Computerized Tomography Guided Percutaneous Renal Cryoablation With the Patient Under Conscious Sedation: Initial Clinical Experience

Ablation of Small Renal Masses

Renal cell carcinoma is most commonly diagnosed in the sixth or seventh decade of life. Historically, surgical extirpation was the gold standard treatment option for small renal masses. However, given the comorbidities in this elderly population, not all patients are candidates for surgery. The development of minimally invasive ablative therapies has solved the surgical dilemma in this patient population. Furthermore, the 2017 American Urological Association guidelines recommends consideration of percutaneous image guided thermal ablation as a treatment option for masses smaller than 3 cm even in healthy individuals. Percutaneous image guided thermal ablation is an attractive treatment option providing excellent local tumor control, fewer complications, better preservation of the renal functions, faster recovery and shorter hospital stay. Various ablative modalities are available in clinical practice. This includes radiofrequency ablation, cryoablation, microwave ablation, irreversible electroporation, high intensity focused ultrasound, and laser ablation. In this review, we focus on the most commonly used modalities including radiofrequency ablation and cryoablation and to a lesser extent microwave ablation and irreversible electroporation.

Efficacy of antegrade and retrograde warm saline pyeloperfusion during renal cryoablation for ureteral preservation

Objective

Cryoablation of renal tumors adjacent to the ureter or pelvicalyceal system carries risks for thermal injury of the collecting system. Although cold antegrade perfusion has been described for radiofrequency ablation, warm saline perfusion for renal cryoablation has not been well-characterized. The purpose of this study was to determine the safety and feasibility of antegrade and retrograde warm saline perfusions during percutaneous renal cryoablation.

Material and methods

A retrospective review was performed on 136 patients treated with percutaneous renal cryoablation at a single academic institution between 2009 and 2015. Six patients undergoing antegrade (n=3) or retrograde (n=3) warm saline perfusion for protection of the collecting system were identified. Warm saline was perfused through a 4 French nephrostomy tube in the antegrade technique and through a 6 French end-hole catheter in the retrograde technique. Outcome measures were tumor recurrence rates, success of urothelial preservation, hospital stay, blood loss and procedural time.

Results

Four tumors were in the lower pole and two tumors in the middle pole. The mean distance from tumor to ureter was 6.8 mm (0.8-11.5 mm) and no patient developed ureteral stricture. There was no tumor recurrence at a median follow-up of 37.3 months (7-65). The median procedural time was 3 hours and 13 minutes. One patient in each group developed minor complications (Clavien I and II) and there were no major complications.

Conclusion

This study demonstrates the feasibility of antegrade and retrograde warm saline perfusion for ureteral preservation during cryoablation, without compromising oncologic outcomes.

AngleNav: MEMS Tracker to Facilitate CT-Guided Puncture

As a low-cost needle navigation system, AngleNav may be used to improve the accuracy, speed, and ease of CT-guided needle punctures. The AngleNav hardware includes a wireless device with a microelectromechanical (MEMS) tracker that can be attached to any standard needle. The physician defines the target, desired needle path and skin entry point on a CT slice image. The accuracy of AngleNav was first tested in a 3D-printed calibration platform in a benchtop setting. An abdominal phantom study was then performed in a CT scanner to validate the accuracy of the device's angular measurement. Finally, an in vivo swine study was performed to guide the needle towards liver targets (n = 8). CT scans of the targets were used to quantify the angular errors and needle tip-to-targeting distance errors between the planned needle path and the final needle position. The MEMS tracker showed a mean angular error of 0.01° with a standard deviation (SD) of 0.62° in the benchtop setting. The abdominal phantom test showed a mean angular error of 0.87° with an SD of 1.19° and a mean tip-to-target distance error of 4.89 mm with an SD of 1.57 mm. The animal experiment resulted in a mean angular error of 6.6° with an SD of 1.9° and a mean tip-to-target distance error of 8.7 mm with an SD of 3.1 mm. These results demonstrated the feasibility of AngleNav for CT-guided interventional workflow. The angular and distance errors were reduced by 64.4 and 54.8% respectively if using AngleNav instead of freehand insertion, with a limited number of operators. AngleNav assisted the physicians to deliver accurate needle insertion during CT-guided intervention. The device could potentially reduce the learning curve for physicians to perform CT-guided needle targeting.

Focal ablation therapy for renal cancer in the era of active surveillance and minimally invasive partial nephrectomy

Partial nephrectomy is the optimal surgical approach in the management of small renal masses (SRMs). Focal ablation therapy has an established role in the modern management of SRMs, especially in elderly patients and those with comorbidities. Percutaneous ablation avoids general anaesthesia and laparoscopic ablation can avoid excessive dissection; hence, these techniques can be suitable for patients who are not ideal surgical candidates. Several ablation modalities exist, of which radiofrequency ablation and cryoablation are most widely applied and for which safety and oncological efficacy approach equivalency to partial nephrectomy. Data supporting efficacy and safety of ablation techniques continue to mature, but they originate in institutional case series that are confounded by cohort heterogeneity, selection bias, and lack of long-term follow-up periods. Image guidance and surveillance protocols after ablation vary and no consensus has been established. The importance of SRM biopsy, its optimal timing, the type of biopsy used, and its role in treatment selection continue to be debated. As safety data for active surveillance and experience with minimally invasive partial nephrectomy are expanding, the role of focal ablation therapy in the treatment of patients with SRMs requires continued evaluation.

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.

