Bernard Van Beers

Magnetic Resonance Elastography for the Noninvasive Staging of Liver Fibrosis

BACKGROUND & AIMS The purpose of our study was to prospectively compare the success rate and diagnostic accuracy of magnetic resonance elastography, ultrasound elastography, and aspartate aminotransferase to platelets ratio index (APRI) measurements for the noninvasive staging of fibrosis in patients with chronic liver disease. METHODS We performed a prospective blind comparison of magnetic resonance elastography, ultrasound elastography, and APRI in a consecutive series of patients who underwent liver biopsy for chronic liver disease in a university-based hospital. Histopathologic staging of liver fibrosis according to the METAVIR scoring system served as the reference. RESULTS A total of 141 patients were assessed. The technical success rate of magnetic resonance elastography was higher than that of ultrasound elastography (133/141 [94%] vs 118/141 [84%]; P = .016). Magnetic and ultrasound elastography, APRI measurements, and histopathologic analysis of liver biopsy specimens were technically successful in 96 patients. The areas under the receiver operating characteristic curves of magnetic resonance elasticity (0.994 for F >or= 2; 0.985 for F >or= 3; 0.998 for F = 4) were larger (P < .05) than those of ultrasound elasticity, APRI, and the combination of ultrasound elasticity and APRI (0.837, 0.709, and 0.849 for F >or= 2; 0.906, 0.816, and 0.936 for F >or= 3; 0.930, 0.820, and 0.944 for F = 4, respectively). CONCLUSIONS Magnetic resonance elastography has a higher technical success rate than ultrasound elastography and a better diagnostic accuracy than ultrasound elastography and APRI for staging liver fibrosis.

Adult polycystic liver disease: is fenestration the most adequate operation for long-term management?

OBJECTIVE The aim of this study was to evaluate the immediate and long-term results in a retrospective series of patients with highly symptomatic adult polycystic liver disease (APLD) treated by extensive fenestration techniques. A classification of APLD was developed as a stratification scheme to help surgeons conceptualize which operation to offer to patients with APLD. SUMMARY BACKGROUND DATA Treatment options for APLD remain controversial, with partisans of fenestration techniques or combined liver resection-fenestration. METHODS Clinical symptoms, performance status, liver volume measurement by computed tomography (CT), and morbidity were recorded before surgery and after surgery. Adult polycystic liver disease was classified according to the number, size, and location of liver cysts and the amount of remaining liver parenchyma. Follow-up was obtained by clinical and CT examinations in all patients. RESULTS Ten patients with highly symptomatic APLD were operated on using an extensive fenestration technique (by laparotomy in 8 patients and by laparoscopy in 2 patients, 1 of whom conversion to laparotomy was required). The mean preoperative liver volume was 7761 cm3. There was no mortality. Postoperative morbidity occurred in 50%, mainly from biliary complications, requiring reintervention in two cases. Massive intraoperative hemorrhage occurred in one patient. During a mean follow-up time of 71 months (range, 17 to 239 months), all patients were improved clinically according to their estimated performance status. The mean postoperative liver volume was 4596 cm3, which represents a mean liver volume reduction rate of 43%. However, in type III APLD, despite absence of clinical symptoms, a significant increase in liver volume was observed in 40% of the patients. CONCLUSIONS Extensive fenestration is effective in relieving symptoms in patients with APLD. Hemorrhage and biliary complications are possible consequences of such an aggressive attempt to reduce liver volume. The procedure can be performed laparoscopically in type I APLD. A longer follow-up period is mandatory in type II APLD, to confirm the usefulness of the fenestration procedure. In type III APLD, significant disease progression was observed in 40% of the patients during long-term follow-up. Fenestration may not be the most appropriate operation for long-term management of all types of APLD.

Assessment of diffusion-weighted MR imaging in liver fibrosis.

To assess whether hepatic fibrosis is associated with a restriction in the diffusion of water that can be analyzed with diffusion‐weighted MR imaging (DWI) of the liver.

Glomerular filtration rate: assessment with dynamic contrast-enhanced MRI and a cortical-compartment model in the rabbit kidney.

To describe the use of MRI and a cortical‐compartment model to measure the glomerular filtration rate (GFR), and compare the results with those obtained with the Patlak‐Rutland model.

Early Detection of Steatohepatitis in Fatty Rat Liver by Using MR Elastography.

