Three-dimensional renal CT angiography for guiding segmental renal artery clamping during laparoscopic partial nephrectomy

Depiction rate of feeding arteries of renal cell carcinoma on four-dimensional computed tomography angiography

PURPOSE

To retrospectively evaluate the depiction rate of feeding arteries in biopsy-proven clear cell renal cell carcinoma (CCRCC) on four-dimensional computed tomography angiography (4D-CTA) images.

MATERIALS AND METHODS

This study included 22 patients with 22 CCRCC and 30 feeding arteries treated with transcatheter renal artery embolization. The depiction rate of the feeding arteries on preprocedural 4D-CTA was evaluated. Images were acquired by 320-row multi-detector computed tomography (CT) 15‒36 s after starting to inject a contrast agent (600 mg/kg iodine) intravenously into patients at 2.1 s intervals (11 phases). Two board-certified radiologists retrospectively assessed the feeder depiction rate in all 11 phases with reference to the procedural images as the gold standard. Discrepancies were resolved by consultation with a third radiologist.

RESULTS

Among the feeders, 11 (36.7%) were segmental or lobar, and 19 (63.3%) were interlobar or arcuate arteries. The feeder depiction rate was the highest (25 [83.3%] of 30) in the 5th phase (delay, 23.4 s) where the gap in contrast enhancement between the renal artery and cortex was the largest. This was followed by the 6th (23 [76.7%] of 30), 4th (22 [73.3%] of 30]), and 7th (21 [70.0%] of 30) phases. The overall rate of depicting feeding arteries in the 11 phases of 4D-CTA was 28 (93.3%) of 30.

CONCLUSIONS

The depiction rate of CCRCC feeding arteries including lobar or smaller artery branches by 4D-CTA was favorable. The feeding arteries were optimally visualized during the phase with the largest contrast gap between the renal artery and cortex.

A novel 3D deep learning model to automatically demonstrate renal artery segmentation and its validation in nephron-sparing surgery

Purpose

Nephron-sparing surgery (NSS) is a mainstream treatment for localized renal tumors. Segmental renal artery clamping (SRAC) is commonly used in NSS. Automatic and precise segmentations of renal artery trees are required to improve the workflow of SRAC in NSS. In this study, we developed a tridimensional kidney perfusion (TKP) model based on deep learning technique to automatically demonstrate renal artery segmentation, and verified the precision and feasibility during laparoscopic partial nephrectomy (PN).

Methods

The TKP model was established based on convolutional neural network (CNN), and the precision was validated in porcine models. From April 2018 to January 2020, TKP model was applied in laparoscopic PN in 131 patients with T1a tumors. Demographics, perioperative variables, and data from the TKP models were assessed. Indocyanine green (ICG) with near-infrared fluorescence (NIRF) imaging was applied after clamping and dice coefficient was used to evaluate the precision of the model.

Results

The precision of the TKP model was validated in porcine models with the mean dice coefficient of 0.82. Laparoscopic PN was successfully performed in all cases with segmental renal artery clamping (SRAC) under TKP model’s guidance. The mean operation time was 100.8 min; the median estimated blood loss was 110 ml. The ischemic regions recorded in NIRF imaging were highly consistent with the perfusion regions in the TKP models (mean dice coefficient = 0.81). Multivariate analysis revealed that the feeding lobar artery number was strongly correlated with tumor size and contact surface area; the supplying segmental arteries number correlated with tumor size.

Conclusions

Using the CNN technique, the TKP model is developed to automatically present the renal artery trees and precisely delineate the perfusion regions of different segmental arteries. The guidance of the TKP model is feasible and effective in nephron-sparing surgery.

Measurement of Glomerular Filtration Rate Using Multiphasic Computed Tomography in Patients With Unilateral Renal Tumors: A Feasibility Study

Objectives

This study was to assess the feasibility of a modified multiphasic CT scan protocol combined with homemade software measurements of glomerular filtration rate (CT-GFR) and explore the effect of renal tumor volume on the calculation of CT-GFR.

Materials and Methods

Prospective observational study comparing three methods of GFR measurement from February 2017 to December 2017, 91 patients with unilateral renal tumor underwent both a modified multiphasic CT scans of kidney and serum creatinine (Scr) tests preoperatively, of which 15 cases underwent additional radionuclide examination. Total and split CT-GFR, with or without renal tumor, were quantified by the homemade software in early and late renal parenchymal phases, respectively. The volume of renal tumor was quantified by the homemade software. Correlation and difference between CT-GFR and traditional methods of GFR measurement, including estimated GFR (eGFR) from Scr concentration and split GFR using of radionuclide examination (R-GFR), were performed.

