Update on Percutaneous Ablation for Sarcoma

PURPOSE OF REVIEW

To provide an update on the current state of percutaneous thermal ablation in the treatment of sarcoma.

RECENT FINDINGS

Data continue to accrue in support of ablation for local control and palliation of specific sarcoma subtypes such as extra-abdominal desmoid fibromatosis and for broader indications such as the treatment of oligometastatic disease. The synergistic possibilities of various combination therapies such as cryoablation and immunotherapy represent intriguing areas of active investigation. Histotripsy is an emerging non-invasive, non-thermal ablative modality that may further expand the therapeutic arsenal for sarcoma treatment. Percutaneous thermal ablation is a valuable tool in the multidisciplinary management of sarcoma, offering a minimally invasive adjunct to surgery and radiation therapy. Although there remains a paucity of high-level evidence specific to sarcomas, ablation techniques are demonstrably safe and effective for achieving local tumor control and providing pain relief in select patients and are of particular benefit in those with metastatic disease or requiring palliative care.

Thermoprotection of Neural Structures During Musculoskeletal Ablation

Percutaneous thermal ablation is widely used for local control and palliation of a variety of lesions throughout the musculoskeletal system. In this setting, safe ablation is predicated on the avoidance of unintentional injury to vulnerable neural structures that are often in proximity to ablation targets. This article highlights key periprocedural considerations in musculoskeletal ablation and reviews the array of active and passive thermoprotective measures that are critical to safe and successful treatment.

Percutaneous Cryoablation of Plasmacytomas: Oncologic Effectiveness and Adverse Events

PURPOSE

To evaluate the oncologic outcomes and adverse events associated with cryoablation of plasmacytomas.

MATERIALS AND METHODS

Retrospective review of an institutional percutaneous ablation database showed 43 patients underwent 46 percutaneous cryoablation procedures for treatment of 44 plasmacytomas between May 2004 and March 2021. Treatment of 25 (25/44, 56.8%) tumors was augmented with bone consolidation/cementoplasty. Median patient age was 64 years [interquartile range (IQR): 54-69], and 30 (30/43, 69.8%) patients were male. Median maximal plasmacytoma diameter was 5.0 cm [IQR: 3.1-7.0]. Thirty (30/44, 68.2%) tumors were periacetabular, vertebral, or located in the iliac wing. Twenty-nine (29/44, 65.9%) cryoablated plasmacytomas were recurrent tumors following prior external beam radiation therapy (EBRT). Survival analyses were performed using the Kaplan-Meier method. Adverse events were graded using Society of Interventional Radiology (SIR) criteria.

RESULTS

Five-year estimated local tumor recurrence-free survival was 85.3% [95% confidence interval (CI): 74.1-98.1%], five-year estimated new plasmacytoma-free survival was 49.9% {95% CI: 33.9-73.4%], and five-year estimated overall survival was 70.4% [95% CI: 56.9-87.1%]. Nine (9/46, 19.6%) major adverse events occurred in 8 patients, including 3 (3/46, 6.5%) new or progressive pathologic fractures at the ablation site requiring surgical intervention, 3 (3/46, 6.5%) nerve injuries, 1 (1/46, 2.2%) avascular necrosis and femoral head collapse, 1 (1/46, 2.2%) septic arthritis, and 1 (1/46, 2.2%) acute renal failure caused by rhabdomyolysis.

CONCLUSIONS

Percutaneous cryoablation is a viable treatment option for patients with plasmacytomas, including those with recurrent plasmacytomas after EBRT. Post-cryoablation adverse events are relatively common.

Feasibility and safety of percutaneous image-guided cryoablation of abdominal wall endometriosis

PURPOSE

To evaluate the feasibility and safety of percutaneous image-guided cryoablation of abdominal wall endometriosis (AWE).

MATERIALS AND METHODS

A retrospective review of percutaneous cryoablation (CT or MR) of AWE was performed from January 2018 to December 2020. Eighteen patients were identified from an internal percutaneous ablation database. Technical success, complications, and outcomes were analyzed according to standard nomenclature.

RESULTS

Patients comprised 18 females (mean age 36.9 years) who underwent 18 cryoablation procedures to treat 23 AWE deposits. Three of the 18 cases were performed under MR guidance, while the remaining 15 employed CT guidance. Technical success was achieved in all 18 cases (100%). Fifteen of 18 patients (83%) had biopsy proven AWE deposits prior to treatment. Hydrodisplacement was used to displace adjacent bowel, bladder, or neurovascular structures in 13/18 cases (72%). The mean number of probes used per case was 3. Sixteen of 23 (70%) of AWE deposits had imaging follow-up (median 85 days). Of the 16 lesions with imaging follow-up, 15 (94%) demonstrated no residual enhancement or T1 hyperintensity at the treatment site and 1 lesion (6%) demonstrated residual/progressive disease. At clinical follow-up, 13 of 14 (93%) patients reported improvement in AWE-related symptoms. Eleven patients had clinically documented pain scores before and after ablation and all demonstrated substantial symptomatic improvement. No society of interventional radiology (SIR) major complications were observed.

