Comparison of pulmonary thin section CT findings and serum KL-6 levels in patients with sarcoidosis

Objective

This study aimed to compare thin-section CT images from sarcoidosis patients who had either normal or elevated serum KL-6 levels.

Methods

101 patients with sarcoidosis who underwent thin-section CT examinations of the chest and serum KL-6 measurements between December 2003 and November 2008 were retrospectively identified. The study group comprised 75 sarcoidosis patients (23 male, 52 female; aged 19–82 years, mean 54.1 years) with normal KL-6 levels (152–499 U ml^–1, mean 305.7 U ml^–1) and 26 sarcoidosis patients (7 male, 19 female; aged 19–75 years, mean 54.3 years) with elevated KL-6 levels (541–2940 U ml^–1, mean 802.4 U ml^–1). Two chest radiologists, unaware of KL-6 levels, retrospectively and independently interpreted CT images for parenchymal abnormalities, enlarged lymph nodes and pleural effusion.

Results

CT findings in sarcoidosis patients consisted mainly of lymph node enlargement (70/75 with normal KL-6 levels and 21/26 with elevated KL-6 levels), followed by nodules (50 and 25 with normal and elevated levels, respectively) and bronchial wall thickening (25 and 21 with normal and elevated levels, respectively). Ground-glass opacity, nodules, interlobular septal thickening, traction bronchiectasis, architectural distortion and bronchial wall thickening were significantly more frequent in patients with elevated KL-6 levels than those with normal levels (p<0.001, p<0.005, p<0.001, p<0.001, p<0.001 and p<0.001, respectively). By comparison, there was no significant difference in frequency of lymph node enlargement between the two groups.

Conclusion

These results suggest that serum KL-6 levels may be a useful marker for indicating the severity of parenchymal sarcoidosis.KL-6 is a mucin-like high molecular weight glycoprotein that is expressed on Type II pneumocytes and respiratory bronchiolar epithelial cells in the normal lung [1, 2]. Serum levels of KL-6 are elevated in various respiratory and non-respiratory conditions, including breast and pancreatic cancers [3, 4] and diabetes mellitus [5]. This observation has led to a focus on the use of KL-6 as a diagnostic and prognostic tool in respiratory diseases.Serum and bronchoalveolar lavage fluid levels of KL-6, first described by Kohno et al [6] in 1988, were raised in patients with interstitial pneumonia [1, 2, 7]. Several investigators have also reported that KL-6 is a useful serum marker to confirm diagnosis and for long-term management in patients with diffuse pulmonary diseases, particularly interstitial lung diseases. Patients with idiopathic pulmonary fibrosis or non-specific interstitial pneumonia showed significantly elevated KL-6 levels [8-13].Several studies indicate that the serum KL-6 level is elevated in patients with sarcoidosis [14-16]. However, no studies describing radiological findings comparing thin-section CT images between patients with elevated KL-6 levels and those with normal KL-6 levels have been published in the English language literature.Thus, we aimed to retrospectively evaluate and compare pulmonary CT findings between patients with elevated KL-6 levels and those with normal KL-6 levels.     

Iron overload: accuracy of in-phase and out-of-phase MRI as a quick method to evaluate liver iron load in haematological malignancies and chronic liver disease

Objectives

The purpose of this prospective study was to evaluate the accuracy of in-phase and out-of-phase imaging to assess hepatic iron concentration in patients with haematological malignancies and chronic liver disease.

Methods

MRI-based hepatic iron concentration (M-HIC, μmol g^–1) was used as a reference standard. 42 patients suspected of having iron overload and 12 control subjects underwent 1.5 T in- and out-of-phase and M-HIC liver imaging. Two methods, semi-quantitative visual grading made by two independent readers and quantitative relative signal intensity (rSI) grading from the signal intensity differences of in-phase and out-of-phase images, were used. Statistical analyses were performed using the Spearman and Kruskal–Wallis tests, receiver operator curves and κ coefficients.

Results

The correlations between M-HIC and visual gradings of Reader 1 (r=0.9534, p<0.0001) and Reader 2 (r=0.9456, p<0.0001) were higher than the correlations of the rSI method (r=0.7719, p<0.0001). There was excellent agreement between the readers (weighted κ=0.9619). Both visual grading and rSI were similar in detecting liver iron overload: rSI had 84.85% sensitivity and 100% specificity; visual grading had 85% sensitivity and 100% specificity. The differences between the grades of visual grading were significant (p<0.0001) and the method was able to distinguish different degrees of iron overload at the threshold of 151 μmol g^–1 with 100% positive predictive value and negative predictive value.

Conclusion

Detection and grading of liver iron can be performed reliably with in-phase and out-of-phase imaging. Liver fat is a potential pitfall, which limits the use of rSI.Iron overload is a clinically recognised condition with variety of aetiologies and clinical manifestations [1-4]. Liver iron concentration correlates closely with the total body iron stores [5]. The excess iron accumulates mainly in the liver and the progressive accumulation of toxic iron can lead to organ failure if untreated [2,4]. Several diseases causing iron overload, such as transfusion-dependent anaemia, haematological malignancies, thalassaemia, haemochromatosis and chronic liver disease, result in a large number of patients with a potentially treatable iron overload [1,2,4].Several quantitative MRI methods for iron overload measurement by multiple sequences have been established, such as proportional signal intensity (SI) methods and proton transverse relaxation rates (R₂, R₂*) [4,6,7]. A gradient echo liver-to-muscle SI-based algorithm [8] has been widely validated and used for quantitative liver iron measurement [8-11]. MRI-based hepatic iron concentration (M-HIC, μmol g^–1 liver dry weight) with corresponding R₂* [9] can be calculated with this method which is a directly proportional linear iron indicator, virtually independent of the fat fraction, as the echo times are taken in-phase [8,9]. This method showed a high accuracy in calibrations with the biochemical analysis of liver biopsies (3–375 μmol g^–1) of 174 patients. The mean difference of 0.8 μmol g^–1 (95% confidence interval of –6.3 to 7.9) between this method and the biochemical analysis is quite similar [8] to the intra-individual variability found in histological samples [12].The quantitative MRI methods are based on progressive SI decay, with the longer echo times due to relaxing properties of iron. Interestingly, this iron-induced effect is seen in MR images with multiple echoes [4,6-11], but also in dual-echo images, namely in-phase and out-of-phase imaging [13,14]. In-phase and out-of-phase imaging has become a routine part of liver MRI, performed initially for liver fat detection [6,13,15]. Quite recently some investigators have noticed an alternative approach of the sequence to detect liver iron overload due to the more pronounced SI decrease on in-phase images with the longer echo time [13,14]. Yet, to our knowledge, this is the first prospective study evaluating the accuracy of in-phase and out-of-phase imaging to assess hepatic iron concentration.The purpose of the study was to evaluate the capability and accuracy of dual-echo in-phase and out-of-phase imaging to assess hepatic iron concentration at 1.5 T in patients with haematological malignancies and chronic liver disease. MRI-based hepatic iron concentration (M-HIC, μmol g^–1) was used as a reference standard [8,9].     

