Effect of intentional cryo-injury to the renal collecting system

Radiofrequency Ablation, Cryoablation, and Microwave Ablation for the Treatment of Small Renal Masses: Efficacy and Complications

Over the last two decades the detection rate of small renal masses has increased, due to improving diagnostic accuracy, and nephron-sparing treatments have become the first-choice curative option for small renal masses. As a minimally invasive alternative, thermal ablation has increased in popularity, offering a good clinical outcome and low recurrence rate. Radiofrequency ablation, Cryoablation, and Microwave ablation are the main ablative techniques. All of them are mostly overlapping in term of cancer specific free survival and outcomes. These techniques require imaging study to assess lesions features and to plan the procedure: US, CT, and both of them together are the leading guidance alternatives. Imaging findings guide the interventional radiologist in assessing the risk of complication and possible residual disease after procedure. The purpose of this review is to compare different ablative modalities and different imaging guides, underlining the effectiveness, outcomes, and complications related to each of them, in order to assist the interventional radiologist in choosing the best option for the patient.

Percutaneous Cryoablation of Renal Tumors: Initial Indian Experience

Objective The purpose of this study was to report short-term outcomes of cryoablation of early-stage renal tumors (T1a and T1b) at a tertiary hospital in India.

Methods This was a retrospective study of consecutive patients who underwent cryoablation for renal cell carcinoma (RCC) from November 2018 to June 2020. Cryoablation was performed under combined ultrasound and computed tomography guidance using a helium-argon cryoablation system. Tumor number, size, location, nephrometry score, relationship of the tumor with pelvicalyceal system, and adjacent organs were tabulated, and technical and clinical success evaluated. Early and late recurrence and complications were also assessed.

Results Eleven patients (median age: 62 years) with 11 tumors underwent cryoablation. The mean tumor size was 2.58 cm (range: 1.62–5.62 cm) with 10 lesions being T1a and one lesion T1b. Tissue sampling was done in 9/11 patients, 3 were papillary RCC and the rest, clear cell RCC. In two patients, the tumor was completely endophytic, three patients had partially endophytic tumors while 6 patients had exophytic lesions. The median nephrometry score was 6 (range: 4–11, Mode 4). Technical success was achieved in all patients. Complete response was achieved in 81% (9/11) of the patients at 1-month follow-up. Median follow-up period was 6 months. Two patients showed residual disease on follow-up imaging at 1 and 3 months, respectively.

Conclusion Cryoablation is a promising, relatively new minimally invasive therapy for treating small renal tumors in India. It is safe, technically feasible, and shows excellent short-term efficacy.

Percutaneous CT-Guided Renal Cryoablation: Technical Aspects, Safety, and Long-Term Oncological Outcomes in a Single Center

Background and objectives: Cryoablation is emerging as a safe and effective therapeutic option for treating renal cell carcinoma. This study analyzed the safety and long-term oncological outcomes of cryoablation in our center. Materials and methods: Patients who underwent computed tomography (CT)-guided percutaneous cryoablation between February 2011 and June 2020 for one or more clinically localized renal tumors were identified. Technical success and treatment efficacy were assessed. Post-procedural complications were classified according to the Clavien-Dindo system. Recurrence-free survival was determined for biopsy-proven malignant renal tumors. Results: A total of 174 renal tumors, 78 of which were biopsy-proven malignant carcinomas, were treated in 138 patients (97 males and 41 females, mean age: 73 years, range: 43-89 years). Mean tumor size was 2.25 cm and 54.6% of the lesions required a complex approach. Technical success was achieved in 171 out of 174 tumors (98.3%). Primary treatment efficacy was 95.3% and increased to 98.2% when retreats were taken into account. The overall complication rate was 29.8%. No complications of Clavien-Dindo grade III or more were encountered. Median follow-up was 21.92 months (range: 0.02-99.87). Recurrence-free survival was 100% at 1 year, 95.3% (95% CI: 82.1%-98.8%) at 3 years, and 88.6% (95% CI: 71.8%-95.7%) at 5 years. Conclusions: Cryoablation is a safe and effective technique for the treatment of small renal lesions, with no major complications when performed by expert interventional radiologists. The multidisciplinary discussion is essential, especially considering the high number of histologically undetermined lesions. Our long-term oncological outcomes are encouraging and in line with the literature.

Safety and effectiveness of percutaneous renal cryoablation with conscious sedation

OBJECTIVE

To investigate complications and treatment failure rates of percutaneous renal cryoablation (PRC) for small renal masses under local anaesthesia and conscious sedation (LACS), to assess the safety and effectiveness of this approach, as PRC is typically performed under general anaesthesia (GA).

PATIENTS AND METHODS

We retrospectively reviewed PRC under LACS from 2003 to 2017. We analysed perioperative parameters between patients who successfully underwent PRC under LACS and patients with post-procedural complications or treatment failure (renal mass enhancement after successful intraoperative tumour ablation). Two-sided non-parametric and Fisher's exact tests were performed to compare uncomplicated or disease-free PRC with the complication or treatment failure group, respectively.

