Volumetric measurement of compensatory hypertrophy in the contralateral normal kidney by the tumor growth

Renal transplants increase in size and function in keeping with compensatory renal hypertrophy

AIM

To evaluate changes in allograft kidney length in renal transplant recipients and the relationship with estimated glomerular filtration rate (eGFR).

METHODS

This single-centre retrospective study of renal transplant recipients was conducted at Flinders Medical Centre (FMC) from January 2007 to June 2020. Donor and recipient details, renal allograft length from transplant ultrasounds at 0, 1, 3, 6 and 12 months were collected. The association between compensatory renal hypertrophy (CRH) and eGFR and its magnitude was analysed using multivariate multilevel mixed-effects linear regression models.

RESULTS

A total of 183 renal transplant recipients were studied. 100 of 175 recipients (62.9%) demonstrated an increase in renal length defined as any increase in maximal longitudinal diameter on serial ultrasounds. Twenty-three recipients (13.1%) had no change in transplant length and 42 recipients (24%) had a decrease in length. The mean increase in kidney length over the first 12 months was 0.57 cm. Ninety of 156 (57.7%) recipients with a renal ultrasound within a month post-transplant demonstrated a mean increase kidney length of 0.3 cm. Multivariate analysis demonstrated that eGFR increased by 2.5 mL/min/1.73 m2 (95% CI 0.72- 4.4; p = .006) with every 1 cm increase in kidney length. Absolute changes in kidney length did not demonstrate any statistically significant correlation with eGFR in both complete case and multiple imputation analysis.

CONCLUSION

An increase in transplant kidney length is common in renal transplant recipients and is associated with enhanced eGFR. However, further studies need to be performed to study the association of absolute change in kidney length and eGFR.

Volumetric and functional outcomes at 1-year between percutaneous-ablation and partial-nephrectomy for T1b renal tumors

INTRODUCTION

Indication for percutaneous-ablation (PA) is gradually expanding to renal tumors T1b (4-7cm). Few data exist on the alteration of renal functional volume (RFV) post-PA. Yet, it is a surrogate marker of post partial-nephrectomy (PN) glomerular filtration rate (GFR) impairment. The objective was to compare RFV and GFR at 1-year post-PN or PA, in this T1b population.

METHODS

Patients with unifocal renal tumor≥4cm treated between 2014 and 2019 were included. Tumor, homolateral (RFVh), contralateral RFV, and total volumes were assessed by manual segmentation (3D Slicer) before and at 1 year of treatment, as was GFR. The loss of RFV, contralateral hypertrophy, and preservation of GFR were compared between both groups (PN vs. PA).

RESULTS

144 patients were included (87PN, 57PA). Preoperatively, PA group was older (74 vs. 59 years; P<0.0001), had more impaired GFR (73 vs. 85mL/min; P=0.0026) and smaller tumor volume(31.1 vs. 55.9cm3; P=0.0007) compared to PN group. At 1 year, the PN group had significantly more homolateral RFV loss (-19 vs. -14%; P=0.002), and contralateral compensatory hypertrophy (+4% vs. +1,8%; P=0.02, respectively). Total-RFV loss was similar between both (-21.7 vs. -19cm3; P=0.07). GFR preservation was better in the PN group (95.9 vs. 90.7%; P=0.03). In multivariate analysis, age and tumor size were associated with loss of RFVh.

CONCLUSION

For renal tumors T1b, PN is associated with superior compensatory hypertrophy compared with PA, compensating for the higher RFVh loss, resulting in similar ΔRFV-total between both groups. The superior post-PN GFR preservation suggests that the preserved quantitative RFV factor is insufficient. Therefore, the underlying quality of the parenchyma would play a major role in postoperative GFR.

Preoperative versus Postoperative Compensation of the Contralateral Normal Kidney in Patients Treated with Radical Nephrectomy for Renal Cell Carcinoma

BACKGROUND

We sought to identify the factors affecting renal compensatory processes that occur preoperatively as well as postoperatively in patients treated with radical nephrectomy (RNx) for renal cell carcinoma (RCC).

