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Liver Cirrhosis: Intravoxel Incoherent Motion MR Imaging—Pilot Study¹

¹ From the INSERM Unite U 841, Equipe 17, Molecular Mechanisms of Liver Fibrosis, Creteil, France (A. Luciani, J.T.V.N., A.M.); Departments of Radiology (A. Luciani, M.C., L.R., J.F.D., P.B., A.R.), Pathology (J.T.V.N.), Hepatology (A.M.), and Liver Surgery (A. Laurent), AP-HP, Groupe Henri Mondor Albert Chenevier, Centre Hospitalo Universitaire Henri Mondor, 51 Avenue du Marechal de Lattre de Tassigny, 94010 Creteil Cedex, France; and Siemens Medical Solutions France, Saint Denis, France (A.V.). Received January 12, 2008; revision requested April 2; revision received May 5; accepted June 12; final version accepted June 25. Address correspondence to A.L. (e-mail: alain.luciani{at}hmn.aphp.fr).

Purpose: 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 perfusion-related (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 signal-intensity decay curves according to b factors were logarithmically plotted. Ten b factors (0, 10, 20, 30, 50, 80, 100, 200, 400, 800 sec/mm²) were used in patients. Patients with documented liver cirrhosis (cirrhotic liver group, n = 12) and patients without chronic liver disease (healthy liver group, n = 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/mm²). 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 = 1.39 x 10^–3 mm²/sec ± 0.2 [standard deviation] vs D = 1.10 x 10^–3 mm²/sec ± 0.7) and in the cirrhotic liver group (ADC = 1.23 x 10^–3 mm²/sec ± 0.4 vs D = 1.19 x 10^–3 mm²/sec ± 0.5) (P = .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.

© RSNA, 2008

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