Imaging of Small Renal Masses before and after Thermal Ablation.

Thermal ablation of small renal masses is increasingly accepted as an alternative to partial nephrectomy, particularly in patients with multiple comorbidities. Many professional societies support this alternate treatment with updated guidelines. Before performing thermal ablation, it is important to stratify risk and assess technical feasibility by evaluating tumor imaging features such as size, location, and centrality. Routine postablation imaging with CT or MRI is necessary for assessment of residual or recurrent tumor, evidence of complications, or new renal masses outside the ablation zone. The normal spectrum and evolution of findings at CT and MRI include a halo appearance of the ablation zone, ablation zone contraction, and ablation zone calcifications. Tumor recurrence frequently manifests at CT or MRI as new nodular enhancement at the periphery of an expanding ablation zone, although it is normal for the ablation zone to enlarge within the first few months. Recognizing early tumor recurrence is important, as small renal masses are often easily treated with repeat ablations. Potential complications of thermal ablation include vascular injury, urine leak, ureteral stricture, nerve injury, and bowel perforation. The risk of these complications may be related to tumor size and location.©RSNA, 2019.

Protection of the renal collecting system during radiofrequency ablation with antegrade cold dextrose infusion.

PURPOSE: To evaluate the feasibility and efficacy of antegrade renal cooling during radiofrequency (RF) ablation to protect the renal collecting system in pigs. MATERIALS AND METHODS: With the approval of the institutional animal care and use committee, RF ablation was planned bilaterally after nephrostomy in 20 kidneys from 10 domestic pigs. A coaxial assembly consisting of a 7-F pigtail catheter and a 12-F arterial sheath was placed at the renal pelvis. Cooled 5% dextrose in water solution was perfused in only one of the kidneys in each pig. A 17-gauge internally cooled tip RF electrode with a 3-cm tip was placed near the renal pelvis with ultrasonographic guidance. On postprocedural days 1 and 7, computed tomography (CT) was performed to evaluate the RF ablation effect, the presence of a fluid collection, and the leakage of contrast material. Ex vivo retrograde pyelography was performed to assess the integrity of the urinary tract after kidney harvest. Histologic findings related to the urothelial damage were scored semiquantitatively. RESULTS: The mean maximal diameter of the RF ablation area measured at CT and in specimens was not significantly different between cooled and noncooled kidneys. A fluid collection around the RF ablation area was seen in eight of the 10 noncooled kidneys on day 7 CT scans compared with two of the 10 cooled kidneys; the difference was statistically significant (P = .035). Ex vivo retrograde pyelography depicted leakage of contrast material in only the noncooled group. The mean histologic damage score was lower in the cooled group than in the noncooled group. CONCLUSION: RF ablation after placement of an antegrade cooling system in pig kidneys was feasible. Antegrade cold dextrose infusion of the urinary tract during RF ablation is effective in protecting the renal collecting system without compromising the RF ablation effect.

Do nonspecific deep corticomedullary sutures performed during partial nephrectomy adequately control major vascular and collecting system injury?

OBJECTIVE: To critically evaluate the effectiveness of placing nonspecific deep corticomedullary sutures in the setting of major vascular and collecting system injury during laparoscopic partial nephrectomy (LPN). We also aimed to evaluate the incidence of ischaemic injury to the remaining renal remnant because of these sutures, as many laparoscopic centres have adopted this practice. MATERIALS AND METHODS: We performed open PN on eight porcine kidneys. Both the artery and vein were clamped. The ureter was transected and tied around an angiocatheter for evaluating collecting system integrity both before and after corticomedullary suturing. The renal artery was cannulated for angiography before and after the corticomedullary suturing. The rate of bleeding was also assessed before and after corticomedullary suturing. RESULTS: There was marked arterial bleeding and large collecting system injury induced in all kidneys. Two of the eight renal units continued to have significant arterial bleeding after the deep corticomedullary sutures were placed. All of the eight units had at least a small urinary leak after suturing, with three having medium-to-large leaks. In four of the renal units, there were major segmental vessels occluded by the sutures, as detected by angiography. CONCLUSIONS: The practice of placing nonspecific deep corticomedullary sutures, during PN, may not adequately control major vascular and collecting system injury. In addition, segmental vessels supplying remnant renal tissue are often affected; thereby further compromising function because of devascularization. The search for the best technique for LPN continues.

Diagnosis and management of urinary extravasation after high-grade renal trauma.