METHODS

We retrospectively reviewed the records of 906 patients treated with RNx for RCC. We defined the early compensatory process (process 1) as compensatory adaptation of the contralateral normal kidney (CNK) before RNx. We defined the late compensatory process (process 2) as compensatory adaptation of the CNK after RNx. Total compensation was defined as the combination of these two processes. Multivariable logistic regression analyses were used to identify significant factors associated with processes 1, 2 and total compensation.

RESULTS

Mean preoperative, 1-week, and 5-year postoperative estimated glomerular filtration rates (eGFR) were 84.5, 57.6 and 63.7 mL/min/1.73 m2, respectively. Female sex (p < 0.001), lower body mass index (BMI) (p < 0.001), absence of hypertension (p = 0.019), lower preoperative eGFR (p < 0.001), larger tumor volume (p < 0.001), and larger CNK volume (p < 0.001) were significantly associated with process 1. Younger age (p = 0.019), higher BMI (p < 0.001), and absence of diabetes mellitus (DM) (p = 0.033) were significantly associated with process 2. Female sex (p < 0.001), younger age (p < 0.001), absence of DM (p = 0.002), lower preoperative eGFR (p < 0.001), and larger tumor (p = 0.001) and CNK volumes (p < 0.001) were significantly associated with total compensation.

CONCLUSIONS

Different factors affected each compensatory process. Process 1 made a greater contribution to the entire renal compensatory process than process 2.

Volumetric assessment of unaffected parenchyma and Wilms' tumours: analysis of response to chemotherapy and surgery using a semi-automated segmentation algorithm in children with renal neoplasms

OBJECTIVE

To present our proof of concept with semi-automatic image recognition/segmentation technology for calculation of tumour/parenchyma volume.

METHODS

We reviewed Wilms' tumours (WTs) between 2000 and 2018, capturing computed tomography images at baseline, after neoadjuvant chemotherapy (NaC) and postoperatively. Images were uploaded into MATLAB-3-D volumetric image processing software. The program was trained by two clinicians who supervised the demarcation of tumour and parenchyma, followed by automatic recognition and delineation of tumour margins on serial imaging, and differentiation from uninvolved renal parenchyma. Volume was automatically calculated for both.

RESULTS

During the study period, 98 patients were identified. Of these, based on image quality and availability, 32 (38 affected moieties) were selected. Most patients (65%) were girls, diagnosed at age 50 ± 37 months of age. NaC was employed in 64% of patients. Surgical management included 27 radical and 11 partial nephrectomies. Automated volume assessment demonstrated objective response to NaC for unilateral and bilateral tumours (68 ± 20% and 53 ± 39%, respectively), as well as preservation on uninvolved parenchyma with partial nephrectomy (70 ± 46 cm³ at presentation to 57 ± 41 cm³ post-surgery).

CONCLUSION

Volumetric analysis is feasible and allows objective assessment of tumour and parenchyma volume in response to chemotherapy and surgery. Our data show changes after therapy that may be otherwise difficult to quantify. Use of such technology may improve surgical planning and quantification of response to treatment, as well as serving as a tool to predict renal reserve and long-term changes in renal function.

Cross-Sectional Investigations of Pre- and Post-Operative Renal Global Function and Renal Parenchymal Volumetry in Both Partial and Radical Nephrectomy Utilizing Film-Based Technology

Objectives

To investigate pre- and post-operative renal global function and renal parenchymal volume (RPV) in both partial nephrectomy (PN) and radical nephrectomy (RN) utilizing film-based technology.

Patients and Methods

The patient cohort consisted of 81 and 82 cases with T1 tumors (≤ 7 cm) treated by PN and RN, respectively. Renal global function was assessed using the estimated glomerular filtration rate (eGFR), and RPV was measured using a Synapse Vincent volumetric analyzer which creates a reconstructed image from a computed tomography scan. Renal global function and RPV were evaluated pre-operatively and 6 months post-operatively.

