The purpose of this paper is to describe the most recent concepts and pertinent findings of hepatocellular adenomas, including clinical presentation, gross pathology and histology, pathogenesis and transformation into hepatocellular carcinoma (HCC), and imaging findings at ultrasound (US), computed tomography (CT), and magnetic resonance (MR) imaging.

Purpose: To assess the relationship between lesion size and MR imaging findings of pathologically-proven hepatocellular carcinoma (HCC). Materials and Methods:In a retrospective, single-center study, 37 consecutive patients were identified between 1999 and 2005 that underwent preoperative MRI and surgical resection of HCC. A total of 47 lesions (mean size ϭ 6.85 cm, range ϭ 1-25 cm) were assessed for signal intensity (SI), enhancement patterns, and secondary morphologic features. Interobserver rating, percentage enhancement, and contrast-to-noise-ratio (CNR) were determined. Lesions were assessed for combinations of typical MRI features. Regression analysis was used to assess relations between MRI findings and tumor size. Results:On fat-suppressed T2-weighted (T2w) fast-spinecho, smaller lesions had lower SI compared to larger lesions (P Ͻ 0.05). In the arterial phase, smaller lesions showed significantly higher percentage enhancement compared to larger lesions (P Ͻ 0.05). In the delayed phase, smaller lesions showed less pronounced washout (P Ͻ 0.05). Heterogeneity of the lesions, including fatty infiltration, internal nodules, or mosaic pattern, was observed significantly more frequently in larger lesions (P Ͻ 0.001). The classic combination of high T2w signal, strong arterial enhancement, and delayed phase washout was present in 23 of 44 lesions (52%). Conclusion:Smaller HCC often showed lower SI on T2w, more intense arterial enhancement, and less pronounced delayed washout compared to larger HCC.

Institutional Review Board approval and signed informed consent were obtained by all participants for an ongoing sequence optimization project at 3.0 T. The purpose of this study was to evaluate breath-hold diffusion-induced black-blood echo-planar imaging (BBEPI) as a potential alternative for specific absorption rate (SAR)-intensive spin-echo sequences, in particular, the fast spin-echo (FSE) sequences, at 3.0 T. Fourteen healthy volunteers (seven men, seven women; mean age +/- standard deviation, 32.7 years +/- 6.8) were imaged for this purpose. Liver coverage (20 cm, z-axis) was always performed in one 25-second breath hold. Imaging parameters were varied interactively with regard to echo time, diffusion b value, and voxel size. Images were evaluated and compared with fat-suppressed T2-weighted FSE images for image quality, liver delineation, geometric distortions, fat suppression, suppression of the blood signal, contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR). An optimized short- (25 msec) and long-echo (80 msec) BBEPI provided full anatomic, single breath-hold liver coverage (100 and 50 sections, respectively), with resulting voxel sizes of 3.3 x 2.7 x 2.0 mm and 3.3 x 2.7 x 4.0 mm, respectively. Repetition time was 6300 msec, matrix size was 160 x 192, and an acceleration factor of 2.00 was used. b Values of more than 20 sec/mm(2) showed better suppression of the blood signal but b values of 10 sec/mm(2) provided improved volume coverage and signal consistency. Compared with fat-suppressed T2-weighted FSE, the optimized BBEPI sequence provided (a) comparable image quality and liver delineation, (b) acceptable geometric distortions, (c) improved suppression of fat and blood signals, and (d) high CNR and SNR. BBEPI is feasible for fast, low-SAR, thin-section morphologic imaging of the entire liver in a single breath hold at 3.0 T.

Kasai portoenterostomy (PE) increases the survival for children with biliary atresia (BA) and consequently postpones subsequential liver transplantation. All long-term survivors, however, develop complications of biliary cirrhosis. We report a case of hepatocellular carcinoma (HCC) in a 19-year-old male patient with BA and Kasai PE. The preoperative abdominal ultrasound and magnetic resonance imaging showed a large hepatic mass (diameter 10 cm). The serum alpha-fetoprotein level was within normal range. Pathologic findings of the mass, after orthotopic liver transplantation, demonstrated a well-differentiated HCC (T1N0M0). HCC is a rare complication of BA, but will intensively impair the survival. Therefore, clinicians should be alert to the development of HCC in this very young patient group. Repeated sequential magnetic resonance imaging of the native liver in patients with Kasai PE is necessary to monitor possible malignant transformation of liver nodules that may potentially develop as a result of chronic cholestatic liver disease.

The purpose of this article is to explain and illustrate the current status and potential applications of automated and color-coded post-processing techniques for the analysis of dynamic multiphasic gadolinium-enhanced magnetic resonance imaging (MRI) of the liver. Post-processing of these images on dedicated workstations allows the generation of time-intensity curves (TIC) as well as color-coded images, which provides useful information on (neo)-angiogenesis within a liver lesion, if necessary combined with information on enhancement patterns of the surrounding liver parenchyma. Analysis of TIC and color-coded images, which are based on pharmacokinetic modeling, provides an easy-to-interpret schematic presentation of tumor behavior, providing additional characteristics for adequate differential diagnosis. Inclusion of TIC and color-coded images as part of the routine abdominal MRI workup protocol may help to further improve the specificity of MRI findings, but needs to be validated in clinical decision-making situations. In addition, these tools may facilitate the diagnostic workup of disease for detection, characterization, staging, and monitoring of antitumor therapy, and hold incremental value to the widely used tumor response criteria.