PREDICTING POSTOPERATIVE RENAL INSUFFICIENCY IN PATIENTS UNDERGOING NEPHRECTOMY FOR RENAL MALIGNANCY: ASSESSMENT BY RENAL SCINTIGRAPHY USING 99m TECHNETIUM-MERCAPTOACETYLTRIGLYCINE

Role of Functional SPECT and PET in Renal Emergencies

Renal scintigraphy is a centerpiece of nuclear medicine and is also commonly applied for (peri-)acute care. In this regard, referrals by the treating physician include: I.) acute obstructions caused by gradual and infiltrative tumor growth or renal off-target effects under anti-tumor treatment, II.) functional issues in infants, for example, structural abnormalities such as duplex kidneys or uroliths in adults, which can also trigger III.) Infections of renal parenchyma. Renal radionuclide imaging is also requested due to IV.) acute trauma to the abdomen, for example, to assess renal scarring or upon further follow-up after reconstructive surgery. We will discuss clinical applications of (peri-)acute renal scintigraphy, along with future prospects on the use of more advanced nuclear imaging techniques such as renal positron emission tomography.

Dexmedetomidine postconditioning provides renal protection in patients undergoing laparoscopic partial nephrectomy: A randomized controlled trial

Background: For localized disease, partial nephrectomy of small tumors continues to be the gold-standard treatment. However, temporary clamping is routinely performed during this process to control renal blood flow, which can cause renal ischemic/reperfusion injury. We evaluated whether dexmedetomidine postconditioning (DPOC) can reduce renal ischemic/reperfusion injury for patients receiving laparoscopic partial nephrectomy (LPN).

Methods: This randomized double-blind controlled trial included 77 patients who were scheduled for LPN at our hospital. Patients were randomly allocated to the DPOC or control group. DPOC was performed via intravenous administration of dexmedetomidine at 0.6 μg kg−1 for 10 min immediately after unclamping the renal artery. In the control group, saline was administered in place of dexmedetomidine under the same protocol. All participants underwent a 6-month follow-up. The primary outcome were the values of 99mTc-DTPA-GFR in the affected kidney at one and 6 months post-LPN.

Result: The GFR values in the DPOC group (35.65 ± 4.89 ml min−1.1.73 m−2) were significantly higher than those the control group (33.10 ± 5.41 ml min−1.1.73 m−2; p = 0.022) at 1 month after LPN. There was no statistically significant difference in GFR value between the two groups at 6 months after LPN.

Conclusion: DPOC provides therapeutic benefits to LPN patients, at least on a short-term basis, by alleviating renal ischemic/reperfusion injury.

Clinical Trial Registration: Chinese Clinical Trial Registry, identifier [ChiCTR-TRC-14004766].

Influence of robot-assisted partial nephrectomy on long-term renal function as assessed using DTPA renal scintigraphy

BACKGROUND

The long-term split renal function after robot-assisted partial nephrectomy (RAPN) is yet to be elucidate. This study aimed to assess long-term renal function RAPN, using renal scintigraphy, and to identify clinical factors related to deterioration of renal function on the affected side of the kidney.

PATIENTS AND METHODS

RAPN for small tumors was performed, and split renal function was evaluated using DTPA renal scintigraphy before and 1 year after surgery. Clinical factors (age, sex, body mass index, tumor side, presence of urinary protein, diabetes, hypertension, and dyslipidemia), perioperative factors (renal nephrectomy score [RNS], tumor diameter, overall surgery duration, console time, warm ischemic time, amount of bleeding), and renal function (estimated glomerular filtration rate (eGFR) and glomerular filtration rate (GFR) measured using scintigraphy on both the affected and contralateral kidneys) were analyzed.

RESULTS

Sixty-six patients were included in the study. The median eGFR decreased from 71.9 ml/min to 63.9 ml/min after 1 year (p<.001), accounting for a mean loss of 10.1%. In scintigraphy examination, the median GFR on the affected kidney side decreased from 41.1 ml/min to 33.7 ml/min after 1 year (p<.001), accounting for a mean loss of 16.8%. RNS was significantly associated with renal function. Among RNS factors, the N factor is　associated with renal function after RAPN.

CONCLUSION

RNS, particularly the N factor, possibly influences the long-term deterioration of renal function after RAPN.

