Segmental liver hyperintensity in malignant biliary obstruction on diffusion weighted MRI: associated MRI findings and relationship with serum alanine aminotransferase levels

Abstract

Segmental liver hyperintensity can be observed in malignant biliary obstruction on diffusion weighted MRI (DW-MRI). We describe MRI findings associated with this sign and evaluate whether DW-MRI segmental hyperintensity has any relationship with serum alanine aminotransferase (ALT) levels. The DW-MRI T(1) weighted, T(2) weighted and gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced T(1) weighted images obtained in 21 patients with hepatic malignancy, who demonstrated biliary obstruction and segmental hyperintensity on DW-MRI (b=0-750 s mm(-2)), were retrospectively reviewed by 2 readers blinded to clinical results. DW-MRI hyperintense liver segments were recorded as hypointense, isointense or hyperintense relative to normal liver on T(1)/T(2) weighted imaging. It was also noted whether contrast enhancement was similar to that observed in normal liver or diminished in the hepatocellular phase. The mean apparent diffusion coefficient (ADC) value (×10(-3) s mm(-2)) of DW-MRI hyperintense segments, normal liver and tumour were compared using Student's t-test. The frequency of MRI findings was corroborated with serum ALT levels, which reflect hepatocyte injury. DW-MRI hyperintense segments frequently showed T(1) hyperintensity (10/21), T(2) hyperintensity (19/21) and/or diminished contrast enhancement (15/21). Tumours showed significantly lower mean ADC values than liver (1.23 ± 0.08 vs 1.43 ± 0.05; p=0.013). Segments showing concomitant T(1) hyperintensity had lower mean ADC values than liver (1.30 ± 0.05 vs 1.43 ± 0.05; p=0.023). The patients (8/10) with concomitant T(1) and DW-MRI segmental hyperintensity showed elevated ALT levels (p=0.030, Fisher's exact test). Concomitantly high T(1) weighted and DW-MRI signal in liver segments was associated with lower ADC values and abnormal liver function tests, which could reflect underlying cellular swelling and damage.