RESULTS

A total of 100 PRCs under LACS were performed during the study period. Of these patients, six patients had at least one postoperative complication (6%), and treatment failure was diagnosed in nine patients (9%) after PRC [mean (SD) follow-up of 42.7 (26.6) months]. The procedural failure rate was 1%. No ablations were converted to GA. The mean tumour size was smaller in patients who had no complications during PRC compared to those who did, at a mean (SD) of 2.2 (0.6) cm vs 3.0 (1.0) cm (P = 0.039). The use of more intraoperative probes during the PRC was also associated with complications, at a mean (SD) 3.0 (1.4) vs 1.8 (0.8) (P = 0.021).

CONCLUSIONS

PRC under LACS is an effective and safe procedural approach for managing small renal masses with low complication, treatment failure, and procedural failure rates. Larger renal masses and intraoperative use of multiple probes is associated with an increased risk of PRC complications.

ABBREVIATIONS

BMI: body mass index; CCI: Charlson Comorbidity Index; GA: general anaesthesia; LACS: local anaesthesia and conscious sedation; PRC: percutaneous renal cryoablation; R.E.N.A.L.: Radius, Exophytic/Endophytic, Nearness, Anterior/Posterior, Location.

Renal cryoablation - does deep endophytic ablation affect the renal collecting system?

Objective: To investigate to what extent the urothelium of the renal collecting system is affected when performing deep endophytic cryoablation.Methods: The study was conducted as an in vivo animal model with a total of 15 female pigs. Each animal was subjected to bilateral endophytioc renal cryoablation and randomized to a postoperative follow-up period of either one, two or four weeks. At the end of follow-up all animals had a magnetic resonance imaging (MRI) examination and bilateral nephrectomy was performed. On MRI-imaging the extent of the cryolesions, as well as signs of urinomas or fistulas, were examined. Histopathologic examinations were performed to investigate the effect on the urothelium.Results: All animals tolerated the procedure well without any postoperative complications. MRI examinations found the renal collecting system to be involved in the cryolesions at all three stages of follow-up and revealed no signs of hematomas, urinomas or fistula formations. Epithelial edema was found at all three stages of follow-up while significant parenchymal fibrosis adjacent to the urothelium was most pronounced in the four weeks of follow-up group. The urothelium was significantly affected with luminal hemorrhage as well as hemorrhage in and underneath the urothelium and urothelial dissociation from the underlying renal parenchyma. Despite these impacts on the urothelium, this was found to be intact and vital at all three stages of follow-up, in sharp contrast to the renal parenchyma that underwent fibrotic changes.Conclusions: In this, in vivo non-tumor pig model CA effectively destroyed the renal parenchyma while the impacted renal urothelium remained intact and did not undergo fibrotic changes, nor was urinomas or fistulas observed.

The effectiveness of RENAL nephrometry score in ablated renal tumors via radiofrequency ablation or cryoablation

Background/aim

This study aimed to evaluate the clinical efficacy of radiofrequency ablation (RFA) and cryotherapy and to scrutinize the therapeutic success of the RENAL (radius, exophytic/endophytic, nearness to collecting system, anterior/posterior, and location) nephrometry score in terms of possible complications and the predictive status of oncological results.

Materials and methods

Forty-five patients with biopsy-proven renal cell carcinomas (32 males, 13 females) treated with RFA and cryotherapy were included. Patients were 22–90 years old (average: 59.2 years). Statistical analyses were performed using SPSS for Windows.

Results

A total of 79 lesions with dimensions varying between 0.9 and 4.5 cm (average: 2.2 cm) were ablated. Complete ablation was achieved for 72 (91.1%) lesions. Six repeat RFA sessions were applied for 4 (5%) lesions with residue/recurrence. The average RENAL nephrometry scores of lesions that underwent complete ablation and those that developed residue/recurrence were 6.3 and 7.7, respectively. The average recurrence-free survival time was 34.8 months (range: 3–55 months), while it was 44.6 months (range: 6–55 months) for cryotherapy and 28.6 months (range: 3–50 months) for RFA.

Conclusion

Ablative therapies are minimally invasive and effective methods for treating small renal tumors. RENAL nephrometry scoring is a valuable system for standardizing renal tumors and evaluating the success of ablative therapies, possible complications, and oncological results.

Ureteral obstruction by sloughed tumor complicating cryoablation of a renal oncocytoma

Percutaneous cryoablation for renal tumors may be associated with rare complications such as injury to the ureter. A 65-year-old woman underwent percutaneous cryoablation after a transcatheter arterial embolization using lipiodol and ethanol for left renal oncocytoma. Two months after the percutaneous cryoablation, computed tomography images showed left hydronephrosis caused by high-density debris, which was assumed to be sloughed tumor with lipiodol accumulation in the left ureter. A stent was placed in the left ureter to enhance the drainage of urine and the necrotic cell debris. Three months later, the ureteral stent was removed, and she remained asymptomatic during the follow-up period of 4 months. We should consider the possibility of urinary tract obstruction by sloughed tumor when hydronephrosis occurs after percutaneous cryoablation of a renal tumor.