Renal trauma research has historically focused on parenchymal injuries and the risk of bleeding. However, much less is known about the diagnosis and optimal management of urinary extravasation, which complicates ~30% of high-grade renal injuries. Immediate or delayed ureteral stenting is the most common procedure used to treat collecting system injuries when intervention is needed. However, the lack of evidence-based guidelines leaves the diagnosis and management of urinary extravasation largely dependent upon physicians' experience, initial and follow-up imaging protocols, and the definitions used for grading the injuries. The knowledge gaps in the management of urinary extravasation that need to be addressed include the timing of excretory-phase CT imaging, patterns of clinically significant urinary extravasation, predictors of complications when urinary extravasation occurs, protocols for obtaining and interpreting follow-up imaging, and the role of ureteral stenting and other interventions in management. To improve the management of urinary extravasation after high-grade renal trauma, large, multi-institutional prospective trails assessing different diagnostic and therapeutic protocols are needed.

Cell-specific image-guided transcriptomics identifies complex injuries caused by ischemic acute kidney injury in mice.

The kidney's inherent complexity has made identifying cell-specific pathways challenging, particularly when temporally associating them with the dynamic pathophysiology of acute kidney injury (AKI). Here, we combine renal cell-specific luciferase reporter mice using a chemoselective luciferin to guide the acquisition of cell-specific transcriptional changes in C57BL/6 background mice. Hydrogen peroxide generation, a common mechanism of tissue damage, was tracked using a peroxy-caged-luciferin to identify optimum time points for immunoprecipitation of labeled ribosomes for RNA-sequencing. Together, these tools revealed a profound impact of AKI on mitochondrial pathways in the collecting duct. In fact, targeting the mitochondria with an antioxidant, ameliorated not only hydrogen peroxide generation, but also significantly reduced oxidative stress and the expression of the AKI biomarker, LCN2. This integrative approach of coupling physiological imaging with transcriptomics and drug testing revealed how the collecting duct responds to AKI and opens new venues for cell-specific predictive monitoring and treatment.

Controlled survival study of the effects of Tisseel or a combination of FloSeal and Tisseel on major vascular injury and major collecting-system injury during partial nephrectomy in a porcine model.

PURPOSE: We report the results of a controlled survival study in a porcine model investigating Tisseel or a combination of FloSeal and Tisseel in dealing with vascular and collecting-system injury during partial nephrectomy. MATERIALS AND METHODS: We performed an open right lower-pole partial nephrectomy on 15 large female pigs. The defect was repaired using standard open techniques (N = 5; controls), Tisseel only (N = 6; group I), or FloSeal followed by Tisseel (N = 4; group II). A Jackson-Pratt drain was placed. Nephrectomy and retrograde pyelography were performed at 1 week. RESULTS: Operative times were shorter in both study groups, achieving statistical significance in group I (P = 0.008). Warm-ischemia times were significantly improved in both study groups (P = 0.029 and P = 0.00005 in groups I and II, respectively). Time to hemostasis was significantly shorter in group II only (P = 0.002) but approached significance in Group I as well (P = 0.09). Estimated blood loss was not significantly different from the controls in either group. When Tisseel was placed alone after hilar control, hematoma formation under the Tisseel was noted on release of the hilar clamp. After 1 week, there was one urinoma and three urine leaks in the control group. In group I, there was one urinoma and four urine leaks, and there was only one urine leak and no urinomas in group II. There were no hematomas in any of the groups. CONCLUSIONS: Tisseel alone is not adequate for either hemostasis or management of major collecting-system injury. FloSeal capped with Tisseel appears sufficient to control major vascular and collecting-system injuries without adjunctive surgical measures. A proposed technique for laparoscopic partial nephrectomy without reconstructive techniques is presented that warrants clinical study.

Gross haematuria associated with penetration of an inferior vena cava filter into the right renal collecting system.

Inferior vena cava (IVC) filters are a viable alternative for patients with venous thromboembolic disease for whom standard anticoagulation therapy is contraindicated. Rare complications associated with their use, however, include misplacement and IVC penetration. We report a case of a 63-year-old woman who developed gross haematuria following IVC filter penetration into both the right renal collecting system and renal pelvis, for which open caval removal and reconstruction was required. This is an unusual case of IVC filter penetration causing symptomatic haematuria and requiring surgical intervention.

Use of fibrin glue and gelfoam to repair collecting system injuries in a porcine model: implications for the technique of laparoscopic partial nephrectomy.

