Contrast-enhanced ultrasound of focal nodular hyperplasia: a matter of size

Objectives

To assess the contrast-enhanced ultrasound (CEUS) frequencies of centrifugal enhancement, spoke-wheel sign and central scar in focal nodular hyperplasia (FNH) as a function of lesion size.

Methods

Ninety-four FNHs were retrospectively reviewed to assess their largest diameter and enhancement pattern, including centrifugal enhancement from one central artery, spoke-wheel sign, diffuse or centripetal enhancement, central scar and late-phase washout.

Results

Mean FNH-lesion size was 3.7?±?2.1 cm. Only 43.6 % of FNHs had centrifugal enhancement, with a spoke-wheel pattern (23.4 %) or without (20.2 %), while 56.4 % showed diffuse or centripetal enhancement. Centrifugal enhancement was observed in 73.9 % of FNHs ≤3.1 cm and 14.6 % of FNHs >3.1 cm (P?–4). Size and frequency of centrifugal enhancement were negatively correlated (r?=?–0.57, P?–4). The spoke-wheel pattern was also seen more frequently in smaller (37 %) than in larger FNHs (10.4 %) (P?–3). Late-phase washout was described in 5.3 % of FNHs and was not size-dependent. Lesions with a central scar were larger than those without, respectively, 5.7?±?1.7 and 3.6?±?2.0 cm (P?=?0.012).

Conclusions

Typical centrifugal enhancement yielding a confident FNH diagnosis is seen significantly more frequently when the lesion is ≤3.1 cm.

Key Points

? CEUS yields confident diagnoses of FNHs ≤3.1 cm ? The larger the FNH, the lower the diagnostic sensitivity of CEUS ? Final diagnosis of FNHs >3.1 cm should be obtained with MRI not CEUS     

Imaging findings of hepatic focal nodular hyperplasia in men and women: are they really different?

Purpose

This study was undertaken to compare the imaging findings of focal nodular hyperplasia (FNH) in men and women, as seen on multidetector computed tomography (MDCT), magnetic resonance imaging (MRI) and contrast-enhanced ultrasound (CEUS).

Materials and methods

Two radiologists reviewed 195 imaging studies (17 MDCT, 81 MRI and 97 CEUS examinations) pertaining to 111 FNHs (mean size 3 cm) in 91 patients (mean age 39 years). For each lesion, the readers assessed size, location, echogenicity, attenuation, or signal intensity in comparison with adjacent liver parenchyma on both unenhanced and postcontrast images.

Results

Eighty-nine FNHs (mean size 3.1 cm) were observed in 73 women (mean age 37.9 years) and 22 FNHs (mean size 2.7 cm) in 18 men (mean age 41.2 years). No statistically significant differences were found between men and women in terms of age, FNH lesions per patient (1.22 and 1.21, respectively), size, baseline and enhancement pattern on MRI, CEUS and MDCT (p < 0.05). A central scar in FNHs was depicted in 4/18 (22.2 %) men and 16/63 (25.4 %) women on MRI (p < 0.05), and in 1/2 (50 %) men and 7/15 (46.7 %) women on MDCT (p < 0.05), whereas a spoke-wheel pattern, central scar, and/or feeding vessel were seen in 5/17 (29.4 %) men and 22/80 (27.5 %) women on CEUS (p < 0.05).

Conclusions

Our results did not show any differences in imaging features, age of occurrence and size of FNH between men and women.     

Evaluation of shearwave elastography for the characterisation of focal liver lesions on ultrasound

Objectives

To determine the elasticity characteristics of focal liver lesions (FLLs) by shearwave elastography (SWE).

Methods

We used SWE in 108 patients with 161 FLLs and in the adjacent liver for quantitative and qualitative FLLs stiffness assessment. The Mann–Whitney test was used to assess the difference between the groups of lesions where a P value less than 0.05 was considered significant.

Results

SWE acquisitions failed in 22 nodules (14 %) in 13 patients. For the 139 lesions successfully evaluated, SWE values were (in kPa), for the 3 focal fatty sparings (FFS) 6.6?±?0.3, for the 10 adenomas 9.4?±?4.3, for the 22 haemangiomas 13.8?±??5.5, for the 16 focal nodular hyperplasias (FNHs) 33?±??14.7, for the 2 scars 53.7?±?4.7, for the 26 HCCs 14.86?±?10, for the 53 metastasis 28.8?±?16, and for the 7 cholangiocarcinomas 56.9?±?25.6. FNHs had significant differences in stiffness compared with adenomas (P?=?0.0002). Fifty percent of the FNHs had a radial pattern of elevated elasticity. A significant difference was also found between HCCs and cholangiocarcinomas elasticity (P?=?0.0004).

