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

Ablation of Kidney Tumors in Patients with Substantial Kidney Impairment: Current Status

PURPOSE OF REVIEW

To review the current status of kidney tumor ablation in patients with substantial kidney impairment.

RECENT FINDINGS

Few reports of kidney tumor ablation in such patients have recently been published. The reported prevalence of patients with stage 4 or 5 chronic kidney disease (CKD) among patients undergoing ablation is 2.0%-10%. In patients with stage 4 or 5 CKD, local tumor control rates were 88%-100%. The effect of ablation on CKD stage is unclear, and the observed deteriorations in kidney function are consistent with both the effect of cryoablation and the natural course of advanced CKD. According to guidelines, active surveillance may be selected. The goals of treatment are complete tumor removal and maintenance of kidney function, both of which can be met by ablation. Given the limited treatment options, ablation may play a pivotal role in the management of patients with advanced CKD.

Safety and Technical Feasibility of Percutaneous Renal Cryoablation of Central Tumors without Pyeloperfusion

PURPOSE

To assess the safety and technical success of percutaneous cryoablation (PCA) without pyeloperfusion in 94 patients with central renal tumors.

MATERIALS AND METHODS

A retrospective review of all central renal tumors treated by PCA without pyeloperfusion was performed. Central tumors were defined as those involving the renal sinus fat on preprocedural cross-sectional imaging. Patient demographics and baseline tumor characteristics were recorded. The details of the PCA procedure, primary and secondary technical success, rates of local recurrence, adverse events (AEs), cancer-specific survival (CSS), and overall survival (OS) were compiled.

RESULTS

Ninety-four patients (48 females [51%]; mean age, 68.2 years [range, 38-87 years]) with 94 central renal tumors were included. The mean maximal tumor diameter and mean RENAL nephrometry score were 37 mm (range, 15-67 mm) and 8 (range, 4-11), respectively. Primary technical success was achieved in 94% (n = 88) of procedures. Of the patients who did not achieve primary technical success, 3 underwent successful repeat PCA (secondary technical success, 97%; n = 91/94). The other 3 patients were surveilled for residual disease. Twenty-four patients (26%) required hydrodissection during PCA. Six patients (6%) experienced major AEs after PCA including hemorrhage requiring embolization (n = 3), hemorrhage requiring transfusions with admission (n = 2), and perinephric abscess necessitating drain placement (n = 1). Twenty-two patients (23%) experienced minor AEs. Nine patients (10%) experienced local recurrence during the follow-up period. OS was 94% (n = 88/94), whereas CSS was 98% (n = 92/94) during the study follow-up period (mean, 16 months [range, 1-102 months]).

CONCLUSIONS

PCA of central renal tumors appears to be safe with high rates of technical success, even without the use of pyeloperfusion.

Single-Probe Percutaneous Cryoablation with Liquid Nitrogen for the Treatment of T1a Renal Tumors

Kidney cancer accounts for 3% of adult malignancies and is increasingly detected through advanced imaging techniques, highlighting the need for effective treatment strategies. This retrospective study assessed the safety and efficacy of a new single-probe percutaneous cryoablation system using liquid nitrogen for treating T1a renal cancers. From May 2019 to May 2022, 25 consecutive patients from two academic hospitals, with a median age of 64.8 years [IQR 59; 75.5], underwent cryoablation for 26 T1a renal tumors. These tumors had a median size of 25.3 mm [20; 30.7] and a median RENAL nephrometry score, indicating tumor complexity, of 7 [5; 9]. No major complications arose, but three non-clinically relevant perirenal hematomas were detected on post-procedure CT scans. With a median follow-up of 795 days [573; 1020], the primary local control rate at one month stood was 80.8% (21 out of 26). The five recurrent lesions, which exhibited a higher renal score (p = 0.016), were treated again using cryoablation, achieving a secondary local control rate of 100%. No patient died, and the disease-free survival rate was 92% (23 out of 25). In conclusion, single-probe percutaneous cryoablation emerges as a promising modality for managing small renal masses. Notably, recurrence rates appear influenced by RENAL nephrometry scores, suggesting a need for further research to refine the technique.

Salvage Percutaneous Cryoablation for Bleeding Upper Tract Urothelial Carcinoma

PURPOSE

Endoscopic access and treatment of bleeding upper urinary tract urothelial carcinomas (UTUCS) is sometimes difficult and inefficient as resection and/or laser coagulation are often incomplete. We report two cases of successful cryoablation of bleeding UTUCs.

MATERIALS AND METHODS

This study evaluated an adjunctive method in using cryoablation as a hemostatic technique. Cryoprobes were inserted inside the affected calices and a standard renal cryoablation protocol was used. Track ablation was performed during the pullback of the cryoprobes to prevent tumor seeding and bleeding.

RESULTS

Cryoablation of the bleeding upper urinary tract tumors allowed to efficiently resolve macrohematuria in both patients and to provide prolonged remission in one patient.

CONCLUSIONS

Taking advantage of the microcirculatory stasis and the hemostatic properties of cryoablation, we achieved palliative cessation of refractory macrohematuria while sparing nephrons, without the need for renal embolization in patients with bleeding UTUCs.

