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Multiparametric Magnetic Resonance Imaging in a Prospective Cohort of Living Kidney Donors, Recipients, and Healthy Controls and Correlations With Markers of Renal Function, Fibrosis, and Aging (MPRENAL): Protocol for a Longitudinal Observational Study

Year: 2026

Type: article

Abstract: Background Renal fibrosis is the final common pathway of chronic kidney disease progression and a critical histological predictor of renal function decline and allograft failure. Routine clinical monitoring with estimated glomerular filtration rate (eGFR) and albuminuria is insensitive to fibrosis development. Renal biopsy is invasive and subject to sampling bias, which limits repeated assessment, thus necessitating noninvasive imaging biomarkers. Multiparametric magnetic resonance imaging (mpMRI) characterizes renal structure and function noninvasively. Individual MRI measures have been associated with fibrosis and with declining renal function. However, longitudinal validation against histology and measured glomerular filtration rate (mGFR) remains limited. Objective This prospective longitudinal observational study aims to validate mpMRI against histological fibrosis assessed by kidney biopsy in kidney transplant recipients (KTRs), and compare the time-dependent trajectories of imaging and functional markers across living kidney donors (LKDs), KTRs, and healthy control (HC) cohorts. Methods The planned sample includes 32 LKDs, 32 KTRs, and 32 HCs. Up to 40 KTRs may be recruited to account for attrition. Baseline assessments are performed before transplantation for LKDs and KTRs, and at enrollment for HCs, with follow-up assessments at 3, 12, and 24 months. mpMRI is performed at 3 tesla (3 T). The MRI protocol includes structural longitudinal relaxation time (T1)–weighted and T2-weighted imaging, T1 mapping, T2 mapping, transverse relaxation time (T2*) mapping, diffusion-weighted imaging, pseudocontinuous arterial spin labeling, non–contrast enhanced angiography, and phase-contrast measurement of renal artery flow. Glomerular filtration rate will be measured by [ 99m Tc]Tc-diethylenetriaminepentaacetic acid (DTPA) clearance. A baseline allograft biopsy is taken during transplantation surgery, with protocol biopsies at 3, 12, and 24 months. Fibrosis is quantified using stereology. The primary outcome is the longitudinal association between the corticomedullary T1 difference and histologically determined renal fibrosis in KTRs across all 4 biopsy time points. Secondary analyses include longitudinal divergence of MRI and functional markers across cohorts, diagnostic performance for fibrosis, and predictive value for mGFR decline in KTRs and LKDs. Linear mixed models will be used to study longitudinal associations. Three additional MRI measures will be tested in a fixed sequence to control multiplicity. Receiver operating characteristic curve analysis will assess diagnostic performance. Results The study was funded in October 2023. Recruitment for the multiparametric renal magnetic resonance imaging (MPRENAL) study commenced on October 29, 2024. As of March 2026, 42 participants were enrolled, and data collection is ongoing. Recruitment is anticipated to close in February 2027, with final study visits by March 2029. The primary results are expected to be published in 2030. Conclusions Successful completion of this study is expected to provide robust histological validation of mpMRI and establish its utility as a noninvasive tool for monitoring renal health.

Source: JMIR Research Protocols

DOI: 10.2196/97152