Conclusions

SWE could be useful in differentiating FNHs and adenomas, or HCCs and cholangiocarcinomas by ultrasound.

Key Points

? Elastography is becoming quite widely used as an adjunct to conventional ultrasound ? Shearwave elastography (SWE) could help differentiate adenomas from fibrous nodular hyperplasia ? SWE could also be helpful in distinguishing between hepatocellular carcinomas and cholangiocarcinomas ? SWE could improve the identify hepatocellular carcinomas in cirrhotic livers     

Gadoxetic acid enhanced MRI for differentiation of FNH and HCA: a single centre experience

Objectives

Evaluation of enhancement characteristics of histopathologically confirmed focal nodular hyperplasias (FNHs) and hepatocellular adenomas (HCAs) with gadoxetic acid-enhanced MRI.

Methods

Sixty-eight patients with 115 histopathologically proven lesions (FNHs, n?=?44; HCAs, n?=?71) examined with gadoxetic acid-enhanced MRI were retrospectively enrolled (standard of reference: surgical resection, n?=?53 patients (lesions: FNHs, n?=?37; HCAs, n?=?53); biopsy, n?=?15 (lesions: FNHs, n?=?7; HCAs, n?=?18)). Two radiologists evaluated all MR images regarding morphological features as well as the vascular and hepatocyte-specific enhancement in consensus.

Results

For the hepatobiliary phase, relative enhancement of the lesions and lesion to liver enhancement were significantly lower for HCAs (mean, 48.7 (±48.4) % and 49.4 (±33.9) %) compared to FNHs (159.3 (±92.5) %; and 151.7 (±79) %; accuracy of 89 % and 90 %, respectively; P?<?0.001). Visual strong uptake of FNHs vs. hypointensity of HCAs in the hepatobiliary phase resulted in an accuracy of 92 %. This parameter was superior to all other morphological and dynamic vascular criteria alone and in combination (accuracy, 54–85 %).

Conclusions

For differentiation of FNHs and HCAs by means of MRI, gadoxetic acid uptake in the hepatobiliary phase was found to be superior to all other criteria alone and in combination.

Key Points

? EOB-MRI is well suited to differentiate FNHs and hepatocellular adenomas. ? For this purpose hepatobiliary phase is superior to unenhanced and dynamic imaging. ? Hepatobiliary phase (peripheral) hyper- or isointensity is typical for FNH. ? Hepatobiliary phase hypointensity is typical for hepatocellular adenomas. ? EOB-MRI helps to avoid misinterpretations of benign hepatocellular lesions.     

MR findings of steatotic focal nodular hyperplasia and comparison with other fatty tumours

Objectives

To correlate MR findings with pathology in steatotic FNHs and to compare the MR findings with those of other fatty tumours developed on noncirrhotic liver in a consecutive series of resected lesions.

Methods

Our population included resected FNH with intralesional steatosis (n?=?25) and other resected fatty tumours selected as controls (hepatocellular adenomas and angiomyolipomas, n?=?34). Lesions were classified into three groups: those with typical FNH without (group 1) or with (group 2) fat on MR and those with atypical lesions (group 3). In group 3, diagnostic criteria for other fatty tumours were applied.

Results

There were 9 lesions in group 1 (15.3 %), 4 in group 2 (16.8 %) and 46 in group 3 (77.9 %). Group 3 contained 12 FNHs (26 %) and all the other fatty tumours. In group 3, the association of lesion homogeneity, signal intensity similar to or slightly different from adjacent liver on in-phase T1- and T2-weighted sequences, and strong arterial enhancement was observed in 7/12 (58 %) of steatotic FNHs and 3/34 (9 %) of other tumours.

Conclusion

On MR, fat within a typical FNH should not reduce the diagnostic confidence. We recommend further investigations including liver biopsy if necessary when fatty tumours exhibit atypical MR findings.

Key Points

? MRI is increasingly used to assess hepatic lesions containing fat. ? Nodules of focal nodular hyperplasia often contain foci of fat. ? However, steatotic FNH does not always demonstrate typical fatty features on MRI. ? The main mimickers of steatotic FNHs are telangiectatic/inflammatory hepatocellular adenomas. ? We recommend liver biopsy when fatty tumours exhibit atypical MR findings.     

Quantitative analysis of contrast-enhanced ultrasonography: differentiating focal nodular hyperplasia from hepatocellular carcinoma

Objective:

To explore the potential of quantitative analysis of contrast-enhanced ultrasonography (CEUS) in differentiating focal nodular hyperplasia (FNH) from hepatocellular carcinoma (HCC).

