) [4]. In 2005, the World Health Organization estimated that 12% of HIV deaths globally were caused by TB, and that there were 630 000 new co-infections with TB and HIV [5]. Disseminated TB accounted for 5.4–8.1% of culture-confirmed TB cases, with 10–14% of patients coinfected with HIV having clinically recognisable dissemination [6, 7].Chest radiography may be helpful in the detection and final diagnosis of miliary TB. The characteristic radiographical findings consist of the presence of fine granular or numerous small nodular opacities measuring 1–3 mm in diameter scattered throughout both lungs [1, 3, 8, 9]. However, the radiograph may appear to be normal in the early stage of disease or in cases with nodules below the threshold of perceptibility; therefore, a diagnosis of miliary TB from chest radiographs can be difficult [10].Several studies have shown that CT imaging is more sensitive for the detection of parenchymal abnormalities in patients with AIDS who have active intrathoracic disease, and it has been suggested that CT may also be helpful in the differential diagnosis [11–14]. In addition, it has been reported that certain imaging techniques provided by multidetector-row CT are useful for the diagnosis of multiple micronodular infiltrative lung disease [15]. CT findings of miliary TB have been described in previous reports [16–18]; however, only a few studies on miliary TB in patients with HIV, particularly with reference to the CD4 count, have been reported [19, 20]. The radiographic manifestations of HIV-associated pulmonary TB are thought to be dependent upon the level of immunosuppression at the time of overt disease [21–23].The purpose of this study was to determine the differences in the CT findings of miliary TB for patients with and without HIV infection and to analyse any correlation between the CT features and the level of immunosuppression in patients.     

Primary vaginal cancer: role of MRI in diagnosis,staging and treatment

Primary carcinoma of the vagina is rare, accounting for 1–3% of all gynaecological malignancies. MRI has an increasing role in diagnosis, staging, treatment and assessment of complications in gynaecologic malignancy. In this review, we illustrate the utility of MRI in patients with primary vaginal cancer and highlight key aspects of staging, treatment, recurrence and complications.The incidence of primary vaginal cancer increases with age, with approximately 50% of patients presenting at age greater than 70 years and 20% greater than 80 years.¹ Around 2890 patients are currently diagnosed with vaginal carcinoma in the USA each year, and almost 30% die of the disease.² The precursor for vaginal cancer, vaginal intraepithelial neoplasia (VAIN) and invasive vaginal cancer is strongly associated with human papillomavirus (HPV) infection (93%).^3,4 In situ and invasive vaginal cancer share many of the same risk factors as cervical cancer, such as tobacco use, younger age at coitarche, HPV and multiple sexual partners.^5–7 In fact, higher rates of vaginal cancer are observed in patients with a previous diagnosis of cervical cancer or cervical intraepithelial neoplasia.^7,8As is true for other gynaecologic malignancies, vaginal cancer diagnosis and staging rely primarily on clinical evaluation by the International Federation of Gynecology and Obstetrics (FIGO).⁹ Pelvic examination continues to be the most important tool for evaluating local extent of disease, but this method alone is limited in its ability to detect lymphadenopathy and the extent of tumour infiltration. Hence, FIGO encourages the use of imaging. Fluorine-18 fludeoxyglucose-positron emission tomography (¹⁸F-FDG-PET), a standard imaging tool for staging and follow-up in cervical cancer, can also be used for vaginal tumours, with improved sensitivity for nodal involvement compared to CT alone.¹⁰ In addition to staging for nodal and distant disease, CT [simulation with three dimensional (3D) conformations] is particularly useful for treatment planning and delivery of external beam radiation. MRI, with its excellent soft tissue resolution, is commonly used in gynaecologic malignancies and has been shown to be accurate in diagnosis, local staging and spread of disease in vaginal cancer.^11,12 While no formal studies are available for vaginal cancer, in cervical cancer MRI actually alters the stage in almost 30% of patients.^13–15Treatment planning in primary vaginal cancer is complex and requires a detailed understanding of the extent of disease. Because vaginal cancer is rare, treatment plans remain less well defined, often individualized and extrapolated from institutional experience and outcomes in cervical cancer.^1,16–19 There is an increasing trend towards organ preservation and treatment strategies based on combined external beam radiation and brachytherapy, often with concurrent chemotherapy,^14,20,21 surgery being reserved for those with in situ or very early-stage disease.²² Increasing utilization of MR may provide superior delineation of tumour volume, both for initial staging and follow-up, to allow for better treatment planning.²³     

Contrast-enhanced ultrasonography of hepatocellular carcinoma: correlation between quantitative parameters and histological grading

Objective

The quantitative parameters in the contrast-enhanced ultrasonography time–intensity curve of hepatocellular carcinoma (HCC) were studied to explore their possible implication for histological grading of HCC.

Methods

A total of 130 HCC patients (115 males and 15 females; age: 48.13±11.00 years) were studied using contrast-enhanced ultrasonography time–intensity curve and histological pathology. The quantification software Sonoliver® (TomTec Imaging Systems, Unterschleissheim, Germany) was applied to derive time–intensity curves of regions of interest in the interior of HCCs and in reference. Quantitative parameters of 115 patients were successfully obtained, including maximum of intensity (IMAX), rise time (RT), time to peak (TTP), rise slope (RS) and washout time (WT). Histological grading of HCC was performed using haematoxylin–eosin staining, and monoclonal antibodies specific for smooth muscle actin were used to observe unpaired arteries (UAs).

Results

There were significant differences among WTs in the three differentiated HCC groups (p<0.05). However, there were no significant differences among RT, TTP, RS and IMAX in the differentiated HCC groups. Moreover, the number of UAs in the differentiated HCC groups showed no statistical significance.

