A. Nicholas Kurup

Comparison of partial nephrectomy and percutaneous ablation for cT1 renal masses.

BACKGROUND Partial nephrectomy (PN) is a preferred treatment for cT1 renal masses, whereas thermal ablation represents an alternative nephron-sparing option, albeit with higher reported rates of recurrence. OBJECTIVE To review our experience with PN, percutaneous radiofrequency ablation (RFA), and percutaneous cryoablation for cT1 renal masses. DESIGN, SETTING, AND PARTICIPANTS A total of 1803 patients with primary cT1N0M0 renal masses treated between 2000 and 2011 were identified from the prospectively maintained Mayo Clinic Renal Tumor Registry. INTERVENTION PN compared with percutaneous ablation. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS Local recurrence-free, metastases-free, and overall survival rates were estimated using the Kaplan-Meier method and compared with log-rank tests. RESULTS AND LIMITATIONS Of the 1424 cT1a patients, 1057 underwent PN, 180 underwent RFA, and 187 underwent cryoablation. In this cohort, local recurrence-free survival was similar among the three treatments (p=0.49), whereas metastases-free survival was significantly better after PN (p=0.005) and cryoablation (p=0.021) when compared with RFA. Of the 379 cT1b patients, 326 patients underwent PN, and 53 patients were managed with cryoablation (8 RFA patients were excluded). In this cohort, local recurrence-free survival (p=0.81) and metastases-free survival (p=0.45) were similar between PN and cryoablation. In both the cT1a and cT1b groups, PN patients were significantly younger, with lower Charlson scores and had superior overall survival (p<0.001 for all). Limitations include retrospective review and selection bias. CONCLUSIONS In a large cohort of sporadic cT1 renal masses, we observed that recurrence-free survival was similar for PN and percutaneous ablation patients. Metastases-free survival was superior for PN and cryoablation patients when compared with RFA for cT1a patients. Overall survival was superior after PN, likely because of selection bias. If these results were validated, an update to clinical guidelines would be warranted. PATIENT SUMMARY Partial nephrectomy and percutaneous ablation for small (<7-cm) and localized renal masses are associated with similar rates of local recurrence.

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.

Percutaneous Ablation of Renal Masses Measuring 3.0 cm and Smaller: Comparative Local Control and Complications After Radiofrequency Ablation and Cryoablation

OBJECTIVE The purpose of this article is to compare the efficacy and complication rates of percutaneous radiofrequency ablation (RFA) and cryoablation in the treatment of renal masses measuring 3.0 cm and smaller. MATERIALS AND METHODS A retrospective review was performed of 385 patients with 445 tumors measuring 3.0 cm or smaller treated with thermal ablation from 2000 through 2010. Two hundred fifty-six tumors in 222 patients were treated with RFA (mean [± SD] tumor size, 1.9 ± 0.5 cm), and 189 tumors in 163 patients were treated with cryoablation (mean tumor size, 2.3 ± 0.5 cm). Major complications and efficacy as measured by technical success and local tumor recurrence rates were recorded. RESULTS There were five (1.1%) technical failures, including one (0.4%) among tumors treated with RFA and four (2.1%) among tumors treated with cryoablation (p = 0.17). Of the 218 tumors treated with RFA and with follow-up beyond 3 months, seven (3.2%) developed local tumor recurrence, at a mean of 2.8 years after treatment (range, 1.2-4.1 years). Of the 145 tumors treated with cryoablation and with follow-up beyond 3 months, four (2.8%) developed local tumor recurrence at a mean of 0.9 years after treatment (range, 0.3-1.6 years). For biopsy-proven renal cell carcinoma, estimated local recurrence-free survival rates at 1, 3, and 5 years after RFA were 100%, 98.1%, and 98.1%, respectively, compared with 97.3%, 90.6%, and 90.6%, respectively, after cryoablation (p = 0.09). Major complications occurred after 4.3% (10/232) of RFAs and 4.5% (8/176) of cryoablation procedures (p = 0.91). CONCLUSION RFA and cryoablation are both effective in the treatment of renal masses measuring 3 cm or smaller. Major complications with either procedure are infrequent.

Percutaneous Cryoablation of Musculoskeletal Oligometastatic Disease for Complete Remission

PURPOSE To assess the safety and effectiveness of percutaneous cryoablation to treat limited metastases to the musculoskeletal system, with the goal of complete disease remission. MATERIALS AND METHODS In a single-institution retrospective study of data from December 2003 to October 2011, 43 consecutive patients underwent initial cryoablation of limited (five or fewer) musculoskeletal metastases with the goal of complete disease remission (ie, no clinical or radiographic evidence of disease). Three patients were lost to follow-up. As a result, the present report describes 40 patients who underwent 40 cryoablation procedures to treat 52 tumors. RESULTS Local control was achieved in 45 of 52 tumors (87%; 95% confidence interval [CI], 75%-93%) at a median follow-up of 21 months (range, 4-62 mo). Thirteen of 19 treated bone metastases (68%) and 32 of 33 soft-tissue metastases (97%) showed local control (P = .007). One- and 2-year overall survival rates were 91% (95% CI, 75%-97%) and 84% (95% CI, 65%-93%), respectively. Median overall survival was 47 months (95% CI, 26-62 mo). One- and 2-year disease-free survival rates were 22% (95% CI, 11%-37%) and 7% (95% CI,<1% to 26%), respectively. Median disease-free survival was 7 months (95% CI, 5-10 mo). Two of 40 procedures (5%) were associated with major complications. CONCLUSIONS Percutaneous cryoablation is a safe and effective treatment to achieve local tumor control and short-term complete disease remission in patients with limited metastatic disease to the musculoskeletal system.