Feasibility and Safety of Single-Probe Cryoablation with Liquid Nitrogen: An Initial Experience in 24 Various Tumor Lesions

Simple Summary

Percutaneous cryoablation was developed to minimally perform multi-organ tumor ablations. The most widely known cryotherapy systems use argon gas (high-pressure) and multiple needles to achieve sufficient ablations. The aim of our retrospective study was to assess the feasibility of a new cryotherapy system using single-probe liquid nitrogen for tumor lesions of various sizes and locations, and to evaluate the safety of cryoablation with this technique. Correlations between ice ball sizes and ablation zone sizes with two needle sizes (10G or 13G) and with the freezing duration were evaluated, as well as the sphericity of the ice ball and ablation zones. We showed that this technique is safe in all organs tested. We showed a correlation between the freezing duration and the ice ball size, but not with the ablation zone, which is useful for planning the procedure and treatment conducted by the oncology team.

Abstract

Background: Percutaneous cryoablation with liquid nitrogen is a new technique being used in the treatment of some malignant tumors. Our objective was to assess its feasibility in the ablation of tumor lesions of various sizes and locations. Methods: This retrospective, monocentric study included all consecutive patients who underwent percutaneous cryoablation with liquid nitrogen between December 2019 and March 2021. Cryoablation was performed using 10G or 13G cryoprobes. The ablation volume was measured on post-treatment CT or MRI. Results: 22 patients (24 lesions) were included, 16 of whom were men (73%), while median age was 66 years. The lesions were located in the bone (42%), kidney (29%), soft tissue (17%), lung (8%), or liver (4%). It was feasible in all tumor locations and produced median ablation zones 25 mm in width and 35 mm in length, with a 23 min median freezing time. Freezing duration was correlated with the ice volume (p Spearman = 0.02), but not with the ablation volume (p = 0.11). The average difference between the ablation zone and ice ball sizes were −6.4 mm in width and −7.7 mm in length. Both ice and ablation volumes were larger when using the 10G probe as compared to when the 13G was used. No complications were reported. Discussion: We showed that this technique was safe and feasible in all organs tested. The freezing duration was correlated with the ice ball size, but not with the ablation zone.

Percutaneous cryoablation for clinical T3a renal cell carcinoma (< 7 cm) with segmental vein involvement or perinephric fat invasion based on preoperative evaluation of high-resolution multidetector computed tomography scan

Purpose

To retrospectively assess the feasibility, safety, renal function, technique efficacy rate, and survival of patients with clinical T3a renal cell carcinoma (RCC).

Materials and methods

Sixteen cryoablation sessions were performed in 14 patients (10 men; mean age, 69.8 ± 10.5 years; range, 49–90 years) with 14 clear cell T3a RCCs (mean, 3.3 ± 0.9 cm; range, 1.9–5.2 cm). One patient was on dialysis. Transcatheter arterial embolization was performed before cryoablation in 15 sessions. The primary endpoint was the technique efficacy rate. The secondary endpoints included feasibility, safety, renal function, and survival.

Results

Cryoablation was technically successful in all RCC cases. In two RCCs, cryoablation was performed twice because of local tumor progression. No major adverse events were observed. All patients were alive without metastases, with a median follow-up of 45 months (6−93 months). Complete response was achieved by cryoablation in 11 RCCs (78.6%). The primary and secondary technique efficacy rates were 77.1% and 84.4% at 1 year, 57.9% and 73.9% at 3 years, and 57.9% and 73.9% at 5 years, respectively. One patient underwent dialysis given a total contralateral nephrectomy due to another RCC 1 month after initial cryoablation and a total ipsilateral nephrectomy 46 months after initial cryoablation due to local progression. Except for two dialysis patients, of the 12 patients with a median follow-up of 41 months (6–93 months), none were on dialysis.

Conclusion

Cryoablation was safe and effective in T3a RCC, which mainly involved the renal venous branches and may represent an alternative treatment for inoperable patients.

Percutaneous ablation of renal tumors versus surgical ablation and partial nephrectomy: Medicare trends and reimbursement cost comparison from 2010 to 2018

PURPOSE

The purpose of this study is to analyze trends in Medicare volume and reimbursement for percutaneous and surgical ablation as well as laparoscopic and open partial nephrectomy for treatment of small renal tumors from 2010 to 2018.

METHODS

Claims from the Medicare Part B Physician/Supplier Procedure Summary from 2010 to 2018 were extracted using CPT codes for percutaneous and surgical renal ablation and surgical and laparoscopic partial nephrectomy. Facility reimbursement and relative value units (RVUs) were obtained using the Centers for Medicare & Medicaid Services physician fee schedule look-up tool.

RESULTS

Volume of percutaneous ablation increased from 2539 to 4571 procedures (80.0%). Specifically, percutaneous cryoablation became the dominant technique, increasing from 1434 to 2981 procedures (107.9%). Overall, volume of partial nephrectomy also increased by 40.4%, driven by an increase in laparoscopic partial nephrectomy from 3227 to 7770 procedures (140.8%) with a decrease in open partial nephrectomy from 3489 to 1661 (- 52.4%). Volume of surgical ablations also decreased 72.7% from 1260 to 344 procedures. In 2018, reimbursement was $358.56 for percutaneous radiofrequency ablation, $481.32 for percutaneous cryoablation, $1216.43 for surgical radiofrequency ablation, $1269.35 for surgical cryoablation, $1381.67 for open partial nephrectomy, and $1552.66 for laparoscopic partial nephrectomy.

CONCLUSION

There has been a trend toward minimally invasive techniques for treatment of small renal tumors among Medicare patients. Laparoscopic partial nephrectomy has become the dominant treatment. In the setting of evidence showing comparable outcomes with surgery as well as lower costs to insurers, the volume of percutaneous ablation has also markedly increased.

