Color Doppler Findings in Transplanted Kidneys and Remnant Kidneys of Donors 6 to 12 Months After Kidney Transplantation

Changes in residual kidney Pulsatility Index following living donor nephrectomy

OBJECTIVE

Nephrectomy in kidney transplant donors provokes a compensatory hyperfiltration process of the residual kidney, characterized by changes in renal vascular hemodynamics. This research aimed to determine the short-term difference in the pulsatility index (PI) of kidney transplant donors' residual kidney before and after nephrectomy.

METHODS

This is a prospective historical study using secondary data from kidney transplant living donors who have undergone nephrectomy at a tertiary referral hospital in Jakarta, Indonesia, from March 2019 to January 2020. PI of renal, segmental, interlobar, and arcuate arteries of the residual kidneys were measured in the preoperative and day-1, day-7, day-30 postoperative period. The pre- and postoperative PI values were statistically analyzed to examine differences between the groups.

RESULTS

PI of 40 residual kidneys were obtained. There were no significant mean PI changes in the arteries except for the middle interlobar artery (p = 0.049), which showed no significant difference after post hoc analysis.

CONCLUSIONS

There is no significant short-term difference in PI of the residual kidney before and after kidney transplant donor nephrectomy.

ADVANCES IN KNOWLEDGE

Short-term postoperative PI of the residual kidney arteries may not be suitable as a predictor for chronic kidney disease in kidney transplant donors. Other quantitative Doppler ultrasound parameters must be considered.

Three-dimensional imaging of living transplanted kidney vasculature by 3D color Doppler ultrasonography

Background: It is of clinical importance to display the vasculature of transplanted kidney in three-dimensional (3D) and in non-invasive way. 3D color Doppler ultrasonographic imaging (3D-CDUI) is a non-invasive technique to display the 3D vasculature of living organs. Objective: Probe into characteristics of 3D vasculature of living transplanted kidney by 3D-CDUI, and evaluate the clinical value of 3D-CDUI on monitoring complications after operation of renal transplant. Methods: Nine patients who received allogeneic transplantation of kidney were monitored with 3D-CDUI. The instruments used included ACUSON Sequoia 512 and TomTec computer station of 3D-CDUI. Using magnetic positioning free-hand scanning, the 3D reconstruction and display of renal tissue structure and blood flow were performed off-line. Results: All patients underwent 3D-CDUI examinations without any side effect or complication. When acute rejection occurred, the 3D distribution change of renal blood flow signal could be observed clearly. During treatment of acute necrosis of renal tubules, changes of renal blood flow signal in 3D color Doppler images could be detected earlier compared with 2D color Doppler images. The position of embolized vassels could be diagnosed accurately by 3D-CDUI. Conclusion: The 3D-CDUI was helpful to improve diagnosis level of ultrasonography by monitoring complications after renal transplantation.

Future of the Renal Biopsy: Time to Change the Conventional Modality Using Nanotechnology

At the present time, imaging guided renal biopsy is used to provide diagnoses in most types of primary and secondary renal diseases. It has been claimed that renal biopsy can provide a link between diagnosis of renal disease and its pathological conditions. However, sometimes there is a considerable mismatch between patient renal outcome and pathological findings in renal biopsy. This is the time to address some new diagnostic methods to resolve the insufficiency of conventional percutaneous guided renal biopsy. Nanotechnology is still in its infancy in renal imaging; however, it seems that it is the next step in renal biopsy, providing solutions to the limitations of conventional modalities.