Outcomes of Radiofrequency Ablation for Kidney Cancer

BACKGROUND

The incidence of small (< 4 cm) solid enhancing renal masses has been rising, and the majority (60% to 80%) of these tumors are renal cell carcinomas (RCCs) when pathologic analysis is performed. Needle ablation for small incidental renal masses is an attractive therapeutic option. Reasons include its decreased morbidity, shorter convalescence, and the ability to avert the higher risk of extirpative surgery in an aging patient population. Radiofrequency ablation (RFA) is a thoroughly studied needle ablative method used for RCC.

METHODS

The current published literature on renal tumor RFA was reviewed. The in vitro experiments, animal studies and clinical experience with RFA for treatment of small RCCs were analyzed and various controversies in renal RFA are presented for discussion.

RESULTS

Percutaneous and laparoscopic renal RFA can be safely performed and can eradicate small RCCs with cancer specific survival rates over 90% to 95% in many series. While long-term (5 years or greater) cancer control data are not yet available, these intermediate-term results are similar to those achieved with traditional nephron-sparing surgical options. However, the optimal method to perform RFA for renal masses is still evolving.

CONCLUSIONS

While long-term cancer control data are not yet available, the current literature suggests that RFA can effectively eradicate small RCCs. Further research is needed to elucidate the influence of various treatment variables, including impedance vs temperature-controlled RFA, sonographic vs computed tomographic guidance, general anesthetic vs conscious sedation, and radiologist vs urologist delivery of renal RFA.

Changes in Perioperative Systolic Blood Pressure in Percutaneous Renal Mass Cryoablation

OBJECTIVES

To analyze changes in systolic blood pressure (SBP) in the perioperative period of percutaneous renal mass cryoablation and risk factors.

METHODS

This retrospective study included 54 patients who underwent percutaneous renal cryoablation. SBP before ablation (pre-Tx), during ablation (intra-Tx), immediately after ablation (post-Tx), and before discharge (discharge) were measured using a BP cuff. The highest SBP during cryoablation was regarded as SBP at intra-Tx. Antihypertensive agents were administrated when SBP was 160 mmHg or greater during cryoablation. Relationship between SBP at pre-Tx, pain degree, tumor size, cryoprobe number, or endophytic extension of the radiographic ice-ball, and SBP elevation or administration of antihypertensive agents was investigated.

RESULTS

Mean SBP elevation from pre-Tx to intra-Tx was 22.9 ± 18.0 mmHg (range -6-78 mmHg). SBP of intra-Tx was significantly higher than that of the other periods (p < .001), while SBP of post-Tx or discharge was similar with that of pre-Tx (p > .05). Tumor size (r = .324; p = .016), cryoprobe number (r = .300; p = .027), and endophytic extension (r = .348; p = .009) were correlated with SBP elevation, while SBP at pre-Tx or pain degree were not (p > .05). Antihypertensive agents were administrated for 24 patients (44.4%). In multivariate analysis, SBP at pre-Tx and endophytic ablation was associated with administration of antihypertensive agents during cryoablation (p < .05).

CONCLUSIONS

SBP elevation may occur during percutaneous renal mass cryoablation, but be improved before discharge. Endophytic extension of the radiographic ice-ball may be associated with significant BP elevation during ablation.

Skin-to-tumor Distance Predicts Treatment Failure of T1A Renal Cell Carcinoma Following Percutaneous Cryoablation

OBJECTIVE

To determine the impact of skin-to-tumor (STT) distance on the risk for treatment failure following percutaneous cryoablation (PCA).

METHODS

We retrospectively reviewed patients who underwent PCA with documented T1a recurrent renal cell carcinoma (RCC) at 2 academic centers between 2005 and 2015. Patient demographics, tumor characteristics, and perioperative and postoperative course variables were collected. Additionally, we measured the STT distance by averaging the distance from the skin to the center of the tumor at 0°, 45°, and 90° on preoperative computed tomography imaging.

RESULTS

We identified 86 patients with documented T1a RCC. The mean age at the time of surgery was 69 years (range: 37-91 years), and the mean tumor size was 2.7 cm (range: 1.0-4.0 cm). With a mean follow-up of 24 months (range: 3-63 months), 11 (12.8%) treatment failures occurred. Patients with treatment failure had significantly higher mean STT distance than those without: 11.0 cm (range: 6.3-20.1 cm) compared to 8.4 cm (range: 4.4-15.2 cm), respectively (P = .002). STT distance was an independent predictor of treatment failure (odds ratio: 1.32, 95% confidence interval: 1.04-1.69, P = .029). STT distance greater than 10 cm had a fourfold increased risk of tumor treatment failure (odds ratio: 4.43, 95% confidence interval: 1.19-16.39, P = .018). Tumor size, R.E.N.A.L. Nephrometry score, and number of cryoprobes placed were not associated with treatment failure.

CONCLUSION

STT, an easily measured preoperative variable, may inform the risk of RCC treatment failure following PCA.

Body-mounted robotic instrument guide for image-guided cryotherapy of renal cancer

PURPOSE

Image-guided cryotherapy of renal cancer is an emerging alternative to surgical nephrectomy, particularly for those who cannot sustain the physical burden of surgery. It is well known that the outcome of this therapy depends on the accurate placement of the cryotherapy probe. Therefore, a robotic instrument guide may help physicians aim the cryotherapy probe precisely to maximize the efficacy of the treatment and avoid damage to critical surrounding structures. The objective of this paper was to propose a robotic instrument guide for orienting cryotherapy probes in image-guided cryotherapy of renal cancers. The authors propose a body-mounted robotic guide that is expected to be less susceptible to guidance errors caused by the patient's whole body motion.