[Image-guided tumor ablation]

INTRODUCTION

Ablatives techniques for destroying in situ a tumoral process aim tissular necrosis by the application of several physical principles.

MATERIAL AND METHODS

We searched MEDLINE^®, Embase^®, using (MeSH) words; from January 2005 through May 2017, and we looked for all the studies. Investigators graded the strength of evidence in terms of methodology, language and relevance.

RESULTS

Forty-seven articles were analyzed. We described ablative techniques and sorted them in thermal and non-thermal therapies according to the used physical principle and their frequency of use in the urological pathology.

CONCLUSION

Percutaneous ablative therapies are mini-invasive techniques, which have an important role in tumors focal treatment. This article is a review of the ablative therapies and describes their physical principles, their equipment and their recent technological modifications, which have been developed to improve the clinical success of these techniques.

Cryosurgical Ablation of Renal Cell Carcinoma

BACKGROUND

Small renal masses are being commonly diagnosed incidentally in older patients. A partial nephrectomy is the first-line nephron sparing treatment option for these lesions. However, probe ablative therapy such as cryoablation is emerging as an alternative option for select patients requiring nephron sparing surgery.

METHODS

The current literature regarding the management of small renal lesions with cryoablation was retrospectively reviewed. We selected six of the largest published series of renal cryoablation with a total of 320 patients. The diagnosis, staging, treatment options, mechanism, efficacy and morbidity associated with renal cryoablation were evaluated.

RESULTS

Renal cryoablation for localized small renal masses is well tolerated and associated with a low complication rate. The range of mean tumor size in our literature review series (320 patients) was 2.3 to 2.6 cm. After a range of mean follow-up of 5.9 to 72 months, including a series with a minimum of 5 years of follow-up, the cancer specific survival was 97% to 100% and overall patient survival was 82% to 90.2%.

CONCLUSIONS

Renal cryoablation, based on available clinical reports, appears to be a curative option for patients with small localized renal cell carcinomas (RCCs) who are unwilling or unable to undergo a partial nephrectomy. With encouraging intermediate oncological follow-up available, longer-term follow-up is needed to validate the use of cryoablation as a primary treatment option.

Decision Making: Thermal Ablation Options for Small Renal Masses

Renal cell carcinoma is a relatively common tumor, with an estimated 63,000 new cases being diagnosed in the United States in 2016. Surgery, be it with partial or total nephrectomy, is considered the mainstay of treatment for many patients. However, those patients with small renal masses, typically less than 3 to 4 cm in size who are deemed unsuitable for surgery, may be suitable for percutaneous thermal ablation. We review the various treatment modalities, including radiofrequency ablation, microwave ablation, and cryoablation; discuss the advantages and disadvantages of each method; and review the latest data concerning the performance of the various ablative modalities compared with each other, and compared with surgery.

Arterial Clamping Increases Central Renal Cryoablation Efficacy: An Animal Study

INTRODUCTION

The minimally invasive treatment of small renal masses with cryoablation has become increasingly widespread during the past 15 years. Studies with long-term follow-up are beginning to emerge, showing good oncological control, however, tumors with a central and endophytic location seem to possess an increased risk of treatment failure. Such tumors are likely to be subjected to a high volume of blood giving thermal protection to the cancerous cells. Arterial clamping during freezing might reduce this effect but at the same time subject the kidney to ischemia. The aim of this study was to evaluate the effect of renal artery clamping during cryoablation in a porcine survival model.

METHODS

Ten Danish Landrace pigs (approximately 40 kg) underwent bilateral laparoscopic cryoablation with clamping of the right renal artery during freezing. The cryoablation consisted of a standard double-freeze cycle of 10-minute freeze followed by 8 minutes of thaw. Arterial clamping subjected the right kidney to 2 cycles of ischemia (10 minutes) with perfusion in between. After surgery, the animals were housed for 14 days prior to computed tomography perfusions scans, radioisotope renography, and bilateral nephrectomy.

RESULTS

No perioperative or postoperative complications were experienced. Mean differential renal function was 44% (95% confidence interval: 42-46) in the clamped right kidney group and 56% (95% confidence interval: 54-58) in the nonclamped left kidney group, P < .05. The ±5% technical inaccuracy is not accounted for in the results. Mean maximum temperature between freeze cycles was 5.13°C (95% confidence interval: -0.1 to 10.3) in the clamped right kidney group and 22.7°C (95% confidence interval: -16.6 to 28.8) in the nonclamped left kidney group, P < .05. Mean cryolesion volume, estimated on computed tomography perfusion, was 12.4 mL (95% confidence interval: 10.35-14.4) in the clamped right kidney group and 6.85 mL (95% confidence interval: 5.57-8.14) in the nonclamped left kidney group, P < .05. Pathological examination shows a higher degree of vital cells in the intermediate zone of the cryolesions in the nonclamped left kidneys when compared with the clamped right kidneys.