The preoperative stratification of patients based on renal scan data is unable to predict the functional outcome after partial nephrectomy

INTRODUCTION

eGFR-categories are used to predict functional outcome after partial nephrectomy (PN); no study categorized patients according to preoperative renal scan (RS) data. Aim of the study was to evaluate if stratification of patients according to RS is a reliable method to predict minor/major loss of renal function after PN.

MATERIALS AND METHODS

We considered patients who underwent PN and RS pre-/post-PN for T1 tumor in our Institution (2007-2017). Demographics, perioperative and specifically functional data were analysed. On the basis of the baseline Split Renal Function (SRF), patients were stratified into risk-categories: 1) baseline operated-kidney SRF range 45-55%; 2) baseline operated-kidney SRF < 45%. Risk categories were analysed with postoperative functional outcome: postoperative operated-kidney SRF decrease below 90% of baseline was considered significant loss of function. Contingency tables and univariate/multivariate regression were analysed looking for independent factors of postoperative functional impairment.

RESULTS

224 patients were analysed, 125 (55.8%) maintained >90% of their baseline function. Worse probability of maintaining ≥90 baseline renal function was found in patients with Charlson's Comorbidity Index (CCI≥3) (p=0.004) and patients with PADUA score ≥8 (p=0.023). After stratification by baseline renal function, ischemia was the only independent factor: no effect on patients with poorer baseline renal function. Patients with baseline SRF 45-55% who did not experience ischemia had the highest probability to maintain ≥90% baseline SRF (p=0.028). Ischemia >25 minutes was detrimental (p=0.017).

CONCLUSIONS

Stratification of patients by SRF before PN is not a reliable predictor of renal functional outcome. Ischemia seems to scarcely influence patients with poorer renal function.

Predictors of Long-Term Survival after Renal Cancer Surgery

PURPOSE

Renal cancer surgery can adversely impact long-term function and survival. We evaluated predictors of chronic kidney disease 5 years and nonrenal cancer mortality 10 years after renal cancer surgery.

MATERIALS AND METHODS

We analyzed the records of 4,283 patients who underwent renal cancer surgery from 1997 to 2008. Radical and partial nephrectomy were performed in 46% and 54% of patients, respectively. Cumulative probability ordinal modeling was used to predict chronic kidney disease status 5 years after surgery and multivariable logistic regression was used to predict nonrenal cancer mortality at 10 years. Relevant patient, tumor and functional covariates were incorporated, including the preoperative glomerular filtration rate (A), the new baseline glomerular filtration rate after surgery (B) and the glomerular filtration rate loss related to surgery (C), that is C = A - B. In contrast, partial or radical nephrectomy was not used in the models due to concerns about strong selection bias associated with the choice of procedure.

RESULTS

Multivariable modeling established the preoperative glomerular filtration rate and the glomerular filtration rate loss related to surgery as the most important predictors of the development of chronic kidney disease (Spearman ρ = 0.78). Age, gender and race had secondary roles. Significant predictors of 10-year nonrenal cancer mortality were the preoperative glomerular filtration rate, the new baseline glomerular filtration rate, age, diabetes and heart disease (all p <0.05). Multivariable modeling established age and the preoperative glomerular filtration rate as the most important predictors of 10-year nonrenal cancer mortality (c-index 0.71) while the glomerular filtration rate loss related to surgery only changed absolute mortality estimates 1% to 3%.

CONCLUSIONS

Glomerular filtration rate loss related to renal cancer surgery, whether due to partial or radical nephrectomy, influences the risk of chronic kidney disease but it may have less impact on survival. In contrast, age and the preoperative glomerular filtration rate, which reflects general health status, are more robust predictors of nonrenal cancer mortality, at least in patients with good preoperative function or mild chronic kidney disease.