Imaging considerations for thermal and radiotherapy ablation of primary and metastatic renal cell carcinoma

Ablative (percutaneous and stereotactic) thermal and radiotherapy procedures for management of both primary and metastatic renal cell carcinoma are increasing in popularity in clinical practice. Data suggest comparable efficacy with lower cost and morbidity compared to nephrectomy. Ablative therapies may be used alone or in conjunction with surgery or chemotherapy for treatment of primary tumor and metastatic disease. Imaging plays a crucial role in pre-treatment selection and planning of ablation, intra-procedural guidance, evaluation for complications, short- and long-term post-procedural surveillance of disease, and treatment response. Treatment response and disease recurrence may differ considerably after ablation, particularly for stereotactic radiotherapy, when compared to conventional surgical and chemotherapies. This article reviews the current and emerging role of imaging for ablative therapy of renal cell carcinoma.

Safety and oncologic efficacy of percutaneous MRI-guided cryoablation of intraparenchymal renal cancers

PURPOSE

The purpose of this study was to evaluate the safety and oncologic efficacy of percutaneous magnetic resonance imaging (MRI)-guided cryoablation of intraparenchymal renal cancer.

MATERIALS AND METHODS

Between February 2009 and August 2019, 31 consecutives patients with 31 entirely intraparenchymal biopsy-proven renal cancers were treated with cryoablation under MRI-guidance in our institution, and were retrospectively included. There were 20 men and 11 women with a mean age of 68.5±12.5 (SD) (range: 40-91years). Patient, tumor- and procedure-related, and follow-up data were retrospectively collected and analyzed. Local recurrence free (LRFS), metastasis free (MFS), disease free (DFS), cancer specific (CSS), and overall survivals (OS) were calculated.

RESULTS

Primary and secondary technical efficacy rates were 94% and 100%, respectively. Median follow-up was 27months. Seven (7/31; 23%) minor complications were noted in 7 patients. Patients showed a significant decline of the estimated glomerular filtration rate (eGFR) between baseline and nadir (mean basal eGFR 65.9±22.4 [SD] mL/min/1.73m²vs. mean nadir eGFR 52.8±26.0 [SD] mL/min/1.73m²; P<0.001), but only two showed a clinically significant renal function decline. Three-year estimates of primary and secondary LRFS, MFS, and DFS were 64% (95% confidence interval [CI]: 47-87%), 89% (95% CI: 78-99%), 83% (95% CI: 77-98%), and 45% (95% CI: 28-73%), respectively. No patients died due to renal cancer evolution (three-year CSS of 100%; 95% CI: 100-100%). One patient died 52months after the percutaneous treatment due to cryoablation-unrelated causes (three-year OS of 100%; 95% CI: 100-100%).

CONCLUSION

MRI-guided percutaneous cryoablation for intraparenchymal renal cancer offers good oncologic outcomes with acceptable complication rates and renal function worsening.

Percutaneous hydrodissection for thermoprotection during cryoablation of periureteric and pyeloureteric junction renal cell carcinomas

OBJECTIVE

To report our experience of percutaneous image-guided cryoablation of renal tumors located within 10 mm of the pyeloureteric junction (PUJ) and/or ureter, with hydrodissection as a stand-alone thermoprotective technique.

MATERIALS AND METHODS

All patients who were offered combined hydrodissection and cryoablation of the PUJ/ureter to treat stage-1 renal cell carcinoma were retrospectively reviewed. Data regarding patients, lesions, and outcomes were collected.

RESULTS

Twenty tumors in 20 patients (13 males:7 females) with a mean age of 74.4 ± 7.5 were included. Mean tumor size was 27.6 ± 6.4 mm. Nearby vulnerable structure(s) were identified as the ureter in 5/20 cases, the PUJ in 8/20 cases and both the PUJ and the ureter in the remaining 7/20 cases (35%) cases. Mean minimal distance between the tumor and the vulnerable organ(s) was 4.8 ± 2.6 mm (range 0-10). A mean of 1.7 ± 0.6 spinal needles were used per intervention with a mean time to complete hydrodissection of 18.6 ± 13.4 min. Primary and secondary technical efficacy rates were 90% and 95%, respectively. Mean follow-up was 23.1 ± 9.2 months. There were no immediate or delayed complications, in particular no urothelial strictures. Two tumor recurrences occurred during follow-up, with a time to disease progression of 13 and 31 months, respectively.

CONCLUSION

hydrodissection of the PUJ/ureter to prevent thermal injury during cryoablation is an effective technique and does not seem to compromise the efficacy of ablation at short or mid-term follow-up.

Safety and Oncologic Outcomes of Magnetic Resonance Imaging-Guided Cryoablation of Renal Cell Carcinoma: A 10-Year Single-Center Experience

OBJECTIVES

Magnetic resonance imaging guidance has been sporadically reported for renal tumor cryoablation (CA); therefore, clinical experience with this modality is still limited.The aim of this study is to retrospectively analyze our 10-year experience with renal tumor CA performed on a 1.5 T magnetic resonance imaging unit with the intent of reporting procedural safety and oncologic outcomes.

MATERIALS AND METHODS

We included 143 patients (102 men; 41 women; median age, 73 years; range, 34-91 years) with 149 tumors (median size, 2.6 cm; range, 0.6-6.0 cm), treated between 2009 and 2019. Patient, tumor, procedure, and follow-up data were collected and analyzed. The Kaplan-Meier method was used to estimate local recurrence-free (LRFS), metastasis-free (MFS), disease-free (DFS), cancer-specific, and overall (OS) survival. Univariate and multivariate models were used to identify factors associated with complications, LRFS, MFS, DFS, and OS.