CONCLUSION

Arterial clamping increases cryolesion size by approximately 80%, and pathologic examinations suggest a decreased risk of vital cells in the intermediate zone. The clamped kidneys showed no sign of injury from the limited ischemic insult. This study was limited by being a nontumor model.

Computed Tomography Perfusion, Magnetic Resonance Imaging, and Histopathological Findings After Laparoscopic Renal Cryoablation: An In Vivo Pig Model

The present study investigates how computed tomography perfusion scans and magnetic resonance imaging correlates with the histopathological alterations in renal tissue after cryoablation. A total of 15 pigs were subjected to laparoscopic-assisted cryoablation on both kidneys. After intervention, each animal was randomized to a postoperative follow-up period of 1, 2, or 4 weeks, after which computed tomography perfusion and magnetic resonance imaging scans were performed. Immediately after imaging, open bilateral nephrectomy was performed allowing for histopathological examination of the cryolesions. On computed tomography perfusion and magnetic resonance imaging examinations, rim enhancement was observed in the transition zone of the cryolesion 1week after laparoscopic-assisted cryoablation. This rim enhancement was found to subside after 2 and 4 weeks of follow-up, which was consistent with the microscopic examinations revealing of fibrotic scar tissue formation in the peripheral zone of the cryolesion. On T2 magnetic resonance imaging sequences, a thin hypointense rim surrounded the cryolesion, separating it from the adjacent renal parenchyma. Microscopic examinations revealed hemorrhage and later hemosiderin located in the peripheral zone. No nodular or diffuse contrast enhancement was found in the central zone of the cryolesions at any follow-up stage on neither computed tomography perfusion nor magnetic resonance imaging. On microscopic examinations, the central zone was found to consist of coagulative necrosis 1 week after laparoscopic-assisted cryoablation, which was partially replaced by fibrotic scar tissue 4 weeks following laparoscopic-assisted cryoablation. Both computed tomography perfusion and magnetic resonance imaging found the renal collecting system to be involved at all 3 stages of follow-up, but on microscopic examination, the urothelium was found to be intact in all cases. In conclusion, cryoablation effectively destroyed renal parenchyma, leaving the urothelium intact. Both computed tomography perfusion and magnetic resonance imaging reflect the microscopic findings but with some differences, especially regarding the peripheral zone. Magnetic resonance imaging seems an attractive modality for early postoperative follow-up.

Laparoscopic Cryotherapy for Renal Tumors

In an effort to decrease operative morbidity, energy based ablative procedures have triggered considerable interest in the treatment of select, small (<3 cm) renal tumors. Renal cryoablation for small renal tumors is a well-studied energy based ablative procedure that shows considerable promise as an alternative to partial nephrectomy. Cryoablation is minimally invasive and has demonstrated acceptable intermediate-term results. In this article we review key laboratory research and current clinical series of renal cryoablation.

A Recent Advance in Image-Guided Locoregional Therapy for Hepatocellular Carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide and the third most common cause of cancer-related deaths. Hepatic resection and liver transplantation are considered to be the preferred treatment for HCC. However, as novel therapeutic options such as image-guided locoregional therapies have emerged and been refined, the manner in which HCC is treated has changed dramatically compared with what it was considered just 2 decades earlier.

SUMMARY

This study reviews the current results of various image-guided locoregional therapies for treating HCC, especially focusing on thermal ablative and transarterial techniques.

KEY MESSAGE

Advances in image-guided locoregional therapies, including local ablative therapy and transarterial therapy, have led to a major breakthrough in the management of HCC. Both survival rates and cure rates of patients with HCC have improved markedly since the introduction of these techniques.

PRACTICAL IMPLICATIONS

Radiofrequency ablation is currently considered as an alternative to surgical resection for patients with early-stage HCC. A newer technique of ablation such as microwave ablation is increasingly being used, especially for large HCC. Transarterial chemoembolization has become a standard care for asymptomatic patients with multinodular tumors in intermediate-stage disease, and transarterial radioembolization has become the method of choice in HCC cases with portal vein thrombosis. Moreover, combination treatment modalities, such as thermal-based ablation combined with transarterial chemoembolization or ¹²⁵I seed implant brachytherapy, may further broaden their clinical indications for HCC. Moreover, use of localized radiation in combination with thermal ablation has been reported to improve tumor control and long-term survival.