Results

There is a strong correlation between CT-GFR with renal tumor and eGFR (r = 0.90, p < 0.001) in early renal parenchymal phase. The relative CT-GFR in early renal parenchymal phase was highly correlated with the relative R-GFR (r = 0.88, p < 0.001). Renal tumor volume significantly correlated with the value of CT-GFR that determined by subtracting the CT-GFR measurement without renal tumor from CT-GFR measurement with renal tumor (r = 0.89, p < 0.001).

Conclusion

A modified multiphasic CT scan protocol combined with homemade software might be an alternative technique for the evaluation of renal function for the patients with unilateral renal tumor.

3D CT of renal pathology: initial experience with cinematic rendering

3D computed tomography (CT) visualizations of volumetric data have become an important aspect of diagnostic imaging. The utility of 3D CT has been well described for the imaging of a number of renal pathologies. Recently, a new 3D visualization technique known as cinematic rendering (CR) has become available and provides photorealistic images derived from standard CT acquisitions by use of a complex global lighting model. Herein, we describe a number of normal variant and pathologic conditions of the kidney visualized with CR. We provide comparisons of findings with CR to traditional methods of 3D imaging and comment on the potential applications of this new method of 3D CT rendering.

Integration of anatomical and radiological analysis suggests more segments in the human kidney

An increasing number of observations have called the general scheme of five renal segments into question: anatomists, radiologists, and surgeons have reported discrepancies between Graves's scheme and morphological observations. The aims of the present study are: (1) to assess the correspondence between a virtual and a real vascular cast of the kidney; (2) to analyze the arterial anatomy with reference to the renal segments. Fifteen kidneys were injected with acrylic resins to obtain vascular casts, which were also analyzed by computed tomography. A mean of 6.3 (range 4-8) avascular fissures was found, indicating a mean of 7.3 segments (range 5-9). In the superior and middle territories there was a single segment in 4 (26.7%) and 8 (53.3%) cases, respectively, and there were two segments in 11 (73.3%) and in 7 (46.7%) cases, respectively. In the inferior territory there was a single segment in two cases (13.3%), two segments in nine (60%), and three segments in four (26.7%). A mean segmental volume of 550.5 mm³ was calculated; the posterior (1,030.1 mm³ , 28.9%) and inferior (450.3 mm³ , 24.2%) segments were the largest. More third order branches were identified in the inferior segments than in the other segments (three branches of the inferior segmental artery in 26.6%). According to these data the inferior segment occupies the inferior pole, extending both anteriorly and posteriorly. In conclusion, the high correspondence between a virtual and a real vascular cast permits more segments to be identified than those described by Graves, and the volume of each segment can be calculated. Clin. Anat., 2018. © 2018 Wiley Periodicals, Inc.

Delayed enhancement of the peritumoural cortex in clear cell renal cell carcinoma: correlation with Fuhrman grade

AIM

To assess the delayed enhancement of the peritumoural cortex (DEC) sign in clear cell renal cell carcinoma (ccRCC), and investigate a possible correlation among DEC and Fuhrman grade.

MATERIALS AND METHODS

This retrospective study included 506 patients with 511 histopathologically proven ccRCCs evaluated by computed tomography (CT) angiography. DEC was detected and compared in groups divided by Fuhrman grades (low grade: 1 and 2, high grade: 3 and 4) using univariate and multivariate analyses.

RESULTS

DEC was detected in 89 of 511 (17.4%) ccRCCs (grade 1: 5.7%, 2/35; grade 2: 16.2%, 70/433; grade 3: 31.4%, 11/35; grade 4: 75%, 6/8; p<0.001). The incidence was higher in high-grade ccRCCs (39.5%, 17/43) than in low-grade ccRCCs (15.4%, 72/468; p<0.001). In multivariate analysis, tumour size >5.4 cm (p<0.001, odds ratio [OR]=3.57, 95% confidence interval [CI]: 1.76-7.23) and detection of DEC (p=0.021, OR=2.33, 95% CI: 1.13-4.80) were independent predictors of high-grade ccRCC. For all ccRCCs, the area under the receiver operating characteristic (ROC) curve (AUC) of DEC in predicting high-grade ccRCC was 0.62 (95% CI: 0.53-0.72) with 39.5% sensitivity and 84.6% specificity, while for ccRCCs of >5.4 cm diameter, the AUC was 0.66 (95% CI: 0.52-0.80) with 68.4% sensitivity and 62.7% specificity.