Ablation of Skeletal Metastases: Current Status

Image-guided percutaneous ablation of bone metastases is an effective, minimally invasive alternative to conventional therapies in the palliation of pain from metastatic disease. Ablative technologies applied in the treatment of skeletal metastases include radiofrequency ablation, cryoablation, microwave ablation, laser ablation, ethanol ablation, and, most recently, focused ultrasound. These ablative methods may be performed in combination with percutaneous cementoplasty to provide support and stabilization for metastases in weight-bearing bones at risk for pathologic fracture.

Image-guided percutaneous ablation of bone and soft tissue tumors.

Image-guided percutaneous ablation of bone and soft tissue tumors is an effective minimally invasive alternative to conventional therapies, such as surgery and external beam radiotherapy. Proven applications include treatment of benign primary bone tumors, particularly osteoid osteoma, as well as palliation of painful bone metastases. Use of percutaneous ablation in combination with cementoplasty can provide stabilization of metastases at risk for fracture. Local control of oligometastatic disease and treatment of desmoid tumors are emerging applications.

Predicting Renal Cryoablation Complications: New Risk Score Based on Tumor Size and Location and Patient History

PURPOSE To identify tumor and patient-related risk factors for major complications following renal cryoablation and to develop a model for predicting these adverse events. MATERIALS AND METHODS Institutional review board approval and informed patient consent were obtained for this HIPAA-compliant retrospective study. All 398 renal cryoablation procedures performed from 2003 through 2011 were reviewed to identify tumor and patient-related risk factors associated with major complications (Clavien-Dindo classification, ≥ grade III). A scoring system for predicting these adverse events was then developed using risk factor weighting obtained from a multivariate logistic regression model. To internally validate this model, the scoring system was then applied to all 73 renal cryoablation procedures performed during 2012. RESULTS Among tumor-related factors evaluated, Maximal tumor diameter (P = .0006) and Central tumor location (P = .02) were significantly associated with major complications. Among patient-related factors evaluated, prior Myocardial infarction (MI) (P = .002) and Complicated diabetes mellitus (P = .01) were significantly associated with major complications. This resulted in the (MC)2 risk scoring system, with (MC)2 risk score = 2.5 points (for tumors ≤ 2.5 cm in maximal diameter) or 0.1 points for each millimeter of maximal tumor diameter (for tumors > 2.5 cm) + 1.5 points (if central tumor location) + 2.5 points (if patient history of prior MI) + 3.0 points (if patient history of complicated diabetes). Mean (MC)2 risk score for all renal cryoablations was 4.7 (standard deviation, 1.9; range, 2.5-15.3). The observed major complication rates were 2.0% (95% confidence interval [CI]: 0.6%, 4.6%) in the low-risk group (score < 5.0), 12.8% (95% CI: 7.5%, 19.9%) in the moderate-risk group (score of 5.0-8.0), and 39.1% (95% CI: 19.7%, 61.5%) in the high-risk group (score > 8.0). Application of the (MC)2 scoring system to the validation group yielded a concordance index of 0.82 (95% CI: 0.62, 1.00). CONCLUSION The results of this study suggest that the (MC)2 risk score is a valuable tool for predicting major complications in patients undergoing renal cryoablation. However, external validation is warranted.

ABLATE: A renal ablation planning algorithm

OBJECTIVE The purpose of this article is to present the ABLATE renal ablation planning algorithm (Table 1), which is based on anatomic renal tumor characteristics critical to ablation. [Table: see text]. CONCLUSION ABLATE provides a systematic method for reviewing cross-sectional imaging of renal masses for ablation planning purposes. The goal of this system is to help proceduralists anticipate and manage potential technical challenges of renal ablations to maximize oncologic outcomes and minimize complications.

Neuroanatomic Considerations in Percutaneous Tumor Ablation

Percutaneous ablation is increasingly being used as focal therapy for tumors in the chest, abdomen, and pelvis, including tumors in proximity to neural structures. To ensure that tumor ablation is performed safely, knowledge of the regional neuroanatomy is particularly important because most relevant nerves are not visualized with the conventional imaging techniques used to guide ablation procedures. Familiarity with the expected course of nerves in commonly targeted areas is helpful in preventing inadvertent nerve injury and in accurately informing the patient of potential risks. In the chest and shoulder girdle, the brachial plexus as well as the phrenic, recurrent laryngeal, intercostal-subcostal, long thoracic, dorsal scapular, and suprascapular nerves may be encountered. Vulnerable neural structures in the abdomen and pelvis arise from the lumbar and sacral plexuses and include the femoral, obturator, sciatic, and pudendal nerves. Nerve protection and monitoring techniques should be used, when appropriate, to minimize the risk of neural injury during percutaneous tumor ablation and depend on the vulnerable nerve, the location of the targeted tumor, and the ablation device used for treatment. Nerves may be protected using displacement techniques, including instillation of air or fluid, insertion and insufflation of angioplastic or endoscopic balloons, and mechanical manipulation of the ablation device. Nerves may be monitored with cross-sectional imaging evaluation of the critical nerve or ablation zone, or with functional evaluation using electromyographic equipment or focused clinical examination. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg334125141/-/DC1.

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.