Charting the course of renal cryoinjury

We sought to characterize a minor renal cryoinjury that allows investigation into renal damage processes and subsequent endogenous repair mechanisms. To achieve this, we induced a small cryoinjury to mice, in which the transient superficial application of a liquid nitrogen-cooled cryoprobe to the exposed kidney induces a localized lesion that did not impair renal function. The resulting cryoinjury was examined by immunohistochemistry and Laser-Doppler flowmetry. Within hours of cryoinjury induction, tubular and vascular necrotic damage was observed, while blood flow in the directly injured area was reduced by 65%. The injured area demonstrated a peak in tubular and perivascular cell proliferation at 4 days postinjury, while apoptosis and fibrosis peaked at day 7. Infiltration of macrophages into the injury was first observed at day 4, and peaked at day 7. Vascular density in the direct injured area was lowest at day 7. As compared to the direct injured area, the (peripheral) penumbral region surrounding the directly injured area demonstrated enhanced cellular proliferation (2.5-6-fold greater), vascular density (1.6-2.9 fold greater) and blood perfusion (twofold greater). After 4 weeks, the area of damage was reduced by 73%, fibrosis decreased by 50% and blood flow in the direct injured area was reestablished by 63% with almost complete perfusion restoration in the injury's penumbral region. In conclusion, kidney cryoinjury provides a flexible facile model for the study of renal damage and associated endogenous repair processes.

Renal ablation update

Thermal ablative technologies have evolved considerably in the recent past and are now an important component of current clinical guidelines for the treatment of small renal masses. Both radiofrequency ablation and cryoablation have intermediate-term oncologic control that rivals surgical options, with favorable complication profiles. Studies comparing cryoablation and radiofrequency ablation show no significant difference in oncologic control or complication profile between the two modalities. Early data from small series with microwave ablation have shown similar promising results. Newer technologies including irreversible electroporation and high-intensity-focused ultrasound have theoretical advantages, but will require further research before becoming a routine part of the ablation armamentarium. The purpose of this review article is to discuss the current ablative technologies available, briefly review their mechanisms of action, discuss technical aspects of each, and provide current data supporting their use.

The role of interventional radiology in the management of hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (hcc) is one of the most common causes of cancer-related death worldwide. Overall, liver transplantation and resection are the only available treatments with potential for cure. Various locoregional therapies are widely used to manage patients with advanced hcc or as a bridging therapy for patients with early and intermediate disease. This article reviews and evaluates the role of interventional radiology in the management of such cases by assessing various aspects of each method, such as effect on rates of survival, recurrence, tumour response, and complications.

METHODS

A systemic search of PubMed, medline, Ovid Medline In-Process, and the Cochrane Database of Systematic Reviews retrieved all related scientific papers for review.

RESULTS

Needle core biopsy is a highly sensitive, specific, and accurate method for hcc grading. Portal-vein embolization provides adequate expansion of the future liver remnant, making more patients eligible for resection. In focal or multifocal unresectable early-stage disease, radiofrequency ablation tops all other thermoablative methods. However, microwave ablation is preferred in large tumours and in patients with Child-Pugh B disease. Cryoablation is preferred in recurrent disease and in patients who are poor candidates for anesthesia. Of the various transarterial modalities-transarterial chemoembolization (tace), drug-eluting beads, and transarterial radio-embolization (tare)-tace is the method of choice in Child-Pugh A disease, and tare is the method of choice in hcc cases with portal vein thrombosis.

CONCLUSIONS

The existing data support the importance of a multidisciplinary approach in hcc management. Large randomized controlled studies are needed to provide clear indication guidelines for each method.

Thermoablation of Renal Masses: The Urologist's Perspective

Thermoablation (TA) has become an increasingly popular treatment for small renal masses (SRMs). Although long-term outcomes are not currently reported, TA may have a role in being an alternative to radical or partial nephrectomy. This review gives a broad overview of TA and discusses current controversies in the field.

Interventional radiological treatment of hepatocellular carcinoma: an update

Hepatocellular carcinoma is the commonest primary liver tumor and its incidence is on an increase.Transplantation and surgical resection are the gold standard curative treatment options but less than 20%patients are surgical candidates because of advanced liver disease and/or co-morbidities.Various interventional radiological procedures have been developed and intensively investigated for treatment of inoperable HCC.This review summarizes the various interventional radiological treatments in HCC including patient selection, procedural considerations and response evaluation. Transarterial chemoembolization, radioembolization and radiofrequency ablation are mainly discussed.

Percutaneous cryoablation of renal lesions with radiographic ice ball involvement of the renal sinus: analysis of hemorrhagic and collecting system complications

OBJECTIVE

The purpose of this study was to determine the incidence of collecting system and hemorrhagic complications resulting from CT-guided percutaneous cryoablation of renal tumors in which the radiographic ice ball abuts or involves the renal sinus.

MATERIALS AND METHODS

From November 2005 through July 2009 at our institution, we performed 129 CT-guided percutaneous cryoablation procedures on 107 patients (mean age, 64 years) with renal masses suspicious of being renal cell carcinoma. Radiographic ice balls that abutted or overlapped the renal sinus were classified as central; the other lesions were classified as noncentral. Medical records and follow-up images were retrospectively reviewed for hemorrhage requiring intervention and for evidence of collecting system injury. The mean follow-up period was 9.3 months.