Conclusion

WT plays an important role in predicting well, moderately and poorly differentiated HCC.The majority of hepatocellular carcinomas (HCCs) develop through multistep hepatocarcinogenesis [1]. Various types of hepatocellular nodules are seen in cirrhotic livers. The International Working Party of the World Congress of Gastroenterology classifies hepatocellular nodules into six types: regenerative nodules, low-grade dysplastic nodules, high-grade dysplastic nodules, well-differentiated HCC, moderately differentiated HCC and poorly differentiated HCC. The histopathological grades and types constitute well-established prognostic factors [2]. Thus, early diagnosis and confirmation of the type of hepatocellular nodules present and cellular differentiation before treatment are important.Although definite differentiation among HCC by imaging is usually impossible, the relationship between tumour cellular differentiation and image findings has been studied using contrast-enhanced (CE) CT, CEMRI and CE ultrasonography (CEUS). Tumour pathological differentiation correlates well with image findings [,3−8].Dynamic CEUS during the past decade has noticeably improved the detection and characterisation of focal liver lesions [9]. A previous study showed that CEUS and spiral CT provided a similar diagnostic accuracy in the characterisation of focal liver lesion [10]. The appearance of HCC on CEUS has also been described well. Current low-mechanical-index techniques for CEUS using second-generation microbubble agents have advantages in characterising HCC, including real-time demonstration of continuous haemodynamic changes in both the liver and hepatocellular nodules. Some studies postulated that variations of enhancement patterns may be related to the pathological function of HCC [,5−8]. Moderately differentiated HCCs generally show classic enhancement features, with presence of hypervascularity in the arterial phase and washout during the portal phase, whereas well and poorly differentiated tumours account for most atypical variations in the arterial phase and portal venous phase [7].Reports assessing hepatocellular nodules have been based on visual analysis, despite the disadvantages of interobserver variability and low reproducibility of results. Although quantitative analysis CEUS perfusion provides more objective, reliable and reproducible results [11], the time–intensity curve (TIC) of CEUS has been obtained by quantification software for offline analysis [,12−14], from which a series of semi-quantitative perfusion parameters is extracted and analysed. An analysis of the parameters of TIC in HCC has proven the correlation of CEUS with unpaired arteries (UAs) in HCC [14]. In the present study, we compare the quantitative parameters in CEUS and UAs in different pathological gradings of HCCs to explore their possible implication for histological grading of HCC.     

Subcutaneous panniculitis-like T-cell lymphoma with breast involvement: functional and morphological imaging findings

Panniculitis-like T-cell lymphoma is a very uncommon subtype of cutaneous T-cell lymphomas. In this case report, we describe the morphological (CT and MRI) and functional (¹⁸F-FDG-PET and bone scan) imaging findings in a 35-year-old patient who suffered from slowly progressing multiple subcutaneous lesions caused by this rare disease.According to the World Health Organization–European Organization for Research and Treatment of Cancer (WHO–EORTC) classification, subcutaneous panniculitis-like T-cell lymphomas (SPTCLs) belong to the group of cutaneous T-cell and natural killer (NK)-cell lymphomas [1]. Less than 1% of all non-Hodgkin lymphomas (NHLs) are SPTCLs. Recent studies differentiate distinct subtypes of SPTCL each with a different prognosis [2]. Only a few reports describe the imaging of primary cutaneous T-cell lymphomas [3–8], even fewer with the imaging of subcutaneous involvement in SPTCLs [4, 9–11]. In this case report, we describe panniculitis-like T-cell lymphoma as a very rare cause of unclear subcutaneous soft-tissue indurations. We detail the morphological and functional CT, MRI, ¹⁸F-FDG-PET and bone scan findings relating to multiple panniculitic lesions in a 35-year-old female patient suffering from this uncommon subgroup of lymphoma.     

An evaluation of four CT-MRI co-registration techniques for radiotherapy treatment planning of prone rectal cancer patients

Objectives

MRI is the preferred staging modality for rectal carcinoma patients. This work assesses the CT–MRI co-registration accuracy of four commercial rigid-body techniques for external beam radiotherapy treatment planning for patients treated in the prone position without fiducial markers.

Methods

17 patients with biopsy-proven rectal carcinoma were scanned with CT and MRI in the prone position without the use of fiducial markers. A reference co-registration was performed by consensus of a radiologist and two physicists. This was compared with two automated and two manual techniques on two separate treatment planning systems. Accuracy and reproducibility were analysed using a measure of target registration error (TRE) that was based on the average distance of the mis-registration between vertices of the clinically relevant gross tumour volume as delineated on the CT image.

Results

An automated technique achieved the greatest accuracy, with a TRE of 2.3 mm. Both automated techniques demonstrated perfect reproducibility and were significantly faster than their manual counterparts. There was a significant difference in TRE between registrations performed on the two planning systems, but there were no significant differences between the manual and automated techniques.