Early impact of robot-assisted partial nephrectomy on renal function as assessed by renal scintigraphy

To measure the early impact of robot-assisted partial nephrectomy (RAPN) on renal function as assessed by renal scan (Tc 99m-DTPA), addressing the issue of risk factors for ischemic damage to the kidney. All patients undergoing RAPN for cT1 renal masses between June 2013 and May 2014 were included in this prospective study. Renal function as expressed by glomerular filtration rate (GFR) was assessed by Technetium 99m-diethylenetriaminepentaacetic acid (Tc 99m-DTPA) renal scan preoperatively and postoperatively at 1 month in every patient. A multivariable analysis was used for the determination of independent factors predictive of GFR decrease of the operated kidney. Overall, 32 patients underwent RAPN in the time interval. Median tumor size, blood loss, and ischemia time were 4 cm, 200 mL, and 24 min, respectively. Two grade III complications occurred (postoperative bleeding in the renal fossa, urinoma). The GFR of the operated kidney decreased significantly from 51.7 ± 15.1 mL/min per 1.73 m(2) preoperatively to 40, 12 ± 12.4 mL/min per 1.73 m(2) 1 month postoperatively (p = 0.001) with a decrease of 22.4 %. On multivariable analysis, only tumor size (p = 0.05) was a predictor of GFR decrease of the operated kidney. Robotic-assisted partial nephrectomy had a detectable impact on early renal function in a series of relatively large tumors and prevailing intermediate nephrometric risk. A mean decrease of 22 % of GFR as assessed by renal scan in the operated kidney was found at 1 month postoperatively. In multivariable analysis, tumor size only was a significant predictor of renal function loss.

Comparing Zero Ischemia Laparoscopic Radio Frequency Ablation Assisted Tumor Enucleation and Laparoscopic Partial Nephrectomy for Clinical T1a Renal Tumor: A Randomized Clinical Trial

PURPOSE

We evaluated the functional outcome, safety and efficacy of zero ischemia laparoscopic radio frequency ablation assisted tumor enucleation compared with conventional laparoscopic partial nephrectomy.

MATERIALS AND METHODS

A prospective randomized controlled trial was conducted from April 2013 to March 2015 in patients with cT1a renal tumor scheduled for laparoscopic nephron sparing surgery. All patients were followed for at least 12 months. Patients in the laparoscopic radio frequency ablation assisted tumor enucleation group underwent tumor enucleation after radio frequency ablation without hilar clamping. The primary outcome was the change in glomerular filtration rate of the affected kidney by renal scintigraphy at 12 months. Secondary outcomes included changes in estimated glomerular filtration rate, estimated blood loss, operative time, hospital stay, postoperative complications and oncologic outcomes. The Pearson chi-square or Fisher exact, Student t-test and Wilcoxon rank sum tests were used.

RESULTS

The trial ultimately enrolled 89 patients, of whom 44 were randomized to the laparoscopic radio frequency ablation assisted tumor enucleation group and 45 to the laparoscopic partial nephrectomy group. In the laparoscopic partial nephrectomy group 1 case was converted to radical nephrectomy. Compared with the laparoscopic partial nephrectomy group, patients in the laparoscopic radio frequency ablation assisted tumor enucleation group had a smaller decrease in glomerular filtration rate of the affected kidney at 3 months (10.2% vs 20.5%, p=0.001) and 12 months (7.6% vs 16.2%, p=0.002). Patients in the laparoscopic radio frequency ablation assisted tumor enucleation group had a shorter operative time (p=0.002), lower estimated blood loss (p <0.001) and a shorter hospital stay (p=0.029) but similar postoperative complications (p=1.000). There were no positive margins or local recurrence in this study.

CONCLUSIONS

Zero ischemia laparoscopic radio frequency ablation assisted tumor enucleation enables tumor excision with better renal function preservation compared to conventional laparoscopic partial nephrectomy. Less blood loss and a shorter operative time were achieved with similar postoperative complication rates.

Evaluation of split renal function before and after renal arterial embolization for angiomyolipoma using absolute ethanol

PURPOSE

Transcatheter arterial embolization (TAE) with absolute ethanol is widely accepted as a therapeutic procedure for renal angiomyolipoma (AML). We aim to evaluate the split renal function before and after AE for renal AML by using 99m-technetium (99mTc)-mercaptoacetyltriglycine 3 (MAG3) renography.

METHODS

This study was approved by the Institutional Review Board. The study population comprised 11 renal AML patients (three males, eight females, age 55.1 ± 13.8 years, AML in eight right and three left kidneys) who received unilateral renal TAE with absolute ethanol from April 2002 to January 2013. Blood renal function (i.e. serum creatinine and estimated glomerular filtration rate [eGFR] and split effective renal plasma flow [ERPF]) calculated on 99mTc-MAG3 renography was compared before and within 1 week after renal AE. Statistical analysis was calculated using Wilcoxon signed-ranked test.