Methods:

34 cases of FNH and 66 cases of HCC (all lesions <5 cm) were studied using CEUS to evaluate enhancement patterns and using analytic software Sonoliver® (Image-Arena™ v.4.0, TomTec Imaging Systems, Munich, Germany) to obtain quantitative features of CEUS in the region of interest. The quantitative features of maximum of intensity (IMAX), rise slope (RS), rise time (RT) and time to peak (TTP) were compared between the two groups and applied to further characterise both FNH and HCC with hypoenhancing patterns in the late phase on CEUS.

Results:

The sensitivity and specificity of CEUS for diagnosis of FNH were 67.6% and 93.9%, respectively. For quantitative analysis, IMAX and RS in FNHs were significantly higher than those in HCCs (p<0.05), while RT and TTP in FNHs were significantly shorter (p<0.05). Both the 11 FNHs and 62 HCCs with hypo-enhancing patterns in the late phase were further characterised with their quantitative features, and the sensitivity and specificity of IMAX for diagnosis of FNH were 90.9% and 43.5%, RS 81.8% and 80.6%, RT 90.9% and 71.0%, and TTP 90.9% and 71.0%, respectively.

Conclusion:

The quantitative features of CEUS in FNH and HCC were significantly different, and they could further differentiate FNH from HCC following conventional CEUS.

Advances in knowledge:

Our findings suggest that quantitative analysis of CEUS can improve the accuracy of differentiating FNH from HCC.Dynamic contrast-enhanced ultrasonography (CEUS) has noticeably improved the detection and characterisation of focal liver lesions during the past decade [1]. The enhancement patterns of the lesion are evaluated in three vascular phases (the hepatic arterial, portal venous and late phases), where the hepatic arterial phase provides information on the degree and pattern of vascularity and the portal venous and late phases provide important information on the differention between benign and malignant liver lesions [1]. A previous study has shown that CEUS using SonoVue® (Bracco, Milan, Italy) and spiral-CT provides similar diagnostic accuracy in the characterisation of focal liver lesions [2].The typical enhancement of focal nodular hyperplasia (FNH) on CEUS showed hyperenhancement in the three vascular phases with a stellate vascular and centrifugal enhancement in the arterial phase or a hypoenhancing central scar in the late phase [1, 3–5]. However, these features have not been observed in all cases of FNH, particularly in small lesions. A study on FNH showed that 3 out of 13 lesions (23.1%) were hypoenhancing in the late phase [6] and 3 out of 10 lesions <3 cm had spoke-wheel patterns and 2 had central scars [4]. There is also a broad variation of stellate vascular enhancement in FNHs with a range from 27.3% to 73.3% and of central scar with a range from 36.4% to 63.3% [3–5]. Thus, it can be difficult to differentiate atypical FNHs from other hypervascular malignant tumours, such as hepatocellular carcinoma (HCC), and hypervascular metastases [3]. Furthermore, a hypoenhancing central scar has been described in fibrolamellar HCC and sclerosing or scirrhous HCC [7, 8], and a central feeding artery with spoke-wheel sign has also been described in two scirrhous HCCs [8]. Hence, a comprehensive approache rather than simply estimating the haemodynamics could be beneficial for differential diagnosis.The current low-mechanical-index techniques for CEUS are capable of real-time demonstration of continuous haemodynamic changes in both the liver and hepatocellular nodules, from which time–intensity curves can be obtained by means of analytic software and then a series of semi-quantitative perfusion measurements extracted and analysed [9–11]. This method has shown a possible benefit in diagnosing FNH by enabling analysis of the quantitative parametric curves of the five types of hypervascular liver lesions [9]. In the present study, CEUS was applied to evaluate enhancing patterns of FNH and HCC; quantitative features of CEUS in the two groups were generated with the analytic software Sonoliver® (TomTec Imaging Systems, Germany) and compared to explore their potential in the differential diagnosis. Furthermore, the quantitative analysis of CEUS was used to characterise both FNH and HCC with hypoenhancing patterns in the late phase on CEUS.     

Contrast enhanced ultrasound in the detection of liver metastases: a prospective multi-centre dose testing study using a perfluorobutane microbubble contrast agent (NC100100)

Objective

To conduct a dose testing analysis of perfluorobutane microbubble (NC100100) contrast-enhanced ultrasound (CEUS) to determine the optimal dose for detection of liver metastases in patients with extra-hepatic primary malignancy.

Methods

157 patients were investigated with conventional US and CEUS. CEUS was performed following intravenous administration of perfluorobutane microbubbles (using one dose of either 0.008, 0.08, 0.12 or 0.36 μL/kg body weight). Three blinded off-site readers recorded the number and locations of metastatic lesions detected by US and CEUS. Contrast enhanced CT and MRI were used as the “Standard Of Reference” (SOR). Sensitivity, specificity and accuracy of liver metastasis detection with US versus CEUS, for each dose group were obtained. Dose group analysis was performed using the Chi-square test.