METHODS

Keeping the device's minimal footprint in mind, the authors developed and validated a body-mounted, robotic instrument guide that can maintain the geometrical relationship between the device and the patient's body, even in the presence of the patient's frequent body motions. The guide can orient the cryotherapy probe with the skin incision point as the remote-center-of-motion. The authors' validation studies included an evaluation of the mechanical accuracy and position repeatability of the robotic instrument guide. The authors also performed a mock MRI-guided cryotherapy procedure with a phantom to compare the advantage of robotically assisted probe replacements over a free-hand approach, by introducing organ motions to investigate their effects on the accurate placement of the cryotherapy probe. Measurements collected for performance analysis included accuracy and time taken for probe placements. Multivariate analysis was performed to assess if either or both organ motion and the robotic guide impacted these measurements.

RESULTS

The mechanical accuracy and position repeatability of the probe placement using the robotic instrument guide were 0.3 and 0.1 mm, respectively, at a depth of 80 mm. The phantom test indicated that the accuracy of probe placement was significantly better with the robotic instrument guide (4.1 mm) than without the guide (6.3 mm, p<0.001), even in the presence of body motion. When independent organ motion was artificially added, in addition to body motion, the advantage of accurate probe placement using the robotic instrument guide disappeared statistically [i.e., 6.0 mm with the robotic guide and 5.9 mm without the robotic guide (p = 0.906)]. When the robotic instrument guide was used, the total time required to complete the procedure was reduced from 19.6 to 12.7 min (p<0.001). Multivariable analysis indicated that the robotic instrument guide, not the organ motion, was the cause of statistical significance. The statistical power the authors obtained was 88% in accuracy assessment and 99% higher in duration measurement.

CONCLUSIONS

The body-mounted robotic instrument guide allows positioning of the probe during image-guided cryotherapy of renal cancer and was done in fewer attempts and in less time than the free-hand approach. The accuracy of the placement of the cryotherapy probe was better using the robotic instrument guide than without the guide when no organ motion was present. The accuracy between the robotic and free-hand approach becomes comparable when organ motion was present.

Image-guided percutaneous renal cryoablation for stage 1 renal cell carcinoma with high surgical risk

BACKGROUND

This study was undertaken to evaluate the feasibility, safety, and therapeutic effects of percutaneous renal cryoablation under local anesthesia with conscious sedation for patients who have unresectable stage 1 (T1NoMo) renal cell carcinoma (RCC) in high surgical risk.

METHODS

Eighteen patients who were not candidates for surgery underwent primary cryosurgery guided by gray-scale ultrasound. Contrast-enhanced ultrasonography (CEUS) and contrast-enhanced computed tomography (CT) were performed to evaluate treatment at completion.

RESULTS

The mean follow-up period was 26.8 months (range, 12-56 months). All tumors were biopsied before cryosurgery. Seventeen tumors remained free of enhancement during follow-up period. No major complications associated with cryoablation procedures were found though two instances of subcapsular hematomas, one of retroperitoneal errhysis and one of nausea, were seen after cryoablation. One patient had a local recurrence of tumor and received additional cryoablation. Local tumor control rate was 100 % of T1NoMo tumors including the recurrence case who underwent additional cryoablation.

CONCLUSIONS

Percutaneous cryoablation can be recommended as a feasible, safe, and promising therapy for the treatment of renal tumor, especially those unresectable stage 1 RCC, with a low risk of complications.

Percutaneous ablation for small renal masses-complications

Although percutaneous ablation of small renal masses is generally safe, interventional radiologists should be aware of the various complications that may arise from the procedure. Renal hemorrhage is the most common significant complication. Additional less common but serious complications include injury to or stenosis of the ureter or ureteropelvic junction, infection/abscess, sensory or motor nerve injury, pneumothorax, needle tract seeding, and skin burn. Most complications may be treated conservatively or with minimal therapy. Several techniques are available to minimize the risk of these complications, and patients should be appropriately monitored for early detection of complications. In the event of a serious complication, prompt treatment should be provided. This article reviews the most common and most important complications associated with percutaneous ablation of small renal masses.

Percutaneous radiofrequency ablation: minimally invasive therapy for renal tumors

Currently, up to 60% of renal tumors are detected incidentally by abdominal imaging. Most of these tumors are small and localized to the kidney. Owing to the shift to lower stage at diagnosis, radical nephrectomy has fallen out of favor and has been replaced by nephron-sparing surgery. Currently, partial nephrectomy is the treatment of choice for patients with small renal tumors. As the trend towards less invasive therapy continues, laparoscopic and percutaneous ablation techniques have gained popularity for the treatment of renal tumors in patients who are high-risk surgical candidates, or have a solitary kidney, limited renal function or multifocal disease. Percutaneous radiofrequency ablation is a safe, minimally invasive treatment option for those patients.

Automatic iceball segmentation with adapted shape priors for MRI-guided cryoablation

PURPOSE

To develop and evaluate an automatic segmentation method that extracts the 3D configuration of the ablation zone, the iceball, from images acquired during the freezing phase of MRI-guided cryoablation.

MATERIALS AND METHODS

Intraprocedural images at 63 timepoints from 13 kidney tumor cryoablation procedures were examined retrospectively. The images were obtained using a 3 Tesla wide-bore MRI scanner and axial HASTE sequence. Initialized with semiautomatically localized cryoprobes, the iceball was segmented automatically at each timepoint using the graph cut (GC) technique with adapted shape priors.

