Apparent diffusion coefficient of fibrosis and regenerative nodules in the cirrhotic liver at MRI

Abstract

Objective: The purpose of this article is to compare the apparent diffusion coefficient (ADC) of fibrosis and regenerative nodules in the cirrhotic liver at MRI, both in vivo and ex vivo.

Subjects and methods: A prospective ex vivo and in vivo study was performed at a tertiary liver center. To characterize the diffusion properties of cirrhotic liver, 63 human liver specimens obtained anonymously from 23 freshly explanted cirrhotic livers underwent T1-, T2-, and diffusion-weighted MRI ex vivo. ADC values of fibrotic bridges and regenerative nodules were calculated. In vivo conventional and diffusion-weighted MRI was performed for 17 cirrhotic patients (12 men and five women; mean age, 54 years; range, 34-77 years) with focal areas of confluent fibrosis. ADC values of confluent fibrosis and background cirrhotic liver parenchyma were calculated. Log-transformed ADC values of fibrosis and regenerative nodules were compared between ex vivo and in vivo images.

Results: Ex vivo, the mean ADC of fibrotic bridges (0.55 +/- 0.24 mm(2)/s [SD]) was greater than that of regenerative nodules (0.36 +/- 0.18 x 10(-3) mm(2)/s) (p < 0.0001). In vivo, the mean ADC value of confluent fibrosis (2.07 +/- 0.39 x 10(-3) mm(2)/s) was greater than that of background cirrhotic liver parenchyma (1.53 +/- 0.35 x 10(-3) mm(2)/s) (p < 0.0001).

Conclusion: The mean ADC of fibrosis is significantly greater than that of regenerative nodules both in vivo and ex vivo. The prevailing paradigm that fibrosis causes the reduced liver ADC observed in cirrhosis may need modification.