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.     

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.     

The effect of adaptive iterative dose reduction on image quality in 320-detector row CT coronary angiography

Objective

To evaluate the effect of adaptive iterative dose reduction (AIDR) on image noise and image quality as compared with standard filtered back projection (FBP) in 320-detector row CT coronary angiography (CTCA).

Methods

50 patients (14 females, mean age 68±9 years) who underwent CTCA (100 kV or 120 kV, 400–580 mA) within a single heartbeat were enrolled. Studies were reconstructed with FBP and subsequently AIDR. Image noise, vessel contrast and contrast-to-noise ratio (CNR) in the coronary arteries were evaluated. Overall image quality for coronary arteries was assessed using a five-point scale (1, non-diagnostic; 5, excellent).

Results

All the examinations were performed in a single heartbeat. Image noise in the aorta was significantly lower in data sets reconstructed with AIDR than in those reconstructed with FBP (21.4±3.1 HU vs 36.9±4.5 HU; p<0.001). No significant differences were observed between FBP and AIDR for the mean vessel contrast (HU) in the proximal coronary arteries. Consequently, CNRs in the proximal coronary arteries were higher in the AIDR group than in the FBP group (p<0.001). The mean image quality score was improved by AIDR (3.75±0.38 vs 4.24±0.38; p<0.001).

Conclusion

The use of AIDR reduces image noise and improves image quality in 320-detector row CTCA.CT coronary angiography (CTCA) is a robust non-invasive imaging modality with high spatial and temporal resolution that enables accurate diagnosis or exclusion of coronary artery disease [1-4]. However, CTCA usually exposes the patient to a substantial amount of radiation (9.4–21.4 mSv) [5-7]. Therefore, several scanning techniques, such as ECG-based tube current modulation, prospective ECG triggering and reduced tube voltage scanning, have been developed to reduce the patient''s radiation exposure [6-8]. Reductions of the tube current also lead to lower radiation exposure, as the tube current correlates to dose in a linear fashion. However, lower radiation leads to an increase in CT image noise because the current reconstruction method, filtered back projection (FBP), is unable to consistently generate diagnostic-quality images with reduced tube currents [9].Recently, the adaptive iterative dose reduction technique has been developed as a new reconstruction algorithm to improve image noise [10-12], and has already been shown to reduce the radiation dose in clinical practice [13-16]. Adaptive iterative dose reduction (AIDR) developed for CT by Toshiba Medical Systems Corporation is a modified iterative reconstruction technique in which the original high-noise image undergoes a number of reconstructions that reduce image noise until the resultant image displays the desired noise level. This technique is expected to reduce the radiation dose for a similar noise level to FBP.To our knowledge, no study has evaluated the quality of CT images using AIDR. The purpose of this study was to evaluate the effect of AIDR regarding image noise and image quality in comparison with FBP, using the same raw data set for both FBP and AIDR, in 320-detector row CTCA.     

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.     

Evaluation of CT coronary artery angiography with 320-row detector CT in a high-risk population

Objectives

The aim of this article was to prospectively evaluate the accuracy and radiation dose of 320-detector row dynamic volume CT (DVCT) for the detection of coronary artery disease (CAD) in a high-risk population.

Methods

60 patients with a high risk of CAD underwent DVCT without preceding heart rate control and also underwent invasive coronary angiography (ICA), which served as the standard reference.

Results

On a per segment analysis, overall sensitivity was 95.3%, specificity was 97.6%, positive predictive value was 90.6%, negative predictive value was 98.8% and Youden index was 0.93. In both heart rate subgroups, diagnostic accuracy for the assessment of coronary artery stenosis was similar. The accuracy of the subgroup with an Agatston score ≥100 was lower than that for patients with an Agatston score <100. However, the difference between DVCT and ICA results was not significant (p=0.08). The mean estimated effective dose of CT was 12.5±9.4 mSv. In those patients with heart rates less than 70 beats per minute (bpm), the mean radiation exposure of DVCT was 5.2±0.9 mSv. The effective radiation dose was significantly lower than that of ICA (14.1±5.9 mSv) (p<0.001). When the heart rate was >70 bpm, a significantly higher dose was delivered to patients with DVCT (22.6±5.2 mSv, p<0.001) than with ICA (15.0±5.3 mSv, p<0.001).

Conclusion

DVCT reliably provides high diagnostic accuracy without heart rate/rhythm control. However, from a dosimetric point of view, it is recommended that heart rate should be controlled to <70 bpm to decrease radiation dose.The small diameter of the coronary segments, their complex three-dimensional geometry and their rapid movement throughout the cardiac cycle represent the major challenges for artefact-free coronary CT angiography (CTA). With each scanner generation, motion artefacts re-appear as a major cause of image quality degradation during coronary CTA [1-10]. Coronary CTA studies of each coronary artery with four-multidetector CT (MDCT) at a gantry rotation time of 500 ms had significantly decreased image quality with increasing mean heart rates [3]. Using 16-MDCT at a gantry rotation time of 420 ms, Hoffmann et al [2] found a significant negative correlation between overall image quality and mean heart rate. Even using 64-section CT, with its gantry rotation speed of 330 ms, elevated and irregular heart beats were found to cause relevant degradation of image quality [1,4,9,11]. Using dual-source CT (DSCT) with an increased temporal resolution of 83 ms, there was no significant correlation between mean heart rate and the overall image quality for any coronary segment or for any individual coronary artery. Nonetheless, irregular heart rates still slightly affect the image quality of non-invasive coronary angiography, even with DSCT [10,12].The 320-detector row dynamic volume CT (DVCT) is characterised by 320 slice detectors with a thickness of 0.5 mm and gantry rotation time of 350 ms. With a wide coverage of 16 cm in the z-axis, the whole heart can be covered within one cardiac cycle. Theoretically, DVCT makes it possible to scan patients with an irregular heart rate without “stair-step” artefacts. At the same time, DVCT avoids the overlapping rotations of helical CT, and the application of prospective echocardiogram (ECG) gating has become more feasible. Recent studies of DVCT have mainly been based on a low heart rate [13-17]. Few studies have investigated the diagnostic accuracy in higher heart rates and arrhythmia. Our purpose was to systematically evaluate the diagnostic accuracy and exposure dose of DVCT in a high-risk population with high and irregular heart rates.     