Results

165 metastases were present in 92 patients who each had 1–7 lesions present on the SOR. Sensitivity of US versus CEUS (for all doses combined) was 38% and 67% (p?=?0.0001). The 0.12 dose group with CEUS (78%) had significantly higher sensitivity and accuracy (70%) compared to other dose groups (p?Conclusion The diagnostic performance of CEUS is dose dependent with the 0.12 μL/kg NC100100 dose group showing the greatest sensitivity and accuracy in detection of liver metastases.     

Intravoxel incoherent motion model-based liver lesion characterisation from three b-value diffusion-weighted MRI

Objective

To evaluate intravoxel incoherent motion (IVIM) model-based liver lesion characterisation from three b-value diffusion-weighted imaging (DWI).

Methods

The 1.5-T DWI data from a respiratory gated spin-echo echo-planar magnetic resonance imaging sequence (b?=?0, 50, 800 s/mm²) were retrospectively analysed in 38 patients with different liver lesions. Conventional apparent diffusion coefficient ADC?=?ADC(0,800) as well as IVIM-based parameters D′?=?ADC(50,800), ADC_low?=?ADC(0,50), and f′ were calculated voxel-wise. Sixty-one regions of interest in hepatocellular carcinomas (HCCs, n?=?24), haemangiomas (HEMs, n?=?11), focal nodular hyperplasias (FNHs, n?=?11), and healthy liver tissue (REFs, n?=?15) were analysed. Group differences were investigated using Student’s t-test and receiver-operating characteristic (ROC) analysis.

Results

Mean values?±?standard deviations of ADC, D′, ADC_low (in 10^-5 mm²/s), and f′ (in %) for REFs/FNHs/HEMs/HCCs were 130?±?11/143?±?27/168?±?16/113?±?25, 104?±?12/123?±?25/162?±?18/102?±?23, 518?±?66/437?±?97/268?±?69/283?±?120, and 18?±?3/14?±?4/6?±?3/9?±?5, respectively. Differences between lesions and REFs were more significant for IVIM-based parameters than for conventional ADC. ROC analysis showed the best discriminability between HCCs and FNHs for ADC_low and f′ and between HEMs and FNHs or HCCs for D′.

Conclusion

Three instead of two b-value DWI enables a numerically stable and voxel-wise IVIM-based analysis for improved liver lesion characterisation with tolerable acquisition time.

Key Points

? Quantitative analysis of diffusion-weighted MRI helps liver lesion characterisation. ? Analysis of intravoxel incoherent motion is superior to apparent diffusion coefficient determination. ? Only three b-values enable separation of diffusion and microcirculation effects. ? The method presented is numerically stable, with voxel-wise results and short acquisition times.     

Hepatocellular carcinoma and focal nodular hyperplasia of the liver: differentiation with CT spectral imaging

Objectives

To investigate the value of CT spectral imaging in differentiating hepatocellular carcinoma (HCC) from focal nodular hyperplasia (FNH) during the arterial phase (AP) and portal venous phase (PP).

Methods

Fifty-eight patients with 42 HCCs and 16 FNHs underwent spectral CT during AP and PP. The lesion–liver contrast-to-noise ratio (CNR) at different energy levels, normalised iodine concentrations (NIC) and the lesion–normal parenchyma iodine concentration ratio (LNR) were calculated. The two-sample t test compared quantitative parameters. Two readers qualitatively assessed lesion types according to imaging features. Sensitivity and specificity of the qualitative and quantitative studies were compared.

Results

In general, CNRs at low energy levels (40–70 keV) were higher than those at high energy levels (80–140 keV). NICs and LNRs for HCC differed significantly from those of FNH: mean NICs were 0.25 mg/mL?±?0.08 versus 0.42 mg/mL?±?0.12 in AP and 0.52 mg/mL?±?0.14 versus 0.86 mg/mL?±?0.18 in PP. Mean LNRs were 2.97?±?0.50 versus 6.15?±?0.62 in AP and 0.99?±?0.12 versus 1.22?±?0.26 in PP. NICs and LNRs for HCC were lower than those of FNH. LNR in AP had the highest sensitivity and specificity in differentiating HCC from FNH.

Conclusions

CT spectral imaging may help to increase detectability of lesions and accuracy of differentiating HCC from FNH.

Key Points

? CT spectral imaging may help to detect hepatocellular carcinoma (HCC). ? CT spectral imaging may help differentiate HCC from focal nodular hyperplasia. ? Quantitative analysis of iodine concentration provides greater diagnostic confidence. ? Treatment can be given with greater confidence.     