RESULTS

The radiographic ice ball was classified as central in 67 cases. In these central ablations, the mean sinus involvement was 6.2 mm (range, 0-19 mm), 41 ice balls overlapping the renal sinus by 6 mm or more (mean, 9.4 mm). No cases of collecting system injury were identified for any ablation. Overall, there was only one hemorrhagic complication requiring intervention, and it occurred in a noncentral ablation.

CONCLUSION

CT-guided percutaneous cryoablation of renal masses with ice ball overlap of the renal sinus resulted in no cases of collecting system injury or serious hemorrhagic complications in our series.

Renal tissue ablation with irreversible electroporation: preliminary results in a porcine model

OBJECTIVES

To evaluate the histopathologic and computed tomography imaging features associated with irreversible electroporation (IRE) ablation performed in normal porcine kidneys. IRE is a nonthermal ablative tool that uses direct electrical pulses to create permanent "pores" in cell membranes and cell death. It does not affect the extracellular matrix.

METHODS

Fifteen female swine were treated with IRE using acute (<24 hours), subacute (36 hours), and chronic (3 weeks) treatment settings. Unipolar IRE applicators were placed under CT guidance. The renal pelvis/calyx was included in 18 ablations. Imaging and histopathologic follow-up were performed.

RESULTS

A total of 29 ablations (19 acute, 4 subacute, and 6 chronic) were created. Acute/subacute ablations showed complete cortical necrosis without intervening live cells. The pelvic epithelium was necrotic with urothelial sloughing; pelvic extracellular matrix was intact. Chronic ablations showed cortical fibrosis, regenerating renal pelvic epithelium and intact pelvic extracellular matrix. No thermal injury, renal pelvic, or blood vessel injury was seen. Immediate postprocedure CT imaging demonstrated a hypodense nonenhancing lesion that persisted at 1 week. Of the 6 chronic lesions, 4 showed complete resolution at 3 weeks on imaging. No collecting system damage was seen.

CONCLUSIONS

This preliminary porcine study demonstrates the nonthermal and connective tissue sparing mechanism of action of IRE. These features may protect against collecting system damage after IRE ablation of renal tissue. IRE could therefore play an important role in ablation of centrally located renal tumors.

Percutaneous cryoablation of renal tumors: patient selection, technique, and postprocedural imaging

Percutaneous cryoablation of renal tumors requires a number of important steps for success and relies heavily on imaging for treatment planning, intraprocedural guidance and monitoring, detection of untreated tumor, and surveillance for disease progression. Imaging-guided percutaneous cryoablation has several advantages over laparoscopic cryoablation. In particular, computed tomography (CT) and magnetic resonance (MR) imaging allow global evaluation of the ablation zone and an accurate depiction of the treatment margin. Ultrasonography allows real-time guidance of probe placement but cannot help depict ice ball formation as accurately as CT or MR imaging. Multiphasic CT or MR imaging should be performed at structured intervals following ablation. Treated tumors are expected to decrease in size over time, and lesion growth and internal or nodular enhancement are suspicious for tumor recurrence or progression. Complications include probe site pain, hematoma, incomplete ablation, and recurrent tumor. Current limitations of percutaneous cryoablation include the inability to control hemorrhage without intraarterial access and a lack of long-term follow-up data. Nevertheless, percutaneous cryoablation is an effective choice for minimally invasive nephron-sparing treatment of renal tumors.

Interventional radiological treatment of hepatocellular carcinoma

BACKGROUND

Locoregional treatments of hepatocellular carcinoma (HCC) have evolved over the past 20 years. Interventional radiologists have developed an important role in the palliative and curative treatment of the disease. This review summarizes commonly used interventional radiological treatment protocols to assist practitioners in understanding the techniques used to treat HCC.

METHODS

Various searches were performed to evaluate recent publications regarding systemic treatments of HCC as well as transplant/surgery, chemoembolization, yttrium-90 radioembolization, percutaneous radiofrequency ablation (RFA), cryoablation, and percutaneous ethanol injection (PEI).

RESULTS

No standard for chemoembolization was found. Two studies evaluating survival with chemoembolization vs medical therapy found benefits with the former. PEI offers favorable outcomes in small HCC but has increased recurrence and decreased long-term survival compared with RFA. Local recurrence, response rates, and mortality from RFA rival surgical resection in HCC less than 3 cm. Cryoablation appears to be effective, and yttrium-90 radioembolization is an additional tool.

CONCLUSIONS

Chemoembolization improves survival and offers improved tumor response compared to systemic treatment. More studies are needed to standardize chemoembolization preparations and techniques. RFA provides better results than PEI but has not been compared with cryoablation. Radioembolization appears to be as effective as chemoembolization, but the preprocedure evaluation and costs may limit its use.

Experimental cryosurgery investigations in vivo

Cryosurgery is the use of freezing temperatures to elicit an ablative response in a targeted tissue. This review provides a global overview of experimentation in vivo which has been the basis of advancement of this widely applied therapeutic option. The cellular and tissue-related events that underlie the mechanisms of destruction, including direct cell injury (cryolysis), vascular stasis, apoptosis and necrosis, are described and are related to the optimal methods of technique of freezing to achieve efficacious therapy. In vivo experiments with major organs, including wound healing, the putative immunological response following thawing, and the use of cryoadjunctive strategies to enhance cancer cell sensitivity to freezing, are described.