Diagnostic performance of multidetector CT for acute cholangitis: evaluation of a CT scoring method

Objective

The aim of this study was to retrospectively assess the diagnostic performance of multidetector CT (MDCT) for the diagnosis of acute cholangitis using a new scoring method.

Methods

Of 80 patients with suspected biliary disease who underwent biphasic CT and endoscopic retrograde cholangiography, 39 were diagnosed as having acute cholangitis (Group 1) and 41 patients were classified as suspected biliary disease (Group 2). 100 age-matched patients without evidence of biliary disease were selected randomly as a control group (Group 3). Each patient''s axial scan was scored by two independent radiologists for the extent of transient hepatic attenuation difference, the presence of biliary dilatation and identification of a biliary obstructive lesion. The difference in the scores among the three groups was evaluated and the optimal cut-off score for the diagnosis of acute cholangitis was determined. Interobserver agreement was also evaluated.

Results

The total scores (mean±standard deviation) for Groups 1, 2 and 3 were 7.0±2.0, 4.4±2.4 and 0.9±1.2, respectively, for Reviewer 1 and 7.2±1.8, 4.3 ±2.7 and 0.7±1.1, respectively, for Reviewer 2. Significant differences were found for the subscores and the total scores among the three groups (p<0.001). Using a cut-off score of ≥5, the sensitivity and specificity for diagnosing acute cholangitis were 84.6% and 83.7%, respectively, for Reviewer 1 and 89.7% and 83.7%, respectively, for Reviewer 2. Agreement for the subscores between readers was good to excellent (κ=0.74–0.86).

Conclusion

Based on dynamic MDCT and the described CT scoring method, the diagnosis of acute choangitis can be made with high sensitivity and specificity.Acute cholangitis is a potentially life-threatening condition that occurs as a result of acute inflammation and infection in an obstructed bile duct [1,2]. Because both biliary obstruction and bile infection are required for the development of acute cholangitis, these factors are essential to the pathophysiology and diagnosis of this entity [3,4].Traditionally, the clinical manifestations, including Charcot''s triad (the presence of fever and/or chills, abdominal pain and jaundice), have been regarded as important factors for making the diagnosis of acute cholangitis [1-4]. However, the frequency of Charcot''s triad varies and has been reported to be present in 15.4–72.0% of patients [4]. Diagnostic criteria were established by. the International Consensus Meeting, held in Tokyo in 2006 [4]. The diagnostic criteria for a definite diagnosis of acute cholangitis include the presence of Charcot''s triad. In addition, laboratory data and imaging findings are needed to support the clinical diagnosis in patients without all of the components of Charcot''s triad. In this situation, laboratory data provide information about infection/inflammation and imaging is used to determine the degree and level of the biliary obstruction and to identify the obstructing lesion in the bile duct. In previous studies, multidetector CT (MDCT) has been shown to be an accurate imaging tool for the detection of biliary obstruction [5,6].Transient hepatic attenuation differences (THADs), which appear as focal or diffuse hyperdense areas during the hepatic arterial phase on the CT, have been reported to be common in patients with acute cholangitis [7-9]. The incidence of THADs in patients with acute cholangitis has ranged from 71% to 98%. In addition, one study reported that the THADs observed in patients with suspected biliary disease correlated with the clinical parameters of inflammation [9]. Therefore, we developed a new scoring method for the diagnosis of acute cholangitis using dynamic contrast-enhanced MDCT. This method considers two important diagnostic factors: biliary obstruction and biliary inflammation. The purpose of this study was to retrospectively assess the diagnostic performance of MDCT for the diagnosis of acute cholangitis using a new scoring system.     

Long-term results of radiofrequency ablation for unresectable colorectal liver metastases: a potentially curative intervention

Objective

The long-term results and prognostic factors of radiofrequency ablation (RFA) for unresectable colorectal liver metastases (CRLM) in a single centre with >10 years of experience were retrospectively analysed.

Methods

A total of 100 patients with unresectable colorectal liver metastases (CRLM) (size 0.2–8.3 cm; mean 2.4 cm) underwent a total of 126 RFA sessions (237 lesions). The mean follow-up time was 29 months (range 6–93 months). Lesion characteristics (size, number and location), procedure characteristics (percutaneous or intra-operative approach) and major and minor complications were carefully noted. Local control, mean survival time and recurrence-free and overall survival were statistically analysed.

Results

No direct procedure-related deaths were observed. Major complications were present in eight patients. Local RFA site recurrence was 12.7% (n = 30/237); for tumour diameters of <3 cm, 3–5 cm and >5 cm, recurrence was 5.6% (n = 8/143), 19.5% (n = 15/77) and 41.2% (n = 7/17), respectively. Centrally located lesions recurred more often than peripheral ones, at 21.4% (n = 21/98) vs 6.5% (n = 9/139), respectively, p = 0.009. Including additional treatments for recurring lesions when feasible, lesion-based local control reached 93%. The mean survival time from RFA was 56 (95% confidence interval (CI) 45–67) months. Overall 1-, 3-, 5- and 8-year survival from RFA was 93%, 77%, 36% and 24%, respectively.

Conclusions

RFA for unresectable CRLM is a safe, effective and potentially curative treatment option; the long-term results are comparable with those of previous investigations employing surgical resection. Factors determining success are lesion size, the number of lesions and location.Colorectal carcinoma is one of the most common malignancies in Western countries. In 20–25% of patients with colorectal carcinoma (synchronous) liver metastases are present at the time of diagnosis of the primary tumour [1-3]. Another 20–30% of patients develop (metachronous) liver metastases, which usually arise within 3 years of initial treatment of the primary tumour [1,3]. In Europe and the USA, colorectal liver metastases (CRLM) are the most frequent cause of malignant hepatic tumours [4]. The prognosis of patients with untreated CRLM (receiving only symptomatic therapy) is poor, with a median survival rate of 4.5–12 months, depending on the extent of metastatic disease at the time of diagnosis [5]. Chemotherapeutics, using oxaliplatin and fluorouracil (5FU), can prolong survival in a palliative setting with a median survival of approximately 18 months [6-8]. More recent results show a median survival of 21.7 months for patients treated with capecitabine, irinotecan and oxaliplatin [9]. Surgical resection is still considered the only method for definite treatment of malignant liver tumours by many [10-17]. Resection of liver metastases with curative intent results in a 5 year overall survival rate of 24–58% and a 10 year survival rate of 28% [11-19]. It is not uncommon, particularly in patients with primary colorectal carcinoma, for the liver to be the only site of metastatic disease [19]. Unfortunately, approximately 70–80% of patients with metastases confined to the liver are not suitable candidates for resection, owing to tumour anatomy (number, size and/or locations), extended extrahepatic disease and/or impaired general health status [20-22]. Therefore, several other local treatment methods such as tumour ablation, originally considered palliative procedures, have been investigated. Radiofrequency ablation (RFA) has shown promising results in the recent literature. It is a procedure with a relatively low complication rate (<10%, mostly minor complications that are often unnecessary to treat) and a very small risk of death (<1%), notably when compared with resection [20,23]. The aim of this study was to retrospectively describe the long-term results and predictive factors of RFA for unresectable CRLM.     