RESULTS

The overall complication rate was 10.7% (16/149 tumors), with 1 major (1/149 [0.7%]; 95% confidence interval, 0.0%-3.7%) hemorrhagic complication. Other minor complications (15/149 [10.1%]; 95% confidence interval, 0.6%-16.1%) did not include any cases of injury to nearby organs. There were no factors associated with complications.Five-year estimates of LRFS (primary/secondary), MFS, DFS, cancer-specific survival, and OS were 82.8%/91.5%, 91.1%, 75.1%, 98.2%, and 89.6%, respectively. Increasing tumor size (hazard radio [HR], 1.8; P = 0.02) and intraparenchymal tumor location (HR, 5.6; P < 0.01) were associated with lower LRFS; increasing patient's age (HR, 0.5; P = 0.01), high tumor grade (HR, 23.3; P < 0.01) and non-clear-cell/nonpapillary histology (HR, 20.1; P < 0.01) with metastatic disease; and high tumor grade (HR, 3.2; P = 0.04) with lower DFS.

CONCLUSION

Magnetic resonance imaging-guided CA of renal tumors is associated with acceptable morbidity and high survival estimates at 5-year follow-up. Given the absence of complications resulting from injuries to nearby organs, further studies are required to evaluate whether the potential reduced incidence of these adverse events justifies large-scale implementation of this interventional modality.

Asian Conference on Tumor Ablation guidelines for renal cell carcinoma

Thermal ablation has been established as an alternative treatment for renal cell carcinoma (RCC) in patients who are poor candidates for surgery. However, while American and European guidelines have been established for American and European patients, respectively, no ablation guidelines for Asian patients with RCCs have been established many years after the Asian Conference on Tumor Ablation (ACTA) had been held. Given that Western guidelines are difficult to apply to Asian patients due to differences in body habitus, economic status, and insurance systems, the current review sought to establish the first version of the ACTA guidelines for treating a RCC with thermal ablation.

Renal mass cryoablation: Melting time analysis of radiographic ice-ball after 5-minute active thawing by using serial ultrasound

OBJECTIVE

Cryoneedles removal before sufficient thawing may lead to tissue damage and bleeding. We analyzed melting time of radiographic ice-ball in renal percutaneous cryoablation (PCA) using ultrasound.

MATERIALS AND METHODS

Consecutive 27 patients who underwent PCA using cryoneedles of 2-4 for the renal mass (median size, 1.9 cm; range, 1.1-4.1 cm) were evaluated. Reconstructed CT images obtained during freezing were used to measure radiographic ice-ball volume. After completing final freezing, 5-min active thawing and following passive thawing were performed. Melting time of radiographic ice-ball during the thawing was analyzed by serial ultrasound examination. Melting time was defined as the time of complete disappearance of intrarenal posterior acoustic shadowing generated by radiographic ice-ball, which was analyzed by two independent radiologists. The relationship between total melting time and radiographic ice-ball volume was also analyzed by Spearman's rank correlation.

RESULTS

Median radiographic ice-ball volume was 30.5 cm³ (range, 26.6-37.3 cm³). After 5-min active thawing, radiographic ice-ball needed additional passive thawing of median 8-min or 9-min for complete melting in analyses of two independent radiologists, respectively (p > 0.05). The range of total melting time during active and passive thawing was 9-min-to-15-min for both radiologists, respectively. A positive correlation was found between total melting time and radiographic ice-ball volume (Spearman's rho, 0.644 and 0.479 for radiologist 1 and 2).

CONCLUSION

In our PCA protocol, radiographic ice-ball needed approximately 10-min passive thawing after 5-min active thawing for complete melting. This may help determine safe removal time of cryoneedles.

Renal cryoablation - a practical guide for interventional radiologists

Renal cryoablation is a treatment option for early stage renal cell carcinomas with excellent oncological outcomes and low morbidity. This review outlines the technique of renal cryoablation and provides a guide for interventional radiologists on setting up an integrated service within a renal cancer network multidisciplinary setting. Patient selection and preparation, together with the technical aspects which ensure optimal oncological outcomes and avoid collateral damage to adjacent organs are highlighted.

Safety and Efficacy of Retrograde Pyeloperfusion for Ureteral Protection during Renal Tumor Cryoablation

PURPOSE

To determine safety and efficacy of retrograde pyeloperfusion for ureteral protection during cryoablation of adjacent renal tumors.

MATERIALS AND METHODS

Retrospective review of 155 patients treated with renal cryoablation, including adjunctive retrograde pyeloperfusion, from 2005 to 2019 was performed. Ice contacted the ureter in 67 of the 155 patients who represented the study cohort. Median patient age was 68 years old (interquartile range [61, 74]), 52 patients (78%) were male, and 37 tumors (55%) were clear cell histology. Mean tumor size was 3.4 ± 1.3 cm, and 42 tumors (63%) were located at the lower pole. Treatment-related complication and oncologic outcomes were recorded based on a review of post-procedural images and chart review.