BACKGROUND AND PURPOSE: One of the challenges of laparoscopic partial nephrectomies is the repair of a collecting system injury. We hypothesized that fibrin glue plus Gelfoam could be sufficient to repair such injuries. MATERIALS AND METHODS: Four pigs (eight kidneys) underwent collecting system injuries of various lengths (3, 5, and 10 mm) (N = 8 each) during partial nephrectomy. Gelfoam soaked in the fibrin glue was applied to seal the collecting system and parenchymal defects. After 1 hour of passive filling, the renal pelvis was distended at supraphysiologic pressure to the point of leakage. Each repair site was examined for urinary extravasation during the physiologic and active phases of filling. RESULTS: Hemostasis was achieved, and all collecting system injuries, regardless of size, were free of urinary leakage at physiologic pressures. Moreover, all defects maintained a seal at supraphysiologic pressures of at least 50 cm H(2)O. CONCLUSION: The combined use of fibrin glue and Gelfoam is an effective means to obtain hemostasis and seal collecting system injuries up to 10 mm at physiologic pressures and up to 50 cm H(2)O in the acute setting. Our hope is that this technique can facilitate both laparoscopic and open partial nephrectomies. New technologies will be employed in an attempt to obtain better seating of the sealant plug in the future. Survival studies are in progress.

Early ureteral luminal enhancement on computed tomography in a renal trauma patient: a characteristic sign of communication between artery and collecting system.

We report the case of a 65-year-old man with blunt abdominal trauma following a fall from a three-meter-high roof. Contrast-enhanced abdominal computed tomography (CT) obtained in early phase showed intense contrast enhancement in the urinary tract as dense as artery. This finding was considered characteristic of traumatic communication between artery and collecting system. In cases of blunt abdominal trauma, contrast-enhanced CT should be obtained in the early phase to diagnose this disorder. When the diagnosis is made, prompt treatment should be initiated.

Should blunt segmental vascular renal injuries be considered an American Association for the Surgery of Trauma Grade 4 renal injury?

BACKGROUND: Renal segmental vascular injury (SVI) following blunt abdominal trauma is not part of the original American Association for the Surgery of Trauma (AAST) renal injury grading system. Recent recommendations support classifying SVI as an AAST Grade 4 (G4) injury. Our primary aim was to compare outcomes following blunt renal SVI and blunt renal collecting system lacerations (CSLs). We hypothesize that renal SVI fare well with conservative management alone and should be relegated a less severe renal AAST grade. METHODS: We retrospectively identified patients with SVI and G4 CSL admitted to a Level 1 trauma center between 2003 and 2010. Penetrating trauma was excluded. Need for surgical intervention, length of stay, kidney salvage (>25% renal preservation on renography 6-12 weeks after injury), and delayed complication rates were compared between the SVI and CSL injuries. Statistical analysis used χ, Fisher's exact, and t tests. RESULTS: A total of 56 patients with SVI and 88 patients with G4 CSL sustained blunt trauma. Age, Injury Severity Score (ISS), and length of stay were similar for the two groups. Five patients in each group died of concomitant, nonrenal injuries. In the G4 CSL group, 15 patients underwent major interventions, and 32 patients underwent minor interventions. Only one patient in the SVI group underwent a major intervention. The renal salvage rate was 85.7% following SVI versus 62.5% following CSL (p = 0.107). CONCLUSION: Overall, surgical interventions are significantly lower among the SVI cohort than the G4 CSL cohort. Further analysis using a larger cohort of patients is recommended before revising the current renal grading system. Adding SVI as a G4 injury could potentially increase the heterogeneity of G4 injuries and decrease the ability of the AAST renal injury grading system to predict outcomes, such as nephrectomy rate. LEVEL OF EVIDENCE: Epidemiologic study, level IV.

Intramural dissection of the renal collecting system during percutaneous nephrostomy: computed tomography findings of a rare complication.

Intramural dissection of the renal collecting system during percutaneous nephrostomy (PCN) is a rare complication that can be challenging to diagnose. In this report, we describe the computed tomography (CT) and fluoroscopic findings of urothelial dissection during CT-guided PCN in a 65-year old patient with an obstructed congenital solitary left kidney due to an urinary bladder carcinoma. To our knowledge, CT findings of urothelial dissection have not yet been described.

Retrograde renal cooling during radio frequency ablation to protect from renal collecting system injury.