Results

The percent eGFR decline of PN cases was significantly reduced compared with RN cases (p < 0.0001). Post-operative RPV of the contralateral side was significantly increased compared with pre-operative RPV (p < 0.0001) in RN cases. The percent change of the contralat-eral side RPV was slightly increased in RN compared with PN cases (p = 0.1881). A strong positive correlation was noted between post-operative eGFR and post-operative total RPV (r = 0.69, p < 0.0001), and a strong negative correlation was noted between percent eGFR decline and post-operative total RPV (r = -0.63, p < 0.0001).

Conclusions

Prominent compensatory renal hypertrophy occurred within 6 months after RN. Post-operative renal functional outcome was closely correlated with the post-operative total RPV. In addition to RPV, further studies to unravel post-operative renal function from multifactorial aspects including surgical factors and intrinsic medical disease should be performed in the future.

Infrared Light Structured Sensor Three-dimensional Approach to Estimate Kidney Volume: A Validation Study

OBJECTIVE

To validate a new procedure for the three-dimensional estimation of total renal parenchyma volumeusing a structured-light infrared laser sensor.

METHODS

To evaluate the accuracy of the sensor for assessing renal volume, we performed 3 experiments. Twenty freshly excised porcine kidneys were obtained. Experiment A, the water displacement method was used to obtain a determination of the renal parenchyma volume after immersing every kidney into 0.9% saline. Thereafter a structured sensor (Occipital, San Francisco, CA) was used to scan the kidney. Kidney sample surface was presented initially as a mesh and then imported into MeshLab (Visual Computing Lab, Pisa, Italy) software to obtain the surface volume. Experiment B, a partial excision of the kidney with measurement of the excised volume and remnant was performed. Experiment C, a renorrhaphy of the remnant kidney was performed then measured. Bias and limits of agreement (LOA) were determined using the Bland-Altman method. Reliability was assessed using the intraclass correlation coefficient (ICC).

RESULTS

Experiment A, the sensor bias was -1.95mL (LOA: -19.5 to 15.59, R² = 0.410) with slightly overestimating the volumes. Experiment B, remnant kidney after partial excision and excised kidneyvolume were measured showing a sensor bias of -0.5mL (LOA -5.34 to 4.20, R²= 0.490) and -0.6mL (LOA: -1.97.08 to 0.77, R² = 0.561), respectively. Experiment C, the sensor bias was -0.89mL (LOA -12.9 to 11.1, R²= 0.888). ICC was 0.9998.

CONCLUSION

The sensor is a reliable method for assessing total renal volume with high levels of accuracy.

A useful method for assessing differences of compensatory hypertrophy in the contralateral kidney before and after radical nephrectomy in patients with renal cell carcinoma: ellipsoid formula on computed tomography

OBJECTIVE

To investigate the usefulness of the ellipsoid formula for assessing compensatory hypertrophy of the contralateral kidney on pre-operative and post-operative CT in renal cell carcinoma (RCC) patients.

METHODS

We retrospectively identified 389 patients who had radical nephrectomy for RCC between 2011  and 2015. Contrast-enhanced CT was performed within 3 months pre-operative and at 1 year post-operative. The kidney volumes were calculated from CT using the ellipsoid formula. We subdivided patients into three groups based on tumour size (I: ≤4 cm, II: 4-7 cm, III: >7 cm). Volumetric renal parameters were compared and multivariate analyses were performed to determine predictors associated with pre-operative  and post-operative compensatory hypertrophy.

RESULTS

Kidney volume calculation using the ellipsoid  method took a median of 51 s. Group III had a significantly larger median pre-operative contralateral renal volume than Groups I and II (I:  140.4, II: 141.6, III: 166.7 ml, p < 0.05). However, the median ratio of post-operative contralateral renal volume change was significantly higher in Groups I and II than Group III (I: 0.36, II: 0.23, III: 0.12, p < 0.001). On multivariate analysis, tumour size revealed the strongest positive association with pre-operative contralateral kidney volume (partial regression coefficient: β = 30.8, >7 cm) and ratio of post-operative contralateral kidney volume change (β  = 0.214, I vs III; β = 0.168, II vs III).