320-detector row CT coronary angiography: effects of heart rate and heart rate variability on image quality, diagnostic accuracy and radiation exposure

Objectives

To evaluate the effects of heart rate and heart rate variability on image quality, patient dose and diagnostic accuracy of 320-detector row CT.

Methods

94 patients were prospectively enrolled. Heart rate was defined as the mean value of different intervals elapsing between two consecutive R waves in an electrocardiogram (R–R intervals) and the heart rate variability was calculated as the standard deviation from the average heart rate. The image quality was evaluated by four grades, according to motion artefacts (“step artefacts” and “blurring artefacts”). The diagnostic accuracy was analysed in 43 patients who were scheduled for invasive coronary angiography (ICA). The coeffects of heart rate and heart rate variability on image quality, radiation dose and diagnostic accuracy were evaluated by multivariate regression.

Results

The mean image quality score was 1.2±0.5 and the mean effective dose was 14.8±9.8 mSv. The results showed that heart rate (74.0±11.2 beats per minute) was the single factor influencing image quality (p<0.001) and radiation dose (p<0.001), while heart rate variability (3.7±4.6) had no significant effect on them (p=0.16 and p=0.47, respectively). For 43 patients who underwent ICA, heart rate and heart rate variability showed no influence on the accuracy (p=0.17 and p=0.12, respectively). Overall sensitivity was 97.4% (37/38), specificity was 99.4% (351/353), positive predictive value was 94.9% (37/39) and negative predictive value was 99.7% (351/352).

Conclusion

320-detector row CT, with improved longitudinal coverage of detector, resolves step artefact and high patient dose caused by irregular heart rate. However, it is still recommended to control heart rate to a lower level to eliminate blurring artefact and radiation dose.As the clinical application of 4-detector CT to scan the coronary arteries by a non-invasive procedure, CT coronary angiography has emerged as an attractive, diagnostic modality for detecting coronary artery disease. However, motion artefact by rapid movement throughout the cardiac cycle and blooming artefact caused by calcified plaque represent the major challenges for artefact-free coronary CT angiography. Generally, “step artefacts” and “blurring artefacts” are two kinds of motion artefact influencing the quality of coronary artery image. To improve image quality, CT scanners with higher spatial resolution, temporal resolution and wider detector array were developed.The Discovery™ CT750 HD (GE Healthcare, Waukesha, WI) improves spatial resolution and decreased calcium blooming artefact significantly [1]. Dual-source CT (DSCT), with two X-ray sources and a temporal resolution of 83 ms, has improved blurring artefacts caused by high heart rate (HR) [2-4]. Nevertheless, as the coverage of the detectors is limited, step artefacts caused by heart rate variability (HRv) is still an inverse factor influencing the image quality [2,3]. Just as the improved temporal resolution should resolve the problem of high HR, the longitudinal coverage of the detector should be expanded further to resolve the influence of HRv [5-8]. 320-detector row dynamic volume CT (DVCT) can cover the whole heart within one heartbeat, which enables DVCT to have the potential to resolve the impact of HRv [9].A previous study has shown that DVCT reliably provides high diagnostic accuracy without HR control [9]. The aim of our study was to evaluate the influence of degree of HR and HRv on image quality, radiation dose and diagnostic accuracy in patients undergoing DVCT.     

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.     

Comparative study of hepatic venography using non-linear-blending images,monochromatic images and low-voltage images of dual-energy CT

Objective:

To investigate the use of non-linear-blending and monochromatic dual-energy CT (DECT) images to improve the image quality of hepatic venography.

Methods:

82 patients undergoing abdominal DECT in the portal venous phase were enrolled. For each patient, 31 data sets of monochromatic images and 7 data sets of non-linear-blending images were generated. The data sets of the non-linear-blending and monochromatic images with the best contrast-to-noise ratios (CNRs) for hepatic veins were selected and compared with the images obtained at 80 kVp and a simulated 120 kVp. The subjective image quality of the hepatic veins was evaluated using a four-point scale. The image quality of the hepatic veins was analysed using signal-to-noise ratio (SNR) and CNR values.

Results:

The optimal CNR between hepatic veins and the liver was obtained with the non-linear-blending images. Compared with the other three groups, there were significant differences in the maximum CNR, the SNR, the subjective ratings and the minimum background noise (p < 0.001). A comparison of the monochromatic and 80-kVp images revealed that the CNR and subjective ratings were both improved (p < 0.001). There was no significant difference in the CNR or subjective ratings between the simulated 120-kVp group and the control group (p = 0.090 and 0.053, respectively).

Conclusion:

The non-linear-blending technique for acquiring DECT provided the best image quality for hepatic venography.

Advances in knowledge:

