Morphometric analyses of small accessory liver lobes using radiological imaging

To investigate the prevalence and morphometric characteristics of small accessory liver lobes using computed tomography (CT) and magnetic resonance (MR) images.

The study population comprised 3269 patients (1671 men and 1598 women; mean age, 67.1 ± 15.2 years) who had undergone abdominal CT examination. Small accessory liver lobes were identified after verification of their continuity with the liver parenchyma on CT images. Their imaging characteristics were analyzed and presented.

Thirty-five small accessory liver lobes in 33 patients (1.01%; 25 men and 8 women, 71.0 ± 11.7 years) were identified. Thirty-one patients (93.9%) had solitary lesions most frequently identified on liver segment 6 (80.0%) with the mean size 9.6 ± 4.8 mm. These showed iso (62.9%), hyper (28.6%), or hypoattenuation (8.6%) on unenhanced CT. Enhanced CT images were available for 29 lesions. Enhancement of 12 lesions (41.4%) was similar to that of the liver parenchyma, whereas 17 lesions (58.6%) showed poor enhancement. MR images were available for 10 lesions, which showed hyperintensity (50.0%) on T2-weighted images and poor enhancement (50.0%). The characteristics of other lesions were similar to those of the liver parenchyma. During observation (mean, 77.0 months; n = 29), 19 lesions remained the same size (65.5%), 5 new lesions increased size (17.2%), and 5 showed reduced size (17.2%).

Small accessory liver lobes, commonly located on segment 6, were frequently observed and did not necessarily show the same findings as the liver parenchyma. Time-dependent morphological changes were observed in approximately one-third of the lesions.