PURPOSE To assess the potential value of magnetic resonance (MR) elastographic imaging to help detect nonalcoholic steatohepatitis in the fatty rat liver. MATERIALS AND METHODS This study was approved by the regional ethics committee. Fifty-four rats were imaged after being fed either a standard diet, a choline-deficient diet for up to 8 weeks to induce steatohepatitis, or a 2-week orotic acid diet to induce steatosis; or were imaged 48 hours after carbon tetrachloride injection to model acute liver injury. MR elastography was performed at 7.0 T to assess viscoelastic liver parameters. Steatosis and fibrosis were quantified with morphometric and biochemical analysis. Myofibroblast activation was assessed with morphometric analysis of alpha-smooth muscle actin. Expression of transforming growth factor beta1 and procollagens 1 and 3 as markers of fibrogenesis was evaluated with real-time reverse transcription polymerase chain reaction. Inflammation was scored at histologic analysis. RESULTS In rats with steatohepatitis, mean elasticity (2.24 kPa +/- 0.19 [standard deviation] vs 1.82 kPa +/- 0.22) and mean viscosity (0.86 kPa +/- 0.10 vs 0.59 kPa +/- 0.12) increased significantly (P < .005) after the 2-week orotic acid diet, while steatosis, inflammation, myofibroblast activation, and increase of other fibrogenesis markers were observed. Fibrosis appeared only after 5 weeks. In rats with steatosis, viscosity increased (0.77 kPa +/- 0.11, P < .005), elasticity remained constant. In rats with acute liver injury, elasticity (2.96 kPa +/- 0.63) and viscosity (0.85 kPa +/- 0.22) increased (P < .005), while fibrogenesis and inflammation were observed without substantial fibrosis or steatosis. At multivariate analysis in all rats, liver elasticity correlated only with myofibroblast activation (P < .001, r > 0.6). CONCLUSION The results suggest that in nonalcoholic fatty rat liver, MR elastography may be useful in the early detection of steatohepatitis by showing increased elasticity and appearing before fibrosis development, which was linked to myofibroblast activation. SUPPLEMENTAL MATERIAL http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.2523081817/-/DC1.

Liver Fibrosis in Chronic Hepatitis C Virus Infection: Differentiating Minimal from Intermediate Fibrosis with Perfusion CT

PURPOSE To prospectively assess the utility of perfusion computed tomography (CT) for differentiating minimal from intermediate fibrosis in treatment-naïve patients with chronic hepatitis C virus (HCV) infection. MATERIALS AND METHODS This study was approved by the Institutional Review Board, and informed consent was obtained. Fifty-two patients with treatment-naïve HCV infection underwent perfusion CT and percutaneous liver biopsy on the same day. Portal vein, arterial, and total liver perfusion; mean transit time; and distribution volumes for the right and left liver lobes were measured. Liver samples were scored for fibrosis, and fibrosis area was determined. Differences in quantitative perfusion parameters between patients with minimal fibrosis (score of F1) and those with intermediate fibrosis (score of F2 or F3) were tested. RESULTS In patients with intermediate fibrosis (F2 and F3) compared with those with minimal fibrosis (F1), the portal venous perfusion (87 mL min(-1) 100 mL(-1) +/- 27 [standard deviation] vs 138 mL min(-1) 100 mL(-1) +/- 112, P = .042) and total liver perfusion (107 mL min(-1) 100 mL(-1) +/- 31 vs 169 mL min(-1) 100 mL(-1) +/- 137, P = .02) were significantly decreased, and the mean transit time was significantly increased (16 seconds +/- 4 vs 13 seconds +/- 5, P = .025). At multivariate analysis, only the mean transit time was an independent factor (odds ratio, 1.18; 95% confidence interval: 1.02, 1.37; P = .030). Receiver operating characteristic curve analysis showed that a mean transit time threshold of 13.4 seconds allowed discrimination between minimal and intermediate fibrosis with a sensitivity of 71% and a specificity of 65%. CONCLUSION The results of this study show that perfusion changes occur early during fibrosis in chronic HCV infection and can be detected with perfusion CT. Perfusion CT may help to discriminate minimal from intermediate fibrosis. Mean transit time appears to be the most promising perfusion parameter for differentiating between fibrosis stages, although the large amount of overlap in the measured parameters limits the clinical utility of this test at present.