CONCLUSION

Kidney volume calculation for assessing pre- and post-operative compensatory hypertrophy of the contralateral kidney in RCC patients can be easily and rapidly performed from CT images using the ellipsoid formula. Advances in knowledge: The ellipsoid formula allows reliable method for assessing pre-operative and post-operative compensatory hypertrophy of the contralateral kidney in RCC.

Benign and tumor parenchyma metabolomic profiles affect compensatory renal growth in renal cell carcinoma surgical patients

BACKGROUND AND OBJECTIVES

Pre-operative kidney volume is an independent predictor of glomerular filtration rate in renal cell carcinoma patients. Compensatory renal growth (CRG) can ensue prior to nephrectomy in parallel to tumor growth and benign parenchyma loss. We aimed to test whether renal metabolite abundances significantly associate with CRG, suggesting a causative relationship.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

Tissue metabolomics data from 49 patients, with a median age of 60 years, were previously collected and the pre-operative fold-change of their contra to ipsi-lateral benign kidney volume served as a surrogate for their CRG. Contra-lateral kidney volume fold-change within a 3.3 +/- 2.1 years follow-up interval was used as a surrogate for long-term CRG. Using a multivariable statistical model, we identified metabolites whose abundances significantly associate with CRG.

RESULTS

Our analysis found 13 metabolites in the benign (e.g. L-urobilin, Variable Influence in Projection, VIP, score = 3.02, adjusted p = 0.017) and 163 metabolites in the malignant (e.g. 3-indoxyl-sulfate, VIP score = 1.3, adjusted p = 0.044) tissues that significantly associate with CRG. Benign/tumor fold change in metabolite abundances revealed three additional metabolites with that significantly positively associate with CRG (e.g. p-cresol sulfate, VIP score = 2.945, adjusted p = 0.033). At the pathway level, we show that fatty-acid oxidation is highly enriched with metabolites whose benign tissue abundances strongly positively associate with CRG, both pre-operatively and long term, whereas in the tumor tissue significant enrichment of dipeptides and benzoate (positive association), glycolysis/gluconeogenesis, lysolipid and nucleotide sugar pentose (negative associations) sub-pathways, were observed.

CONCLUSION

These data suggest that specific biological processes in the benign as well as in the tumor parenchyma strongly influence compensatory renal growth.

The significance of predictable traumatic area by renorrhaphy in the prediction of postoperative ipsilateral renal function

Introduction

To determine the relationship between the actual renal function loss and volume loss in robot-assisted partial nephrectomy (RAPN) using a novel three-dimensional volume analyzer.

Material and methods

We respectively evaluated the medical records of 23 consecutive patients who underwent RAPN between January 2012 and March 2016 and the data on their kidney function and parenchymal mass specific to the operated kidney. Parenchymal volume was measured by computerized tomography and reconstructed with a Synapse Vincent volumetric analyzer. Using this system, we predicted the renal vascular territory and other trauma areas involved in renorrhaphy. All measurements were taken within 3 and 6 months pre- and postoperatively, respectively.

RESULTS

The actual postoperative renal parenchymal volume was significantly correlated with the virtual predicted residual renal volume excluding the tumor and resected margin (r = 0.435, p <0.05). The ratio of split estimated glomerular filtration rate (eGFR) postoperative/preoperative) was significantly correlated with the virtual predicted residual renal volume excluding the resected margin and the traumatic area by renorrhaphy (r = 0.401, p <0.05).

Conclusions

When predicting the reduction of renal function of the diseased side following partial nephrectomy, adding the extent of the area traumatized by renorrhaphy might be useful for predicting the postoperative split renal function of the affected kidney.