Conclusion

For patients with rectal cancer, MRI acquired in the prone treatment position without fiducial markers can be accurately registered with planning CT. An automated registration technique offered a fast and accurate solution with associated uncertainties within acceptable treatment planning limits.Randomised trials have demonstrated that adjuvant radiotherapy (RT) in patients with resectable rectal cancer offers a statistically significant reduction in the risk of local recurrence compared with surgery alone [1]. Two meta-analyses and a systematic review have confirmed this finding [2-4]: cancer-specific survival was found to be improved when RT was delivered with biological equivalent doses of >30 Gy pre-operatively. Two further trials have confirmed similar benefit when short-course pre-operative RT was combined with total mesorectal excision (TME) [5,6].Three further randomised trials have evaluated the role of pre-operative adjuvant chemoradiotherapy (CRT) for patients with stage T3–T4 or node-positive disease. Two of these studies demonstrated a reduction in local recurrence when pre-operative adjuvant CRT was used rather than long-course adjuvant RT alone [7,8]. The third study demonstrated both reduced local recurrence and reduced acute and late toxicity for pre-operative CRT compared with post-operative CRT [9]. The Cochrane review [4] also examined CRT and concluded that CRT provided incremental benefit in local control, irrespective of the timing of the chemotherapy. These results have led to a significant increase in the use of pre-operative radiation for patients with rectal cancer.MRI offers increased soft-tissue contrast compared with other radiographic imaging modalities such as CT. This improvement allows the accurate identification of the gross tumour and the mesorectal fascia in at least three planes. A number of studies have recommended using high-resolution MRI as a tool to determine the relationship between the potential circumferential resection margin (CRM) and the tumour [10-15], with one recent large prospective multicentre study demonstrating a specificity of 92% in predicting an involved CRM [16]. These results are supported by a recent meta-analysis of nine studies (529 patients) that revealed an overall sensitivity of 94% and specificity of 85% [17]. The review article by Klessen et al [18] also suggests that MRI is the only imaging modality that enables such accurate evaluation. Consequently, MRI is the reference standard for the clinical assessment of patients with colorectal cancer and is recommended for routine use by the National Institute for Clinical Excellence (NICE) in the UK [19].Current clinical practice at St James’s Institute of Oncology is for patients to be selected for pre-operative CRT if the margins of resection are considered at risk by the colorectal multidisciplinary team. The patient is CT-scanned in the prone treatment position and the oncologist defines the gross tumour volume (GTV) on individual transaxial images, leading to the determination of the planning target volume (PTV). To assist in the definition of the GTV, the oncologist is aided by diagnostic CT and/or MRI and other clinical information. Where diagnostic MRI is available, it is usually acquired in a different patient orientation (e.g. supine position) or radiographic plane (e.g. orthogonal to the long axis of the tumour) and at a different time to the CT study, meaning that the anatomy may differ in appearance. Furthermore, the MRI may be on radiographic film or on a different computer system to the planning CT.Image co-registration is the process of finding the mathematical transformation that aligns several different radiographic studies [20]. Various rigid-body co-registration techniques are currently offered by commercial RT treatment planning systems (TPSs), including those that employ operator-defined corresponding landmarks, interactive drag-and-drop or full automation.There are obvious potential advantages of including image registration in the treatment planning process [21], but historically, technical issues associated with MRI distortion, artefacts and lack of electron density information, along with little evidence of its positive effect on patient outcome, are likely to have precluded its universal use in treatment planning [22]. Despite these issues, studies have demonstrated the feasibility of pelvic image registration for RT treatment planning [23-26].Furthermore, rectal cancer specifically has been identified as a disease for which co-registered MRI could enhance treatment planning [27,28]. There is considerable interest in RT in which the GTV is defined on MR imaging in the same frame of reference as the planning CT. Increased accuracy in defining the GTV and/or clinical target volume (CTV) would give a more accurate definition of the dose required to those volumes or allow dose escalation to the GTV in patients with locally advanced disease. Acquiring an MRI with the patient in the prone position, however, introduces a new set of potential challenges, including increased respiratory artefacts that affect registration accuracy.Several studies have investigated the accuracy of image registration in a RT context, but as concluded by Sharpe and Brock [29] in their review of image registration quality assurance, there is no consistent approach. One approach is to image phantoms with objects of known spatial location with both CT and MRI [30-33]. This has the advantage of enabling controlled measurement of errors throughout the entire process of image acquisition and image registration, with a ground truth established through the objects with known spatial location. Such phantoms can also be used to estimate the spatial distortion in the images. However, these studies are all based on the use of MRI to image the head and neck rather than the pelvis. The studies’ dependence on physical phantoms means that uncertainties that may arise from natural variations in shape, size and composition in the patient population are not measured. Furthermore, the two studies evaluating the performance of commercial registration algorithms using patient images are both based on the registration of images of the head [32,34].Several studies have employed CT-MRI co-registration for pelvic sites [23-26,35,36], but few data exist on measured image registration uncertainties using existing image registration functionality in commercial TPSs. Furthermore, no evidence could be found of image registration for patients imaged in the prone position.The primary aim of this study is to assess the co-registration accuracy of two fully automated and two hybrid manual-automatic techniques using two commercial TPSs. On the basis of these results, this study aims to determine the most appropriate clinical image registration process and whether manual adjustments after automatic image registration are necessary or even beneficial. It is expected to provide supporting information for RT centres that are considering utilising co-registered prone MRI in treatment planning for rectal cancer.     

Comparison of mammography, sonography, MRI and clinical examination in patients with locally advanced or inflammatory breast cancer who underwent neoadjuvant chemotherapy

Objectives

The purpose of this study was to determine the relative accuracies of mammography, sonography, MRI and clinical examination in predicting residual tumour size and pathological response after neoadjuvant chemotherapy for locally advanced or inflammatory breast cancer. Each prediction method was compared with the gold standard of surgical pathology.

Methods

43 patients (age range, 25–62 years; mean age, 42.7 years) with locally advanced or inflammatory breast cancer who had been treated by neoadjuvant chemotherapy were enrolled prospectively. We compared the predicted residual tumour size and the predicted response on imaging and clinical examination with residual tumour size and response on pathology. Statistical analysis was performed using weighted kappa statistics and intraclass correlation coefficients (ICC).

Results

The ICC values between predicted tumour size and pathologically determined tumour size were 0.65 for clinical examination, 0.69 for mammography, 0.78 for sonography and 0.97 for MRI. Agreement between the response predictions at mid-treatment and the responses measured by pathology had kappa values of 0.28 for clinical examination, 0.32 for mammography, 0.46 for sonography and 0.68 for MRI. Agreement between the final response predictions and the responses measured by pathology had kappa values of 0.43 for clinical examination, 0.44 for mammography, 0.50 for sonography and 0.82 for MRI.

Conclusion

Predictions of response and residual tumour size made on MRI were better correlated with the assessments of response and residual tumour size made upon pathology than were predictions made on the basis of clinical examination, mammography or sonography. Thus, the evaluation of predicted response using MRI could provide a relatively sensitive early assessment of chemotherapy efficacy.The advantages of neoadjuvant chemotherapy are multiple and it has been used widely during the past few years [1]. Its primary role is to induce tumour shrinkage and permit breast-conserving surgery, primarily in patients with advanced breast cancer [2-4]. Neoadjuvant chemotherapy allows earlier treatment of micrometastatic disease and the study of biological markers that might predict tumour response [5]. The effectiveness of chemotherapeutic agents in treating both primary breast cancer and potential metastatic disease may be enhanced by the presence of tumour neovascularity. If chemotherapy is given before surgery, while tumour vascularity remains intact, the chemotherapeutic agents may be better able to reach the tumour and thus be more effective.Neoadjuvant chemotherapy of locally advanced breast cancer (LABC) has also been shown to improve the resectability rate, offering disease-free and overall survival rates that are at least equivalent to those offered by surgery alone [6,7]. Pathological complete response (pCR) is clinically significant because it is associated with improved long-term prognosis and decreased risk of recurrence [6,8]. Decisions regarding the continuation of current regimens and the appropriate type and timing of surgery depend on the radiological and clinical assessment of residual tumour size during neoadjuvant chemotherapy [9,10]. Until now, many studies have shown that physical examinations, mammography and sonography provide suboptimal evaluations of lesion extent that do not allow accurate assessments of pathological response or residual tumour size [5^,11-13]. In the case of LABC, physical examination, mammography or sonography may be suitable for detecting the larger lesions of non-responders, but they have limited sensitivity for responders with smaller residual lesions [14,15]. For mammography, calcifications may persist or even increase in patients who respond to neoadjuvant chemotherapy [14,16,17].Many previous studies have shown that MRI is the most reliable technique for evaluating residual disease after neoadjuvant chemotherapy, although initial reports described frequent false-negatives with smaller-volume disease [18-27]. Recent studies have increased the sensitivity of MRI, with increased resolution, reduced slice thickness and lower enhancement thresholds being used to minimise the underestimation of residual disease [15^,22-27]. It is still difficult, however, to distinguish residual scarring, necrosis and fibrosis from viable residual malignancy and to predict accurate response after neoadjuvant chemotherapy, especially in responders. Few published studies have described work with patients with inflammatory breast cancer who underwent neoadjuvant chemotherapy because the incidence of this disease is very low [28,29]. The purpose of our study was to determine the relative accuracies of mammography, sonography, MRI and clinical examination in predicting residual tumour size and pathological response after neoadjuvant chemotherapy for locally advanced and inflammatory breast cancer. We compared each prediction method with the gold standard of surgical pathology.     

