29, 30 We did not attempt to diagnose regenerative or dysplastic nodules in this study. A lesion was diagnosed as HCC on DWI if it showed the following: mild to moderate hyperintensity compared with liver parenchyma on DW images at b 50, restricted diffusion (remained hyperintense) at b 500 and/or b 1,000, with ADC visually lower or equal to that of surrounding liver parenchyma.12 ADC values were not measured in this study. A maximum number of five HCCs per patient was recorded on the basis of the largest size. All data (including

lesion location and size) were transcribed from hard copies to electronic format by a third observer 3 (M.-S. P., 7 years of experience in abdominal MRI), who was responsible for MR-pathologic correlation (see below). The third observer (M.-S. P.) correlated MRI findings as diagnosed by the first two observers ERK inhibitor with the pathologic findings based on the size and segment location of the lesions on explant. All 52 explanted livers were initially sectioned into 5-8

mm contiguous slices in the coronal plane. HCCs were identified grossly as those that were distinct from surrounding regenerative nodules in terms of size, texture, color, or degree of bulging beyond the cut surface of the liver. Livers were photographed, Selleck Epigenetics Compound Library and all lesions other than ordinary regenerative nodules were sampled for histologic examination. Using the diagnostic criteria of the International Working Party’s Terminology of Nodular Hepatocellular Lesions,31 the routine hematoxylin 上海皓元 and eosin–stained slices from the nodules were classified as follows: regenerative nodule; dysplastic nodule, low grade; dysplastic nodule, high grade; small HCC (<2 cm); or HCC (≥2 cm). The HCCs were categorized as well-differentiated, moderately differentiated, and poorly differentiated.

Microvascular invasion was noted. SAS version 9.0 was used for all statistical computations. Generalized estimating equations based on a binary logistic regression model were used to compare the three sets of images. The model included imaging modality and observer as fixed classification factors, and the correlation structure was modeled by assuming observations to be correlated only when derived for the same patient. For the analysis of diagnostic accuracy on a per-subject basis, a patient was classified as positive for HCC if at least one HCC lesion was seen at pathology and was negative for HCC otherwise. Patients were defined as test-positive for HCC whenever an observer diagnosed at least one lesion as HCC using a given imaging modality and test-negative for that given combination of reader and modality otherwise.