CONCLUSIONS

The DEC sign may predict aggressive biological behaviour of ccRCC, irrespective of tumour size.

Virtual and Augmented Reality Systems for Renal Interventions: A Systematic Review

PURPOSE

Many virtual and augmented reality systems have been proposed to support renal interventions. This paper reviews such systems employed in the treatment of renal cell carcinoma and renal stones.

METHODS

A systematic literature search was performed. Inclusion criteria were virtual and augmented reality systems for radical or partial nephrectomy and renal stone treatment, excluding systems solely developed or evaluated for training purposes.

RESULTS

In total, 52 research papers were identified and analyzed. Most of the identified literature (87%) deals with systems for renal cell carcinoma treatment. About 44% of the systems have already been employed in clinical practice, but only 20% in studies with ten or more patients. Main challenges remaining for future research include the consideration of organ movement and deformation, human factor issues, and the conduction of large clinical studies.

CONCLUSION

Augmented and virtual reality systems have the potential to improve safety and outcomes of renal interventions. In the last ten years, many technical advances have led to more sophisticated systems, which are already applied in clinical practice. Further research is required to cope with current limitations of virtual and augmented reality assistance in clinical environments.

Application of Three-Dimensional Visualization Technology in Laparoscopic Partial Nephrectomy of Renal Tumor: A Comparative Study

PURPOSE

To compare the effectiveness and safety of individualized three-dimensional visualization technology (3DVT) on surgical planning and perioperative outcomes in laparoscopic partial nephrectomy (LPN) for renal cell carcinoma (RCC) with routine computed tomography (CT) examination in the treatment of renal tumor.

METHODS

From May 2015 to March 2016, a total of 94 patients with cT1 RCC who underwent surgical treatment in our department were analyzed retrospectively. Among these patients, a total of 49 cases received LPN with operation plan based on 3DVT. Surgical plan was obtained by virtual operation and morphometry on 3D reconstruction model. The remaining 45 cases received surgical treatment with traditional CT examination. Patient demographic, surgical outcome, and postoperative parameters were compared between these two groups.

RESULTS

No significant difference was found in blood loss volume, postoperative complication, selective clamping success rate, changes in postoperative renal function, and operative and ischemic time between the two groups. However, when handling complicated tumor with R.E.N.A.L score ≥8, operation time (126.7 ± 36.4 versus 154.8 ± 34.7, P = .018) and occurrence of postoperative urinary leak (0 versus 4, 0% versus 22.2%, P = .033) were diminished significantly in the 3DVT group.

CONCLUSIONS

3DVT provided precise information of anatomical structure in the operative area and reliable guidance for preoperative plan design. Our results indicated that 3DVT facilitated accurate visible image-guided tumor resection with ideal renal function preservation in LPN for renal tumor of high complexity.

Selective arterial clamping does not improve outcomes in robot-assisted partial nephrectomy: a propensity-score analysis of patients without impaired renal function

OBJECTIVES

To assess the benefit of selective arterial clamping (SAC) as an alternative to main renal artery clamping (MAC) during robot-assisted partial nephrectomy (RAPN) in patients without underlying chronic kidney disease (CKD).

PATIENTS AND METHODS

Our study cohort comprised 665 patients without impaired renal function undergoing MAC (n = 589) or SAC (n = 76) during RAPN from four medical institutions in the period 2008-2015. We compared complication rates, positive surgical margin (PSM) rates, and peri-operative and intermediate-term renal functional outcome between 132 patients undergoing MAC and 66 undergoing SAC after 2-to-1 nearest-neighbour propensity-score matching for age, sex, body mass index, RENAL nephrometry score, tumour size, baseline estimated glomerular filtration rate (eGFR), American Society of Anesthesiologists (ASA) score, Charlson comorbidity index (CCI) and warm ischaemia time (WIT).

RESULTS

In propensity-score-matched patients, PSM (5.7 vs 3.0%; P = 0.407) and complication rates (13.8 vs 10.6%; P = 0.727) did not differ between the MAC and SAC groups. The incidence of acute kidney injury for MAC vs SAC (25.0 vs 32.0%; P = 0.315) within the first 30 days was similar. At a median follow-up of 7.5 months, the percentage reduction in eGFR (-9.3 vs -10.4%; P = 0.518) and progression to CKD ≥ stage 3 (7.2 vs 8.5%; P = 0.792) showed no difference.

CONCLUSIONS

Our study findings show no difference in PSM rates, complication rates or intermediate-term renal functional outcomes between patients with unimpaired renal function who underwent SAC vs those who underwent MAC. When expected WIT is low, the routine use of SAC may not be necessary. Further studies will need to determine the role of SAC in patients with a solitary kidney or with significantly impaired renal function.

