MRI-serum-based score accurately identifies patients undergoing liver transplant without rejection avoiding the need for liver biopsy: A multisite European study.

Serum liver tests (serum tests) and histological assessment for T-cell-mediated rejection are essential for post-liver transplant monitoring. Liver biopsy carries a risk of complications that are preferably avoided in low-risk patients. Multiparametric magnetic resonance imaging (mpMRI) is a reliable noninvasive diagnostic method that quantifies liver disease activity and has prognostic utility. Our aim was to determine whether using mpMRI in combination with serum tests could noninvasively identify low-risk patients who underwent liver transplants who are eligible to avoid invasive liver biopsies. In a multicenter prospective study (RADIcAL2), including 131 adult and pediatric (children and adolescent) patients with previous liver transplants from the Netherlands, Portugal, and the United Kingdom, concomitant mpMRI and liver biopsies were performed. Biopsies were centrally read by 2 expert pathologists. T-cell-mediated rejection was assessed using the BANFF global assessment. Diagnostic accuracy to discriminate no rejection versus indeterminate or T-cell-mediated liver transplant rejection was performed using the area under the receiver operating characteristic curve. In this study, 52% of patients received a routine (protocol) biopsy, while 48% had a biopsy for suspicion of pathology. Thirty-eight percent of patients had no rejection, while 62% had either indeterminate (21%) or T-cell-mediated rejection (41%). However, there was a high interobserver variability (0 < Cohen's Kappa < 0.85) across all histology scores. The combined score of mpMRI and serum tests had area under the receiver operating characteristic curve 0.7 (negative predictive value 0.8) to identify those without either indeterminate or T-cell-mediated rejection. Combining both imaging and serum biomarkers into a composite biomarker (imaging and serum biomarkers) has the potential to monitor the liver graft to effectively risk stratify patients and identify those most likely to benefit from a noninvasive diagnostic approach, reducing the need for liver biopsy.