CT volumetry is superior to nuclear renography for prediction of residual kidney function in living donors

Abstract

Living kidney donor evaluation commonly includes nuclear renography to assess split kidney function and computed tomography (CT) scan to evaluate anatomy. To streamline donor workup and minimize exposure to radioisotopes, we sought to assess the feasibility of using proportional kidney volume from CT volumetry in lieu of nuclear renography. We examined the correlation between techniques and assessed their ability to predict residual postoperative kidney function following live donor nephrectomy. In a cohort of 224 live kidney donors, we compared proportional kidney volume derived by CT volumetry with split kidney function derived from nuclear renography and found only modest correlation (left kidney R(2) =26.2%, right kidney R(2) =26.7%). In a subset of 88 live kidney donors with serum creatinine measured 6 months postoperatively, we compared observed estimated glomerular filtration rate (eGFR) at 6 months with predicted eGFR from preoperative imaging. Compared to nuclear renography, CT volumetry more closely approximated actual observed postoperative eGFR for Chronic Kidney Disease Epidemiology Collaboration (J-test: P=.02, Cox-Pesaran test: P=.01) and Mayo formulas (J-test: P=.004, Cox-Pesaran test: P<.001). These observations support the use of CT volumetry for estimation of split kidney function in healthy individuals with normal kidney function and morphology.

Split renal function in patients with renal masses: utility of parenchymal volume analysis vs nuclear renal scans

“…NRS also requires intravenous exposure to 259–407 MBq (7–11 mCi) of radioactive isotope and represents an additional preoperative study with cost of $500–1000 USA dollars . In part due to these considerations, SRF for renal donors is now more commonly accomplished by evaluation of differential PVA and this approach has been shown to be more accurate than NRS in this population .…”

“…Occasional isodense tumours mandate preliminary free‐hand marking to exclude the tumour, after which the software can again be used to assess the parenchymal volumes. Strong consideration should be given to adding PVA to the template for CT/MRI reporting for patients with renal masses, similar to what is done for renal donors , or at least this should be available when requested.…”

“…SRF has traditionally been obtained by nuclear renal scan (NRS), although this requires exposure to radioactive isotopes, increases the cost and burden of the preoperative evaluation, and has limitations including suboptimal interpretation reproducibility . In renal transplant donors, the current standard of care for estimation of SRF at most centres is differential parenchymal volume analysis (PVA) . Based on these data the transplant team can ensure that the donor retains the better kidney, and it also allows prediction of new baseline GFR in both the recipient and the donor .…”

“…In renal transplant donors, the current standard of care for estimation of SRF at most centres is differential parenchymal volume analysis (PVA) . Based on these data the transplant team can ensure that the donor retains the better kidney, and it also allows prediction of new baseline GFR in both the recipient and the donor . In fact, analysis of SRF by PVA has been shown to be more accurate than SRF from NRS for predicting such outcomes after living renal donor transplantation .…”

“…Based on these data the transplant team can ensure that the donor retains the better kidney, and it also allows prediction of new baseline GFR in both the recipient and the donor . In fact, analysis of SRF by PVA has been shown to be more accurate than SRF from NRS for predicting such outcomes after living renal donor transplantation . However, this patient population is generally young and healthy, and in this setting renal function is likely to correlate more directly with parenchymal volume.…”