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Focal nodular hyperplasia (FNH) is the second most common benign liver tumor after hemangioma. FNH is classified into two types: classic (80% of cases) and nonclassic (20%). Distinction between FNH and other hypervascular liver lesions such as hepatocellular adenoma, hepatocellular carcinoma, and hypervascular metastases is critical to ensure proper treatment. An asymptomatic patient with FNH does not require biopsy or surgery. Magnetic resonance (MR) imaging has higher sensitivity and specificity for FNH than does ultrasonography or computed tomography. Typically, FNH is iso- or hypointense on T1-weighted images, is slightly hyper- or isointense on T2-weighted images, and has a hyperintense central scar on T2-weighted images. FNH demonstrates intense homogeneous enhancement during the arterial phase of gadolinium-enhanced imaging and enhancement of the central scar during later phases. Familiarity with the proper MR imaging technique and the spectrum of MR imaging findings is essential for correct diagnosis of FNH.

Objective-In a previous in vitro study we have demonstrated that atherosclerotic plaque components can be characterized with multidetector computed tomography (MDCT) based on differences in Hounsfield values (HV). Now we evaluated the use of MDCT in vivo to characterize and quantify atherosclerotic carotid plaque components compared with histology as reference standard. Methods and Results-Fifteen symptomatic patients with carotid stenosis (Ͼ70%) underwent MDCT angiography before carotid endarterectomy (CEA). From each CEA specimen 3 histological sections and corresponding MDCT images were selected. The HV of the major plaque components were assessed. The measured HV were: 657Ϯ416HU, 88Ϯ18HU, and 25Ϯ19HU for calcifications, fibrous tissue, and lipid core, respectively. The cut-off value to differentiate lipid core from fibrous tissue and fibrous tissue from calcifications was based on these measurements and set at 60 HU and 130 HU, respectively. Regression plots showed good correlations (R 2 Ͼ0.73) between MDCT and histology except for lipid core areas, which had a good correlation (R 2 ϭ0.77) only in mildly calcified (0% to 10%) plaques. Conclusions-MDCT is able to quantify total plaque area, calcifications, and fibrous tissue in atherosclerotic carotid plaques in good correlation with histology. Lipid core can only be adequately quantified in mildly calcified plaques. Key Words: carotid stenosis Ⅲ computerized tomography Ⅲ magnetic resonance imaging Ⅲ imaging T he severity of luminal stenosis, caused by the atherosclerotic plaque in the carotid bifurcation, is an important risk factor for (recurrent) stroke and is used in therapeutic decision making: ie, patients with symptomatic or asymptomatic carotid stenosis above a certain degree are considered candidates for carotid intervention such as carotid endarterectomy (CEA) or stent placement. 1 However, morphology studies on carotid atherosclerotic plaque have revealed that plaque morphology could be an important additional feature in the risk assessment of patients with carotid stenosis. 2,3 Computed tomography angiography (CTA) is an accurate modality to grade the severity of stenosis 4 and is increasingly used in the evaluation of stroke patients. The question then arises whether CT can also provide detailed information about plaque morphology.Earlier studies in which 3-mm-thick single-slice CT images were compared with histology sections of CEA specimens yielded confusing results. 5,6 Multidetector CT (MDCT) allows evaluating carotid atherosclerosis with thinner slices (0.5 to 1.0 mm) and less volume averaging. More detailed analysis of plaque composition may now become possible.A previous in vitro validation study showed that thin-section MDCT is capable of characterizing and quantifying calcifications and lipid core regions in CEA specimens based on differences in Hounsfield values (HV). 7 However, in vitro studies have inherent limitations attributable to the presence of air around the specimen and the absence of contrast in the vessel lumen. The purpose ...

Acute exacerbations of chronic hepatitis B virus (HBV) infection occur after withdrawal of lamivudine therapy in approximately 16% of patients and are considered of little clinical significance. We observed "lamivudine withdrawal hepatitis" accompanied by jaundice and incipient liver failure, but also followed by complete recovery and viral clearance. To investigate the incidence, severity, timing, and virologic characteristics of "lamivudine withdrawal hepatitis" we monitored 41 patients for at least 6 months after discontinuation of nucleoside analogue therapy. The incidence of hepatitis flares was estimated to be 7 of 41 (17%); in 2 of 41 cases (5%), hepatitis flares were associated with jaundice and incipient liver failure. A noticeable feature of the "lamivudine withdrawal hepatitis" flares were the high HBV-DNA levels at the time of the alanine transaminase (ALT) peak. Patients with chronic hepatitis B virus (HBV) infection can suffer acute exacerbations under various conditions. Studies in Taiwan showed an annual incidence of spontaneous acute exacerbation of 27% for hepatitis B e antigen (HBeAg) positive patients and 10% for anti-HBe-positive patients.

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