Kidney transplant: usefulness of real-time elastography (RTE) in the diagnosis of graft interstitial fibrosis

The aim of this study is to evaluate the usefulness of real-time elastography (RTE) in the diagnosis of graft interstitial fibrosis. We prospectively enrolled 50 patients clinically suspected of graft fibrosis. RTE was performed with a broadband linear transducer using a dedicated ultrasound machine. Tissue mean elasticity (TME) was calculated by two blinded operators. All patients underwent biopsy after RTE. To determine cortical fibrosis Banff score was used. The receiver operating characteristic curves analysis was performed to evaluate the accuracy of TME to discriminate between patients with mild fibrosis (F1) versus patients with moderate to severe fibrosis (F2-F3). Inverse correlation between TME values and the degree of fibrosis has been shown (p < 0.05). Patients with F1 had mean TME values significantly higher compared with TME in patients with F2 (p = 0.005) and F3 (p = 0.004). The diagnostic accuracy of TME measurement for F2-F3 evaluated by area under the curve-receiver operating characteristic analysis was 0.95. RTE was able to evaluate kidney fibrosis in a non-invasive way and could be used as complementary imaging during follow-up of renal transplant patients.

Time-dependent Doppler ultrasonographic findings in transplanted kidneys from living donors: a 5-year follow-up study

INTRODUCTION

Ultrasonography and color Doppler have been used extensively to evaluate transplanted kidneys. Several recent studies have suggested its value to assess renal transplant dysfunction, particularly in the early postoperative period. The aim of the present study was to evaluate the time-dependent changes in color Doppler ultrasonography (DUS) findings during the first 5 years after renal transplantation.

METHODS

Among a prospective cohort we evaluated the results of collar Doppler findings in renal allograft recipients over 5 years after transplantation. For this purpose we compared the DUS findings of kidney size, pulsatile index (PI), resistive index (RI) and renal artery flow before transplantation in living donor kidneys versus 6-12 months as well as 5 years after transplantation in 23 patients. The statistical analysis was performed using SPSS version 16. P value was set at .05.

RESULTS

The mean length of the transplanted kidney was 110.60±7.92 mm before transplantation in the living donors body versus 120.29±9.01 mm and 119.36+/-9.9 mm at 6-12 months versus more than 5 years after transplantation, respectively. Mean PI and RI were 1.00+/-0.14 and 0.60+/-0.05 before transplantation and 1.00+/-0.22 and 0.61+/-0.08 and 1.07+/-0.26 and 0.63+/-0.07 at 6-12 months versus more than 5 years after transplantation, respectively. There was no significant difference in mean PI and RI during the 5 years of the follow-up study. Mean length and anteroposterior diameter increased significantly at 6-12 months and 5 years after transplantation when compared with the results before transplantation (P<.05). No significant difference was present in Doppler findings of transplanted kidneys between 6-12 months and 5 years after transplantation. In conclusion we observed increasing kidney size after transplantation that remained constant during 5 year follow-up among renal allograft recipients.

Can Doppler ultrasonographic indices of the renal artery predict the presence of supernumerary renal arteries?

BACKGROUND

Variations of the renal arteries, including the presence of supernumerary renal arteries, are important to be identified prior to renal transplant. Angiography has been the gold standard test for the pretransplant evaluation of the renal vasculature. However, this modality is expensive and invasive. The aim of this study was to assess whether Doppler ultrasonographic (DU) indices of the renal artery could predict the presence of supernumerary renal arteries.

METHODS AND MATERIALS

Retrospectively, we analyzed multidetector computed tomography angiography (presence or absence of the supernumerary renal artery), DU (peak systolic velocity, resistive index, pulsatility index, end-diastolic velocity, and acceleration time) findings of 30 healthy potential renal transplant donors. Recipient operator characteristic (ROC) curves were used to examine the predictive values of the available DU indices for supernumerary renal arteries.

RESULTS

The mean age of donors was 28.4 +/- 4.1 years. Of 60 kidneys evaluated, a supernumerary renal artery was found in 10%. The ROC curve analysis revealed an area under the curve of noninformative (below 0.5) for all DU parameters, indicating that none of the studied parameters could predict the presence of a supernumerary renal artery.

CONCLUSIONS

Although the smaller diameter of the main renal artery has previously been found to predict the presence of supernumerary renal arteries, the present study revealed that DU indices of the renal artery may not indicate the presence of supernumerary renal arteries.