RESULTS

Technical success of cryoablation was attained in 67 cases (100%), and technical success of pyeloperfusion was attained in 66 cases (99%). A total of 13 patients (19.4%) experienced SIR major C or D complications related to the procedure, including hemorrhage (n = 4), urine leak (n = 3), transient urinary obstruction (n = 2), pulmonary embolism (n = 1), hypertensive urgency (n = 1), acute respiratory failure (n = 1), and ureteropelvic junction (UPJ) stricture (n = 1). No complications were attributable to pyeloperfusion. Three of 45 patients with biopsy-proven renal cell carcinoma experienced local recurrence resulting in local recurrence-free survival of 92% (95% confidence interval, 81.5%-100%) 3 years after ablation.

CONCLUSIONS

Retrograde pyeloperfusion of the renal collecting system is a relatively safe and efficacious option for ureteral protection during renal tumor cryoablation. This adjunctive procedure should be considered for patients in whom cryoablation of a renal mass could potentially involve the ureter.

Computed tomography-guided percutaneous cryoablation of T1b renal tumors: safety, functional and oncological outcomes

Purpose: To evaluate the safety, functional and oncological outcomes associated with percutaneous cryoablation of stage T1b renal cell carcinoma (RCC). Materials and methods: Institutional database was reviewed to identify patients treated by percutaneous CT-guidance cryoablation between 2013 and 2018 for biopsy-proven RCC tumors measuring 4.1-7.0 cm. The main outcome parameters analyzed were primary and secondary technique efficacy, progression-free survival (PFS), cancer-specific survival (CSS), loss of estimated glomerular filtration rate (eGFR) and complications. PFS and CSS were estimated by the Kaplan-Meier method. Complications were graded by the Clavien-Dindo system. Results: Twenty-three consecutive patients were included (mean tumor diameter: 45.6 ± 6.2 mm; mean RENAL score: 8.1 ± 1.8). The technical success rate was 95.7%. Primary and secondary technique efficacy rates were 86.3 and 100%, respectively. Three patients found to have incomplete ablations at 3 months were successfully treated by repeat cryoablation. Median duration follow-up was 11 months (range: 3-33). Imaging showed PFS to be 85.7% at 6 months, 66.7% at 12 months and 66.7% at 24 months. One patient with a local recurrence at 12 months was treated by radical nephrectomy. One patient died from progression of disease within 12 months. One patient reported a complication grade ≥ II (4.3%). Mean eGFR loss was 4.4 ± 8.5 ml/min/1.73m², which was significantly higher among those treated for central tumors (p < .05). Conclusion: Cryoablation for stage T1b renal tumors is technically feasible, with favorable oncological and perioperative outcomes. Longer-term studies are needed to verify our findings.

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.

Ionomycin-Induced Changes in Membrane Potential Alter Electroporation Outcomes in HL-60 Cells

Previous studies have shown greater fluorophore uptake during electroporation on the anode-facing side of the cell than on the cathode-facing side. Based on these observations, we hypothesized that hyperpolarizing a cell before electroporation would decrease the requisite pulsed electric field intensity for electroporation outcomes, thereby yielding a higher probability of reversible electroporation at lower electric field strengths and a higher probability of irreversible electroporation (IRE) at higher electric field strengths. In this study, we tested this hypothesis by hyperpolarizing HL-60 cells using ionomycin before electroporation. These cells were then electroporated in a solution containing propidium iodide, a membrane integrity indicator. After 20 min, we added trypan blue to identify IRE cells. Our results showed that hyperpolarizing cells before electroporation alters the pulsed electric field intensity thresholds for reversible electroporation and IRE, allowing for greater control and selectivity of electroporation outcomes.

Imaging findings during and after percutaneous cryoablation of hepatic tumors

OBJECTIVE

Imaging plays a key role in the assessment of patients before, during, and after percutaneous cryoablation of hepatic tumors. Intra-procedural and early post-procedure imaging with CT and MRI is vital to the assessment of technical success including adequacy of ablation zone coverage. Recognition of the normal expected post-procedure findings of hepatic cryoablation such as ice ball formation, hydrodissection, and the normal appearance of the ablation zone is crucial to be able to differentiate from complications including vascular, biliary, or non-target organ injury. Delayed imaging is essential for determination of clinical effectiveness and detection of unexpected findings such as residual unablated tumor and local tumor progression. The purpose of this article is to review the spectrum of expected and unexpected imaging findings that may occur during or after percutaneous cryoablation of hepatic tumors.

CONCLUSION

Differentiating expected from unexpected findings during and after hepatic cryoablation helps radiologists identify residual or recurrent tumor and detect procedure-related complications.

Assessment of cold sink effect in postulated renal cryoablation by analyzing radiographic ice ball on computed tomography

OBJECTIVE

We analyzed CT characteristics of radiographic ice ball according to anatomical location and freezing number in renal cryoablation.

METHODS

30 patients who underwent percutaneous cryoablation for renal lesions. Computed tomography (CT) was conducted at 9 min during every freezing in order to evaluate a radiographic ice ball. Software was used to reconstruct CT images of the radiographic ice ball perpendicular to cryoprobes. For each radiographic ice ball, two types of radius were measured: (a) lateral radius from epicenter to perirenal direction and (b) medial radius from epicenter to renal sinus direction. Lateral and medial radius or diameters (lateral radius plus medial radius) during the first and second freezing were compared using paired t-test, respectively.

RESULTS

Medial radius of radiographic ice ball was significantly shorter than lateral radius (first freezing, 13.8 vs 17.0 mm, p < 0.001; second freezing, 16.0 vs 19.3 mm, p < 0.001). The diameter during the second freezing was significantly longer than that during the first freezing (35.3 vs 30.8 mm, p < 0.001).