Contrast-enhanced ultrasound after devascularisation of neuroendocrine liver metastases: functional and morphological evaluation

Objective

To evaluate morphological and perfusion changes in liver metastases of neuroendocrine tumours by contrast-enhanced ultrasound (CEUS) after transarterial embolisation with bead block (TAE) or trans-arterial chemoembolisation with doxorubicin-eluting beads (DEB-TACE).

Methods

In this retrospective study, seven patients underwent TAE, and ten underwent DEB-TACE using beads of the same size. At 1 day before embolisation, 2 days, 1 month and 3 months after the procedure, a destruction-replenishment study using CEUS was performed with a microbubble-enhancing contrast material on a reference tumour. Relative blood flow (rBF) and relative blood volume (rBV) were obtained from the ratio of values obtained in the tumour and in adjacent liver parenchyma. Morphological parameters such as the tumour’s major diameter and the viable tumour’s major diameter were also measured. A parameter combining functional and morphological data, the tumour vitality index (TVI), was studied. The Wilcoxon rank-sum test and Fisher’s test were used to compare treatment groups.

Results

At 3 months rBF, rBV and TVI were significantly lower (P?=?0.005, P?=?0.04 and P?=?0.03) for the group with doxorubicin. No difference in morphological parameters was found throughout the follow-up.

Conclusions

One parameter, TVI, could evaluate the morphological and functional response to treatments.

Key Points

? Contrast-enhanced ultrasound provides morphological and functional information about neuroendocrine hepatic metastases ? CEUS can evaluate changes after transarterial chemoembolisation, transarterial-embolisation and transarterial radioembolisation ? Functional (but not morphological) imaging reveals differences between TAE and DEB-TACE therapy ? To combine morphological and functional parameters, a tumour vitality index is proposed ? TVI can be used to monitor treatments acting on tumour vascularisation     

Contrast-enhanced ultrasound (CEUS) follow-up after radiofrequency ablation or cryoablation of focal liver lesions: treated-area patterns and their changes over time

Objectives

To describe the early patterns of liver lesions successfully treated with radiofrequency ablation (RFA) or cryoablation (CA) and their changes over time.

Methods

Twenty-two RFA-treated and 17 CA-treated patients underwent CEUS from week 1 to year 3 post-ablation. Patterns, margins and volumes of RF-induced and cryolesions were evaluated and compared over time.

Results

After contrast enhancement, shortly after ablation, undefined margins with persistent enhancing small vessels penetrating >2 mm into the treated zone were significantly more frequent after CA (67 %) than RFA (22 %) (P?<?0.02). During the arterial phase, a thin, enhancing marginal rim was seen during week 1 (T1) in around 28 % of RF lesions, while 75 % of cryolesions had thick enhancing rims (P?<?0.02). The mean RF-induced lesion volume, maximum at T1 (44.1?±?37.5 ml), shrank slowly over time, remaining clearly visible at 1 year (8.3?±?7.4 ml). Cryolesions shrank faster (P?=?0.009), from an average of 16.6?±?7.1 ml at T1 to 1.7?±?1.3 ml 1-year post-ablation.

Conclusion

RF-induced and cryolesions differ, particularly their margins and shrinkage rates. Knowing these differences allows avoidance of incomplete treatment or falsely diagnosed recurrence, especially after CA.

Key Points

? Contrast-enhanced ultrasound (CEUS) provides new follow-up information following hepatic radiological inyervention. ? CEUS provides good visualisation of vascular modifications after thermoablation. ? RFA-induced lesions and cryoablated lesions differ. ? Knowledge about RF and cryolesion patterns is essential for correct CEUS follow-up. ? Cryolesions have thicker peripheral inflammatory reactions and shrink faster than RFA-induced lesions.     

Correlation of contrast-enhanced ultrasound kinetics with prognostic factors in invasive breast cancer

Objectives

To correlate contrast-enhanced ultrasound (CEUS) kinetic parameters with traditional and molecular prognostic factors in invasive breast cancer.

Methods

Seventy-five invasive breast cancers were evaluated with contrast harmonic imaging after the injection of a bolus dose of 2.4 ml sulphur hexafluoride microbubble contrast agent. The lognormal function was used for quantitative analysis of kinetic data. These parameters correlated with traditional prognostic factors (tumour size, histological type, tumour grade, axillary lymph node status) and immunohistochemical biomarkers (ER, PR and HER2 status).

Results

Statistically significant correlation was found between time-to-peak and tumour grade (P value?=?0.023), PR status (P value?=?0.042) and axillary node status (P value?=?0.025). Wash-out ratio, measured at 21 s was significantly associated with ER status (P value?=?0.042) and PR status (P value?=?0.026).