Accessory or additional renal arteries show no relevant effects on the width of the upper urinary tract: a 64-slice multidetector CT study in 1072 patients with 2132 kidneys

Objective

The aim of this study was to find out on an unselected patient group whether crossing vessels have an influence on the width of the renal pelvis and what independent predictors of these target variables exist.

Methods

In this cross-sectional study, 1072 patients with arterially contrasted CT scans were included. The 2132 kidneys were supplied by 2736 arteries.

Results

On the right side, there were 293 additional and accessory arteries in 286 patients, and on the left side there were 304 in 271 patients. 154 renal pelves were more than 15 mm wide. The greatest independent factor for hydronephrosis on one side was hydronephrosis on the contralateral side (p<0.0001 each). Independent predictors for the width of the renal pelvis on the right side were the width of the renal pelvis on the left, female gender, increasing age and height; for the left side, predictors were the width of the renal pelvis on the right, concrements, parapelvic cysts and great rotation of the upper pole of the kidney to dorsal. Crossing vessels had no influence on the development of hydronephrosis. Only anterior crossing vessels on the right side are associated with widening of the renal pelvis by 1 mm, without making it possible to identify the vessel as an independent factor in multivariate regression models.

Conclusion

The width of the renal pelvis on the contralateral side is the strongest independent predictor for hydronephrosis and the width of the renal pelvis. There is no link between crossing vessels and the width of the renal pelvis.Obstructions of the ureteropelvic junction (UPJ) can be caused by intrinsic or extrinsic factors [1]. Although there are no studies of this to date, crossing the UPJ by an aberrant crossing vessel is considered the most important [2] of the extrinsic factors [3]. Crossing vessels, which are thought to cause from 40% to over 50% of the extrinsic UPJ obstructions in adults [4, 5], are located ventral more often than dorsal to the UPJ. These are usually normal vessels of the lower pole segment [4, 6–9], which can be divided into additional renal arteries arising from the aorta, and accessoric renal arteries arising from branches of the aorta [10, 11]. The primary surgical therapy of choice is endoscopic endopyelotomy [12]. The success rate of 89–90% [12, 13] is thought to be noticeably poorer in patients with crossing vessels [12, 13]; however, this is not undisputed [14, 15]. Be that as it may, to prevent bleeding complications it is necessary to be familiar with the vascular situation around the UPJ prior to the procedure [3, 16–18]. CT angiography is used for this purpose, as it is highly accurate, quick to perform and shows all relevant anatomical structures in relation to one another [3, 19, 20]. The objective of this study was to determine whether or not there are vascular morphological patterns or other factors that influence the width of the renal collecting system, regardless of the definitions of hydronephrosis.     

Towards clinical assessment of velopharyngeal closure using MRI: evaluation of real-time MRI sequences at 1.5 and 3 T

Objective

The objective of this study was to demonstrate soft palate MRI at 1.5 and 3 T with high temporal resolution on clinical scanners.

Methods

Six volunteers were imaged while speaking, using both four real-time steady-state free-precession (SSFP) sequences at 3 T and four balanced SSFP (bSSFP) at 1.5 T. Temporal resolution was 9–20 frames s⁻¹ (fps), spatial resolution 1.6×1.6×10.0–2.7×2.7×10.0 mm³. Simultaneous audio was recorded. Signal-to-noise ratio (SNR), palate thickness and image quality score (1–4, non-diagnostic–excellent) were evaluated.

Results

SNR was higher at 3 T than 1.5 T in the relaxed palate (nasal breathing position) and reduced in the elevated palate at 3 T, but not 1.5 T. Image quality was not significantly different between field strengths or sequences (p=NS). At 3 T, 40% acquisitions scored 2 and 56% scored 3. Most 1.5 T acquisitions scored 1 (19%) or 4 (46%). Image quality was more dependent on subject or field than sequence. SNR in static images was highest with 1.9×1.9×10.0 mm³ resolution (10 fps) and measured palate thickness was similar (p=NS) to that at the highest resolution (1.6×1.6×10.0 mm³). SNR in intensity–time plots through the soft palate was highest with 2.7×2.7×10.0 mm³ resolution (20 fps).

Conclusions

At 3 T, SSFP images are of a reliable quality, but 1.5 T bSSFP images are often better. For geometric measurements, temporal should be traded for spatial resolution (1.9×1.9×10.0 mm³, 10 fps). For assessment of motion, temporal should be prioritised over spatial resolution (2.7×2.7×10.0 mm³, 20 fps).

