Structural changes of magnetic resonance imaging of transplanted deceased donors kidneys in the early post-transplant period

Background / Objective This study investigates the microstructural changes in deceased donors kidneys post-transplantation by The Magnetic Resonance Imaging (MRI). The aim is to compare the MRI of transplanted kidneys (kTx) 7-10 days post-transplantation with healthy native kidneys (control group). Methods A prospective study was conducted at the Hospital of Lithuanian University of Health Sciences Kaunas Clinics. MRIs were performed on 34 kTx and 30 control group kidneys using a 3T Siemens Skyra scanner. Parametric MRI v1.2.31-b was used for T1, T2 Map, and Apparent Diffusion Coefficient (ADC) analyses. Two regions, the cortex and medulla, were defined for kidneys. Measurements were averaged across two observers, and corticomedullary difference (CMD) was calculated. Clinical and laboratory data were collected, and statistical analysis was performed using IBM SPSS Statistics version 29. Results The results showed a decrease in CMD on the T1 kTx map (140.55 SD 67.74 ms and 541.57 SD 217.54 ms, p<0.001), primarily due to a significantly lower T1 relaxation time (rt) in the medulla of kTx (1710.50 SD 231.5 ms and 2068.27 SD 286.93 ms, p<0.001). The T1 cortex rt was similar between groups (1569.95 SD 212.05 vs 1526.70 SD 116.00, p=0.243). The T2 map of kTx showed significantly longer rt in both cortical and medullar regions, (79.1 SD 11.55 ms vs 72.41 SD 10.55 ms, p=0.003) and (78.80 SD 10.03 ms vs 63.60 SD 10.56 ms, p<0.001), resulting in a significant decrease in CMD (0.3 SD 4.93 ms and 8.81 SD 3.82 ms, p<0.001). The ADC of kTx showed significantly reduced cortical values (1927.53 SD 236.67 x 10-6 mm2/s vs 2037.78 SD 73.48 x 10-6 mm2/s, p=0.01) and significantly increased medullar values (1884.66 SD 159.17 x 10-6 mm2/s vs 1730.36 SD 69.69 x 10-6 mm2/s p<0.001). The ADC CMD of kTx was significantly lower than in the control group (42.87 SD 101.34 x 10-6 mm2/s vs 307.41 SD 59.14 x 10-6 mm2/s, p<0.001). Conclusions According to the T2 map, kTx experience ischemia-reperfusion syndrome-induced edema. The cortex of the kTx is well perfused, which we presume is the reason the T1 map is similar to healthy kidneys. However, the relaxation time is significantly shorter in the medulla of kTx, possibly due to reduced blood flow in the peritubular capillaries or reduced urine production. Different ADC values in kTx are indicative of ongoing cell swelling and capillary leakage in the acute phase.