DECT can enhance the contrast of hepatic veins and the liver, potentially allowing the wider use of low-dose contrast agents for CT examination of the liver.CT venography (CTV) is an important non-invasive examination to assess the hepatic veins and plays an important role in the pre-operative evaluation of liver transplants and the diagnosis of hepatic venous diseases.^1,2 Compared with CT hepatic artery angiography or multiphasic liver CT, CTV often requires a larger dose of the contrast agent to achieve sufficient contrast for filling in the hepatic veins.³ Increasing the contrast agent not only increases the economic burden of the patient but also raises the incidence of side effects and complications related to the contrast agent. One of the goals in the advancement of CT techniques is to continuously improve the image quality and clinical applications while reducing radiation exposure and promoting the reasonable use of contrast agents. Several studies suggest that low tube voltage CTV reduces radiation and improves vascular contrast^4–6 because iodinated contrast material is more conspicuous in low-kilovolt peak(kVp) images with an approximately 80% increase in CT attenuation at 80 kVp compared with that at 140 kVp.^6–8Dual-source CT (DSCT) was recently introduced into clinical practice. It can simultaneously acquire low- and high-energy image data using two X-ray tube and detector systems mounted in one gantry.⁹ Dual-energy CT (DECT) could improve the contrast and thereby the image quality of CTV images by virtual monochromatic imaging¹⁰ and non-linear-blending⁸ and linear-blending techniques.^7,11,12 Studies have shown that a DECT non-linear-blending technique could improve the conspicuity of myocardial delayed enhancement.⁸ The clinical application of DSCT undoubtedly greatly aides the choice of a suitable application from a variety of post-processing techniques that can significantly improve the contrast enhancement of hepatic veins. However, the ability to improve the conspicuity of hepatic veins via a dual-source DECT non-linear-blending technique and the performance of non-linear-blending and monochromatic imaging techniques have not been studied. Therefore, the purpose of our study was to improve the image quality of hepatic venography over single-energy CT by using DECT virtual monochromatic imaging and a non-linear-blending technique.     

Dose and image quality comparison between prospectively gated axial and retrospectively gated helical coronary CT angiography

Objective

Our aim was to compare image quality, coronary segment assessability and radiation dose in prospectively gated axial (PGA) coronary CT angiography (CTA) and conventional retrospectively gated helical (RGH) coronary CTA.

Methods

Institutional review committee approval and informed consent were obtained. RGH CTA was performed in 41 consecutive patients (33 males, 8 females; mean age 52.6 years), then the PGA CTA technique was evaluated in 41 additional patients (24 males, 17 females; mean age 57.3 years) all with a pre-scan heart rate of ≤70 beats per minute (bpm). Two radiologists, blinded to clinical information, independently scored subjective image quality on a five-point ordinal scale.

Results

The mean effective dose in the PGA group was 4.7±0.9 mSv, representing a 69% dose reduction compared with the RGH CTA group (15.1±1.9 mSv, p<0.001). The mean segmental image quality score was significantly higher in the PGA group (3.4 vs 3.2) than in the RGH CTA group (p<0.005). The percentage of assessable segments was 98.1% in the PGA group and 97.3% in the RGH group (p = 0.610).

Conclusion

PGA CTA offers a significant reduction in radiation dose compared with RGH CTA, with comparable image quality for patients with heart rates below 70 bpm.Rapid advances in multidetector CT (MDCT) technology have enabled non-invasive coronary angiography with high diagnostic accuracy [1–4]. However, the potential radiation risks associated with standard retrospectively gated helical (RGH) techniques for MDCT-based coronary CT angiography (CTA) have become a concern [5, 6]. Reported radiation doses from coronary CTA have ranged from 11 to 27 mSv [1, 7–10]: nearly 2–4 times the radiation dose attributed to typical invasive diagnostic angiography [11, 12]. Consequently, reducing cardiac CT doses to levels as low as reasonably achievable has become a major issue. A new prospectively gated axial (PGA) acquisition protocol has recently been introduced [13] to reduce the radiation dose by scanning only the mid-diastolic phase [8–10] of the cardiac cycle. The acquisition is based on a prospective electrocardiogram (ECG)-triggered sequential axial acquisition mode in opposition to the standard retrospectively gated continuous helical acquisition. Our aim was to compare image quality and radiation dose of PGA-based coronary CTA with the standard helical mode on a 64-channel CT.     

Comparison of conventional and three-dimensional conformal CT planning techniques for preoperative chemoradiotherapy for locally advanced rectal cancer

Objectives

We assessed the impact of three-dimensional (3D) conformal planning vs conventional planning of preoperative chemoradiotherapy (CRT) for locally advanced rectal cancer (LARC) on small bowel and bladder sparing and in optimising coverage of tumour target volume.

Methods

Conformal and conventional plans were created for 50 consecutive patients. The conformal plan delineated a gross tumour volume (GTV), a clinical target volume (CTV) 1 to cover potential subclinical disease spread, a CTV2 to outline the mesorectum and lymph node areas at risk, and a planning target volume (PTV) to cover set-up error and organ movement. The conventional plan was created using digitally reconstructed radiographs (DRRs). Patients were treated with a dose of 45 Gy in 25 fractions with concurrent chemotherapy over 5 weeks. Dose–volume histograms (DVHs) were created and compared for GTV, PTV, small bowel and bladder. The GTV was covered by the conventional plan in all patients.

Results

Significant differences were shown for median PTV coverage with conformal planning compared with conventional planning: 99.2% vs 94.2% (range 95.9–100% vs 75.5–100%); p<0.05. The median volume of irradiated small bowel was significantly lower for CT plans at all DVH levels. Median bladder doses did not differ significantly.

Conclusion

3D conformal CT planning is superior to conventional planning in terms of coverage of the tumour volume. It significantly reduces the volume of small bowel irradiated with no decrease in the rate of R0 resection compared with published data, and at the present time should be considered as the standard of care for rectal cancer planning.Chemoradiotherapy (CRT) followed by total mesorectal excision is the standard for care when MRI staging demonstrates threatened surgical margins in locally advanced rectal cancer (LARC) [1, 2]. Radiotherapy planning for rectal cancer uses conventional orthogonal simulation with standardised radiation fields based on patterns of loco-regional relapse in relation to pelvic bony anatomy [3]. Three-field conventional orthogonal planning is considered an acceptable technique for planning preoperative CRT and major trials evaluating long-course chemoradiation for rectal cancer have permitted the use of conventional planning within their protocols [4, 5]. In recent years, the treatment of rectal cancer has improved through advances in the planning and delivery of radiotherapy as well as improved preoperative imaging with MRI, the development of surgical techniques using total mesorectal excision (TME) and more accurate histopathological reporting [6]. Radiotherapy planning must ensure all clinically and radiologically identifiable disease is encompassed while still minimising the dose to the surrounding organs at risk, particularly the small bowel and bladder. Potential areas of microscopic spread and the appropriate pelvic lymph nodes should also be treated.Preoperative MRI has improved the knowledge of pelvic anatomy and identification of pelvic lymph nodes at risk according to tumour location. This knowledge together with our current understanding of where rectal cancer recurs following TME and radiotherapy [7, 8] suggests that standard treatment planning by the use of traditional bony landmarks is now likely to be inadequate. Furthermore, clinical data indicate that the larger the volume of small bowel irradiated the higher the risk of acute and late toxicity [9–12]. Intensity-modulated radiotherapy (IMRT) has more recently been recommended as an advanced radiotherapy planning technique to optimise a reduction in the volume of small bowel irradiated [13–15]. However, at present there is limited Phase I and II trial data for IMRT in the treatment of locally advanced rectal cancer [16, 17], and currently in the UK many centres still use conventional planning techniques for preoperative CRT. Therefore, before advancing to and developing IMRT, we need to evaluate conformal three-dimensional (3D) CT planning. There is little published data directly comparing CT planning with conventional planning techniques [18]. This study aims to directly compare the techniques of conformal CT planning with conventional planning of preoperative CRT in the treatment of locally advanced rectal cancer, in terms of small bowel and bladder sparing, and in optimising coverage of the tumour target volume.     