CONCLUSION

In renal cryoablation, evaluating radiographic ice ball helps identify potential postulated cold sink effect in the central portion of kidney.

ADVANCES IN KNOWLEDGE

Radiologic information of postulated cold sink effect in the kidney may help secure sufficient safety margins.

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.

Thermal Ablation of T1c Renal Cell Carcinoma: A Comparative Assessment of Technical Performance, Procedural Outcome, and Safety of Microwave Ablation, Radiofrequency Ablation, and Cryoablation

PURPOSE

To evaluate perioperative outcomes of thermal ablation with microwave (MW), radiofrequency (RF), and cryoablation for stage T1c renal cell carcinoma (RCC).

MATERIALS AND METHODS

A retrospective analysis of 384 patients (mean age, 71 y; range, 22-88 y) was performed between October 2006 and October 2016. Mean radius, exophytic/endophytic, nearness to collecting system or sinus, anterior/posterior, and location relative to polar lines; preoperative aspects and dimensions used for anatomic classification; and centrality index scores were 6.3, 7.9, and 2.7, respectively. Assessment of pre- and postablation serum blood urea nitrogen, creatinine, and estimated glomerular filtration rate was performed to assess functional outcomes. Linear regression analyses were performed to compare sedation medication dosages among the three treatment cohorts. Univariable and multivariable logistic regression analyses were performed to compare rates of residual disease and complications among treatment modalities.

RESULTS

A total of 437 clinical stage T1N0M0 biopsy-proven RCCs measuring 1.2-6.9 cm were treated with computed tomography (CT)-guided MW ablation (n = 44; 10%), RF ablation (n = 347; 79%), or cryoablation (n = 46; 11%). There were no significant differences in patient demographic or tumor characteristics among cohorts. Complication rates and immediate renal function changes were similar among the three ablation modalities (P = .46 and P = .08, respectively). MW ablation was associated with significantly decreased ablation time (P < .05), procedural time (P < .05), and dosage of sedative medication (P < .05) compared with RF ablation and cryoablation.

CONCLUSIONS

CT-guided percutaneous MW ablation is comparable to RF ablation or cryoablation for the treatment of stage T1N0M0 RCC with regard to treatment response and is associated with shorter treatment times and less sedation than RF ablation or cryoablation. In addition, the safety profile of CT-guided MW ablation is noninferior to those of RF ablation or cryoablation.

Image-Guided Percutaneous Radiofrequency Ablation of Central Renal Cell Carcinoma: Assessment of Clinical Efficacy and Safety in 31 Tumors

PURPOSE

To assess clinical efficacy and safety of image-guided percutaneous radiofrequency (RF) ablation of central renal cell carcinoma with adjunctive pyeloperfusion.

MATERIALS AND METHODS

Patients with central renal tumors who underwent percutaneous RF ablation between 2005 and 2010 were retrospectively evaluated. Thirty patients with 31 central renal tumors underwent 39 RF ablation sessions. Mean tumor diameter was 3.7 cm (range, 2-7 cm). Median distance between tumor and renal pelvis was 5 mm (range, 0-15 mm). Pyeloperfusion was performed in 27 patients (27/30; 90%). Contrast-enhanced CT or MR imaging was performed to evaluate treatment response.

RESULTS

Technical success of RF ablation was achieved in 38/39 (97.4%) ablation sessions. Primary efficacy was 83.9% (26/31) on first follow-up imaging. One (3.2%) case of local tumor progression was detected 6 months after initial ablation. Secondary efficacy was 96.8% (30/31) after repeat RF ablation for residual tumor or local tumor progression. Median follow-up was 88 months (mean 82.6 mo ± 30.7; range, 9-121 mo). Major complications occurred in 5/39 (12.8%) RF ablation sessions. Complications were significantly higher for tumors located within 5 mm of the renal pelvis or 0 mm of a major calyx (28.6% vs 4.0%; P < .05). Overall survival was 96.0% (95% CI, 88.4%-100.0%), and progression-free survival at 5 years was 80.9% (95% CI, 65.8%-95.9%).

CONCLUSION

Image-guided percutaneous RF ablation combined with pyeloperfusion has satisfactory clinical efficacy in treating central renal tumors. Although clinically effective, RF ablation of central tumors may also be associated with significant major complications.

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.

Percutaneous image-guided cryoablation: current applications and results in the oncologic field

Percutaneous imaging-guided cryoablation (PICA) is a recently developed technique, which applies extreme hypothermia to destroy tumours under close imaging surveillance. It is minimally invasive, safe, repeatable, and does not interrupt or compromise other oncologic therapies. It presents several advantages over more established heat-based thermal ablation techniques (e.g. radiofrequency ablation; RFA) including intrinsic analgesic properties, superior monitoring capability on multi-modal imaging, ability to treat larger tumours, and preservation of tissue collagenous architecture. There has been a recent large increase in reports evaluating the utility of PICA in a wide range of patients and tumours, but systematic analysis of the literature is challenging due to the rapid pace of change and predominance of extensively heterogeneous level III studies. The precise onco-therapeutic role of PICA has not been established. This narrative review outlines the available evidence for PICA in a range of tumours. Current indications include curative therapy of small T1a renal tumours; curative/palliative therapy of small primary/secondary lung tumours where RFA is unsuitable; palliation of painful bone metastases; and urologic treatment of organ-confined prostate cancer. There is growing evidence to support its use for small hepatic tumours, and encouraging results have been obtained for breast tumours, extra-abdominal desmoid tumours, and management of higher-stage tumours and oligometastatic disease. However, the overall evidence base is weak, effectively restricting PICA to cases where standard therapy and RFA are unsuitable. As the technique and evidence continue to mature, the benefits of this emerging technique will hopefully become more widely available to cancer patients in the future.