Conclusions

Invasive breast carcinomas exhibiting earlier peak enhancement and faster elimination of microbubble contrast agent at CEUS are found to be associated with established predictors of poor prognosis.

Key Points

? Contrast-enhanced ultrasound (CEUS) can potentially determine the aggressiveness of invasive breast cancers. ? Early peak enhancement and accelerated wash-out at CEUS suggest poor prognosis. ? CEUS kinetics are similar to that of DCE-MRI in assessing tumour aggressiveness.     

Intrahepatic cholangiocarcinoma and hepatocellular carcinoma: differential diagnosis with contrast-enhanced ultrasound

Objective

We assessed the usefulness of contrast-enhanced ultrasound (CEUS) in the differentiation of intrahepatic cholangiocarcinoma (ICC) and hepatocellular carcinoma (HCC).

Methods

The CEUS enhancement patterns of 50 ICCs were retrospectively analysed and compared with 50 HCCs. Two readers independently reviewed the baseline ultrasound (BUS) and CEUS images and the diagnostic performances were evaluated by receiver operating characteristic (ROC) analysis. Time–intensity curves (TIC) were plotted for quantification analysis.

Results

In the arterial phase, peripheral rim-like hyperenhancement, heterogeneous hyperenhancement, homogeneous hyperenhancement and heterogeneous hypoenhancement were found in 25, 10, 3 and 12 of the ICCs versus 2, 29, 19 and 0 of the HCCs (P?<?0.001), respectively. The diagnostic performance of both readers in terms of the area under the ROC curve (0.745 vs. 0.933 for reader 1, and 0.803 vs. 0.911 for reader 2), sensitivity (28% vs. 90%, and 44% vs. 82%) and accuracy (64% vs. 90%, and 71% vs. 90%) improved significantly after CEUS (all P?<?0.05). The interobserver agreement increased from κ?=?0.575 at BUS to κ?=?0.720 after CEUS. TICs demonstrated that the intensities of the peripheral and central portions of the ICCs were lower than those of HCCs (both P?<?0.05).

Conclusion

CEUS improves the diagnostic performance significantly in the differentiation between ICC and HCC.     

Diagnostic accuracy of 18F-FDG PET/CT for detection of suspected recurrence in patients with oesophageal carcinoma

Purpose

To evaluate the role of ¹⁸F-FDG PET/CT in the detection of recurrence in patients with oesophageal carcinoma, suspected clinically or following conventional investigations.

Methods

This was a retrospective study. Data from 180 patients (age 56.3?±?10.4 years; 126 men, 54 women) with histopathologically proven oesophageal carcinoma (squamous cell 115, adenocarcinoma 59, neuroendocrine carcinoma 4, small cell 1, poorly differentiated 1) who had undergone 227 ¹⁸F-FDG PET/CT studies for suspected recurrence were analysed. Recurrence was suspected clinically or following conventional investigations. PET/CT images were revaluated by two nuclear medicine physicians in consensus. Findings were grouped into local, nodal and distant recurrence. Results were compared to those from contrast-enhanced (CE) CT when available (109 patients). Clinical/imaging follow-up (minimum 6 months) with histopathology (when available) was taken as the reference standard.

Results

Of the 227 ¹⁸F-FDG PET/CT studies,166 were positive and 61 were negative for recurrent disease. PET/CT showed local recurrence in 134, nodal recurrence in 115 and distant recurrence in 47, with more than one site of recurrence in 34. The PET/CT findings were true-positive in 153 studies, true-negative in 54, false-positive in 13 and false-negative in 7. The sensitivity of ¹⁸F-FDG PET/CT was 96 %, the specificity was 81 %, the positive and negative predictive values were 92 % and 89 %, respectively, and the accuracy was 91 %. PET/CT showed similar accuracy in patients with squamous cell carcinoma and in those with adenocarcinoma (P?=?0.181).¹⁸F-FDG PET/CT was more specific than CECT (67 % vs. 21 %; P?<?0.0001). PET/CT was superior to CECT for the detection of nodal recurrence (P?<?0.0001), but not local recurrence (P?=?0.093) or distant metastases (P?=?0.441).

Conclusion

¹⁸F-FDG PET/CT shows high accuracy in the detection of suspected recurrence in patients with oesophageal carcinoma. It is more specific than and is superior to CECT in the detection of nodal recurrence.     

Screening for renal insufficiency following ESUR (European Society of Urogenital Radiology) guidelines with on-site creatinine measurements in an outpatient setting

Objective

To report the results and implications for workflow following introduction of ESUR guidelines to screen for potential renal insufficiency (RI) in private practice with on-site creatinine measurements.

