3D-liver perfusion MRI with the MS-325 blood pool agent: A noninvasive protocol to asses liver fibrosis
Résumé
Purpose: To evaluate a 1.5T magnetic resonance imaging (MRI) protocol, including a dedicated acquisition sequence and a postprocessing tool for the quantitative analysis of hepatic tissue perfusion. Estimated perfusion parameters and histological results based on the METAVIR classification were prospectively compared for hepatic fibrosis assessment. Materials and Methods: The study protocol was approved by the experimentation Ethics Committee and informed consent was obtained. Sixteen patients (6 women, 10 men; average age, 52.4 ± 14.8 years) with chronic liver diseases were prospectively enrolled after a liver biopsy. MS-325 (paramagnetic blood pool agent)-enhanced MRI was performed using a free-breath 3D-VIBE T1w sequence. Image volumes were registered by an automatic rigid method. Liver perfusion was modeled by a dual-input-one-compartment model and quantitative perfusion parameters such as arterial, portal, and total perfusion mean transit time (MTT) and hepatic perfusion index (HPI) were obtained using in-house developed software. Results: Arterial perfusion increased with METAVIR stage, whereas portal perfusion decreased leading to an HPI increase with fibrosis stage. MTT increased with F3, F4. A nonparametric Mann-Whitney test demonstrated that HPI and portal perfusion were relevant in discriminating between advanced and nonadvanced fibrosis, between fibrosis and cirrhosis, then between nonfibrosis and fibrosis (P < 0.01). A strong correlation was found between portal perfusion fall-off and HPI increase (r = −0.97; P < 0.001). HPI and portal perfusion were strongly correlated with fibrosis stage (r = 0.83 and −0.88; P < 0.001, respectively). Conclusion: HPI and portal perfusion could be relevant indicators for the clinical follow-up in patients with chronic liver diseases.