RESULTS

The average Dice Similarity Coefficients (DSC), compared with manual segmentations, were 0.88, 0.92, 0.92, 0.93, and 0.93 at 3, 6, 9, 12, and 15 min timepoints, respectively, and the average DSC of the total 63 segmentations was 0.92 ± 0.03. The proposed method improved the accuracy significantly compared with the approach without shape prior adaptation (P = 0.026). The number of probes involved in the procedure had no apparent influence on the segmentation results using our technique. The average computation time was 20 s, which was compatible with an intraprocedural setting.

CONCLUSION

Our automatic iceball segmentation method demonstrated high accuracy and robustness for practical use in monitoring the progress of MRI-guided cryoablation.

Review of the efficacy and safety of cryoablation for the treatment of small renal masses

PURPOSE

Small renal masses are increasingly being discovered incidentally on imaging for another reason. The standard of care of these masses involves excision by open or laparoscopic techniques. Recently, ablative techniques, such as radiofrequency ablation (RFA) and cryoablation, have taken a more prominent role in the treatment algorithm of these masses. We evaluate the effectiveness and safety of cryoablation to treat renal tumours.

METHODS

A review of the literature was conducted. There was no language restriction. Studies were obtained from the following sources: the Cochrane Library, PUBMED, EMBASE and LILACS.

RESULTS

There was no clinical trial identified in the literature. Thus, we described the results from 23 case series and retrospective studies with a reasonable sample size (number of reported patients in each study ≥30), with a total of 2104 analyzed tumours from 2038 patients. There was wide variability in the outcomes reported, but success rates were generally good. Follow-up was generally short, but some series reported outcomes at 5 years. The most common complications reported were hemorrhage (some of the patients requiring transfusion), perinephric hematoma and urine leaks.

CONCLUSION

Cryoablation presents a feasible treatment for patients with small renal masses. Only short-term data are available and, as such, meaningful conclusions regarding long-term cancer control cannot be made. More rigorous studies are needed.

Cryotherapy and its applications in the management of urologic malignancies: a review of its use in prostate and renal cancers

Cryotherapy has been established as an ablative modality for the treatment of a wide range of malignancies. Being minimally invasive, it is associated with less morbidity than conventional extirpative surgical procedures. In recent years, it has been used with success for treating two of the common urologic malignancies, that is, prostate and renal cancer. In this review, we highlight the role of cryotherapy as a treatment modality, the proposed destructive mechanisms of action and the risks of its use in the management of prostate and renal malignancy.

Percutaneous cryoablation of solitary sporadic renal cell carcinomas

What's known on the subject? and What does the study add? Percutaneous renal cryoablation is a safe and effective treatment for patients with small renal masses, who are poor surgical candidates. Oncological outcomes from previous percutaneous ablation studies are difficult to interpret because of the large number of patients treated with a history of RCC (38% in our experience) and the large number of treated renal masses without a pathology-proven diagnosis. This cryoablation study addresses these issues by evaluating only solitary, sporadic biopsy-proven RCC. Oncological outcomes and complications were also evaluated by tumour T-stage, which allows some degree of comparison with previously published surgical results.

OBJECTIVE

• To evaluate retrospectively our single institution experience with percutaneous cryoablation of solitary, sporadic renal cell carcinomas (RCCs), and to compare the efficacy and safety of this technique for treatment of different T-stage RCC.

PATIENTS AND METHODS

• 116 patients were treated with percutaneous cryoablation for a solitary, sporadic biopsy-proven RCC in a single treatment session between November 2003 and November 2010. • The technical success of the ablation procedure, complications and evidence for local or metastatic tumour recurrence were evaluated for each patient.

RESULTS

• 83 patients (72%) were treated for a stage T1a RCC, 27 patients (23%) for a stage T1b RCC, and six patients (5%) for a stage T2 RCC. • Technical success was achieved in the treatment of 115 of 116 (99%) renal tumours. The single technical failure occurred in the treatment of a 4.3-cm RCC. • Local recurrent tumour was identified in one of 88 patients (1%) with follow-up computed tomography (CT) or magnetic resonance imaging available for review >3 months from the time of ablation. The median (range) imaging follow-up in these patients was 21 (3-73) months. The local tumour recurrence was identified on CT 11 months after the ablation procedure in a patient treated for a 2.7 cm RCC. • None of the patients developed metastatic RCC. • The major complication rate was 4% for patients with stage T1a tumours, 15% for those with stage T1b tumours, and 33% for those with stage T2 tumours. There were no procedural-related deaths.

CONCLUSIONS

• Percutaneous renal cryoablation of RCC can be performed with high technical success in patients with tumours up to, and beyond 7 cm in maximum diameter. • The tumour recurrence rate after percutaneous renal cryoablation was low, and recurrence was not related to tumour size in this group of patients. • Statistically significant higher complication rates were seen with treatment of larger (higher T-stage) RCCs.

Cryoablation vs radiofrequency ablation for the treatment of renal cell carcinoma: a meta-analysis of case series studies

Study Type - Therapy (systematic review). Level of Evidence 2b What's known on the subject? and What does the study add? The oncological success of partial nephrectomy in the treatment of small renal masses is well established. However, partial nephrectomy has largely supplanted the radical approach. In the last decade, laparoscopy has been adopted as the new surgical approach for the treatment of renal cell carcinoma. Laparoscopy offers the advantage of lower analgesic use, shorter hospital stay, and quicker recovery time. More recently, ablative technologies have been investigated as an alternative to laparoscopic partial nephrectomy. These techniques can often be performed percutaneously in the radiology suite, or laparoscopically without the need for hilar clamping. However, only the cryoablation and radiofrequency ablation modalities have had widespread use with several series reporting short to intermediate results. This review shows that both cryoablation and radiofrequency ablation are promising therapies in patients with small renal tumours (<4 cm), who are considered poor candidates for more involved surgery.

