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 P=0.000). In patients with elevated creatinine as a measure of compromised function, significantly (P=0.016) higher values (TPI=1.70) were found at distal cortical level compared to patients with normal creatinine (TPI=1.34). After transplantation, TPI rises significantly: 1.10 in 0-1 years vs. 1.41 in 1-2.9 years, P=0.002; 1.10 in 0-1 years vs. 1.37 in 3-4.9 years, P=0.000; 1.10 in 0-1 years vs. 1.31 in 7-8.9 years, P=0.049). TPI declines later on in our population to significantly lowered values in the group more than 9 years after transplantation (1.10 in 0-1 years vs. 0.94 in >9 years, P=0.044). CONCLUSION: : With the novel TPI, we could demonstrate significant differences between proximal and distal cortical perfusion, between compromised and well-functioning transplants, and could observe significant changes of transplant perfusion at various points at the posttransplantation time scale.

Dynamic tissue perfusion measurement: a novel tool in follow-up of renal transplants.

BACKGROUND: The authors applied the novel method of noninvasive dynamic color Doppler sonographic parenchymal perfusion measurement to renal transplants. METHODS: Color Doppler sonographic videos of renal transplants from 38 renal transplant recipients were recorded under defined conditions. Specific tissue perfusion was calculated as mean flow velocity encoded by color Doppler signals of a region of interest during one full heart cycle. RESULTS: The authors could demonstrate significant differences of central versus peripheral cortical perfusion intensity (1.36 vs. 0.60 cm/sec) and a significant loss of perfusion intensity in the posttransplantation period in the peripheral cortex from 1.06 cm/sec in the first year to a minimum of 0.39 cm/sec in the 3- to 5-year interval, with stronger perfusion in longer surviving transplants: 0.71 cm/sec more than 9 years after transplantation. In the central cortex, a similar but less pronounced pattern could be demonstrated. A significant drop of parenchymal perfusion was found in patients with elevated serum creatinine (1.36 cm/sec in cases with normal and 0.82 cm/sec in those with elevated creatinine at the proximal cortical level). The perfusion ratio of the central 50% and the peripheral 50% shows marked changes over time: in the first year, the ratio was 2.99, climbing to 5.56 at the 3- to 5-year interval and declining later on. CONCLUSIONS: Cortical tissue perfusion in renal transplants was quantified noninvasively from color Doppler signal data in an easily accomplishable manner. Renal transplants showed a marked decline in tissue perfusion after transplantation. Perfusion is significantly lower in transplant function loss with elevated serum creatinine.