The value of quantitative 99M technetium dimercaptosuccinic acid renal scintigraphy for predicting postoperative renal insufficiency in patients undergoing nephrectomy

Predictive preoperative factors for renal insufficiency in patients followed for more than 5 years after radical nephrectomy

Purpose

We assessed the predictive factors for renal insufficiency in patients followed for more than 5 years after radical nephrectomy.

Materials and Methods

Age, gender, history of diabetes, history of hypertension, body mass index, preoperative estimated glomerular filtration rate (eGFR), serum uric acid, urine albumin, normal renal parenchymal volume, tumor size, and ratio of normal parenchymal volume of the removed kidney to that of the remaining kidney were evaluated retrospectively in 89 patients who underwent radical nephrectomy from January 2001 to December 2005. Patients were included whose renal parenchymal volume was measurable by use of perioperative imaging (computed tomography or magnetic resonance imaging), whose preoperative eGFR was greater than 60 mL/min/1.73 m², and who were followed for more than 5 years. To measure renal parenchymal volume from imaging, we integrated the extent of the normal renal parenchyma from axial slides of images.

Results

In univariate and multivariate binary regression analysis, the parenchymal volume of the remnant kidney (p=0.001), a history of diabetes (p=0.035), and preoperative eGFR (p=0.011) were independent factors for renal insufficiency. By use of a receiver operating characteristic curve, a volume of 170 mL was determined to be an appropriate cutoff value, with sensitivity of 58.7% and specificity of 74.4% for the parenchymal volume of the remnant kidney for predicting eGFR less than 60 mL/min/1.73 m² (area under the curve, 0.678). The parenchymal volume of the remnant kidney was also an independent factor for the downgrading of the chronic kidney disease category in the multivariate linear regression analysis (p=0.021).

Conclusions

Preoperative eGFR, a history of diabetes, and the radiologic volume of the remaining kidney parenchyma could be useful factors for predicting postoperative renal function. Patients with parenchymal volumes of less than 170 mL have a higher risk of postoperative renal insufficiency, which should be considered carefully when choosing a treatment modality.

Assessing renal function after partial nephrectomy using renal nuclear scintigraphy and estimated glomerular filtration rate

OBJECTIVE

To create a model intended to more accurately characterize renal function alteration after partial nephrectomy using a combination of renal scintigraphy and estimated glomerular filtration rate (eGFR).

METHODS

Thirty-two partial nephrectomy patients from a single center with preoperative and postoperative renal scans were reviewed. Renal scan data were used to calculate proportional eGFR in the involved kidney as a product of the percentage function of the operated kidney and total eGFR. Linear regression models were created to describe endpoints (postoperative eGFR, involved kidney percent function, proportional eGFR) as functions of clinical variables associated with kidney damage.

RESULTS

For the ipsilateral kidney, mean preoperative percent function and eGFR were 50% (SD, 4.8) and 31 mL/min/m(2) (SD, 3.4), respectively; postoperative percent function and involved kidney eGFR were 44% (SD, 9.0) and 27 mL/min/m(2) (SD, 9.0), respectively. Decreased postoperative proportional eGFR was significantly associated with increased clamp time and tumor size in univariate linear regression models. Clamp time was associated with total eGFR, where tumor size was not. Additionally, clamp time and tumor size explain more of the variation in proportional eGFR (R(2) = 0.39 and R(2) = 0.17, respectively), compared to percent effort and total eGFR.

CONCLUSION

Proportional eGFR has a stronger association with putative factors of renal dysfunction after partial nephrectomy, including clamp time and tumor size, compared to total eGFR, indicating it may be a more sensitive marker of renal function after partial nephrectomy.