Hemorrhagic Complications of Percutaneous Cryoablation for Renal Tumors: Results from a 7-year Prospective Study

PURPOSE

Cryoablation of renal tumors is assumed to have a higher risk of hemorrhagic complications compared to other ablative modalities. Our purpose was to establish the exact risk and to identify hemorrhagic risk factors.

MATERIALS AND METHODS

This IRB approved, 7-year prospective study included 261 renal cryoablations. Procedures were under conscious sedation and CT guidance. Pre- and postablation CT was obtained, and hemorrhagic complications were CTCAE tabulated. Age, gender, tumor size, histology, and probes number were tested based on averages or proportions using their exact permutation distribution. "High-risk" subgroups (those exceeding the thresholds of all variables) were tested for each variable alone, and for all combinations of variable threshold values. We compared the subgroup with the best PPV using one variable, with the subgroup with the best PPV using all variables (McNemmar test).

RESULTS

The hemorrhagic complication rate was 3.5 %. Four patients required transfusions, two required emergent angiograms, one required both a transfusion and angiogram, and two required bladder irrigation for outlet obstruction. Perirenal space hemorrhage was more clinically significant than elsewhere. Univariate risks were tumor size >2 cm, number of probes >2, and malignant histology (P = 0.005, 0.002, and 0.033, respectively). Multivariate analysis showed that patients >55 years with malignant tumors >2 cm requiring 2 or more probes yielded the highest PPV (7.5 %).

CONCLUSIONS

Although older patients (>55 years old) with larger (>2 cm), malignant tumors have an increased risk of hemorrhagic complications, the low PPV does not support the routine use of embolization. Percutaneous cryoablation has a 3.5 % risk of significant hemorrhage, similar to that reported for other types of renal ablative modalities.

Indications for biopsy and the current status of focal therapy for renal tumours

The increased detection of small renal masses (SRMs) has focused attention on their uncertain natural history. The development of treatment alternatives and the discovery of biologically targeted drugs have also raised interest. Renal mass biopsies (RMBs) have a crucial role as they provide the pathological, molecular and genetic information needed to classify these lesions and guide clinical management. The improved accuracy has improved our knowledge of the behaviour of different tumour histologies and opened the potential for risk-adapted individualized treatment approaches. To date, studies have demonstrated that percutaneous ablation is an effective therapy with acceptable outcomes and low risk in the appropriate clinical setting. Although partial nephrectomy (PN) is still considered the standard treatment for SRM, percutaneous ablation is increasingly being performed and if long-term efficacy is sustained, it may have a wider application for SRMs after biopsy characterization.

Percutaneous tumor ablation tools: microwave, radiofrequency, or cryoablation--what should you use and why?

Image-guided thermal ablation is an evolving and growing treatment option for patients with malignant disease of multiple organ systems. Treatment indications have been expanding to include benign tumors as well. Specifically, the most prevalent indications to date have been in the liver (primary and metastatic disease, as well as benign tumors such as hemangiomas and adenomas), kidney (primarily renal cell carcinoma, but also benign tumors such as angiomyolipomas and oncocytomas), lung (primary and metastatic disease), and soft tissue and/or bone (primarily metastatic disease and osteoid osteomas). Each organ system has different underlying tissue characteristics, which can have profound effects on the resulting thermal changes and ablation zone. Understanding these issues is important for optimizing clinical results. In addition, thermal ablation technology has evolved rapidly during the past several decades, with substantial technical and procedural improvements that can help improve clinical outcomes and safety profiles. Staying up to date on these developments is challenging but critical because the physical properties underlying the different ablation modalities and the appropriate use of adjuncts will have a tremendous effect on treatment results. Ultimately, combining an understanding of the physical properties of the ablation modalities with an understanding of the thermal kinetics in tissue and using the most appropriate ablation modality for each patient are key to optimizing clinical outcomes. Suggested algorithms are described that will help physicians choose among the various ablation modalities for individual patients.

Percutaneous tumor ablation tools: microwave, radiofrequency, or cryoablation--what should you use and why?

Image-guided thermal ablation is an evolving and growing treatment option for patients with malignant disease of multiple organ systems. Treatment indications have been expanding to include benign tumors as well. Specifically, the most prevalent indications to date have been in the liver (primary and metastatic disease, as well as benign tumors such as hemangiomas and adenomas), kidney (primarily renal cell carcinoma, but also benign tumors such as angiomyolipomas and oncocytomas), lung (primary and metastatic disease), and soft tissue and/or bone (primarily metastatic disease and osteoid osteomas). Each organ system has different underlying tissue characteristics, which can have profound effects on the resulting thermal changes and ablation zone. Understanding these issues is important for optimizing clinical results. In addition, thermal ablation technology has evolved rapidly during the past several decades, with substantial technical and procedural improvements that can help improve clinical outcomes and safety profiles. Staying up to date on these developments is challenging but critical because the physical properties underlying the different ablation modalities and the appropriate use of adjuncts will have a tremendous effect on treatment results. Ultimately, combining an understanding of the physical properties of the ablation modalities with an understanding of the thermal kinetics in tissue and using the most appropriate ablation modality for each patient are key to optimizing clinical outcomes. Suggested algorithms are described that will help physicians choose among the various ablation modalities for individual patients.