The UCI Seldinger technique for percutaneous renal cryoablation: protecting the tract and achieving hemostasis

PURPOSE

To describe our Seldinger technique of percutaneous renal cryoablation that was devised to facilitate renal biopsy, cryoprobe placement, and instillation of adjunctive hemostatics while protecting surrounding tissues from cryoinjury.

PATIENTS AND METHODS

This approach was used to manage 13 renal masses in 12 adult patients. Under CT-fluoroscopic guidance, an access needle was inserted to abut the surface of the tumor, followed by an Amplatz super-stiff guidewire and a customized coaxial catheter system, which was used as a conduit for needle biopsy, cryoprobe insertion, and FloSeal instillation. In addition, a porcine model was used to compare the temperature readings adjacent to the sheathed and the unsheathed cryoprobe during percutaneous renal cryoablation.

RESULTS

In all patients, the use of this access approach was accomplished without incident. Two patients needed blood transfusions. No patient had significant skin, muscle, or nerve debility. At a mean follow-up of 11 months, none had evidence of persistent disease on CT or MRI contrast imaging. In the porcine model, the customized sheath protected the surrounding tissues from reaching temperatures below 5 degrees C while temperatures down to -15 degrees C were obtained when no insulating sheath was used.

CONCLUSIONS

A modified Seldinger technique enabled us to perform percutaneous renal cryotherapy through a single access channel, which facilitated access for biopsy, cryoprobe placement, and instillation of hemostatic agents. This approach may provide a protective barrier against cryogenic damage to neighboring tissues and could theoretically help minimize the chance of tract seeding.

Bladder cryoablation in a porcine model: evaluation of three surgical approaches and cryolesion predictability

PURPOSE

To determine the feasibility of bladder cryoablation (BC) applied laparoscopically, percutaneously, and transurethrally in a porcine survival study. The expected and observed area of cell death after BC was also examined.

MATERIALS AND METHODS

Nine pigs were divided equally into the three treatment groups. Cryoablation was performed with two freeze-thaw cycles after the bladder had been insufflated with CO2. Each animal was observed for 7 days after the procedure for treatment-related complications. After cystectomy, each specimen was examined pathologically to determine the degree and dimension of cell death achieved.

RESULTS

BC applied via the laparoscopic and percutaneous approach is feasible and safe. No BC-related complications occurred in these two groups. A complication resulting from BC developed in all three animals that were treated cystoscopically, including two intraperitoneal bladder perforations at the time of BC necessitating immediate sacrifice, and one enterovesical fistula discovered at cystectomy. Transmural necrosis was demonstrated in seven of seven animal specimens that survived to the end of the protocol. The observed diameter of tissue necrosis was highly predictable based on the reported cryoprobe isotherms given by the manufacturer.

CONCLUSION

All locations within the bladder can be successfully and predictably treated with cryoablation. Of the three approaches, laparoscopically administered BC appears to be the most safe and consistent method. Transurethral BC was not safe with the equipment available without laparoscopic assistance to prevent bowel complications.

Complications of laparoscopic surgery for renal masses: prevention, management, and comparison with the open experience

CONTEXT

The initial excitement about the laparoscopic treatment of renal masses has been tempered by concerns related to increased operative time, technical complexity, and the suitability of laparoscopic approaches to oncologic surgery.

OBJECTIVE

To provide a comprehensive review of intraoperative and postoperative complications and their prevention and management during laparoscopic surgery of renal tumors.

EVIDENCE ACQUISITION

A literature review of the Medline and Google Scholar databases was performed, searching for renal cell carcinoma, renal mass, laparoscopy, laparoscopic radical nephrectomy, open radical nephrectomy, laparoscopic partial nephrectomy, open partial nephrectomy, laparoscopic cryoablation, laparoscopic radiofrequency ablation, complications, intra-operative, and post-operative. English-language articles published between 1990 and 2008 were reviewed.

EVIDENCE SYNTHESIS

Laparoscopic radical nephrectomy (LRN), whether transperitoneal or retroperitoneal, can be performed safely. The overall complication rate is low and does not significantly differ from that of the open experience. Laparoscopic partial nephrectomy (LPN), in contrast, is a technically challenging procedure. Although the intermediate oncologic outcomes are comparable to those of the open experience, there are concerns related to warm ischemia time, and there is a risk of major complications such as urinary leakage and hemorrhage requiring transfusion. Laparoscopic-assisted ablative therapies (cryotherapy and radiofrequency) are being performed more commonly for the treatment of small exophytic renal lesions with a low complication rate and intermediate oncologic outcomes similar to LRN and LPN.

CONCLUSIONS

Complications associated with the laparoscopic management of renal masses vary among the different procedures and with surgeon experience. The rate of complication appears to be similar to that of open surgery.