Capillarization of the sinusoids in liver fibrosis: Noninvasive assessment with contrast-enhanced MRI in the rabbit

Sinusoidal capillarization induces microcirculatory changes in liver cirrhosis and fibrosis. The purpose of this study was to assess whether contrast‐enhanced MRI can be used to demonstrate the effects of sinusoidal capillarization in liver fibrosis. Dynamic MRI after injection of a low‐molecular‐weight contrast agent of 0.56 kDa (Gd‐DOTA), and two high‐molecular‐weight contrast agents of 6.47 kDa and 52 kDa (P792 and P717) was performed in rabbits with liver fibrosis induced by cholesterol and diethylstilbestrol. The hepatic distribution volume accessible to the high‐molecular‐weight agents decreased in the rabbits with liver fibrosis (P792: 7.8% ± 1.7% vs. 10.1% ± 1.8% in normal rabbits, P = .038; P717: 6.2% ± 2.1% vs. 9.7% ± 1.6% in normal rabbits, P = .007), whereas the hepatic mean transit time (MTT) of the low‐molecular‐weight agent was increased (15.9 ± 8.0 s vs. 8.8 ± 2.6 s in normal rabbits, P = .015). In rabbits with liver fibrosis, the clearance of indocyanine green (ICG) was correlated with the volume accessible to the high‐molecular‐weight agents (P792: r = 0.810, P = .015; P717: r = 0.857, P = .007). The collagen content of the liver was inversely correlated with the distribution volume of P717 (r = –.833, P = .010) and with the ICG clearance (r = –.810, P = .015). It was concluded that the microcirculatory changes induced by sinusoidal capillarization in liver fibrosis can be demonstrated noninvasively with MRI. Magn Reson Med 49:692–699, 2003.

Hepatic viscoelastic parameters measured with MR elastography: correlations with quantitative analysis of liver fibrosis in the rat.

To determine the correlations between the viscoelastic parameters of the liver measured with in vivo MR elastography and quantitative analysis of liver fibrosis.

Benign hepatocellular tumors: MRI after superparamagnetic iron oxide administration.

Objective Our goal was to describe the features of benign hepatocellular tumors on superparamagnetic iron oxide (SPIO)–enhanced MR images and to evaluate the potential role of SPIO administration in the diagnosis of these tumors. Materials and Methods The T1− and T2-weighted SE images were performed before and after SPIO administration in 19 patients with focal nodular hyperplasia (FNH) or adenomas. The lesions were counted and qualitatively assessed. In 32 tumors with a diameter of >10 mm, the contrast-to-noise ratio (CNR) and the liver and tumor enhancement were calculated. Results Thirty-seven tumors were detected on MR images: 29 before and 36 after SPIO administration (p < 0.05). The SPIO-enhanced T1-weighted images provided the highest detection rate and CNR. The central scar was most conspicuous on SPIO-enhanced T2-weighted images. Most FNHs and adenomas lost less signal than the liver, three tumors did not lose signal, and four FNHs showed a signal loss equal to or greater than that of the liver. Conclusion The SPIO-enhanced T1-weighted images increased the CNR and the detection rate of benign hepatocellular tumors. On T2-weighted images, most benign hepatocellular tumors showed a signal decrease after SPIO administration. No significant difference in signal loss was observed between FNH and adenomas.

Intrahepatic cholangiocarcinoma: MRI and pathologic correlation in 14 patients

PURPOSE Our goal was to determine the MR features of intrahepatic cholangiocarcinoma and to correlate them with pathologic findings in a surgical series. METHOD MRI in 14 patients with intrahepatic cholangiocarcinoma who had undergone resection was reviewed. All patients had T1- and T2-weighted SE sequences. Contrast-material-enhanced MRI was performed in 12 cases. Comparison between findings at MRI and pathologic examination was made. RESULTS MRI depicted all the lesions but one satellite nodule of 2 cm diameter. All lesions were hypointense relative to the liver on T1-weighted images. On T2-weighted images, the tumors were predominantly isointense or slightly hyperintense relative to liver parenchyma in nine cases (64%) and were strongly hyperintense in five cases (36%). Central hypointense areas or bands were seen in eight cases. No capsule was detected. On contrast-enhanced MR studies, all lesions had progressive and concentric filling with contrast material. Associated findings such as vascular encasement, focal liver atrophy, or dilatation of intrahepatic bile ducts were observed in 10 cases (71%). Comparison with pathologic examination revealed that lesion signal intensity on T2-weighted MR images was due mostly to the amount of fibrosis, necrosis, and mucous secretion within the lesion. The nine isointense or slightly hyperintense lesions contained abundant fibrosis and had a low content of mucous secretion or necrosis, whereas the five hyperintense lesions contained low or moderate fibrosis and prominent mucous secretion and/or necrosis. CONCLUSION Our study suggests that the MR features of intrahepatic cholangiocarcinoma are well correlated with pathologic findings, but are nonspecific. Associated findings may strengthen the diagnosis of intrahepatic cholangiocarcinoma at MRI.