Advances in knowledge

Diagnostic quality real-time soft palate MRI is possible using clinical scanners and optimised protocols have been developed. 3 T SSFP imaging is reliable, but 1.5 T bSSFP often produces better images.Approximately 450 babies born in the UK every year have an orofacial cleft [1], the majority of which include the palate [2]. While a cleft palate is commonly repaired surgically at around 6 months [3], residual velopharyngeal insufficiencies require follow-up surgery in 15–50% of cases [4]. This residual defect results in an incomplete closure of the velopharyngeal port, which in turns leads to hypernasal speech. Assessment of velopharyngeal closure in speech therapy is commonly performed using X-ray videofluoroscopy or nasendoscopy [5,6]. While nasendoscopy is only minimally invasive, it may be uncomfortable and provides only an en face view of the velopharyngeal port. In contrast, X-ray videofluoroscopy is non-invasive and produces an image which is a projection of the target anatomy. Additional information may be obtained from projections at multiple angles [5,7], but anatomical structures may overlie each other. Furthermore, soft tissue contrast, such as that from the soft palate, is poor, although it may be improved using a barium contrast agent coating [8] at the expense of making the procedure more invasive and unpleasant. Arguably the greatest drawback of X-ray videofluoroscopy is the associated ionising radiation dose, which carries increased risk in paediatric patients [9].An increasing number of research studies have used MRI to image the soft palate [10-13] and upper vocal tract [14-17]. In contrast to X-ray videofluoroscopy and nasendoscopy, MRI provides tomographic images in any plane with flexible tissue contrast. As a result, MRI has been used to obtain images of the musculature of the palate at rest and during sustained phonation [10,18,19]. It has also been used to image the whole vocal tract at rest or during sustained phonation [20-27] and with a single mid-sagittal image dynamically during speech [13,15-17,28-35].For assessment of velopharyngeal closure, dynamic imaging with sufficient temporal resolution and simultaneous audio recording is required. Audio recording during imaging is complicated by the loud noise of the MRI scanner, and both the safety risk and image degradation caused by using an electronic microphone within the magnet. As a result, optical fibre-based equipment with noise cancellation algorithms must be used [36].In order to fully resolve soft palate motion, Narayanan et al [30] suggested that a minimum temporal resolution of 20 frames s⁻¹ (fps) is required. A similar conclusion was reached by Bae et al [13], based on measurements of soft palate motion extracted from X-ray videofluoroscopy. Using segmented MRI, Inoue et al [35] demonstrated that changes in the velar position that were evident at acquired frame rates of 33 fps were not observed at 8 fps. However, MRI is traditionally seen as a slow imaging modality and achieving sufficient temporal resolution at an acceptable spatial resolution is challenging. Furthermore, as the soft palate is bordered on both sides by air, the associated changes in magnetic susceptibility at the interfaces make images prone to related artefacts.Dynamic MRI of the vocal tract has been performed using both segmented [17,33,37] and real-time acquisitions [13,15,16,28,31,38]. Segmented acquisitions [39] acquire only a fraction of the k-space data required for each image during one repetition of the test phrase and, hence, require multiple identical repetitions. While these segmented techniques permit high temporal and spatial resolutions [35], they require reproducible production of the same phrase up to 256 times [34], leading to subject fatigue. Differences between repeats of up to 95 ms in the onset of speech following a trigger have also been demonstrated [36].In contrast to segmented techniques, real-time dynamic methods permit imaging of natural speech, but require extremely rapid acquisition and often advanced reconstruction methods. The turbo spin echo (TSE) zoom technique [40] has been used to perform real-time MRI of the vocal tract [29,31] and is available as a clinical tool. The zoom technique excites a reduced field of view in the phase encode direction, hence allowing a smaller acquisition matrix and shorter scan for a constant spatial resolution. While such spin echo-based techniques are less susceptible to magnetic field inhomogeneity related signal dropout artefacts than other sequences, the frame rates achieved with these sequences are limited to 6 fps [31]. Gradient echo-based techniques have also been used to achieve similar temporal resolution [12,41,42] in the upper vocal tract, but are often used at much higher frame rates in other MRI applications such as cardiac imaging [43,44]. A number of gradient echo sequence variants exist. Fast low-angle shot (FLASH) type sequences [45] spoil any remaining transverse magnetisation at the end of every sequence repetition (TR). In contrast, steady-state free-precession (SSFP) sequences are not spoiled [46] and the remaining transverse magnetisation is used in the next TR to improve the signal-to-noise ratio (SNR), but renders the images sensitive to signal loss in the presence of motion. Balanced SSFP (bSSFP) sequences include additional gradients to bring the transverse magnetisation completely back into phase at the end of every TR [47,48]. The result is that bSSFP sequences have high SNR and are less sensitive to motion than SSFP sequences, but are more sensitive to field inhomogeneities, which cause bands of signal dropout.Both TSE and the gradient echo techniques discussed here sample in a rectilinear or Cartesian fashion, where one line of k-space is sampled in each echo. However, for real-time speech imaging, the highest acquired frame rates have been achieved by sampling k-space along a spiral trajectory [15,16,30,49]. While spiral imaging is an efficient way to sample k-space and is motion-resilient, it is prone to artefacts, particularly blurring caused by magnetic field inhomogeneities and off-resonance protons (i.e. fat) [50]. Recently, one group successfully used spiral imaging with multiple saturation bands and an alternating echo time (TE) to achieve an acquired real-time frame rate of 22 fps [13,16]. The saturation bands were used to allow a small field of view to be imaged without aliasing artefacts. The alternating TE was used to generate dynamic field maps which were incorporated into the reconstruction to compensate for magnetic field inhomogeneities. However, such advanced acquisition and reconstruction techniques are only available in a small number of research centres.The aim of this work is to optimise and demonstrate high-temporal-resolution real-time sequences available on routine clinical MRI scanners for assessment of soft palate motion and velopharyngeal closure. Consequently, radial and spiral acquisitions were excluded and the work focuses on Cartesian gradient echo sequences with parallel imaging techniques. As more clinical MRI departments now have 3 T scanners, imaging was performed at both 1.5 and 3 T to enable comparisons. At each field strength, we optimised sequences and implemented four combinations of spatial and temporal resolution in six subjects with simultaneous audio recordings.     

Inter- and intrascanner variability of pulmonary nodule volumetry on low-dose 64-row CT: an anthropomorphic phantom study

Objective:

To assess inter- and intrascanner variability in volumetry of solid pulmonary nodules in an anthropomorphic thoracic phantom using low-dose CT.

Methods:

Five spherical solid artificial nodules [diameters 3, 5, 8, 10 and 12 mm; CT density +100 Hounsfield units (HU)] were randomly placed inside an anthropomorphic thoracic phantom in different combinations. The phantom was examined on two 64-row multidetector CT (64-MDCT) systems (CT-A and CT-B) from different vendors with a low-dose protocol. Each CT examination was performed three times. The CT examinations were evaluated twice by independent blinded observers. Nodule volume was semi-automatically measured by dedicated software. Interscanner variability was evaluated by Bland–Altman analysis and expressed as 95% confidence interval (CI) of relative differences. Intrascanner variability was expressed as 95% CI of relative variation from the mean.

Results:

No significant difference in CT-derived volume was found between CT-A and CT-B, except for the 3-mm nodules (p<0.05). The 95% CI of interscanner variability was within ±41.6%, ±18.2% and ±4.9% for 3, 5 and ≥8 mm nodules, respectively. The 95% CI of intrascanner variability was within ±28.6%, ±13.4% and ±2.6% for 3, 5 and ≥8 mm nodules, respectively.

Conclusion:

Different 64-MDCT scanners in low-dose settings yield good agreement in volumetry of artificial pulmonary nodules between 5 mm and 12 mm in diameter. Inter- and intrascanner variability decreases at a larger nodule size to a maximum of 4.9% for ≥8 mm nodules.

