Prospective study of multiparametric renal MRI for CKD progression (AFiRM)

IntroductionChronic kidney disease (CKD) has major population health implications, but current imaging approaches provide limited pathophysiological insights. We designed a study to evaluate renal multiparametric MRI (mpMRI) as a tool to improve diagnosis, risk stratification, disease monitoring, and therapeutic decision-making in CKD.MethodsThe AFiRM study (NCT04238299) is a multicentre, prospective, observational cohort study in people with CKD. Participants undergo renal mpMRI using the harmonised cross-vendor UKRIN-MAPS protocol at baseline and at 2-years. Clinical data are collected annually for four years with kidney failure outcomes assessed at 10 years. Primary objectives are to determine associations between MRI measures of kidney morphology, inflammation, fibrosis, perfusion and oxygenation with CKD progression, and to quantify longitudinal changes in mpMRI measures. A biopsy sub-study compares mpMRI measures with histology to explore mechanistic processes including fibrosis.ResultsAcross nine centres, 420 participants (biopsy sub-study n=43) completed baseline assessments and mpMRI. Mean age is 55 years (SD 13) and 63.8% are male. Median eGFR is 39ml/min/1.73m2 (IQR 29 - 53), median uACR 47mg/mmol (IQR 8.3 to 127.1), and median 5-year Kidney Failure Risk Equation score is 5.6% (IQR 1.0-20.8%). Most common CKD aetiologies are IgA nephropathy (22.4%), CKD of unknown aetiology (19.5%), and diabetic kidney disease (14.3%). Biopsy sub-study participants were demographically similar to the full cohort.ConclusionThe AFiRM study has established a representative CKD cohort undergoing advanced renal mpMRI with long-term follow-up. This is an important resource to study how renal MRI measures and their longitudinal changes relate to CKD severity and progression.