Abstract
BackgroundDespite improvement in short-term outcome of kidney transplants, the long-term survival of kidney transplants has not changed over past decades. Kidney biopsy is the gold standard of transplant pathology but it’s invasive. Quantification of transplant blood flow could provide a novel non-invasive method to evaluate transplant pathology. The aim of this retrospective cross-sectional pilot study was to evaluate positron emission tomography (PET) as a method to measure kidney transplant perfusion and find out if there is correlation between transplant perfusion and histopathology.MethodsRenal cortical perfusion of 19 kidney transplantation patients [average time from transplantation 33 (17–54) months; eGFR 55 (47–69) ml/min] and 10 healthy controls were studied by [15 O]H2O PET. Perfusion and Doppler resistance index (RI) of transplants were compared with histology of one-year protocol transplant biopsy.ResultsRenal cortical perfusion of healthy control subjects and transplant patients were 2.7 (2.4–4.0) ml min− 1 g− 1 and 2.2 (2.0–3.0) ml min− 1 g− 1, respectively (p = 0.1). Renal vascular resistance (RVR) of the patients was 47.0 (36.7–51.4) mmHg mL− 1min− 1g− 1 and that of the healthy 32.4 (24.6–39.6) mmHg mL− 1min−1g−1 (p = 0.01). There was a statistically significant correlation between Doppler RI and perfusion of transplants (r = − 0.51, p = 0.026). Transplant Doppler RI of the group of mild fibrotic changes [0.73 (0.70–0.76)] and the group of no fibrotic changes [0.66 (0.61–0.72)] differed statistically significantly (p = 0.03). No statistically significant correlation was found between cortical perfusion and fibrosis of transplants (p = 0.56).Conclusions[15 O]H2O PET showed its capability as a method in measuring perfusion of kidney transplants. RVR of transplant patients with stage 2–3 chronic kidney disease was higher than that of the healthy, although kidney perfusion values didn’t differ between the groups. Doppler based RI correlated with perfusion and fibrosis of transplants.
Highlights
Renal allograft survival has improved over past decades mainly because of increased first-year survival [1, 2]
All the kidney transplant patients were on antihypertensive medication
Values are median (Q1-Q3) RI Renal artery resistance index measured by Doppler ultrasound, mean arterial pressure (MAP) Mean arterial pressure *P < 0.05, controls versus kidney transplant patients
Summary
Renal allograft survival has improved over past decades mainly because of increased first-year survival [1, 2]. Changes in renal tissue oxygenation and microvasculature are considered as major determinants of progression of chronic kidney disease (CKD), irrespective of its Kidney biopsy, which is the gold standard of evaluation of transplant parenchyma, is invasive and prone to sampling errors [12]. Despite improvement in short-term outcome of kidney transplants, the long-term survival of kidney transplants has not changed over past decades. Kidney biopsy is the gold standard of transplant pathology but it’s invasive. Quantification of transplant blood flow could provide a novel non-invasive method to evaluate transplant pathology. The aim of this retrospective cross-sectional pilot study was to evaluate positron emission tomography (PET) as a method to measure kidney transplant perfusion and find out if there is correlation between transplant perfusion and histopathology
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