CONCLUSIONS

Percutaneous cryoablation of AWE is feasible with a favorable safety profile. Further longitudinal studies are needed to document durable response over time.

Improving Root Cause Analysis of Patient Safety Events in Radiology

Patient safety events occur in health care, and root cause analysis (RCA) meetings held after these incidents often reveal valuable insights into systemic barriers between optimal processes or stated policies and actual practice, providing critical opportunities for improvement. The patient safety team that facilitates RCA meetings in the radiology department at the authors' institution received feedback suggesting dissatisfaction with the RCA process. The team followed a structured process improvement framework to analyze the root causes of this dissatisfaction and create a better system. Using a post-RCA survey to target satisfaction scores as an improvement goal, the team successfully increased participant and facilitator satisfaction levels with sustained results. The patient safety team applied structured process improvement methodologies to their own daily work, learning lessons about measuring difficult processes and choosing appropriate metrics, the benefits of standardized work, and how to continuously improve a quality program. In the course of improving the satisfaction of employees participating in the RCA process, a more robust, continuously improving patient safety program has emerged to enhance the ability of those within the department to report, learn from, and hopefully prevent patient safety events in the future.^©RSNA, 2020.

Cryoablation for Palliation of Painful Bone Metastases: The MOTION Multicenter Study

PURPOSE

To assess the clinical effectiveness of cryoablation for palliation of painful bone metastases.

MATERIALS AND METHODS

MOTION (Multicenter Study of Cryoablation for Palliation of Painful Bone Metastases) (ClinicalTrials.gov NCT02511678) was a multicenter, prospective, single-arm study of adults with metastatic bone disease who were not candidates for or had not benefited from standard therapy, that took place from February 2016 to March 2018. At baseline, participants rated their pain using the Brief Pain Inventory-Short Form (reference range from 0 to 10 points); those with moderate to severe pain, who had at least one metastatic candidate tumor for ablation, were included. The primary effectiveness endpoint was change in pain score from baseline to week 8. Participants were followed for 24 weeks after treatment. Statistical analyses included descriptive statistics and logistic regression to evaluate changes in pain score over the postprocedure follow-up period.

RESULTS

A total of 66 participants (mean age, 60.8 years ± 14.3 [standard deviation]; 35 [53.0%] men) were enrolled and received cryoablation; 65 completed follow-up. Mean change in pain score from baseline to week 8 was -2.61 points (95% CI: -3.45, -1.78). Mean pain scores improved by 2 points at week 1 and reached clinically meaningful levels (more than a 2-point decrease) after week 8; scores continued to improve throughout follow-up. Quality of life improved, opioid doses were stabilized, and functional status was maintained over 6 months. Serious adverse events occurred in three participants.

CONCLUSION

Cryoablation of metastatic bone tumors provided rapid and durable pain palliation, improved quality of life, and offered an alternative to opioids for pain control.Keywords: Ablation Techniques, Metastases, Pain Management, Radiation Therapy/OncologySupplemental material is available for this article.© RSNA, 2021.

Image-guided tumor ablation in gynecologic oncology: Review of interventional oncology techniques and case examples highlighting a collaborative, multidisciplinary program

As interventional oncology services within radiology mature, image-guided ablation techniques are increasingly applied to recurrent gynecologic malignancies. Ablation may be performed using thermal techniques like cryoablation, microwave ablation, or radiofrequency ablation, as well as non-thermal ones, such as focused ultrasound or irreversible electroporation. Feasibility and approach depend on tumor type, size, number, anatomic location, proximity of critical structures, and goals of therapy. Current indications include local control of limited metastatic disease or palliation of painful bone metastases refractory or unsuitable to conventional therapies. Technical aspects of these procedures, including methods to protect nearby critical structures are presented through illustrative examples. Cases amenable to image-guided ablation include, but are not limited to, hepatic or pulmonary metastases, musculoskeletal metastases, retroperitoneal nodal metastases, pelvic side wall disease, abdominal wall disease, and vaginal or vulvar tumors. Protective maneuvers, such as hydro-displacement of bowel, neuromonitoring, and retrograde pyeloperfusion through ureteral stents, permit safe ablation despite close proximity to vulnerable nerves or organs. Image-guided ablation offers an alternative modality to achieve local tumor control without the risks associated with surgery or systemic treatment in appropriately selected patients. A multidisciplinary approach to use of image-guided ablation includes collaboration between gynecologic oncology, interventional radiology, anesthesia, urology and radiation oncology teams allowing for appropriate patient-centered case selection. Long-term follow up and additional studies are needed to determine the oncologic benefits of such techniques.