RESULTS

TAE for renal AML was technically successful in all patients. Serum creatinine and eGFR did not change before and after TAE. ERPF on the embolized kidney did not change before (127.3 ± 60.8 ml/min) and after (127.6 ± 47.4 ml/min) TAE (p = 0.9726). ERPF on the nonembolized kidney showed a statistically significant increase before (152.5 ± 46.8 ml/min) and within 1 week after (169.1 ± 41.5 ml/min) TAE (p = 0.0093 and p < 0.05, respectively).

CONCLUSION

TAE for renal AML may not induce renal dysfunction on the embolized kidney and may immediately increase the renal blood flow of the nonembolized kidney.

Compensatory hypertrophy after partial and radical nephrectomy in adults

PURPOSE

We assessed compensatory hypertrophy in the contralateral kidney after partial and radical nephrectomy in adults. We also examined predictive factors to facilitate more accurate estimation of global renal function after surgery.

MATERIALS AND METHODS

We analyzed the records of 172 patients who underwent partial or radical nephrectomy with appropriate studies to determine function and parenchymal mass specifically in the operated and contralateral kidneys. All patients required renal scans to provide split renal function preoperatively and postoperatively. Parenchymal volume was measured by computerized tomography. All studies were done less than 2 months preoperatively and 4 to 12 months postoperatively.

RESULTS

A total of 113 and 59 patients underwent partial and radical nephrectomy, and median tumor size was 3.5 and 7.0 cm, respectively (p <0.0001). Of patients treated with partial nephrectomy 19% had high complexity tumor compared to 80% of those treated with radical nephrectomy (p <0.0001). Median ipsilateral parenchymal volume was reduced 18% after partial nephrectomy and the median glomerular filtration rate in this kidney decreased 24.4%. The median contralateral kidney function increase after partial nephrectomy was 2.3% vs 21.1% after radical nephrectomy (p <0.0001). Median global function decreased 9.6% after partial nephrectomy vs 32.2% after radical nephrectomy (p <0.0001). A larger percent parenchymal volume loss (p = 0.0001) and fewer comorbidities (p = 0.0072) significantly correlated with greater compensatory hypertrophy in the contralateral kidney on multivariable analysis.

CONCLUSIONS

Compensatory hypertrophy in adults was limited after partial nephrectomy and it correlated significantly with the amount of parenchymal volume excised. Healthier patients also appeared to respond better. These results may allow for more accurate estimation of global renal function after partial and radical nephrectomy.

Factors that affect proportional glomerular filtration rate after minimally invasive partial nephrectomy

BACKGROUND AND PURPOSE

Several factors have been shown to impact the overall glomerular filtration (GFR) rate after partial nephrectomy. Change in overall GFR, however, does not necessarily reflect the impact of these factors on the operated kidney. Using preoperative and postoperative renal scintigraphy, we sought to assess the impact of patient, tumor, and operative factors on GFR of the affected kidney (proportional GFR).

PATIENTS AND METHODS

We identified 73 patients who underwent minimally invasive partial nephrectomy with preoperative and postoperative renal scans from two institutions. Patient, tumor, and operative characteristics were recorded. We used multiple linear regression to determine the patient and clinical factors predictive of postoperative proportional GFR in the operated kidney. We tested for an interaction between preoperative proportional GFR and nephrometry score and ischemia. We further fitted two separate linear models to compare the proportion of variance (R(2)) explained by ischemia time in change in renal function in the operated kidney with the change in renal function in both kidneys.

RESULTS

Surgical parameters (procedure approach, ischemia time, and estimated blood loss) and preoperative proportional GFR were significantly associated with postoperative proportional GFR. Preoperative proportional GFR (β=5.93, 95% confidence interval [CI]: 3.88, 7.97, P<0.0005) and procedure approach (β=8.67, 95% CI: 4.50, 12.80, P<0.0005) were strongly associated with outcome while ischemia time (β=-1.80, 95% CI: -3.48, -0.11, P=0.04) and estimated blood loss (β=-1.15, 95% CI: -0.29, -0.01, P=0.04) just reached statistical significance. The interaction term between preoperative proportional GFR and nephrometry score or ischemia time was not statistically significant (nephrometry, P=0.2 continuous or P=0.6 categorical, and ischemia, P=0.7, respectively).

