Liver fibrosis: noninvasive diagnosis with double contrast material-enhanced MR imaging

Abstract

Purpose: To retrospectively evaluate the accuracy of double contrast material-enhanced (hereafter double-enhanced) magnetic resonance (MR) imaging depiction of hepatic fibrosis, with histopathologic analysis findings as the reference standard.

Materials and methods: The institutional review board approved this HIPAA-compliant study and waived the requirement for informed consent. One hundred one patients (58 men, 43 women; mean age +/- standard deviation, 52 years +/- 10) who underwent double-enhanced MR imaging with superparamagnetic iron oxide (SPIO)-enhanced and double-enhanced spoiled gradient-echo (SPGR) sequences between 2001 and 2004 and had a reliable reference standard for the diagnosis of liver fibrosis were included. Two blinded MR radiologists retrospectively scored qualitative (reticulation, nodularity, and total scores) and quantitative (contrast-to-noise ratio between hyperintense and hypointense liver regions, coefficient of variation, and noise-corrected coefficient of variation) liver texture features on MR images in consensus. The image scores for patients with advanced (METAVIR fibrosis score >/= 3) versus those for patients with mild (METAVIR score </= 2) fibrosis were compared, and receiver operating characteristic curves were determined. Diagnostic performance values were calculated at the optimal operating point. Mann-Whitney U and unpaired Student t tests were performed.

Results: Qualitative and quantitative image scores were significantly higher for patients with METAVIR fibrosis scores of 3 or higher than for those with scores of 2 or lower (P < .001); on SPIO-enhanced SPGR images, differences increased with increasing echo time. Diagnostic performance for detection of grade 3 or more severe fibrosis was better with the double-enhanced sequence than with the SPIO-enhanced sequences, and qualitative scores had higher diagnostic performance than quantitative scores. The sensitivity, specificity, and accuracy of qualitative scores on double-enhanced SPGR images were higher than 90%.

Conclusion: Advanced hepatic fibrosis can be detected by using double-enhanced MR imaging. Although diagnostic performance depended on the sequence and scoring system used, sensitivity, specificity, and accuracy values higher than 90% were achievable.