Renal T1 times reference values to improve risk stratification in patients with concomitant cardiac and renal disease: A 1.5 T CMR study

Abstract Background Multiparametric imaging is well established in cardiac disease, but less is known about its value in noncardiac tissues. Two primary pathologies are reflected by increased T1 times: edema (an increase in tissue water, e.g., associated with acute infarction or inflammation) or an increase in interstitial space (e.g., fibrosis, scarring, or amyloid deposition). Recently, several studies have reported an association between renal T1 times and renal function parameters, with elevated renal T1 times serving as a surrogate for renal fibrosis, providing evidence for the routine use of renal T1 times. To date, reference values for renal T1 times using 1.5 Tesla (T) cardiac magnetic resonance (CMR) are lacking. Objective The aim of this study was to define normal values for renal cortical T1 times in subjects with normal renal function undergoing 1.5 T CMR, to extend the widespread use of mapping sequences and to provide further evidence for risk stratification in patients with concomitant cardiac and renal disease. Methods Renal T1 times were measured in the native short-axis view in an all-comers cohort undergoing CMR (Figure1). Three regions of interest (ROIs) were delineated manually in the upper, middle, and lower portions of the renal cortex and mean values were calculated (Figure1b). Only patients without known renal disease and with an estimated glomerular filtration rate (eGFR) greater than 90 mL/min/1.73 m2 were included in our analysis. Based on the presence of arterial hypertension (aHTN) and diabetes mellitus (DM), subjects were divided into control, aHTN, DM, and aHTN-DM groups. Results A total of 128 patients were evaluated. Patients were stratified by sex and age for comparison. Mean global renal cortical T1 times were 1057±48 ms. Compared to men, women showed slightly longer renal cortical T1 times (1072±35ms vs.1047±53 ms, p=.006), while age did not result in different values in the compared groups. In a subgroup analysis, the aHTN-DM (1088±44 ms) group had significantly longer renal T1 times than the control group (1057±48 ms), aHTN (1069±46 ms) and DM (1063±39 ms) groups (p<0.05). Conclusion Our results provide reference values for renal T1 times in patients undergoing 1.5 T CMR. Given the established association between renal and cardiac disease and the known prognostic impact of renal fibrosis, the assessment of renal T1 times on standard CMR scans as a surrogate for renal fibrosis may facilitate risk stratification in complex patient populations.Example of a CMR short-axis view.