OBJECTIVE

• To determine the current status of the literature regarding the clinical efficacy and complication rates of cryoablation vs radiofrequency ablation in the treatment of small renal tumours.

METHODS

• A review of the literature was conducted. There was no language restriction. Studies were obtained from the following sources: MEDLINE, EMBASE and LILACS. • Inclusion criteria were (i) case series design with more than one case reported, (ii) use of cryoablation or radiofrequency ablation, (iii) patients with renal cell carcinoma and, (iv) outcome reported as clinical efficacy. • When available, we also quantified the complication rates from each included study. • Proportional meta-analysis was performed on both outcomes with a random-effects model. The 95% confidential intervals were also calculated.

RESULTS

• Thirty-one case series (20 cryoablation, 11 radiofrequency ablation) met all inclusion criteria. • The pooled proportion of clinical efficacy was 89% in cryoablation therapy from a total of 457 cases. There was a statistically significant heterogeneity between these studies showing the inconsistency of clinical and methodological aspects. • The pooled proportion of clinical efficacy was 90% in radiofrequency ablation therapy from a total of 426 cases. There was no statistically significant heterogeneity between these studies. • There was no statistically significant difference regarding complications rate between cryoablation and radiofrequency ablation.

CONCLUSIONS

• This review shows that both ablation therapies have similar efficacy and complication rates. • There is urgency for performing clinical trials with long-term data to establish which intervention is most suitable for the treatment of small renal masses.

Complications following 573 percutaneous renal radiofrequency and cryoablation procedures

PURPOSE

To review complications related to percutaneous renal tumor ablation.

MATERIALS AND METHODS

Prospectively collected data related to renal radiofrequency (RF) ablation and cryoablation procedures performed from May 2000 through November 2010 were reviewed. This included 573 renal ablation procedures performed in 533 patients to treat 633 tumors. A total of 254 RF ablation and 311 cryoablation procedures were performed; eight patients underwent simultaneous RF ablation and cryoablation. The mean age of patients at the time of the procedure was 70 years (range, 24-93 y), and 382 of 573 procedures (67%) were performed in male patients. Complications were recorded according to the Clavien-Dindo classification scheme. Duration of hospitalization was also documented.

RESULTS

Of the 573 procedures, 63 produced complications (11.0% overall complication rate). There were 66 reported complications, of which 38 (6.6% of total procedures) were Clavien-Dindo grade II-IV major complications; there were no deaths. Major complication rates did not differ statistically (P = .15) between cryoablation (7.7%; 24 of 311) and RF ablation (4.7%; 12 of 254). Of the complications related to cryoablation, bleeding and hematuria were most common. Bleeding during cryoablation was associated with advanced age, increased tumor size, increased number of cryoprobes, and central position (P < .05). Of those treated with RF ablation, nerve and urothelial injury were most common. Mean hospitalization duration was 1 day for RF ablation and cryoablation.

CONCLUSIONS

Complications related to percutaneous renal ablation are infrequent. Recognition of potential complications and associated risk factors can allow optimization of periprocedural care.

Induction of specific cellular and humoral responses against renal cell carcinoma after combination therapy with cryoablation and granulocyte-macrophage colony stimulating factor: a pilot study

Cryotherapy offers a minimally invasive treatment option for the management of both irresectable and localized prostate, liver, pulmonary, and renal tumors. The antineoplastic effects of cryotherapy are mediated by direct tumor lysis and by indirect effects, such as intracellular dehydration, pH changes, and microvascular damage resulting in ischemic necrosis. In this study, we investigated whether percutaneous cryoablation of lung metastasis from renal cell carcinoma (RCC) in combination with aerosolized granulocyte-macrophage colony stimulating factor can induce systemic cellular and humoral immune responses in 6 patients with RCC. Peripheral blood mononuclear cells (PBMCs) were sequentially studied up to 63 days post cryoimmunotherapy (CI). PBMC from pre and post CI were phenotyped for lymphocyte subsets and tested for cytotoxicity and interferon-γ EliSpots directed at RCC cells. Humoral responses were measured by in vitro antibody synthesis assay directed at RCC cells. The immune monitoring data showed that CI induced tumor specific cytotoxic T lymphocyte, specific in vitro antitumor antibody responses, and enhanced Th1 cytokine production in 4 of 6 patients. More importantly, the magnitude of cellular and humoral antitumor response seems to be associated with clinical responses. These pilot data show that CI can induce robust and brisk cellular and humoral immune responses in patients with metastatic RCC, but requires further evaluation in optimized protocols.

Radiation dose reduction for CT-guided renal tumor cryoablation

OBJECTIVE

The purpose of this article is to retrospectively determine the image quality and degree of radiation dose reduction that is clinically acceptable for CT-guided renal tumor cryoablation.