The effect of contralateral kidney volume on renal function after radical nephroureterectomy: Implications for eligibility for neoadjuvant chemotherapy for upper tract urothelial cancer

PURPOSE

We investigated the effect of preoperative contralateral kidney (CK) volume on renal function after radical nephroureterectomy (RNU).

METHODS

We reviewed 630 patients who underwent RNU between September 1994 and December 2013. Of these 630 patients, 135 patients with advanced upper tract urothelial cancer were ultimately included. Preoperative CK volume was measured from computed tomography images of the venous phase using a specialized volumetric program. Glomerular filtration rate (GFR) was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations and checked preoperatively, 7 days, 1, 3, and 12 months postoperatively.

RESULTS

The mean age at surgery was 62.1 (10.1) years and the mean CKD-EPI GFR was 73.8 (75.5) ml/min/1.73m². After RNU, new-onset CKD was identified in 69 (51.1%) patients. On multivariate logistic regression analysis, high body mass index (95% CI: 1.08-1.51, P = 0.005), low preoperative CKD-EPI GFR (95% CI: 0.92-0.98, P = 0.037), and low CK volume (95% CI: 0.96-0.99, P<0.001) were associated with new-onset CKD at 1 month after RNU. There was a positive correlation between CK volume and CKD-EPI GFR at 1 month after RNU (Spearman ρ = 0.495, P<0.001). When stratified according to CK volume, CK volume less than 150ml was significantly associated with new-onset CKD after RNU (95% CI: 2.49-26.29, P = 0.001).

CONCLUSIONS

High body mass index, low preoperative CKD-EPI GFR, and low CK volume are significantly associated with new-onset CKD. Therefore, they could be used to identify patients eligible for neoadjuvant chemotherapy in upper tract urothelial cancer.

Comparison of preoperative adaptive enlargement of the contralateral normal kidney in patients nephrectomized for benign non-functioning kidney versus renal cell carcinoma

OBJECTIVES

To investigate the potential effects of preoperative volumetric compensation of the contralateral normal kidney on renal function after simple nephrectomy or radical nephrectomy.

METHODS

A total of 306 patients (80 simple nephrectomy patients and 226 radical nephrectomy patients) with 1:3 propensity score matching were included between October 1996 and December 2013. Preoperative three-dimensional kidney volume was estimated from computed tomography images using a specialized volumetric program. Glomerular filtration rate assessed using the Chronic Kidney Disease Epidemiology Collaboration equations was checked preoperatively, 1 week, 3 months and 1 year after nephrectomy.

RESULTS

Preoperative mean Chronic Kidney Disease Epidemiology Collaboration glomerular filtration rate was 76.5 mL/min/1.73 m(2) in the simple nephrectomy group and 89.2 mL/min/1.73 m(2) in the radical nephrectomy group. In simple nephrectomy patients, mean Chronic Kidney Disease Epidemiology Collaboration glomerular filtration rate showed a stable pattern up to 3 months (75.5 mL/min/1.73 m(2) at 7 days and 76.2 mL/min/1.73 m(2) at 3 months), and decreased slightly to 72.6 mL/min/1.73 m(2) at 1 year. However, in radical nephrectomy patients, mean Chronic Kidney Disease Epidemiology Collaboration glomerular filtration rate decreased immediately to 63.4 mL/min/1.73 m(2) at 7 days after surgery, and then increased gradually to 64.6 mL/min/1.73 m(2) at 3 months and 65.9 mL/min/1.73 m(2) at 1 year. Preoperative mean contralateral normal kidney volume was 225.7 mL in the simple nephrectomy group and 180.1 mL in the radical nephrectomy group (P < 0.001). The contralateral normal kidney volume to total normal kidney volume ratio was 0.74 in the simple nephrectomy group and 0.51 in the radical nephrectomy group (P < 0.001).

CONCLUSIONS

Preoperative volumetric compensation of the contralateral normal kidney is important to maintain postoperative renal function in patients undergoing nephrectomy.