Liver cirrhosis: intravoxel incoherent motion MR imaging--pilot study.
OBJECTIVE
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.


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/mm(2)) 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/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 = 1.39 x 10(-3) mm(2)/sec +/- 0.2 [standard deviation] vs D = 1.10 x 10(-3) mm(2)/sec +/- 0.7) and in the cirrhotic liver group (ADC = 1.23 x 10(-3) mm(2)/sec +/- 0.4 vs D = 1.19 x 10(-3) mm(2)/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).


CONCLUSIONS
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.
Luciani
Alain
A
INSERM Unite U 841, Equipe 17, Molecular Mechanisms of Liver Fibrosis, Creteil, France. alain.luciani@hmn.aphp.fr
Vignaud
Alexandre
A
Cavet
Madeleine
M
Nhieu
Jeanne Tran Van
JT
Mallat
Ariane
A
Ruel
Lucile
L
Laurent
Alexis
A
Deux
Jean-François
JF
Brugieres
Pierre
P
Rahmouni
Alain
A
D000328:Adult; D000368:Aged; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008099:Liver / Q000473:pathology; D008103:Liver Cirrhosis / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D010865:Pilot Projects; D012189:Retrospective Studies