MATERIALS AND METHODS

A total of 15 patients (17 procedures; mean age, 67 years; range, 38-85 years) undergoing clinically indicated CT-guided renal tumor cryoablation procedures were included in this retrospective study. A previously validated noise-insertion tool was used to simulate reduced-dose scans at 75%, 50%, 25%, and 10% of the original dose at four representative phases of the cryoablation procedure. Images obtained at different dose levels were randomized and reviewed by three radiologists blinded to the level of dose reduction, who scored them independently with a 5-point scale (1-5, with 5 the best). Images with a mean score of 3 or higher were considered diagnostically acceptable. The minimal acceptable dose was that at which 90% of images were considered diagnostically acceptable. Interrater agreement was assessed using the weighted kappa statistic.

RESULTS

The weighted kappa value was 0.68, indicating substantial agreement among the reviewers. The averaged percentage of diagnostically acceptable images for the four series was 100% for a full dose, 98-100% for the 75% dose level, 94-98% for the 50% dose level, and less than 90% for images obtained at the 25% and 10% dose levels, which was considered unacceptable.

CONCLUSION

On the basis of results from 15 patients (17 procedures), images obtained from CT acquisitions at 50% (volume CT dose index, 12.2 mGy) of the original dose level (volume CT dose index, 24.4 mGy) were acceptable for the purpose of CT monitoring of renal cryoablation procedures.

Estimated effective dose of CT-guided percutaneous cryoablation of liver tumors

PURPOSE

To estimate effective dose during CT-guided cryoablation of liver tumors, and to assess which procedural factors contribute most to dose.

MATERIALS AND METHODS

Our institutional review board approved this retrospective, HIPAA-compliant study. A total of 20 CT-guided percutaneous liver tumor cryoablation procedures were performed in 18 patients. Effective dose was determined by multiplying the dose length product for each CT scan obtained during the procedure by a conversion factor (0.015mSv/mGy-cm), and calculating the sum for each phase of the procedure: planning, targeting, monitoring, and post-ablation survey. Effective dose of each phase was compared using a repeated measures analysis. Using Spearman correlation coefficients, effective doses were correlated with procedural factors including number of scans, ratio of targeting distance to tumor size, anesthesia type, number of applicators, performance of ancillary procedures (hydrodissection and biopsy), and use of CT fluoroscopy.

RESULTS

Effective dose per procedure was 72±18mSv. The effective dose of targeting (37.5±12.5mSv) was the largest component compared to the effective dose of the planning phase (4.8±2.2mSv), the monitoring phase (25.5±6.8mSv), and the post-ablation survey (4.1±1.9mSv) phase (p<0.05). Effective dose correlated positively only with the number of scans (p<0.01).

CONCLUSIONS

The effective dose of CT-guided percutaneous cryoablation of liver tumors can be substantial. Reducing the number of scans during the procedure is likely to have the greatest effect on lowering dose.

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.

Percutaneous cryoablation of small hepatocellular carcinomas using a 17-gauge ultrathin probe

AIM

To evaluate the feasibility and safety of percutaneous cryoablation (PCA) of small hepatocellular carcinomas (HCCs) using a 17 G ultrathin cryoprobe.

MATERIALS AND METHODS

Twenty patients (male:female ratio14:6) with 20 HCCs, who were not surgical candidates, underwent ultrasound (US)-guided PCA for treatment of HCCs. Single HCCs less than 3cm in diameter were included in this study. Ablation was performed using a 17 G cryoprobe. The effectiveness was determined by the changes in alpha-foetoprotein level and degree of tumour necrosis on follow-up computed tomography (CT); complete response (100% necrosis), partial response (100%>necrosis≥30%), stable disease (any cases not qualifying for either partial response or progressive disease) and progressive disease (increase of at least 20% in diameter of viable tumour). Haemoglobin, white blood cell count (WBC), serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), and total bilirubin were compared before and after the procedure, and the technical feasibility, complications, clinical outcomes and survival of each patient were also evaluated.

RESULTS

All procedures were technically successful. Each patient complained of negligible pain and there was no other procedure-related complication or mortality. The mean level of alpha-foetoprotein declined significantly from 53.2 to 20.4ng/ml 1 month after the procedure (p<0.05). At 1-month follow-up CT, there were 13 complete responses, four partial responses, three patients with stable disease, and no patients had progressive disease. Six of seven lesions that did not present with a complete response underwent further treatment. On long-term follow up (6-30 months; mean 20.7), a local recurrence was seen in one of 13 lesions (8%) with complete response revealed. Laboratory findings showed no significant changes except for the transient increase of SGOT and SGPT.

CONCLUSION

US-guided PCA using a 17 G cryoprobe was feasible and safe for the treatment of HCC smaller than 3cm.

Percutaneous cryoablation of anterior renal masses: technique, efficacy, and safety

OBJECTIVE

The safety and efficacy of renal tumor ablation are related, in part, to tumor location. Anterior tumors present a challenge due to the risk of injury to adjacent structures. The purpose of this study was to review the techniques, complications, and short-term outcomes of percutaneous cryoablation of anterior renal masses at a single institution.

MATERIALS AND METHODS

We retrospectively identified the cases of 35 patients with 38 anterior renal masses managed with percutaneous imaging-guided cryoablation of renal tumors from March 2003 through February 2009. The technical success of the ablation procedure, serious complications, and evidence of local tumor recurrence were evaluated for each patient.

RESULTS

The average maximal diameter of the anterior renal masses was 2.9 cm (SD, 0.9 cm; range, 1.4-4.8 cm). A single cryoablation procedure was performed for treatment of each patient, and technically successful ablation was achieved for all 38 tumors. A single severe adverse event occurred in one of the 35 patients (3% major complication rate). This patient had a pulmonary embolism (diagnosed at CT angiography the day after ablation). He recovered and was discharged from the hospital with anticoagulant medication only 2 days after the procedure. No local tumor recurrence was identified in any of the 29 patients who underwent follow-up contrast-enhanced CT or MRI with images available for review 3 months or longer from the time of ablation (mean, 18 months; range, 3-45 months).