Advances in knowledge:

The commonly accepted cut-off of 25% to determine nodule growth has the potential to be reduced for ≥8 mm nodules. This offers the possibility of reducing the interval for repeated CT scans in lung cancer screenings.Lung cancer is the primary cancer in males and the second most common cancer in females worldwide, causing 18% of the total number of deaths [1]. Many lung cancers are found at a relatively late stage, resulting in a 5-year survival of only 15% or less [2]. Low-dose CT is a promising screening method for early detection of lung cancer [3–7]. The first result indicates that CT lung cancer screening can reduce lung cancer-specific mortality [8].In lung cancer screening, treatment decisions usually depend on pulmonary nodule size for the nodules at first detection and on the growth rate at follow-up [4]. Therefore, it is essential to assess the nodule size and growth rate accurately and reproducibly [9,10]. Variability has been found in CT-derived nodule size assessment [11,12]. In view of the current practice of patients frequently undergoing follow-up examinations, sometimes not on the same scanner, reliable inter- and intrascanner reproducibility of nodule volumetry is important.However, previous studies reported inconsistent results regarding the reproducibility of nodule volumetry. Some in vitro studies have been performed in which artificial nodules were placed at known locations in a thoracic phantom without pulmonary vessels [13–15]. Some of these studies were based on older generation CT scanners [13,16]. These studies generally showed a small margin of variability in nodule volumetry for software from different vendors. On the other hand, in vivo studies have shown that variability can be considerable, with variability up to 25% for 15 to 500 mm³ nodules [11,17–19]. A study to investigate inter- and intrascanner variability under optimally controlled conditions, yet resembling human lungs, using a more realistic phantom, has not been performed. Nowadays, 64-row multidetector CT (64-MDCT) scanners are most commonly utilised, as well as in lung cancer screenings. The variability of nodule volumetry of these scanners impacts nodule management, e.g. the interval of repeated CT scanning. As an extension to our recent study on observer detection and accuracy of manual and semi-automated volumetry [10], the focus of this study is on reproducibility between and within 64-MDCT systems. We assessed the inter- and intrascanner variability of pulmonary nodule volumetry on low-dose 64-MDCT, using randomly placed solid nodules in an anthropomorphic thoracic phantom with a background of pulmonary vasculature.     

The intravertebral cleft in benign vertebral compression fracture: the diagnostic performance of non-enhanced MRI and fat-suppressed contrast-enhanced MRI

We compared the diagnostic performance of non-enhanced MRI and fat-suppressed contrast-enhanced MRI (CEMRI) in diagnosing intravertebral clefts in benign vertebral compression fractures (VCFs). We retrospectively reviewed 99 consecutive patients who had undergone percutaneous vertebroplasty for VCFs. A cleft was defined as a signal void or hyperintense area on non-enhanced MRI (T₁ and T₂ weighted imaging) or as a hypointense area within a diffusely enhanced vertebra on CEMRI. A cleft was confirmed as a solid opacification on post-procedural radiographs. The interobserver reliability and MRI diagnostic performance were evaluated. The interobserver reliability of non-enhanced MRI was substantial (k _ 0.698) and the interobserver reliability of CEMRI was almost perfect (k _ 0.836). Post-procedural radiographs showed solid cleft opacification in 32 out of the 99 cases. The sensitivity and specificity of non-enhanced MRI were 0.72 and 0.82 (observer 1) and 0.63 and 0.87 (observer 2), respectively. The sensitivity and specificity of CEMRI were 0.94 and 0.63 (observer 1) and 0.85 and 0.60 (observer 2), respectively. The sensitivity of CEMRI was significantly higher than that of non-enhanced MRI, and the specificity of non-enhanced MRI was higher than that of CEMRI. CEMRI was highly reliable and sensitive, and non-enhanced MRI was specific for intravertebral clefts. Therefore, spine MRIs, including CEMRI, could provide useful information about intravertebral clefts before percutaneous vertebroplasty.Intravertebral clefts associated with vertebral compression fractures (VCFs) are radiographic signs representing cavities within fractured vertebrae and have long been considered pathognomonic for avascular necrosis of the spine (Kümmell’s sign) [1–3]. However, several investigators have observed that intravertebral clefts are common in patients with osteoporotic compression fractures [4–6]. Currently, clefts are thought to represent corticocancellous disruption in mobile osteoporotic fractures, rather than avascular necrotic disease [4, 6].Percutaneous vertebroplasty (PV) is an effective and minimally invasive procedure for the treatment of osteoporotic compression fractures [7, 8]. The advent of PV as the major treatment option for VCFs has prompted interest in intravertebral clefts occurring in benign VCFs. Recent studies have suggested that the clinical outcomes and complications associated with PV are influenced by the presence of clefts [4, 9–13]. Thus, radiological detection of clefts is indispensable for managing patients with VCFs.Spine MRI is commonly used for the evaluation of acute VCFs. MRI is useful in distinguishing malignancy from acute osteoporotic VCFs [14, 15] and is effective in demonstrating bone marrow oedema associated with acute compression fractures, which is one of the indications for performing PV [14, 16]. The MRI findings associated with intravertebral clefts have been well described [3–5]. However, there is controversy concerning the efficacy of MRI in diagnosing clefts. Specifically, the reliability and effectiveness of contrast-enhanced MRI (CEMRI), first assessed by Oka et al in 2005 [11], has not been properly evaluated. Such evaluation is important, given that CEMRI entails additional expense.To evaluate the efficacy of the CEMRI for the prediction of intravertebral clefts, we assessed the interobserver reliability and diagnostic performance of non-enhanced T₁ weighted and T₂ weighted MRI (T1WI and T2WI) and CEMRI in the identification of intravertebral clefts in VCFs. We then compared the diagnostic performance of CEMRI with that of non-enhanced MRI.     

Non-osseous incidental findings in low-dose whole-body CT in patients with multiple myeloma

Objective:

The purpose of this study was to identify the frequency and grading of non-osseous incidental findings (NOIF) in non-contrast whole-body low-dose CT (LDCT) in patients with multiple myeloma.

Methods:

In the time period from 2010 to 2013, 93 patients with multiple myeloma were staged by non-contrast whole-body LDCT at our radiological department. LDCT images were analysed retrospectively for NOIF, which also included unsuspected extramedullary manifestation of multiple myeloma. All NOIF were classified as major or clinically significant, moderate or possibly clinically significant and minor or not clinically significant. Medical records were analysed regarding further investigation and follow-up of the identified NOIF.

