Measurement and comparison of T1 relaxation times in native and transplanted kidney cortex and medulla

Abstract

PURPOSE: To measure and compare cortical and medullary T1 values in native and transplanted kidneys with a wide range of function as measured by estimated glomerular filtration rate (eGFR). MATERIALS AND METHODS: A total of 27 subjects (12 native and 15 transplants) were studied. Two magnetic resonance imaging (MRI) exams of T1 measurement were performed on separate days for reproducibility study. Group-wise comparisons of renal T1 on day 1 were performed between subjects with native and transplanted kidneys and also between subjects based on an eGFR threshold of 60 mL/min/1.73 m(2). RESULTS: Transplanted kidneys had higher cortical renal T1 (1183 ± 136 msec) than native kidneys (1057 ± 94 msec) with similar results in the medulla. Subjects with an eGFR < 60 mL/min/1.73 m(2) had higher renal T1 than subjects with an eGFR > 60 mL/min/1.73 m(2) (cortical T1: P < 0.0001; medullary T1: P = 0.008). Renal T1 was highly reproducible for both native and transplant groups (with percent differences less than 10%). CONCLUSION: There are differences in cortical and medullary T1 between native and transplanted kidneys at different levels of function.