CONCLUSION

Lower preoperative proportional GFR, longer ischemia times, and higher blood loss all negatively impact postoperative proportional GFR while tumor complexity as gauged by morphometry scoring does not. Larger studies are needed to determine whether renal scintigraphy is a more accurate method of measuring the impact of the ischemia time on postoperative proportional GFR.

Demonstration of Adaptive Functional Differences Seen in Kidneys Accompanying a Nonfunctioning/Hypofunctioning Partner, using Camera Based Tc 99m MAG3 Clearance Measurement Technique

OBJECTIVE

The aim of this study was to demonstrate the functional compensation that occurs in kidneys which accompany a partner with total or partial loss of renal functioning mass, using camera-based Tc 99m MAG3 clearance technique.

MATERIAL AND METHODS

Eighty five patients (43M, 42F, age: 44.8±12.6, range: 18-77 years) with normal serum creatinine levels and normal (<Grade 1) Tc 99m MAG3 renogram curves were enrolled for this retrospective study. Patients were grouped as having; group 1: solitary normal kidney (unilateral atrophied/agenetic) (n=23), group 2: normal kidney with contralateral hypoplasic/hypofunctioning kidney (split renal function<30%), (n=24), group 3: bilateral normal kidneys (n=38). The measured camera based Tc 99m MAG3 clearances of normal kidneys in each group were compared.

RESULTS

Total Tc 99m MAG3 clearances (mL/min/1.73m2) were significantly lower in group 1 and group 2 compared to group 3 (281.5±46, 260.5±61.7 and 316.1±84, respectively). Highest isolated Tc 99m MAG3 clearances among normal functioning kidneys were observed in group 1 (281.5±45.6) followed by group 2 (204.4±55) and group 3 (157.5±44). Moderate negative correlation was detected between the Tc99m MAG3 clearances of normal kidneys and contralateral renal function (r=-0.5, p<0.001).

CONCLUSION

Normal kidneys can compensate for the loss of contralateral kidney function via increasing their clearances, which seems to be dependent on the residual function of their partner. Camera based Tc 99m MAG3 clearance measurement is an objective method to demonstrate compensatory differences in renal function seen between kidneys with contralateral normofunctioning, hypofunctioning and nonfunctioning partner.

CONFLICT OF INTEREST

None declared.

Effect of remote ischaemic preconditioning on renal protection in patients undergoing laparoscopic partial nephrectomy: a 'blinded' randomised controlled trial

OBJECTIVE

To evaluate whether remote ischaemic preconditioning (RIPC) reduces renal injury in patients undergoing laparoscopic partial nephrectomy (LPN).

PATIENTS AND METHODS

In all, 82 patients undergoing LPN were randomly assigned to either the RIPC or control group, with 40 and 38 patients, respectively completing 6-months follow-up. RIPC was conducted after induction of anaesthesia, which consisted of three 5-min cycles of right lower limb ischaemia and 5 min of reperfusion during each cycle. The primary outcome was the absolute change in glomerular filtration rate (GFR) of the affected kidney by renal scintigraphy from baseline to 6 months. The secondary outcomes included urinary retinol-binding protein (RBP) levels measured at 24 and 48 h, serum creatinine, and estimated GFR (eGFR) at 1 and 6 months, and changes in GFR by renal scintigraphy.

RESULTS

There were no differences in the change of GFR of the affected kidney at 6 months, while it was significantly decreased by 15.0% in the control group vs 8.8% in the RIPC group at 1 month (P = 0.034). The urinary RBP levels increased 8.4-fold at 24 h in the control group compared with a lower increase of 3.9-fold in the RIPC group (P < 0.001). There were no differences in the serum creatinine level or eGFR at 1 and 6 months between the two groups.

CONCLUSIONS

In patients undergoing LPN, RIPC using transient lower limb ischaemia may reduce renal impairment in the short term, but failed in the longer term despite a non-significant trend in favour of RIPC. These novel data support the need for a larger study of RIPC during LPN surgery.

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.