Diffusion-weighted imaging in the assessment of tumour grade in endometrial cancer

Objective

Endometrial cancer is the most common gynaecological malignancy in developed countries. Histological grade and subtype are important prognostic factors obtained by pipelle biopsy. However, pipelle biopsy “samples” tissue and a high-grade component that requires more aggressive treatment may be missed. The purpose of the study was to assess the use of diffusion-weighted MRI (DW-MRI) in the assessment of tumour grade in endometrial lesions.

Method

42 endometrial lesions including 23 endometrial cancers and 19 benign lesions were evaluated with DW-MRI (1.5T with multiple b-values between 0 and 750 s mm⁻²). Visual evaluation and the calculation of mean and minimum apparent diffusion coefficient (ADC) value were performed and correlated with histology.

Results

The mean and minimum ADC values for each histological grade were 1.02 ± 0.29×10⁻³ mm² s⁻¹ and 0.74 ± 0.24×10⁻³ mm² s⁻¹ (grade 1), 0.88 ± 0.39×10⁻³ mm² s⁻¹ and 0.64 ± 0.36×10⁻³ mm² s⁻¹ (grade 2), and 0.94 ± 0.32×10⁻³ mm² s⁻¹ and 0.72 ± 0.36×10⁻³ mm² s⁻¹ (grade 3), respectively. There was no statistically significant difference between tumour grades. However, the mean ADC value for endometrial carcinoma was 0.97 ± 0.31, which was significantly lower (p<0.0001) than that of benign endometrial pathology (1.50 ± 0.14). Applying a cut-off mean ADC value of less than 1.28 × 10⁻³ mm² s⁻¹we obtained a sensitivity, specificity, positive predictive value and negative predictive value for malignancy of 87%, 100%, 100% and 85.7%, respectively.

Conclusion

Tumour mean and minimum ADC values are not useful in differentiating histological tumour grade in endometrial carcinoma. However, mean ADC measurement can provide useful information in differentiating benign from malignant endometrial lesions. This information could be clinically relevant in those patients where pre-operative endometrial sampling is not possible.Endometrial carcinoma is the commonest gynaecological malignancy in developed countries [1,2]. The majority of patients present with intermenstrual or post-menopausal bleeding, with approximately 70–80% having early (Stage I) disease at presentation [1,3]. Despite the relatively high incidence, endometrial cancer is not a common cause of cancer death with a 5 year survival of approximately 80% when all stages are considered together [4].The most important prognostic indicators in endometrial cancer are FIGO (International Federation of Gynecology and Obstetrics) stage, lymphovascular invasion, histological subtype and grade, and the presence of lymph node metastases [4-8]. FIGO staging of endometrial cancer is a surgico-pathological staging system that includes total hysterectomy, bilateral salpingo-oophrectomy and peritoneal washings with full pelvic lymphadenectomy [9]. The overall rate of lymph node involvement in endometrial cancer is low (5–8%) and lymphadenectomy carries a reported complication risk of up to 17–19% [10,11], which is particularly marked in patients who are at high surgical risk, such as those who are obese, diabetic or suffer from ischaemic heart disease [12]. As a result, only around 30% of endometrial cancer patients undergo lymphadenectomy in the USA as a whole, increasing to 48.3% in specialised cancer centres [13]. The role of lymphadenectomy in the management of endometrial cancer is currently an area of controversy in gynaecological oncology with no clear evidence regarding the survival benefits associated with the procedure [14-17]. However, in patients who are at high risk of nodal metastases most centres continue to perform lymphadenectomy.Accurate pre-operative identification of patients at high risk of nodal metastases would allow the selection of patients for lymphadenectomy, while those at low risk could be treated with simple hysterectomy. Histological tumour grade is a strong predictor of nodal invasion and thereby prognosis in endometrial cancer [18,19]. In patients with FIGO Stage 1 disease, grade 1 or grade 2 histology carries a less than 10% risk of nodal metastases. However, grade 3 histology carries an overall risk of 18% in Stage 1 disease, which increases to 34% when considering patients with deep myometrial invasion [18,19]. Pre-operative cytology from pipelle or curettage specimens only samples the endometrial tissue and therefore does not always provide accurate assessment [20,21]. In a study of patients with grade 1 histology pre-operatively 19% were upgraded following surgical resection [22].Diffusion-weighted MRI (DW-MRI) is a functional imaging technique that looks at the Brownian motion of water in tissues. In biological tissues this is restricted by interactions with cell membranes and macromolecules on a microscopic level. Increased tissue cellularity, as seen in tumours, restricts Brownian motion, which can be quantified by calculation of the apparent diffusion coefficient (ADC) [23].Previous publications have demonstrated that endometrial carcinoma may be distinguished from normal endometrium on DW-MRI [24-30]. It has also been suggested that DW-MRI may be useful in the pre-operative assessment of tumour grade [26,31]. The purpose of this study is to determine if there is a correlation between histological tumour grade and ADC value in endometrial cancer.     

Comparison of different volumes of saline flush in the assessment of perivenous artefacts in the subclavian vein during cervical CT angiography

Objectives

The aim of this study was to examine attenuation values in the central vein and perivenous artefacts at the subclavian vein in cervical CT angiography (CTA) when using 40 ml contrast material (CM) followed by different volumes (25 ml vs 40 ml) of saline flush (SF).

Methods

61 patients underwent CTA between the aortic arch (AA) and distal to the circle of Willis (cW). After calculating test-bolus time to peak enhancement at the cW (Tc), scanning delay was represented as [(Tc + 4) – scan duration between AA and cW] s. 28 patients (Group A) received 40 ml of 370 mg iodine (I) ml^–1 CM followed by 25 ml of SF, and 33 patients (Group B) received the same CM followed by 40 ml of SF, both administered through the right antecubital vein. Arterial attenuation was measured at seven points in the aorto-carotid artery and at three points in the vertebrobasilar artery. Venous attenuation in the central vein was measured at four points. Mean attenuation values were analysed quantitatively. Axial and post-processing three-dimensional images were assessed qualitatively.