Methods

A total of 1,766 consecutive outpatients scheduled for contrast-enhanced CT (CECT) completed the ESUR questionnaire enquiring about kidney disease, renal surgery, proteinuria, diabetes mellitus, hypertension, gout or use of nephrotoxic drugs. Patients with positive risk factors underwent on-site creatinine measurement and calculation of estimated glomerular filtration rate (eGFR). Attending radiologists adapted subsequent imaging depending on renal function and presence of risk factors.

Results

One or more ESUR risk factors were present in 796 (45.1%) patients, including hypertension (37.7%), nephrotoxic medication (21.3%), diabetes mellitus (8.0%), proteinuria (3.9%), renal disease (4.1%), gout (3.1%) and renal surgery (2.6%). Pre-procedural creatinine measurements revealed severe RI (eGFR?<?30 ml min^?1 1.73 m^?2) in 10 (1.3%) and moderate RI (eGFR 30–59 ml min^?1 1.73 m^?2) in 106 (13.8%). Imaging work-up was adapted in 132 (16.6%) as follows: reduction of contrast material dose (n?=?85), CT without contrast (n?=?40), changeover to MRI (n?=?3) or scintigraphy (n?=?4).

Conclusion

Screening for RI following ESUR guidelines requires creatinine measurements in nearly half of outpatients scheduled for CECT and reveals moderate to severe renal impairment in 6.6%.     

Detection of underlying malignancy in patients with paraneoplastic neurological syndromes: comparison of 18F-FDG PET/CT and contrast-enhanced CT

Purpose

To determine the value of combined ¹⁸F-FDG PET/CT with diagnostic contrast-enhanced CT (CECT) in detecting primary malignancies and metastases in patients with paraneoplastic neurological syndromes (PNS) and to compare this with CECT alone.

Methods

PET/CT scans from 66 patients with PNS were retrospectively evaluated. Two blinded readers initially reviewed the CECT portion of each PET/CT scan. In a second session 3 months later, the readers analysed the combined PET/CT scans. Findings on each study were assessed using a four-point-scale (1 normal/benign; 2 inconclusive, further diagnostic work-up may be necessary; 3 malignant; 4 inflammatory). Sensitivity and specificity for malignant findings were calculated for PET/CT and CECT. Interreader agreement was determined by calculating Cohen’s kappa. Pooled data from clinical follow-up (including histopathology and follow-up imaging, median follow-up 20.0 months) served as the reference gold standard.

Results

Both readers classified 12 findings in ten patients (15 %) as malignant on the PET/CT scans (two patients had two primary tumours). One such imaging finding (suspected thymic cancer) was false-positive (i.e. benign histology). The most common tumours were bronchial carcinoma (n?=?3), lymph node metastases of gynaecological tumours (n?=?3) and tonsillar carcinoma (n?=?2). Three of 12 findings (25 %) were not detected by CECT alone (cervical carcinoma, lymph node metastasis and tonsillar carcinoma). In a per-patient analysis, sensitivity and specificity for malignant findings were 100 % and 90 % for PET/CT and 78 % and 88 % for CECT. In 24 % (reader 1) and 21 % (reader 2) of the patients, the PET/CT findings were inconclusive. Of these findings, 57 % (reader 1) and 56 % (reader 2) were only diagnosed with PET (e.g. focal FDG uptake of the thyroid, gastrointestinal tract and ovaries). On follow-up, none of these findings corresponded to malignancy. Overall agreement between the two readers was excellent with a Cohen’s kappa of 0.95?±?0.04 (p?<?0.001) for PET/CT and 0.97?±?0.03 (p?<?0.001) for CECT alone.

Conclusion

In this cohort of patients with PNS, PET/CT exhibited improved detection of underlying malignancy versus CECT alone. While hybrid imaging produces a greater number of inconclusive findings, sensitivity is increased for the detection of head and neck and gynaecological malignancies as well as metastatic lymph node involvement.     

Real-time contrast-enhanced ultrasound imaging of focal liver lesions in fatty liver

PurposeThe objective of this study was to investigate the contrast-enhanced ultrasound (CEUS) imaging features of focal liver lesions (FLLs) in fatty liver.MethodOne hundred FLLs in 98 patients with fatty liver were evaluated with real-time CEUS.ResultsAll malignant FLLs showed hyperenhancement in arterial phase and contrast washout in portal and late phases. Among the FLLs, 3.3% of hemangiomas, 12.5% of focal nodular hyperplasias (FNHs), and 2.5% of focal fatty sparing lesions showed contrast washout in the late phase. The sensitivity and specificity for the characterization of hepatocellular carcinoma, metastasis, hemangioma, FNH, and focal fatty sparing lesions were 100% and 95.6%, 60% and 100%, 93.3% and 98.6%, 87.5% and 97.8%, and 92.6% and 100%, respectively.ConclusionsCorrect characterization of FLLs in fatty liver by CEUS is possible based on their typical enhancement patterns.     