Renal thermal ablative therapy

Energy targeting is greatly enhanced through imaging modalities, which greatly assist needle placement or energy delivery to the optimal location for maximal effectiveness. When vital structures obscure access to the renal lesion, laparoscopic mobilization of these structures with direct visualization of the tumor can increase the likelihood of ablation success and minimize complication risk. Ablative therapies are attractive because of their minimal impact on patient quality of life in addition to their morbidity and cost. Although they show promise of efficacy, they must be evaluated with long-term follow-up before they are considered the standard of oncologic care. Renal masses can be treated with a laparoscopic or percutaneous approach depending on tumor location, size, and the available technology and experience of the center.

Cryoablation and radiofrequency for kidney tumor

The detection of incidental and asymptomatic renal cortical neoplasms has concomitantly increased with radiographic imaging use. The gold standard for treating small renal tumors includes open and laparoscopic partial nephrectomy. Ablative renal procedures intend to duplicate the excellent oncologic outcomes of partial nephrectomy, while decreasing complications and shortening hospitalization time and convalescence. Only short and medium-term data are available, but ablation with cryotherapy or radiofrequency probes may achieve these goals. Ablation also offers the advantages of a minimally invasive surgical approach, with a significantly lower complication rate than partial nephrectomy. Ablated lesions are typically left in situ. Leaving potentially malignant tissues in place, albeit in a nonviable condition, certainly represents a major change in surgical thinking processes. This article reviews the status of cryoablation and radiofrequency ablation, the two ablative modalities currently available for clinical application.

Percutaneous renal cryoablation: current status

Over the last 13 years, renal cryoablation has emerged as a promising technique for the treatment of solid renal tumors. The improvement in imaging modalities such as ultrasound, computed tomography and MRI, as well as the introduction of thinner probes, has led to the spread of the minimally invasive percutaneous approach. We review the historical background of percutaneous renal cryoablation (PRC), present its basic principles, mention the contemporary clinical data and outcomes of this technique and suggest future directions for its wider application in renal tumors. Early results have demonstrated that it may offer an alternative for the treatment of small renal masses with the advantages of minimal complications, spared renal function, decreased overall costs and equivalent oncologic efficacy. Long-term results are required in order to apply this minimally invasive technique to a broader spectrum of patients.

Urothelial sloughing with obstruction after laparoscopic cryoablation of small renal carcinoma in solitary kidney

Laparoscopic cryoablation is a minimally invasive treatment that is currently used to treat small renal tumors. Despite its growing use and promising outcomes, complications can occur. We report the first clinical case of urothelial sloughing with obstruction after cryoablation of a small renal tumor in a solitary kidney.

Transurethral bladder cryoablation in the porcine model

OBJECTIVES

To examine the feasibility of transurethral, focal, full-thickness bladder wall cryoablation in the porcine model using a novel 38-cm cryoablation probe.

METHODS

A total of 18 pigs were divided into three groups. Groups 1 (n = 6) and 2 (n = 6) underwent transurethral bladder wall cryoablation in a saline environment with two freeze-thaw cycles. The pigs in groups 1 and 2 were killed after 1 and 3 weeks, respectively. The pigs in group 3 (n = 6) underwent transurethral cryoablation after the bladder had been insufflated with carbon dioxide gas. The pigs in group 3 were killed after 1 week. In all groups, laparoscopic access was obtained to protect the abdominal contents from the transmural cryoablation process. Bladder integrity was evaluated with cystography and laparoscopic visualization, and each cryolesion was excised en bloc for extensive histopathologic evaluation.

RESULTS

All 18 pigs successfully underwent bladder wall cryoablation. For all groups, the preoperative, postoperative, and sacrifice cystograms were without evidence of extravasation. No urinomas, hematomas, or adhesions were present in groups 1 and 2. Minimal adhesions were identified in 3 (50%) of 6 pigs in group 3. For groups 1, and 2, the mean length and width of the area of complete necrosis on histopathologic evaluation was 6.5 and 3.0 mm and 2.3 and 1.3 mm, respectively. For group 3, the mean diameter of the cryolesion was 8.2 mm. Full-thickness necrosis was confirmed in all groups.

CONCLUSIONS

The results of our study have shown that, in this model, complete full-thickness transurethral bladder wall cryoablation, with maintenance of bladder wall integrity, is feasible.

Persistent Urine Leak after Cryoablation of a Renal Tumor in a Patient with an Ileal Conduit

Thermal ablation is expanding as a technique to treat small renal masses. Damage to the collecting system is uncommon with either radiofrequency ablation or cryoablation. Early evidence suggests that cryoablation is less damaging to the urinary tract, and investigators have advocated the use of aggressive treatment in central tumors in contact with the renal hilum. The authors report a nonhealing urinary fistula after successful cryoablation of an exophytic upper pole renal mass in a patient with an ileal conduit. The presence of an ileal conduit may present an increased risk of urinary fistula after thermal ablation.