Results

When Groups A and B were compared, there were no differences in the mean attenuation values in either the aorto-carotid artery (p=0.78) or the vertebrobasilar artery (p=0.82). Mean venous attenuation values were lower (p=0.002) in Group B than in Group A. Although the qualitative assessment of arterial images showed no differences between the two groups overall, perivenous artefacts at the subclavian vein were assessed as less prominent (p<0.01) in Group B.

Conclusions

When compared with CTA followed by 25 ml of SF, CTA followed by 40 ml of SF can reduce venous attenuation values and perivenous artefacts at the subclavian vein.Cervical CT angiography (CTA) has high sensitivity and specificity for the detection of carotid artery stenosis, suggesting that it is suitable for screening symptomatic patients with atherosclerotic disease in anterior and posterior circulation [1]. In modern 32- or 64-multidetector row CT (MDCT) systems, small volumes of contrast material (CM) can provide sufficient early arterial enhancement in the cervical CTA [1-3].Several reports on thoracic CT and CTA have stated that saline flush (SF) after injection of the main CM bolus into the central veins can help to reduce perivenous streak artefacts at the brachiocepalic vein and superior vena cava [4-7]. In general, the suggested flush volumes range from 15 to 50 ml, but most authors report using 15–20 ml of SF [4-9].To reduce perivenous artefacts in cervical CT on a 16-MDCT system, Yoon et al [9] used 80 ml CM followed by 40 ml of SF [9], and de Monyé at al [2] suggested the craniocaudal scan direction. We recently reported that CTA on a 32-MDCT in the caudocranial direction can provide adequate arterial enhancement using 40 ml of highly concentrated CM followed by 25 ml of SF [3]; however, perivenous artefacts were often present in the subclavian vein. To improve images of the subclavian artery and upper extremity vasculature, pushing an extra flush volume of 30–40 ml injected at a rate equal to that of CM injection has been recommended [10]. Therefore, we anticipated that a combination of 40 ml of SF would reduce perivenous artefacts at the subclavian vein. Thus, the purpose of this study was to compare the CTA images obtained using 40 ml of 370 mg iodine (I) ml^–1 CM followed by either 40 ml or 25 ml of SF qualitatively (in terms of prevalence of artefacts) and quantitatively (in terms of arterial and venous enhancement).     

Simplified rules for everyday delineation of lymph node areas for breast cancer radiotherapy

The aim of this study was to present the simplified rules of delineation of lymph node (LN) volumes in breast irradiation. Practical rules of delineation of LN areas were developed in the Department of Radiation Oncology of the Institut Curie. These practical guidelines of delineation were based on different specific publications in the field of breast and LN anatomy. The principal characteristic of these rules is their clearly established relationship with anatomical structure, which is easy to find on CT slices. The simplified rules of delineation have been published in pocket format as the illustrated atlas “Help of delineation for breast cancer treatment”. In this small pocket guide, delineation using the practical rules is illustrated, with examples from anatomical CT slices. It is shown that there is an improvement in delineation after the use of these simplified rules and the guide. In conclusion, this small guide is useful for improving everyday practice and decreasing the differences in target delineation for breast irradiation between institutions and observers.The value of lymph node irradiation has already been demonstrated by various studies and meta-analyses [1–3]. In the age of new conformal techniques, there is a real need for a clear definition of treated volumes, such as breast, tumour bed, lymph node areas and organs at risk (OAR) [4–10]. Many teams have been working for several years on the definition of treated volumes. Some delineation studies are exclusively theoretical and some provide a good anatomical atlas, but this information is difficult to use in everyday practice [4–15]. The treatment position has also been shown to be an important factor of variability in the depth and situation of lymph node volumes [5, 6]. Conformal and intensity-modulated radiotherapy (IMRT) require an exact definition of target volumes in terms of their anatomical limits for delineation on CT scans. Some authors have proposed anatomically based landmarks specific for breast cancer radiotherapy in order to delineate all regional lymph nodes and the breast [5, 6, 8, 10, 15, 16]. Despite this work, two recent papers have demonstrated the individual interobserver variability and differences in target and OAR delineation for breast irradiation, especially in lymph node areas [7, 8].This study was designed to propose a practical method to improve and facilitate the everyday delineation process for the clinicians of our department.     

Imaging assessment of desmoid tumours in familial adenomatous polyposis: is state-of-the-art 1.5 T MRI better than 64-MDCT?

Objective

Desmoid tumour is a common extraintestinal manifestation of patients with familial adenomatous polyposis (FAP) who have undergone prophylactic colectomy. We aimed to determine whether MRI provides equivalent or better assessment of desmoid tumours than CT, the current first-line investigation.

Methods

Following ethics approval and informed consent, FAP patients with known desmoid tumour underwent contrast-enhanced 64-slice multidetector CT (MDCT) and 1.5 T MRI (incorporating T₁ weighted, T₂ weighted, short tau inversion–recovery and T₁ weighted with contrast, axial, sagittal and coronal sequences). The number, site, size, local extent, tumour signal intensity and desmoid-to-aorta enhancement ratio were analysed.

Results

MRI identified 23 desmoid tumours in 9 patients: 9 intra-abdominal desmoid (IAD) tumours, 10 abdominal wall desmoid (AWD) tumours and 4 extra-abdominal desmoid (EAD) tumours. CT identified only 21 desmoids; 1 EAD and 1 AWD were not identified. The two modalities were equivalent in terms of defining local extent of desmoid. Five IAD tumours involved the bowel, six caused ureteric compression and none compromised the proximal superior mesenteric artery. There was no difference in median desmoid size: 56.7 cm² (range 2–215 cm²) on MDCT and 56.3 cm² (3–215 cm²) on MRI (p=0.985). The mean MRI enhancement ratio, at 1.12 (standard deviation 0.43), was greater than the CT enhancement ratio, which was 0.48 (0.16) (p<0.0001). High signal intensity on T₂ MRI was associated with increased MRI enhancement ratio (p=0.006).