PURPOSE: We evaluated the protective effect of continuous retrograde irrigation of ice-cold saline on the renal collecting system during central parenchymal temperature based radio frequency ablation (RFA). MATERIALS AND METHODS: In 10 domestic pigs bilateral, centrally located renal parenchymal RFA lesions (intended 2 cm in diameter) were created that intentionally involved the collecting system. RFA probe placement was guided by fluoroscopy with retrograde collecting system opacification and simultaneous direct laparoscopic visualization. In 1 renal unit RFA was performed while infusing ice-cold saline through a previously placed ureteral access sheath and pigtail stent. RFA without renal cooling was performed in the contralateral renal unit. Kidneys were harvested at 7 days. The renal collecting system was inspected for injury by performing retrograde pyelograms and by histological examination of the collecting system adjacent to the ablation zone. The size of RFA lesions was measured. RESULTS: In retrograde cooling procedures the temperature of saline irrigant was -1.0C and the mean temperature of the effluent was 13C. One of 10 cooled renal units demonstrated contrast material extravasation from the collecting system involved by the ablation zone compared with 7 of 10 noncooled renal units (p = 0.025). Lesion size was comparable between cooled kidneys and controls (2.67 and 2.72 cm, respectively, p = 0.629). CONCLUSIONS: Retrograde renal cooling helps protect the renal collecting system from injury during RFA without a decrease in expected lesion size. Clinically retrograde renal cooling may decrease the risk of collecting system injury and subsequent complications during RFA.

Laparoscopic partial nephrectomy: comparison of transperitoneal and retroperitoneal approaches.

PURPOSE: Laparoscopic partial nephrectomy has become an effective alternative for small renal tumors. Previous reports include transperitoneal and retroperitoneal approaches but to our knowledge the indications for when to apply the techniques have not been defined. We report our experience with comparing the 2 techniques. MATERIALS AND METHODS: A retrospective review of 51 laparoscopic partial nephrectomies was performed. Patients were analyzed based on the surgical approach, operative parameters and postoperative recovery. The 2 approaches used similar operative techniques to control parenchymal bleeding and collecting system entry. RESULTS: There were 32 retroperitoneal and 19 transperitoneal partial nephrectomies. Mean operative time (3.5 vs 5.4 hours, p = 0.000001) and blood loss (192 vs 403 cc, p = 0.002) was significantly less for the retroperitoneal approach. Renal vessel clamping was performed in 81% of retroperitoneal and 63% of transperitoneal operations. Warm ischemia time was not significantly different between the groups. Patients undergoing the retroperitoneal approach had a statistically significant decrease in time to tolerating a regular diet (1.2 vs 1.7 days, p = 0.02), catheter removal (1.4 vs 2.5 days, p = 0.004) and discharge home (2.3 vs 3.6 days, p = 0.0008). CONCLUSIONS: Based on tumor location as the selection criteria the retroperitoneal approach was associated with shorter operative time, less blood loss, more rapid return of bowel function and shorter hospitalization compared with those in patients selected for the transperitoneal technique. Based on our experience we believe that the decision on the approach should be based on the tumor location on the kidney surface. For polar or posterolateral masses the retroperitoneal approach is preferred. The transperitoneal approach is best suited to anterior and medial lesions.

Intrathoracic extension of retroperitoneal urine collections.

Five patients with retroperitoneal urine collections (urinomas) had clinical and radiographic evidence of intrathoracic disease. All five patients rapidly accumulated pleural fluid, documented chemically in three patients to be urine. Two patients developed acute mediastinal widening which rapidly cleared after surgical drainage of the retroperitoneal urinoma. Although rare, thoracic collections of urine should be considered when pleural effusions or mediastinal widening occur in patients with urinary tract obstruction or retroperitoneal urinomas.

Effect of intentional cryo-injury to the renal collecting system.

