title: Gadoxetate disodium-enhanced MR imaging: differentiation between early-enhancing non-tumorous lesions and hypervascular hepatocellular carcinomas.
abstract: OBJECTIVE
  To retrospectively assess imaging features that help differentiate early-enhancing non-tumorous (EN) hepatic lesions from hepatocellular carcinomas (HCCs) on gadoxetate disodium-enhanced MR imaging.
  
  
  METHODS
  Our institutional review board approved this retrospective study. We reviewed the studies of 158 patients (92 men and 65 women; age range: 29-91; mean age: 65.6 years) with chronic liver damage, who underwent gadoxetate disodium-enhanced MR imaging at 3T MR scanner. Hypervascular lesions identified during the hepatic artery phase were selected for a study cohort. The location, shape, size (maximum diameter and maximum area), and contrast enhancement signal intensity characteristics of the lesions were evaluated, then compared between the EN and HCC lesions.
  
  
  RESULTS
  A total of 65 EN lesions (range: 3-60mm, mean: 13.6 ± 10.6 mm) from 35 patients and 33 HCCs (range: 9-61 mm, mean: 19.3 ± 12.6 mm) from 20 patients were identified. Lesions were more frequently round or oval in shape for HCCs (n=29; 88%) than ENs (n=26; 40%) (P<0.01). Unexpectedly, some ENs (n=12; 18%) showed hypointensity on hepatocyte-phase, and 6 (50%) of them were T2 hyperintense. For lesions smaller than 2 cm (9 ENs and 21 HCCs) on hepatic arterial-phase images, the mean area of hypointensity in hepatocyte-phase (54.2 ± 33.1 mm(2)) was significantly smaller than those of the corresponding hyperintensity in hepatic arterial-phase (97.1 ± 42.0 mm(2)) for EN lesions (P=0.019), whereas no significant difference in area was found for HCCs.
  
  
  CONCLUSIONS
  EN lesions may occasionally present with hypointensity during the hepatocyte-phase; presenting a diagnostic dilemma. In this situation, EN lesions may be differentiated from HCCs when a hypointense area in hepatocyte-phase is smaller than the corresponding hypervascular area in hepatic-arterial phase.
authors: Department of Radiology, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1193, Japan. gossy@par.odn.ne.jp
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