CONCLUSION

Percutaneous cryoablation of anterior renal masses can be performed with high technical success and low complication rates. The lack of local renal tumor recurrence at short-term follow-up evaluation in this study is encouraging, but long-term follow-up is necessary to ensure the durability of treatment.

Thermal ablation of renal cell carcinoma: triage, treatment, and follow-up

The incidence of renal cell carcinoma (RCC) is increasing. With the increasing emphasis on minimally invasive nephron-sparing surgery, thermal ablation is playing a larger role in the management of patients with this disease. This review outlines imaging management, intraoperative and percutaneous ablation, and postprocedural follow-up of RCC.

Percutaneous cryoablation of renal masses >or=3 cm: efficacy and safety in treatment of 108 patients

PURPOSE

To evaluate our single institution experience with percutaneous cryoablation of renal masses >or=3 cm in diameter for complications and short-term outcomes.

PATIENTS AND METHODS

Between March 2003 and February 2009, 108 patients with 110 renal masses >or=3 cm in diameter were treated with percutaneous cryoablation therapy. Technical success of the ablation procedure, complications, and evidence for local tumor recurrence were evaluated for each patient.

RESULTS

Average maximal renal tumor diameter was 4.1 cm (range 3.0-8.3 cm; standard deviation 1.1 cm). A single cryoablation procedure was performed for treatment of each patient. A technically successful ablation was achieved for 107 of 110 (97%) tumors. The three technical failures all resulted from incomplete cryoablation of the deepest margin of a centrally located renal tumor. A total of 9 severe adverse events occurred in six patients, resulting in an 8% major complication rate. Two patients in whom major complications developed were part of the group of only four patients for whom ablation was performed for tumors > 7 cm in diameter. There were no procedural-related deaths. No evidence for local tumor recurrence was identified in any patients with follow-up contrast-enhanced CT or MRI obtained 3 months or longer from the time of the ablation. Follow-up in these patients averaged 15 months (range 3-42 mos).

CONCLUSION

Percutaneous cryoablation of renal masses >or=3 cm in diameter can be performed with high technical success and low complication rates. Extra scrutiny is needed during cryoablation of central renal masses to make sure the ablation zone extends to include the deepest margin of the tumor. Although our experience is limited, percutaneous cryoablation of renal tumors > 7 cm in diameter may be associated with increased complications. The lack of local renal tumor recurrences seen in this study on short-term follow-up is encouraging, but long-term follow-up remains necessary to ensure treatment durability.

Prospects in percutaneous ablative targeting: comparison of a computer-assisted navigation system and the AcuBot Robotic System

AIM

Precise targeting is essential for adequate treatment of lesions during image-guided therapy. The aim of this study was to compare the performance of two emerging image-guided targeting technologies in a phantom model.

MATERIALS AND METHODS

A computer-assisted navigation system and AcuBot were tested using three operators: an interventional radiologist and two endourologists. Fiducials were placed in an anatomic gelatin phantom and targeted by both systems. The images were reconstructed and analyzed using a specialized software package (Amira; Visage Imaging, Carlsbad, CA). Accuracy was assessed by measuring proximity of the tip of the needle to the fiducial on computed-tomography-guided imaging. Accuracy and time to target were quantified and compared.

RESULTS

The mean distance from the desired target for AcuBot was 1.2 mm (range: 0.39-2.82). The mean distance from the desired target for the navigation system was 5.8 mm (range: 1.8-11.9). The AcuBot was significantly more accurate than the navigation system (p < 0.0001). The mean time from target acquisition to needle placement was 37 seconds (range: 15-75) for the AcuBot and 108 seconds (range: 45-315) for the navigation system (p = 0.001).

CONCLUSION

Emerging technologies hold promise for increased accuracy during percutaneous targeted procedures. Both the AcuBot and the computer-assisted navigation system were accurate and efficient in a phantom targeting model. AcuBot was significantly more accurate, faster, and less user dependent than the navigation system. Further studies in animal and clinical studies are warranted to further advance this promising technology.

Role of intraarterial embolization before cryoablation of large renal tumors: a pilot study

A retrospective review of patients who underwent percutaneous cryoablations of renal tumors (> or = 5 cm) with/without previous selective intraarterial embolization from March 2003 to January 2008 was performed to compare periprocedural complications. Of 129 treated tumors, 11 (8.5%) were larger than 5 cm. One patient was lost to follow-up. Of the remaining 10 follow-up patients, four (40%) underwent selective intraarterial tumor embolization before cryoablation. The mean hematoma volume in patients who underwent embolization before cryoablation (n = 4) was 18.3 mL +/- 25.9, whereas that in patients who underwent cryoablation alone (n = 6) was 357.3 mL +/- 460.9 (P< .01). Only one patient required transfusion and prolonged hospitalization. Combination therapy can provide a decrease in postprocedural cryoablation-related hemorrhage.

Prospective analysis of the safety and efficacy of percutaneous cryoablation for pT1NxMx biopsy-proven renal cell carcinoma

PURPOSE

Our objective was to determine the efficacy and safety of image-guided, percutaneous cryoablation for American Joint Committee on Cancer pT1ANxMx and pT1BNxMx biopsy-proven renal cell carcinoma (RCC).