A model for assuring clamping success during laparoscopic partial nephrectomy with segmental renal artery clamping

OBJECTIVES

A model for assuring clamping success was established for laparoscopic partial nephrectomy (LPN) with segmental renal artery clamping (SRAC).

MATERIALS AND METHODS

Patients (n = 107; December 2009-September 2011) who underwent LPN with SRAC dependent on the experience of the surgeon and CTA were retrospectively reviewed to determine the optimal characteristics of target arteries. After multiple logistic regression analysis, variables used to build a nomogram were selected using a backward elimination scheme. A model for a clamping program customized to the patient was designed. The surgical outcomes of patients (n = 141; October 2011-June 2014) who subsequently underwent LPN-SRAC with the applied model were compared with those of the first group of patients.

RESULTS

Five potential predictors were initially assessed: segmental renal artery angle, target artery diameter, and distance (d) to the abdominal aorta, renal hilum (d RH), and kidney midline (d KML). The regression equation was set up as: [Formula: see text]Comparing the patient groups, those for whom the new SRAC model was applied had a significantly better success rate of clamping (P < 0.001), less total operative time (P < 0.001), and less operative blood loss (P = 0.042). No obvious differences were observed in time of warm ischemia, postoperative hospitalization, RENAL nephrometry score, or number of final clamped branches.

CONCLUSIONS

The model for assuring clamping success was helpful in designing an SRAC program and thus benefiting the LPN procedure.

Assessment and classification of cystic arteries with 64-detector row computed tomography before laparoscopic cholecystectomy

PURPOSE

Major complications of laparoscopic cholecystectomy are bleeding and bile duct injury, and it is necessary to clearly identify structures endoscopically to keep bleeding and injury from occurring. The aim of this study was to depict the anatomical variation between cystic arteries among patients using 64-detector row spiral computed tomography (CT) prior to laparoscopic cholecystectomy.

METHODS

A total of 78 patients (31 men, 47 women) who underwent cholecystectomy were examined preoperatively using 64-detector row spiral CT between April 2012 and June 2013. The origin and number of cystic arteries and their relationship with the Calot triangle was evaluated by two independent observers. CT images were compared with laparoscopic cholecystectomy results.

RESULTS

The cystic arteries were delineated by CT in 73 of the 78 patients. The relationship between the cystic arteries and the Calot triangle was identified in 71 of the 78 patients. One cystic artery was found in 53 (73%) of the 73 patients, while two cystic arteries were found in 20 (27%) of the patients. A total of 55 (60%) of the 91 cystic arteries passed through the Calot triangle. The remaining 36 cystic arteries (40%) passed anterior, posterior, or inferior to the cystic duct. The relationship between the cystic arteries and the Calot triangle detected by CT was in agreement with the surgical records for all patients.

CONCLUSION

The configuration of the cystic arteries and their relationship with the Calot triangle can be identified using 64-detector row CT before laparoscopic cholecystectomy.

Accuracy of preoperative CT T staging of renal cell carcinoma: which features predict advanced stage?

AIMS

To characterise CT findings in renal cell carcinoma (RCC), and establish which features are associated with higher clinical T stage disease, and to evaluate patterns of discrepancy between radiological and pathological staging of RCC.

MATERIALS AND METHODS

Preoperative CT studies of 92 patients with 94 pathologically proven RCCs were retrospectively reviewed. CT stage was compared with pathological stage using the American Joint Committee on Cancer (AJCC), 7(th) edition (2010). The presence or absence of tumour necrosis, perinephric fat standing, thickening of Gerota's fascia, collateral vessels were noted, and correlated with pT stage. The sensitivity, specificity, and positive (PPV) and negative predictive values (NPV) for predicting pT stage ≥pT3a were derived separately for different predictors using cross-tabulations.

RESULTS

Twenty-four lesions were pathological stage T1a, 21 were T1b, seven were T2a, 25 were T3a, 11 were T3b, four were T3c, and two were T4. There were no stage T2b. Sixty-three (67%) patients had necrosis, 27 (29%) thickening of Gerota's fascia (1 T1a), 25 had collateral vessels (0 T1a), 28 (30%) had fat stranding of <2 mm, 20 (21%) of 2-5mm and one (1%) of >5 mm. For pT stage ≥pT3a, the presence of perinephric fat stranding had a sensitivity, specificity, PPV and NPV of 74%, 65%, 63%, and 76%, respectively. Presence of tumour necrosis had a sensitivity, specificity, PPV, and NPV of 81%, 44%, 54%, and 72%, respectively. Thickening of Gerota's fascia had a sensitivity, specificity, PPV, and NPV of 52%, 90%, 81% and 70%, respectively; and enlarged collateral vessels had a sensitivity, specificity, PPV, and NPV value of 52%, 94%, 88%, and 71% respectively.