Percutaneous Cryoablation for Renal Cell Carcinoma

Renal cell carcinoma (RCC) is the most common type of kidney cancer in adults. Nephron sparing resection (partial nephrectomy) has been the “gold standard” for the treatment of resectable disease. With the widespread use of cross sectional imaging techniques, more cases of renal cell cancers are detected at an early stage, i.e. stage 1A or 1B. This has provided an impetus for expanding the nephron sparing options and especially, percutaneous ablative techniques. Percutaneous ablation for RCC is now performed as a standard therapeutic nephron-sparing option in patients who are poor candidates for resection or when there is a need to preserve renal function due to comorbid conditions, multiple renal cell carcinomas, and/or heritable renal cancer syndromes. During the last few years, percutaneous cryoablation has been gaining acceptance as a curative treatment option for small renal cancers. Clinical studies to date indicate that cryoablation is a safe and effective therapeutic method with acceptable short and long term outcomes and with a low risk, in the appropriate setting. In addition it seems to offer some advantages over radio frequency ablation (RFA) and other thermal ablation techniques for renal masses.

Efficacy of percutaneous cryoablation of renal cell carcinoma in older patients with medical comorbidities: Outcome study in 70 patients

INTRODUCTION

The aim of this study was to establish the efficacy of cryoablation for incidentally discovered small renal cell carcinomas in older patients with medical comorbidities.

METHODS

We carried out a retrospective chart analysis of outcomes of 70 patients treated by cryoablation. The inclusion criteria were age >56 years, medical comorbidities (Charlson class I-III), and suitability for cryoablation established by urologists and interventional radiologists. In total, 43 patients were male, 27 female, and the age range was 56 to 89. The lesions measured 1.5 to 4 cm; 29 were high-grade Fuhrman and 41 were low grade. All lesions were treated by 2 10-minute freezing cycles separated by an 8-minute thawing period. One to seven cryoprobes were inserted according to a preoperative, 3D computed tomography (CT)-based plan.

RESULTS

Results were assessed on follow-up CTs (at 8-9 months). Of the 70 patients, 68 were treated by cryoablations and surgical salvage procedures; these patients were free of disease for 23 to 72 months (mean 39). One patient experienced recurrence and the other was lost to follow-up. One or two cryoablations rendered 66 patients tumour-free and additional surgery rendered another 2 patients tumour-free. The location and configuration of the lesion affected outcomes. Of the 27 posterior lesions, there was 1 failure; of the postero-lateral lesions, there were 4 failures; of the anterior lesions, there were 5 lesions; finally of the 32 central or deep seated lesions, there were 9 failures. Implants with one and two cryoprobes had a high recurrence rate. Three major complications were managed by minor interventions. The mean hospitalization was 1.3 days and the procedure times were variable.

CONCLUSION

Percutaneous cryoablation is recommended as a minimally invasive nephron-sparing treatment for amenable lesions in older patients with medical comorbidities.

The feasibility of percutaneous renal cryoablation under local anaesthesia

OBJECTIVES

The aim of this study was to evaluate the feasibility of cryoablation of renal tumours without sedation.

MATERIALS AND METHODS

We prospectively evaluated 149 computed tomography-guided renal cryoablation procedures that were performed at our institution between 2009 and 2013. The patients received only 1 g of IV paracetamol prior to the procedure; intraprocedural, local anaesthesia was administered. We recorded the date and duration of the procedure, size and location of the tumour, number of cryoneedles used, need for dissection with saline or carbon dioxide and intraprocedural degree of pain, which was scored using an established visual analogue pain score (VAS) (0-10). Multivariate analysis was used to identify the associations between the recorded parameters and VAS.

RESULTS

An interventional radiologist and a technician could perform all procedures without the help of anaesthesiologists and with adequate analgesia. The pain level ranged from 0 to 8 (mean, 2.0). It did not correlate with the tumour size or with the number of cryoneedles. It was significantly greater when the ice ball involved renal cavities (p = .0033) and when carbon dioxide was used for dissection (p < .0001). Conversely, the team experience was positively correlated with lower pain levels (p = .0381).

CONCLUSION

This study demonstrates that the cryoablation of renal tumours is feasible by interventional radiologists alone using a combination of IV paracetamol and local anaesthesia.

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.

Radiofrequency thermal ablation of renal tumors

Percutaneous radiofrequency ablation (PRFA) of renal malignancies is currently a therapeutic option for patients who are not able to undergo surgery. Some authors consider PRFA as the therapeutic standard in the treatment of renal neoplasms in non-operable patients due to comorbid conditions and in patients with mild-moderate renal failure, to preserve residual renal functionality. The use of PRFA has become more and more widespread due to a rise in the incidental detection of renal cell carcinomas with the ever-increasing use of Imaging for the study of abdominal diseases. Clinical studies indicate that RF ablation is an effective therapy with a low level of risk of complications, which provides good results in selected patients over short and medium term periods of time, however up to now few long-term studies have been carried out which can confirm the effectiveness of PRFA.

Cancer concepts and principles: primer for the interventional oncologist-part II

This is the second of a two-part overview of the fundamentals of oncology for interventional radiologists. The first part focused on clinical trials, basic statistics, assessment of response, and overall concepts in oncology. This second part aims to review the methods of tumor characterization; principles of the oncology specialties, including medical, surgical, radiation, and interventional oncology; and current treatment paradigms for the most common cancers encountered in interventional oncology, along with the levels of evidence that guide these treatments.