Contrast-enhanced ultrasound in the staging of acute pancreatitis

Objective

To determine the diagnostic value of contrast-enhanced ultrasound (CEUS) in the assessment of acute pancreatitis, with computed tomography (CT) as the reference standard.

Methods

Fifty consecutive patients (mean age 58.4 years; range 23–86 years) with acute pancreatitis underwent prospectively both CT and ultrasonography, including CEUS, within a 24-h interval. Pancreatic vascularisation was evaluated with CEUS after injection of a second-generation US contrast-enhancing agent. Acute pancreatitis severity was graded according to the Balthazar index. The results were compared with CT severity index and clinical outcome by using Spearman’s correlation coefficient.

Results

A significant correlation between CT and CEUS was found for the CT severity index (r?=?0.926), extent of necrosis (r?=?0.893) and Balthazar grade (r?=?0.884). The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for detecting severe acute pancreatitis based on CT findings (severity index greater than 3 and/or presence of necrosis) were respectively 91%, 100%, 100% and 83%. A significant correlation between CEUS severity index and clinical variables was found: Ranson score (r?=?0.442), C-reactive protein (CRP) levels 48 h after admission (r?=?0.385) and length of hospital stay (r?=?0.362).

Conclusion

CEUS is comparable to CT in detecting pancreatic necrosis as well as predicting its clinical course. Therefore, when CT is contraindicated CEUS may be a valid alternative.     

Radiofrequency ablation of hepatic tumours: effect of post-ablation margin on local tumour progression

Purpose

The purpose of this study was to retrospectively evaluate the relationship between post-ablation margins and local tumour progression following radiofrequency ablation (RFA) of hepatocellular carcinomas and colorectal liver metastases.

Methods

Eighty-three patients with 107 hepatic tumours who underwent RFA were divided into two groups: the hepatocellular carcinoma (HCC) group (55 patients with 69 lesions) and the colorectal liver metastases group (28 patients with 38 lesions). Post-ablation margins were calculated on 1-month follow-up contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI) studies. Efficacy was evaluated at 1-month post-ablation, then at 3-month intervals for the first year and biannually thereafter.

Results

The results of the log-rank test showed that the minimum threshold post-ablation margin of 0.4 cm (P?=?0.020) and tumour size smaller than 2.5 cm (P?=?0.001) significantly correlated with local control for the HCC group. In the colorectal liver metastases group, the results of the log-rank test showed that the minimum threshold post-ablation margin of 0.4 cm (P?=?0.345) and tumour size smaller than 2.5 cm (P?=?0.168) did not correlate with local control.

Conclusion

Percutaneous RFA is more effective in achieving local control in patients with HCCs than with colorectal liver metastases.     

Determination of optimal intravenous contrast agent iodine dose for the detection of liver metastasis at 80-kVp CT

Objectives

To determine the optimal iodine mass (IM) to achieve a 50-HU increase in hepatic attenuation for the detection of liver metastasis based on total body weight (TBW) or body surface area (BSA) at 80-kVp computed tomography (CT) imaging of the liver.

Methods

One-hundred and fifty patients who underwent contrast-enhanced CT at 80-kVp were randomised into three groups: 0.5 gI/kg, 0.4 gI/kg and 0.3 gI/kg. Portal venous phase images were evaluated for hepatic parenchymal enhancement (?HU) and visualisation of liver metastasis. Iodine mass per BSA (gI/m²) calculated in individual patients were evaluated.

Results

Mean ?HU for the 0.5 gI/kg group (84.2 HU) was higher than in the 0.4 gI/kg (66.1 HU) and 0.3 gI/kg (53.7 HU) groups (P?<?0.001). Linear correlation equations between ?HU and IM per TBW or BSA are ?HU?=?7.0?+?153.0?×?IM/TBW (r?=?0.73, P?<?0.001) and ?HU?=?11.4?+?4.0?×?IM/BSA (r?=?0.75, P?<?0.001), respectively. The three groups were comparable for the visualisation of hepatic metastases.

Conclusions

The iodine mass to achieve a 50-HU increase in hepatic attenuation at 80-kVp CT was estimated to be 0.28 gI/kg of body weight or 9.6 gI/m² of body surface area.

Key Points

? Hepatic enhancement is expressed as ?HU?=?7.0?+?153.0?×?IM [g]/TBW [kg]. ? Hepatic enhancement is expressed as ?HU?=?11.4?+?4.0?×?IM [g]/BSA [m ² ]. ? Essential iodine dose at 80-kVp CT was 0.28 gI/kg or 9.6 gI/m ² .