CONCLUSION

The presence of perinephric stranding and tumour necrosis were not reliable signs for pT stage >T3a. Thickening of Gerota's fascia and the presence of collateral vessels in the peri- or paranephric fat had 90% and 94% specificity, with 82% and 88% PPV, respectively, for the presence of tumour stage for pT stage >T3a. These are considered reliable signs of locally advanced renal cancer.

Decline in renal function after partial nephrectomy: etiology and prevention

PURPOSE

Partial nephrectomy is the reference standard for the management of small renal tumors and is commonly used for localized kidney cancer. A primary goal of partial nephrectomy is to preserve as much renal function as possible. New baseline glomerular filtration rate after partial nephrectomy can have prognostic significance with respect to long-term outcomes. Recent studies provide an increased understanding of the factors that determine functional outcomes after partial nephrectomy as well as preventive measures to minimize functional decline. We review these advances, highlight ongoing controversies and stimulate further research.

MATERIALS AND METHODS

A comprehensive literature review consistent with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) criteria was performed from January 2006 to April 2014 using PubMed®, Cochrane and Ovid Medline. Key words included partial nephrectomy, renal function, warm ischemia, hypothermia, nephron mass, parenchymal volume, surgical approaches to partial nephrectomy, preoperative and intraoperative imaging, enucleation, hemostatic agents and energy based resection. Relevant reviews were also examined as well as their cited references. An additional Google Scholar search was conducted to broaden the scope of the review. Only English language articles were included in the analysis. The primary outcomes of interest were the new baseline level of function after early postoperative recovery, percent decline in function, potential etiologies and preventive measures.

RESULTS

Decline in function after partial nephrectomy averages approximately 20% in the operated kidney, and can be due to incomplete recovery from the ischemic insult or loss of nephron mass related to parenchymal excision or collateral damage during reconstruction. Compensatory hypertrophy in the contralateral kidney after partial nephrectomy in adults is marginal and decline in global renal function for patients with 2 kidneys averages about 10%, although there is some variance based on tumor size and location. Irreversible ischemic injury can be minimized by pharmacological intervention or surgical approaches such as hypothermia, limited warm ischemia, or zero or segmental ischemia. Excessive loss of nephron mass can be minimized by improved preoperative or intraoperative imaging, use of a bloodless field, enucleation and vascular microdissection. Hemostatic agents or energy based resection that minimizes the need for parenchymal and capsular suturing can also optimize preservation of the vascularized nephron mass.

CONCLUSIONS

Our understanding of the decline in renal function after partial nephrectomy has advanced considerably, including better appreciation of its magnitude and impact in various settings, possible etiologies and potential preventive measures. Many controversies persist and this remains an important area of investigation.

Safety and Postoperative Outcomes of Regional versus Global Ischemia for Partial Nephrectomy: A Systematic Review and Meta-Analysis

OBJECTIVE

To analyze current evidence comparing the safety and outcomes of regional and global ischemia for partial nephrectomy (PN).

MATERIALS AND METHODS

A systematic search of the PubMed and Web of Science databases was conducted in May 2014 to identify studies comparing the safety and outcomes of regional and global ischemia for PN. A systematic review and meta-analysis was also performed.

RESULTS

Six retrospective observational studies were selected for the analysis, including 363 patients who underwent PN (162 regional ischemia and 201 global ischemia cases). Operation times were not statistically different [weighted mean difference (WMD) = 20.35 min, 95% CI: -0.28-40.97, p = 0.05], but estimated blood loss was significantly higher in the regional ischemia group (WMD = 52.04 ml, 95% CI: 14.30-89.78, p = 0.007) than in the global ischemia group. Complication rates [odds ratio (OR) = 1.16; 95% CI: 0.63-2.15, p = 0.63] and blood transfusion rates (OR = 1.85; 95% CI: 0.86-4.01, p = 0.12) of the two groups were not significantly different. The regional ischemia group showed better postoperative renal function (WMD = 4.23 ml/min, 95% CI: 2.61-5.85, p < 0.00001) than the global ischemia group, and all cases in the regional ischemia group showed negative margins.

CONCLUSIONS

Regional ischemia is as safe to perform as global ischemia, and the former leads to better postoperative renal functions than the latter. These findings support the application of regional ischemia for PN.