Implementing a Radiology Residency Quality Curriculum to Develop Physician Leaders and Increase Value for Patients

Diagnostic and interventional radiology residency programs must educate trainees on quality and patient safety topics to meet board requirements and prepare residents to become effective physician leaders. A quality curriculum should encompass process improvement methodology as well as instruction about crucial patient safety subjects. The authors have developed a standardized and structured approach to fulfill this need using didactic and experiential learning. The educational format includes short lectures, peer-to-peer instruction, and self-study, with the value of presented information reinforced by physician leaders and process improvement specialists. Equally important is a structured experience in departmental quality improvement wherein trainees learn the collaborative nature of effective durable process change in areas of interest to them. This curriculum is implemented during the 3rd year of radiology residency to leverage residents' knowledge and experience with radiology workflows and proximity to the American Board of Radiology Core Exam. Feedback from educators and trainees as well as objective examination data support this approach. This article shares guidance and lessons learned from the authors' radiology residency educational efforts and offers a framework for successful implementation of a comprehensive quality curriculum at any residency training program. This curriculum serves the dual purpose of developing skilled future physician leaders and promoting value for patients. ^©RSNA, 2020.

Impact of a 3D printed model on patients' understanding of renal cryoablation: a prospective pilot study

PURPOSE

To determine whether a 3D printed model improves patients' understanding of renal cryoablation and the involved anatomy.

METHODS

This prospective study included 25 control patients, who received standard of care renal cryoablation education (verbal explanation accompanied by review of relevant 2D imaging) and 25 experimental patients, who received education using a 3D printed renal cryoablation model in addition to standard of care. Subsequent patient surveys included 5 anatomy and 5 procedural knowledge questions. The experimental cohort also subjectively graded the importance of the 3D model for understanding the renal cryoablation procedure and associated anatomy.

RESULTS

Mean percent of anatomy questions answered correctly was significantly higher in the experimental cohort than that in the control group (87.2% vs. 72.8%; p = 0.007). After adjusting for the physician providing the education, however, the 3D model was no longer significantly associated with patient anatomy knowledge (p = 0.22). Mean percent of procedure-related questions answered correctly was higher in the experimental cohort (93.6%) than that in the control group (89.6%) (p = 0.16). The experimental cohort graded the importance of the 3D model for understanding their renal tumor anatomy and upcoming procedure to be very high (mean 9.4 and 9.5, respectively, on a 0-10 point scale). Twenty-three (92%) patients "definitely recommended" continued use of the 3D model as a patient educational tool.

CONCLUSIONS

Although patients' objective anatomy and procedural knowledge was not significantly improved with the 3D renal cryoablation model in this small pilot study, patients' high perceived value of the model supports investigation in a larger study.

Thermal ablation of intrahepatic cholangiocarcinoma: Safety, efficacy, and factors affecting local tumor progression

PURPOSE

To evaluate the safety and oncologic efficacy of percutaneous thermal ablation of intrahepatic cholangiocarcinoma (ICC) and identify risk factors for local tumor progression (LTP).

MATERIALS AND METHODS

Retrospective review of an institutional tumor ablation registry demonstrated that 20 patients (9 males, 11 females; mean age 62.5 ± 15.8 years) with 50 ICCs (mean size 1.8 ± 1.3 cm) were treated with percutaneous radiofrequency ablation (RFA) or microwave ablation (MWA) between 2006 and 2015. Thirty-eight of the treated ICCs (76%) were metastases that developed after surgical resection of the primary tumor. Patient demographics, procedure technical parameters, and clinical outcomes were reviewed. A Cox proportional hazards model was used to examine the risk of LTP by ablation modality. Survival analyses were performed using the Kaplan-Meier method.

RESULTS

Mean imaging follow-up time was 41.5 ± 42.7 months. Forty-four (88%) ICCs were treated with RFA, and 6 (12%) with MWA. Eleven (22%) cases of LTP developed in 5 (25%) patients. The median time to LTP among these 11 tumors was 7.1 months (range, 2.3-22.9 months). Risk of LTP was not significantly different for ICCs treated with MWA compared to RFA (HR 2.72; 95% CI 0.58-12.84; p = 03.21). Median disease-free survival was 8.2 months (1.1-70.4 months), and median overall survival was 23.6 months (7.4-122.5 months). No major complication occurred.

