Liver Cirrhosis: Intravoxel Incoherent Motion MR Imaging—Pilot Study (original) (raw)

To retrospectively evaluate a respiratory-triggered diffusion-weighted (DW) magnetic resonance (MR) imaging sequence combined with parallel acquisition to allow the calculation of pure molecular-based (D) and perfusionrelated (D*, f) diffusion parameters, on the basis of the intravoxel incoherent motion (IVIM) theory, to determine if these parameters differ between patients with cirrhosis and patients without liver fibrosis. Materials and Methods: The institutional review board approved this retrospective study; informed consent was waived. IVIM DW imaging was tested on three alkane phantoms, on which the signalintensity decay curves according to b factors were logarithmically plotted. Ten b factors (0, 10, 20, 30, 50, 80, 100, 200, 400, 800 sec/mm 2) were used in patients. Patients with documented liver cirrhosis (cirrhotic liver group, n ϭ 12) and patients without chronic liver disease (healthy liver group, n ϭ 25) were included. The mean liver D, D*, and f values were measured and compared with the apparent diffusion coefficient (ADC) computed by using four b values (0, 200, 400, 800 sec/mm 2). Liver ADC and D, f, and D* parameters were compared between the cirrhotic liver group and healthy liver group. Means were compared by using the Student t test. Results: Signal-intensity decay curves were monoexponential on phantoms and biexponential in patients. In vivo, mean ADC values were significantly higher than D in the healthy liver group (ADC ϭ 1.39 ϫ 10 Ϫ3 mm 2 /sec Ϯ 0.2 [standard deviation] vs D ϭ 1.10 ϫ 10 Ϫ3 mm 2 /sec Ϯ 0.7) and in the cirrhotic liver group (ADC ϭ 1.23 ϫ 10 Ϫ3 mm 2 /sec Ϯ 0.4 vs D ϭ 1.19 ϫ 10 Ϫ3 mm 2 /sec Ϯ 0.5) (P ϭ .03). ADC and D* were significantly reduced in the cirrhotic liver group compared with those in the healthy liver group (respective P values of .03 and .008). Conclusion: Restricted diffusion observed in patients with cirrhosis may be related to D* variations, which reflect decreased perfusion, as well as alterations in pure molecular water diffusion in cirrhotic livers.