MATERIALS AND METHODS

Computed tomography (CT)-guided, percutaneous cryoablation was used to treat 117 renal lesions in 113 consecutive patients with pT1NxMx RCC. All 117 ablations were included in the safety analysis, and complications were categorized according to Common Terminology Criteria for Adverse Events version 3.0 (CTCAE v3.0). Eighty-one lesions were biopsy-proven RCC and were included in the efficacy analysis. Technical success was defined as the "ice-ball" covering the entire lesion plus a minimum 5-mm margin. Efficacy was defined as complete lack of enhancement and continuous decrease in size on subsequent follow-up imaging studies.

RESULTS

Technical success was 100%, with 15% of ablations requiring air or saline injection to prevent nontarget ablation. We recorded a 7% rate of clinically significant complications (CTCAE category≥2) and 0% mortality. Renal function was not adversely affected. Seventy percent of patients were discharged to home on the same day. Efficacy was 98.7% for a median follow-up of 67 weeks (range 7-172). For the subgroup of patients that reached a median follow-up of 2 (n=59) and 3 years (n=13), efficacy was 98.3 and 92.3%, respectively. Cancer specific survival was 100%.

CONCLUSIONS

CT-guided, percutaneous cryoablation has an excellent safety and efficacy profile for stage T1A and T1B RCC; however, longer follow-up is needed to compare it with other nephron-sparing surgical treatments. It is a great option for nonsurgical patients, those in whom renal function cannot be further sacrificed, and those at risk for metachronous lesions.

Image registration of pre-procedural MRI and intra-procedural CT images to aid CT-guided percutaneous cryoablation of renal tumors

PURPOSE

To determine whether a non-rigid registration (NRR) technique was more accurate than a rigid registration (RR) technique when fusing pre-procedural contrast-enhanced MR images to unenhanced CT images during CT-guided percutaneous cryoablation of renal tumors.

METHODS

Both RR and NRR were applied retrospectively to 11 CT-guided percutaneous cryoablation procedures performed to treat renal tumors (mean diameter; 23 mm). Pre-procedural contrast-enhanced MR images of the upper abdomen were registered to unenhanced intra-procedural CT images obtained just prior to the ablation. RRs were performed manually, and NRRs were performed using an intensity-based approach with affine and Basis-Spline techniques used for modeling displacement. Registration accuracy for each technique was assessed using the 95% Hausdorff distance (HD), Fiducial Registration Error (FRE) and the Dice Similarity Coefficient (DSC). Statistical differences were analyzed using a two-sided Student's t-test. Time for each registration technique was recorded.

RESULTS

Mean 95% HD (1.7 mm), FRE (1.7 mm) and DSC (0.96) using the NRR technique were significantly better than mean 95% HD (6.4 mm), FRE (5.0 mm) and DSC (0.88) using the RR technique (P < 0.05 for each analysis). Mean registration times of NRR and RR techniques were 15.2 and 5.7 min, respectively.

CONCLUSIONS

The non-rigid registration technique was more accurate than the rigid registration technique when fusing pre-procedural MR images to intra-procedural unenhanced CT images. The non-rigid registration technique can be used to improve visualization of renal tumors during CT-guided cryoablation procedures.

MR imaging-guided interventions in the genitourinary tract: an evolving concept

MR imaging-guided interventions are well established in routine patient care in many parts of the world. There are many approaches, depending on magnet design and clinical need, based on MR imaging providing excellent inherent tissue contrast without ionizing radiation risk for patients. MR imaging-guided minimally invasive therapeutic procedures have advantages over conventional surgical procedures. In the genitourinary tract, MR imaging guidance has a role in tumor detection, localization, and staging and can provide accurate image guidance for minimally invasive procedures. The advent of molecular and metabolic imaging and use of higher strength magnets likely will improve diagnostic accuracy and allow targeted therapy to maximize disease control and minimize side effects.

Laparoscopic renal cryoablation: 8-year, single surgeon outcomes

PURPOSE

We present 5 to 11-year (median 8) oncological outcomes after laparoscopic renal cryoablation.

MATERIALS AND METHODS

Between September 1997 and October 2008 we performed renal cryoablation in 340 patients, of whom 80 treated laparoscopically by a single surgeon before October 2003 had a minimum 5-year followup. Followup involved magnetic resonance imaging on postoperative day 1, at 3, 6 and 12 months, and annually thereafter. Cryolesion biopsy was performed at 6 months. All data were prospectively accrued.

RESULTS

In the 80 patients with minimum 5-year followup mean age was 66 years, mean tumor size was 2.3 cm (range 0.9 to 5.0), median American Society of Anesthesiologists score was 3 and mean body mass index was 28 kg/m(2). Five patients had local recurrence, 2 had locoregional recurrence with metastasis and 4 had distant metastasis without locoregional recurrence. Six patients died of cancer. In the 55 patients with biopsy proven renal cell cancer at a median followup of 93 months (range 60 to 132) 5-year overall, disease specific and disease-free survival rates were 84%, 92% and 81%, and 10-year rates were 51%, 83% and 78%, respectively. On multivariate analysis previous radical nephrectomy for RCC was the only significant predictor of disease-free and disease specific survival (p = 0.023 and 0.030, respectively).

CONCLUSIONS

Laparoscopic renal cryoablation is effective oncological treatment for a renal mass in select patients. A disease specific survival rate of 92% at 5 years and 83% at 10 years is possible. Preceding radical nephrectomy for renal cell carcinoma was the only independent factor predicting disease-free and disease specific survival.