Elsevier

Transplantation Proceedings

Volume 41, Issue 8, October 2009, Pages 3024-3027
Transplantation Proceedings

Renal transplantation
Outcome
Renal Parenchyma Perfusion Spectrum and Resistive Index (RI) in Ultrasound Examinations With Contrast Medium in the Early Period After Kidney Transplantation

https://doi.org/10.1016/j.transproceed.2009.08.023Get rights and content

Abstract

The main diagnostic method for renal graft dysfunction is color Doppler ultrasound with the use of spectrae evaluation of blood flow within the main and intrarenal arteries. Ultrasound with contrast medium (US-CM) enhances the possibilities of this tool. The aim of this study was to evaluate the efficacy of US-CM to assess renal graft perfusion among 18 kidney allograft recipients at 5 to 10 days after transplantation. Patients underwent pulse inversion sonography of the graft during intravenous injections of 2.4 mL SonoVue (Bracco-Altana, Italy). Images were quantitatively assessed using computer software to compare the time to peak contrast enhancement effect in the renal cortex and renal pyramids. The results were compared to Doppler ultrasonography of the renal arteries and estimated glomerular filtration rate (eGFR; Modification of Diet in Renal Disease [MDRD]). A correlation was observed between eGFR and blood flow parameters within the renal arteries, as well between the flow time of contrast medium from the artery within the renal hilus to the renal cortex. Increased eGFR correlated with subsequent improvement in graft function (r = −.806; P = .001), and resistive index (RI) of the renal artery was inversely related to subsequent delayed graft function (r = .544; P = .029). Negative correlations were observed between eGFR and renal artery RI, as well as between eGFR and time from renal artery contrast to maximal contrast enhancement of the renal pyramids. A negative correlation was found as well between eGFR and time difference of contrast enhancement of the cortex and pyramids. In conclusion, US-CM enhanced the efficacy of ultrasound diagnostics of the renal graft and may be used as a predictor of graft function in the early posttransplantation period.

Section snippets

Materials and Methods

The study enrolled 18 patients (11 females and 7 males) of overall mean age of 50.17 ± 15.08 years who at 5 to 10 days after transplantation were displaying variable graft function. In 10 patients graft function was seen at the first day after transplantation; in 3 cases at 2 days; in 1 case at 3 days; in 1 case at 5 days; in 2 cases at 6 days; and in 1 case at 10 days after transplantation.

All contrast-enhanced ultrasound (CEUS) examinations were performed by one senior radiologist using a

Results

The contrast-enhanced examination revealed equal, efficient inflow of the contrast agent into all areas of the transplanted kidney. After an intravenous injection and a lapse of a dozen seconds, contrast agent was apparent within the renal artery in the renal hilus; thereafter contrast was observed in the renal cortex and finally in the renal pyramids. Analysis of the collected data (parenchymal perfusion curves) revealed relations between eGFR and parameters of blood flow within the renal

Discussion

The transplanted kidney is well vascularized, so the use of contrast media allows quantitative evaluation of parenchymal perfusion. The protocol of contrast-enhanced US examination of transplanted kidneys was introduced by Fischer et al.5 It is well known that US examinations depend on the examiner and are limited in obese individuals or in cases when the graft lies deep within the iliac fossa.6 These circumstances can impair the examination and increase the misinterpretation. The renal RI is

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