Tissue pulsatility index: a new parameter to evaluate renal transplant perfusion.

Background. Chronic allograft nephropathy (CAN) is characterized by loss of parenchymal perfusion. We applied therefore the novel parameter Tissue Pulsatility Index (TPI) to quantify transplant perfusion in the long-term surveillance of renal transplants. Methods. Color Doppler sonographic videos of renal transplants from 38 renal transplant recipients were recorded under defined conditions. TPI was calculated as ratio of the difference of mean systolic and diastolic velocities of the entire region and the average velocity. Results. TPI was significantly different between the proximal and distal cortical layers (1.12 vs. 1.56, respectively P0.000). In patients with elevated creatinine as a measure of compromised function, significantly (P0.016) higher values (TPI1.70) were found at distal cortical level compared to patients with normal creatinine (TPI1.34). After transplantation, TPI rises significantly: 1.10 in 0–1 years vs. 1.41 in 1–2.9 years, P0.002; 1.10 in 0–1 years vs. 1.37 in 3–4.9 years, P0.000; 1.10 in 0–1 years vs. 1.31 in 7–8.9 years, P0.049). TPI declines later on in our population to significantlyloweredvaluesinthegroupmorethan9yearsaftertransplantation(1.10in0–1yearsvs.0.94in9years, P0.044). Conclusion. With the novel TPI, we could demonstrate significant differences between proximal and distal cortical perfusion,betweencompromisedandwell-functioningtransplants,andcouldobservesignificantchangesoftransplant perfusion at various points at the posttransplantation time scale.