PURPOSE: We determined the short-term and long-term sequelae of intentional cryoablation of the renal pelvicaliceal system and evaluated whether continuous irrigation of the renal pelvicaliceal system with warm saline protects it against cryo-injury. MATERIALS AND METHODS: In 12 swine open bilateral renal cryoablation using an argon gas based system was performed to create a cryolesion in the lower pole that was intentionally extended into the collecting system. A single cryoprobe was used to create a 3 cm ice ball in group 1 (6 animals) and 2, 3 mm cryoprobes were used to create a 4.5 cm ice ball in group 2 (6). In all 12 right kidneys pelvicaliceal warming (range 38C to 42C) was performed using continuous retrograde saline irrigation through an indwelling 5Fr ureteral catheter. In all 12 left kidneys cryoablation was performed without pelvicaliceal warming. Real-time confirmation of caliceal involvement by the cryolesion was obtained by retrograde ureteropyelogram. Immediately after cryo-injury 6 left and 6 right kidneys were harvested for histology and the animals with a solitary kidney were followed for 1 to 3 months. RESULTS: Nadir cryoprobe tip temperature was -136C with a mean cryolesion time of 10.5 minutes. Cryolesion size was comparable in the right vs left kidneys in groups 1 and 2 (2.9 vs 3.0 and 4.7 vs 4.6 cm, respectively). Similarly cryoablation time was comparable between the right and left kidneys in groups 1 and 2 (11.3 vs 10.8 and 11.9 vs 12.2 minutes, respectively). Two animals died of aspiration pneumonia (1) and wound dehiscence (1). In all 10 surviving animals no instance of urinary extravasation was noted. At 1-month followup regrowth of normal urothelium occurred with some scarring of the lamina propria or underlying smooth muscle. Adjacent renal parenchyma was replaced by fibrous scar. At 3 months the cryo-injured collecting system was completely healed with a fibrous scar. There were no appreciable histological differences between the kidneys with or without warm pelvicaliceal irrigation. CONCLUSIONS: Our data suggest that absent physical puncture injury of the collecting system with the cryoprobe tip the cryodamaged renal collecting system heals by secondary intention in a watertight manner. These data have clinical relevance for facilitating cryoablation of a small, localized, central renal tumor in proximity to the pelvicaliceal system.

Collecting system laceration following percutaneous renal biopsy.

Percutaneous renal biopsy is used frequently in the investigation of renal disease. While the usual complications include flank pain, hematuria and retroperitoneal hematoma, collecting system injuries rarely are reported. The diagnosis and treatment of such an injury are discussed.

Separation of renal fragments by a urinoma after renal trauma: percutaneous drainage accelerates healing.

BACKGROUND: Two boys suffered blunt abdominal trauma resulting in renal injury. In both cases the damaged kidney was fractured through its mid-portion, and the upper and lower fragments of the kidney became widely separated by a urinoma. MATERIALS AND METHODS: US-guided drainage of the urinoma resulted in immediate apposition of the renal fragments. The drains were left on free drainage by gravity for 1 week before removal. RESULTS: The urinomas did not reaccumulate and follow-up DMSA scans showed good residual function. CONCLUSION: We suggest that drainage of urinomas that separate renal fragments should be considered since this may accelerate healing and help preserve renal function.

Conservative management with percutaneous intervention of major blunt renal injuries.

This retrospective study assessed the results of treatment of patients with renal trauma to determine the optimal management (conservative or surgical) for patients with grade III renal injuries. During the past 12 years 108 patients (including 43 children) with renal injuries were managed: 43 had grade I injuries (renal contusion), 33 had grade II (minor laceration), 31 had grade III (major laceration), and 1 had grade IV (pedicle injury). All patients with grades I and II injuries were successfully managed conservatively. The patient with renal pedicle injury underwent uneventful nephrectomy. Nineteen patients with grade III injuries (including 5 patients with shattered kidneys and 3 patients with polar avulsion) were managed conservatively, and 2 developed progressively enlarging urinomas that required percutaneous drainage with complete resolution. No patient in this group developed perinephric abscess or urinary fistulae, and no delayed nephrectomy was necessary. Long-term follow-up of 7 patients in this group, including 3 with shattered kidneys and 2 with polar avulsion, showed that none have developed hypertension. Twelve patients with grade III injuries were managed surgically. Six (50%) patients underwent total (4 patients) or partial (2 patients) nephrectomy. In 6 patients, the surgical intervention was only open drainage of the perinephric collection and/or parenchymal suturing. It was concluded that conservative management with timely percutaneous or endoscopic intervention in patients with major renal injuries results in minimal loss of renal tissue without significant late complications.

Adhesion of calcium oxalate crystals to Madin-Darby canine kidney cells and some effects of glycosaminoglycans or cell injuries.

The present investigation studied the quantitative adhesion of calcium oxalate monohydrate (COM) crystals to the surface of Madin-Darby canine kidney cells, which exhibit many characteristics of renal cortical collecting tubule cells. COM crystals adhered to the cell surface, and the attachment showed a time and concentration dependency with plateau. The results suggested that the attachment of microcrystals to the cortical tubular cell might be one of the earliest processes in the formation of kidney stones. Pretreatment with glycosaminoglycans significantly reduced the adherent crystals. Injuries to the Madin-Darby cells induced by 0.1 M HCl and gentamicin resulted in significant decreases of COM crystal adhesion to the cell surface. It was suggested that urinary glycosaminoglycans might play some critical role in preventing crystal adhesion to these cellular membranes and that cell injuries might not be essential for the attachment of microcrystals to the tubular cells.