Results:

In the 93 patients, 295 NOIF were identified (on average, 3.2 NOIF per patient). Most of the NOIF (52.4%) were not clinically significant, 25.8% of the NOIF were possibly clinically significant and 21.8% of the NOIF were clinically significant. Clinically significant NOIF were investigated further by CT after intravenous administration of contrast medium and/or by ultrasound or MRI. In 34 of these cases, extramedullary relapse of myeloma, occult carcinoma or infectious/septic incidental findings were diagnosed (11.5% of all NOIF). In the remaining 10.3% of the NOIF classified as clinically significant, various benign lesions were diagnosed.

Conclusion:

LDCT detected various non-osseous lesions in patients with multiple myeloma. 36.6% of the patients had clinically significant NOIF. Therefore, LDCT examinations in patients with multiple myeloma should be evaluated carefully for the presence of NOIF.

Advances in knowledge:

LDCT identified several NOIF. A total of 36.6% of patients with multiple myeloma had clinically significant NOIF. Radiologists should analyse LDCT examinations in patients with multiple myeloma not only for bone lesions, but also for lesions in other organs.CT is used for screening or staging in several malignancies.^1–8 As reported previously, the staging CT examination also provides additional information regarding the general health status of the patient or so-called incidental findings (IF).^1,3,6,7 Several IF on CT examinations were described in the literature.^1–6 According to previous reports, IF can be classified into five different categories: Group “0”, limited examination, that is, evaluation of IF are severely limited; Group “1”, normal findings or anatomic variant; Group “2”, clinically unimportant findings, such as liver or kidney cysts; Group “3”, likely unimportant findings; and Group “4”, potentially important findings, such as solid renal masses or lymphadenopathy.⁵ In another publication, a three-part classification of IF according to their clinical importance was proposed, namely major, moderate and minor IF.¹Most of the IF are clinically non-significant, such as colonic diverticula or simple cysts.^1–7 However, serious IF, such as aortic aneurysm or dissection, thrombosis, pulmonary embolism and second primary tumours, can also occur,^1,3,6,7 and some of them may be not visible on low-dose CT (LDCT).Most reports regarding IF are based on contrast-enhanced CT.^1,7,9–11 There are only a few reports regarding IF in LDCT.¹² They described IF in screening programmes for lung cancer and based the findings on thoracic LDCT only.¹² In addition, non-contrast LDCT has been established for staging of bone lesions in multiple myeloma.^13–16 However, radiologists should analyse LDCT examinations not only for bone lesions but also for lesions in other organs, which may include extramedullary manifestation of multiple myeloma as well as unrelated IF.Although IF in multiple myeloma have also been described previously,¹⁴ to the best of our knowledge, there exists no analysis focused on frequency and distribution of non-osseous IF (NOIF) on whole-body LDCT. Therefore, the purpose of this study was to identify the frequency and grading of NOIF in non-contrast whole-body LDCT in patients with multiple myeloma.     

Radiofrequency ablation combined with transcatheter arterial embolisation in rabbit liver: investigation of the ablation zone according to the time interval between the two therapies

Objectives

This study was designed to evaluate the extent of the radiofrequency ablation zone in relation to the time interval between transcatheter arterial embolisation (TAE) and radiofrequency ablation (RFA) and, ultimately, to determine the optimal strategy of combining these two therapies for hepatocellular carcinoma.

Methods

15 rabbits were evenly divided into three groups: Group A was treated with RFA alone; Group B was treated with TAE immediately followed by RFA; and Group C was treated with TAE followed by RFA 5 days later. All animals underwent perfusion CT (PCT) scans immediately after RFA. Serum liver transaminases were measured to evaluate acute liver damage. Animals were euthanised for pathological analysis of ablated tissues 10 days after RFA. Non-parametric analyses were conducted to compare PCT indices, the RFA zone and liver transaminase levels among the three experimental groups.

Results

Group B showed a significantly larger ablation zone than the other two groups. Arterial liver perfusion and hepatic perfusion index represented well the perfusion decrease after TAE on PCT. Although Group B showed the most elevated liver transaminase levels at 1 day post RFA, the enzymes decreased to levels that were not different from the other groups at 10 days post-RFA.

Conclusions

When combined TAE and RFA therapy is considered, TAE should be followed by RFA as quickly as possible, as it can be performed safely without serious hepatic deterioration, despite the short interval between the two procedures.Surgical resection is still considered standard curative therapy for hepatocellular carcinomas (HCCs), but only a small proportion of patients can undergo curative resection at initial presentation owing to the advanced stage of HCCs or liver dysfunction caused by an underlying liver disease [1,2]. Therefore, local ablation therapy, such as radiofrequency ablation (RFA), has been widely utilised as an alternative treatment. RFA shows promising results for managing HCCs less than 3 cm in diameter [3,4]. However, managing medium-sized and large HCCs with RFA seems to be less robust owing to the limited ablation zone. One of the main reasons is that intratumoral energy by RFA is insufficient to produce complete coagulation necrosis of liver tumours probably because of the heat dispersion by blood flow. To overcome these problems, transcatheter arterial embolisation (TAE) can reduce the heat sink effect for subsequent RFA when TAE is followed by RFA, which can lead to a larger ablation zone to treat larger HCCs [5-7]. Therefore, the combined therapy is beneficial compared with TAE or RFA alone due to a synergistic effect of those two therapies, particularly when treating larger HCCs (i.e. >3 cm diameter) that do not respond adequately to either procedure alone [6,8-13].No consensus exists on the time interval between combined TAE and RFA. Kang et al [13] reported on a single-session combined therapy in which RFA was performed immediately following chemoemobolisation. Takaki et al [12] reported on a dual-session combined therapy in which RFA was performed 1–2 weeks after TAE. The extent of the ablation zone and the safety of combined therapy in relation to the time interval between the two treatments have not been investigated. During the single-session combined therapy, the ablation zone is assumed to be larger than the dual-session combined therapy owing to the maximised perfusion reduction by TAE just prior to RFA. However, acute liver damage may be more severe with the single-session combined therapy than with the dual-session combined therapy.The aim of this study was to evaluate the differences in liver perfusion, the extent of the ablation zone and the degree of acute liver damage according to the time interval between TAE and RFA, and to determine the optimal strategy for combining these two therapies for treating HCCs.     

Correlation of the apparent diffusion coefficiency values on diffusion-weighted imaging with prognostic factors for breast cancer

Objective

The aim of this study was to correlate the apparent diffusion coefficient (ADC) value of breast cancer with prognostic factors.

