Prospective Study of Multiparametric Renal MRI for CKD Progression (AFiRM).

Abstract

Introduction: Chronic kidney disease (CKD) has major population health implications, but current imaging approaches provide limited pathophysiological insights. We designed a study to evaluate renal multiparametric magnetic resonance imaging (MRI; mpMRI) as a tool to improve diagnosis, risk stratification, disease monitoring, and therapeutic decision-making in CKD.

Methods: The application of functional renal MRI to improve assessment of CKD (AFiRM study; NCT04238299) is a multicenter, prospective, observational cohort study in people with CKD. Participants underwent renal mpMRI using the harmonized cross-vendor UK Renal Imaging Network: MRI Acquisition and Processing Standardization (UKRIN-MAPS) protocol at baseline and at 2-years. Clinical data are collected annually for 4 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 substudy compares mpMRI measures with histology to explore mechanistic processes including fibrosis.

Results: Across 9 centers, 420 participants (biopsy substudy n = 43) completed baseline assessments and mpMRI. Mean age is 55 years (SD 13), and 63.8% are male. Median estimated glomerular filtration rate (eGFR) is 39 ml/min per 1.73 m2 (IQR 29-53), median urine albumin-creatinine ratio (uACR) 47 mg/mmol (IQR 8.3-127.1), and median 5-year Kidney Failure Risk Equation score is 5.6% (IQR 1.0-20.8%). Most common CKD etiologies are IgA nephropathy (22.4%), CKD of unknown etiology (19.5%), and diabetic kidney disease (14.3%). Biopsy substudy participants were demographically similar to the full cohort.

Conclusion: The 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.