Conclusions

MRI is at least equivalent (and may be superior) to MDCT for the detection of desmoid tumours in FAP. Coupled with the advantage of avoiding radiation, it should be considered as the primary imaging modality for young FAP patients.Familial adenomatous polyposis (FAP) is an autosomal dominant disease predisposing to the development of hundred to thousands of colorectal adenomatous polyps. It is caused by a germline mutation in the APC tumour suppressor gene. The modern management of FAP, incorporating predictive genetic testing and prophylactic surgery, has meant that extracolonic manifestations of FAP, particularly desmoid tumours and polyposis of the upper gastrointestinal tract, are now the leading cause of mortality among patients having undergone prophylactic colectomy [1-3].Desmoids are myofibroblastic proliferations that occur in 10–15% of patients with FAP [4]. An APC mutation 3′ to codon 1399 predisposes to an increased desmoid risk [5]. FAP-associated desmoids have a propensity for intra-abdominal sites and the abdominal wall, and frequently occur following surgery [6]. While they are non-metastasising, they can be locally invasive, resulting in symptoms through a mass or pressure effect. Aggressive mesenteric desmoids can lead to small bowel obstruction, ischaemia and perforation. Their proximity to the proximal superior mesenteric artery makes surgical excision challenging, often necessitating significant enterectomy. Retroperitoneal desmoids can cause hydronephrosis owing to ureteric impingement and often necessitate ureteric stenting.Desmoids have a variable clinical course, with the majority undergoing cycles of growth and resolution, and only 10% growing relentlessly to cause mortality [7]. 70% of FAP-related desmoids are intra-abdominal desmoid (IAD) tumours, and are associated with significantly poorer survival than abdominal wall desmoid (AWD) tumours and extra-abdominal desmoid (EAD) tumours [8]. Surgical resection is the recommended first-line treatment for symptomatic abdominal wall and extra-abdominal desmoid tumours [4]. For IAD tumours, non-steroidal anti-inflammatory drugs (NSAIDs) and/or anti-oestrogen (tamoxifen/torimifene) are used as first-line therapy, with cytotoxic chemotherapy reserved for less responsive desmoids [4]. Owing to very high morbidity and recurrence rate, surgery is not recommended as first-line treatment for IAD tumours [9], but still remains a valuable option when medical treatment of large IAD fails [10].CT is currently the standard technique for evaluating suspected IAD in FAP [11]. Intuitively, MRI may provide better assessment of desmoids, being the modality of choice in the diagnosis and prognostication of other benign and malignant soft-tissue tumours, owing to its superior contrast-to-noise ratio [12]. Nevertheless, to date there have been limited MRI data relating to FAP-associated desmoids. Various case reports and small series describe the MRI features of desmoids [13-16]. However, these combine sporadic and FAP-related desmoids to maximise case numbers. Clinically, this is less useful as FAP-related desmoids differ from sporadic desmoids in both their clinical traits and biology: FAP desmoids have an underlying “second-hit” somatic APC mutation [5]; sporadic desmoids tend to occur in extra-abdominal sites and usually cause less morbidity and mortality than the more commonly occurring IAD found in FAP patients.A previous study [17] comparing MRI and CT for assessing desmoids in FAP demonstrated that MRI can show both IAD and AWD in FAP patients, but the anatomical imaging by CT was superior. This study also showed high signal intensity on T₂ weighted images to be predictive of aggressive desmoid behaviour [17]. Since that study, MRI and CT techniques have improved substantially. To the best of our knowledge no studies have compared state-of-the-art MRI and multidetector CT (MDCT). The aim of this study was to establish whether current MRI techniques provide equivalent or superior assessment of FAP-related desmoids to 64-slice MDCT.     

Micro-CT enables microlocalisation and quantification of Her2-targeted gold nanoparticles within tumour regions

Objectives

Gold nanoparticles are of interest as potential in vivo diagnostic and therapeutic agents, as X-ray contrast agents, drug delivery vehicles and radiation enhancers. The aim of this study was to quantitatively determine their targeting and microlocalisation in mouse tumour models after intravenous injection by using micro-CT.

Methods

Gold nanoparticles (15 nm) were coated with polyethylene glycol and covalently coupled to anti-Her2 antibodies (Herceptin). In vitro, conjugates incubated with Her2+ (BT-474) and Her2– (MCF7) human breast cancer cells showed specific targeted binding with a Her2+ to Her2– gold ratio of 39.4±2.7:1. Nude mice, simultaneously bearing subcutaneous Her2+ and Her2– human breast tumours in opposite thighs were prepared. Gold nanoparticles alone, conjugated to Herceptin or to a non-specific antibody were compared. After intravenous injection of the gold nanoparticles, gold concentrations were determined by atomic absorption spectroscopy. Microlocalisation of gold was carried out by calibrated micro-CT, giving both the radiodensities and gold concentrations in tumour and non-tumour tissue.

Results

All gold nanoparticle constructs showed accumulation, predominantly at tumour peripheries. However, the Herceptin–gold nanoparticles showed the best specific uptake in their periphery (15.8±1.7% injected dose per gram), 1.6-fold higher than Her2– tumours and 22-fold higher than surrounding muscle. Imaging readily enabled detection of small, 1.5 mm-thick tumours.

Conclusion

In this pre-clinical study, antibody-targeted 15 nm gold nanoparticles showed preferential uptake in cognate tumours, but even untargeted gold nanoparticles enhanced the visibility of tumour peripheries and enabled detection of millimetre-sized tumours. Micro-CT enabled quantification within various regions of a tumour.Antibodies bound to conventional iodine CT contrast agents have not provided sufficient targeted CT contrast since they only load around three iodine atoms per antibody. However, gold nanoparticles (AuNPs) can load antibodies with a greater number of heavier atoms. A 15 nm AuNP contains approximately 100 000 gold atoms, thus promising to provide useful X-ray contrast for targeted tumours [1,2]. AuNPs have been shown to confer designable blood half-lives from several minutes [3] to 15 h [2], making them interesting X-ray vascular imaging agents. Their blood half-lives are longer than iodine agents and promote better tumour uptake. Optical in vivo imaging has been achieved using near-infrared optical coherence tomography [4] or surface-enhanced Raman spectroscopy [5]. If tumours are targeted with AuNPs, they can be used for drug delivery [6], near-infrared hyperthermia ablation [4,7] or enhancement of radiotherapy [8-11]. However, the microlocalisation of AuNPs in tumours after intravenous (iv) injection has not been extensively studied. In this report, we quantify tumour loading by Herceptin-targeted and untargeted AuNPs in mice using micro-CT and atomic absorption spectroscopy. Trastuzumab (Herceptin) is a humanised monoclonal antibody currently used to treat human breast cancers with upregulated Her2 (human epidermal growth factor receptor 2) expression, which occurs in approximately 30% of breast cancer patients [12]. Tumour contrasting could be useful for early detection and visualising a tumour’s true extent to assist in image-guided surgeries, radiotherapy planning, non-invasive tumour typing, detection of lymph node involvement, drug, infrared and X-ray therapies, and monitoring.