Methods

335 patients with invasive ductal carcinoma not otherwise specified (IDC NOS) and ductal carcinoma in situ (DCIS) who underwent breast MRI with diffusion-weighted imaging were included in this study. ADC of breast cancer was calculated using two b factors (0 and 1000 s mm^–2). Mean ADCs of IDC NOS and DCIS were compared and evaluated. Among cases of IDC NOS, mean ADCs were compared with lymph node status, size and immunochemical prognostic factors using Student''s t-test. ADC was also correlated with histological grade using the Kruskal–Wallis test.

Results

Mean ADC of IDC NOS was significantly lower than that of DCIS (p<0.001). However, the mean ADC of histological grade of IDC NOS was not significantly different (p=0.564). Mean ADC of oestrogen receptor (ER)-positive or progesterone receptor (PR)-positive cancer was significantly lower than that of ER-negative or PR-negative cancer (p=0.003 vs p=0.032). Mean ADC of Ki-67 index-positive cancer was significantly lower than that of Ki-67 index-negative cancer (p=0.028). Mean ADC values of cancers with increased microvascular density (MVD) were significantly lower than those of cancer with no MVD increase (p=0.009). No correlations were observed between mean ADC value and human growth factor receptor 2 expression, tumour size and lymph node metastasis.

Conclusion

Low ADC value was correlated with positive expression of ER, PR, increased Ki-67 index, and increased MVD of breast cancer.Breast MRI is an established supplemental technique to mammography and ultrasonography for evaluation of suspicious breast lesions. Diffusion-weighted MRI (DWI) has recently been integrated into the standard breast MRI for discrimination of benign and malignant breast lesions obtained with dynamic contrast-enhanced MRI [1-13]. DWI is a non-invasive technique that represents the biological character of the mainly Brownian movement of protons in bulk water molecules in vivo. Apparent diffusion coefficient (ADC) values are quantified by measurement of mean diffusivity along three orthogonal directions, which are affected by cellularity of the tissue, fluid viscosity, membrane permeability and blood flow [7,9-11]. Microstructural characteristics, including water diffusion and blood microcirculations in capillary networks, were associated with ADC value. Decreased movement of molecules in highly cellular tissue showed correlation with a low ADC value [3,4]. Several studies of DWI of the breast have reported significantly lower ADC values in malignant tumours, compared with benign breast lesions and normal tissue [1-3,5-11,14]. Classic prognostic markers, including tumour size and grade, and lymph node status in patients with breast cancer, and molecular markers, including oestrogen receptor (ER), progesterone receptor (PR), Ki-67 index, human growth factor receptor 2 (HER2) protein and angiogenic molecular markers, have been reported [1,15,16]. Few studies have examined the correlation between ADC values and prognostic factors [1,8]. The purpose of this study is to compare ADC values of DWI of breast cancer with prognostic factors.     

Pancreatic ductal adenocarcinoma with intratumoral cystic lesions on MRI: correlation with histopathological findings

The purpose of this study was to evaluate intratumoral cystic lesions of pancreatic ductal adenocarcinoma (PDAC) depicted on MRI, and to correlate these cystic lesions with their histopathological findings. This study included 12 patients (7 males and 5 females; mean age, 59 years) with intratumoral cystic lesions of PDAC detected on a retrospective MRI review. We reviewed the histopathological findings of the cystic lesions within PDACs and analysed the MRI findings, focusing on the appearance of the intratumoral cystic lesions, i.e. the size, number, margin and intratumoral location, and on the ancillary findings of PDAC, i.e. peripancreatic infiltration, upstream pancreatic duct dilatation and distal parenchymal atrophy. Intratumoral cystic lesions were classified as neoplastic mucin cysts (n = 7, 58%) or cystic necrosis (n = 5, 42%) according to the histopathological findings; they ranged in greatest dimension from 0.5 cm to 3.4 cm (mean, 1.7 cm). Seven patients had only one cystic lesion each, while the remaining five had multiple cystic lesions. Most of the neoplastic mucin cysts had smooth margins (n = 6, 86%) and eccentric locations (n = 6), whereas most cystic necroses had irregular margins (n = 4, 80%) and centric locations (n = 4). The most common ancillary findings of PDAC were peripancreatic infiltration, distal pancreatic atrophy and upstream pancreatic duct dilatation (92%, 75% and 58%, respectively). The intratumoral cystic lesions of PDACs on MRI were classified as either neoplastic mucin cysts with smooth margins and eccentric locations or cystic necroses with irregular margins and centric locations.Pancreatic cancer is the fifth leading cause of cancer-related death in both men and women and is responsible for 5% of all cancer-related deaths in the United States [1]. Despite the advances in surgical techniques, as well as the major improvements in chemotherapy and radiotherapy protocols, the prognosis of pancreatic ductal adenocarcinoma (PDAC) usually implies a 1-year survival rate of <20% and a 5-year survival rate of <5% [2].PDAC typically presents as an irregular solid tumour with a scirrhous character resulting from a prominent desmoplastic reaction. However, recent studies have shown that PDAC may be accompanied by cystic changes within or adjacent to the mass, and that the incidence of PDAC with cystic changes ranges from <1% to 8% [3, 4]. Radiologists should be familiar with PDACs with cystic changes as they may resemble more common cystic pancreatic lesions, such as pseudocysts, intraductal papillary mucinous neoplasms (IPMNs), solid pseudopapillary tumours and non-functioning islet cell tumours, all of which are managed differently and usually have better patient survival rates [5–7].Many studies have discussed the radiological appearance of PDAC accompanied by cystic lesions [6–11]. Most of these studies have discussed pseudocysts or retention cysts depicted adjacent to the PDAC or in the extrapancreatic area in the clinical setting of pancreatitis [8–11], whereas only a few studies have discussed intratumoral cystic lesions, such as cystic necroses, in larger ordinary PDACs [6, 7]. Some case reports have described the intratumoral cystic changes of PDAC variants, i.e. adenosquamous carcinoma [12], mucinous adenocarcinoma (colloid or mucinous non-cystic carcinoma) [13], osteoclast-like giant cell carcinoma [14] and pleomorphic giant cell carcinoma [15]. To the best of our knowledge, there have been no radiological reports regarding the intratumoral cystic lesions of ordinary PDAC. Compared with CT, MRI has the advantage of being able to detect cystic changes within pancreatic masses and to provide more accurate morphological detail on these changes [16]. Therefore, the aims of this study were to evaluate intratumoral cystic lesions of ordinary PDAC detected on MRI and to correlate the cystic lesions with their histopathological findings.