Predictive ability of renal cortex enhancement in dynamic computed tomography for residual renal function after nephroureterectomy: Comparison with ^99mTc‐diethylenetriaminopentacetic acid renography and validation study

Abstract

Objective To estimate postoperative residual renal function after radical nephroureterectomy for upper tract urothelial carcinoma using the preoperative dynamic computed tomography renal cortex enhancement ratio in comparison with the split kidney glomerular filtration rate measured by 99mTc‐diethylenetriaminopentacetic acid renography. Methods A total of 47 patients who received radical nephroureterectomy and underwent both preoperative dynamic computed tomography and renography were the model‐development cohort; and 109 patients who underwent dynamic computed tomography alone were the validation cohort. Postoperative renal function of the unremoved kidney was estimated using the following formulas: preoperative estimated glomerular filtration rate × the percentage of total renal cortex radiodensity for the intact kidney in Hounsfield units obtained from corticomedullary phase images in the computed tomography‐based model, or the percentage of the total glomerular filtration rate measured by renography in the nuclear model. The correlation between observed and estimated postoperative renal function was determined. The computed tomography‐based prediction model derived from linear regression analysis was validated externally. Results The correlation of computed tomography‐based split renal function with the observed postoperative estimated glomerular filtration rate (r = 0.80) was equivalent to that of nuclear split renal function (r = 0.78). In the validation cohort, the computed tomography‐based prediction model showed an equivalently strong correlation (r = 0.78). Conclusions The present study showed that the percentage of total renal cortex radiodensity for the intact kidney is a useful tool for predicting unremoved kidney function in upper tract urothelial carcinoma patients, thereby allowing appropriate patient selection for perioperative cisplatin‐based combination chemotherapy.

Potential of Perfusion Magnetic Resonance Imaging to Predict Residual Renal Function after Radical Nephroureterectomy

“…External radionuclide counting is considered a common way to determine SRF. The measured value itself, however, poorly correlated with postoperative renal function, and the approach of splitting the Cr-based total eGFR value would be needed [2]. In the current study, the ability to predict postoperative renal function using DWI was equal to the predictive capacity of renography.…”

“…In dynamic CT, the radiodensity in Hounsfield units of each pixel was reported to reflect the blood volume contained within glomeruli and peritubular capillaries in each pixel [1]. Therefore, Hounsfield units can serve as surrogate indicators of renal function, as we have previously showed [2]. However, patients who might require reductions in the dosage of cisplatin-based chemotherapy due to impaired renal functioning were often unable to be given adequate levels of radiocontrast agents [3].…”

“…It has previously been reported that the radiodensity measured within the renal cortex using a dynamic CT reflects the blood volume contained within the glomeruli and peritubular capillaries [1]. Similarly, it has been shown that the radiodensity of the renal cortex was a useful tool as renography for quantitatively predicting postoperative residual renal function in UTUC patients [2]. However, patients with borderline levels of renal function for full-dose cisplatin-based combination chemotherapy typically cannot be given the contrast agent [3].…”

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

“…Intra‐ and inter‐observer variance or discordance can be substantial with NRS, ranging from 10–15% and 6–19%, respectively . 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 .…”

Changes in kidney function according to ischemia type during partial nephrectomy for T1a kidney cancer

“…The parenchymal thickness and parenchymal enhancement were measured at the hilar level of the ipsilateral kidney without overlapping the renal mass 8 . Parenchymal enhancement was calculated on the arterial phase of 3D-kidney CT. Parenchymal enhancement was normalized by defining it as the ratio of Hounsfield unit of parenchyma to that of the aorta 11,12,16 . The parenchymal thickness and parenchymal enhancement, measured by different urologists, were averaged.…”