CONCLUSIONS

Percutaneous thermal ablation is a safe and effective treatment for patients with ICCs and may be particularly valuable in unresectable patients, or those who have already undergone hepatic surgery. Tumor size and ablation modality were not associated with LTP, whereas primary tumors and superficially located tumors were more likely to subsequently recur.

Thermal Ablation of Bone Metastases

Image-guided, minimally invasive, percutaneous thermal ablation of bone metastases has unique advantages compared with surgery or radiation therapy. Thermal ablation of osseous metastases may result in significant pain palliation, prevention of skeletal-related events, and durable local tumor control. This article will describe current thermal ablation techniques utilized to treat bone metastases, summarize contemporary evidence supporting such thermal ablation treatments, and outline an approach to percutaneous ablative treatment.

Imaging following renal ablation: what can we learn from recurrent tumors?

PURPOSE

The purpose of the study was to evaluate the post-contrast appearance of local tumor progression (LTP) following renal ablation to better understand patterns of tumor recurrence and to optimize follow-up imaging protocols.

METHODS

From 2002 to 2015, 913 patients underwent 988 renal ablation procedures for treatment of 1064 tumors. LTP was identified in 24 (2.6%) patients during median imaging follow-up of 30 months (range 0-139). One patient with LTP was followed with non-contrast MRI only and was excluded from evaluation. Three body radiologists reviewed the contrast-enhanced CT and/or MRI follow-up imaging in the remaining 23 patients to determine the timing and imaging appearance of the recurrent tumor.

RESULTS

Local tumor progression was identified on contrast-enhanced CT or MRI at median 11 months (range 1 and 68) after renal ablation. Corticomedullary phase imaging was performed in 16/23 (70%) patients. LTP was identified on the corticomedullary phase in all cases, and was most conspicuous on the corticomedullary phase compared to any other phase of imaging in 15/16 (94%) patients. No cases of LTP were best visualized on non-contrast or excretory phase images.

CONCLUSIONS

Delayed recurrence following renal ablation is possible; therefore, extended follow-up is indicated in ablation patients. Almost all cases of LTP were best visualized on the corticomedullary phase of imaging, which should be included in any post-ablation imaging protocol. Excretory phase images were not required to diagnose LTP in any case and could be excluded from routine post-ablation follow-up.

Palliative Percutaneous Cryoablation and Cementoplasty of Acetabular Metastases: Factors Affecting Pain Control and Fracture Risk

PURPOSE

To characterize the response of patients with acetabular metastases following combined cryoablation and cementoplasty (CCC) for pain palliation and fracture risk reduction, based on completeness of ablation and the presence of pre-existing pathologic fracture.

MATERIALS AND METHODS

Thirty-nine consecutive acetabular CCC procedures were performed in 37 patients (24 M:13F, age 66 ± 8 years). Pain was assessed using a 0-10 numeric rating scale. Development of new or progression of pre-existing fractures and local tumor progression (LTP) were determined on follow-up imaging. Pain score reduction and fracture development rates were compared by ablation completeness and the presence of pre-existing fractures.

RESULTS

Twenty-three of 27 (85%) patients with evaluable pain scores had reduced pain, decreasing from 7.5 ± 2.1 to 3.6 ± 2.6 (p < 0.0001). Of 39 tumors, 28 (72%) were completely ablated with no significant difference in pain reduction after complete versus incomplete ablations (p = 0.9387). Six of 30 (20%) patients with follow-up imaging demonstrated new/progressive acetabular fractures. Four of 5 (80%) patients with LTP developed new/progressive fractures compared to 2 of 25 (8%) without tumor progression (p = 0.0003). Pre-existing fracture was not associated with subsequent fracture/fracture progression (p = 0.2986). However, patients with prior acetabular radiation therapy or surgery had increased fractures following treatment (p = 0.0380).

CONCLUSION

Complete acetabular tumor ablation during CCC was not associated with superior pain relief compared to subtotal ablation but did result in improved fracture stabilization. Pre-treatment pathologic fractures were not associated with fracture progression, but new/progressive fractures were more frequent in patients with prior radiation therapy or surgery.

Radiofrequency Ablation Versus Stereotactic Body Radiotherapy for Localized Hepatocellular Carcinoma in Nonsurgically Managed Patients: Analysis of the National Cancer Database

Purpose Data that guide selection of optimal local ablative therapy for the management localized hepatocellular carcinoma (HCC) are lacking. Because there are limited prospective comparative data for these treatment modalities, we aimed to compare the effectiveness of radiofrequency ablation (RFA) versus stereotactic body radiotherapy (SBRT) by using the National Cancer Database. Methods We conducted an observational study to compare the effectiveness of RFA versus SBRT in nonsurgically managed patients with stage I or II HCC. Overall survival was compared by using propensity score-weighted and propensity score-matched analyses based on patient-, facility-, and tumor-level characteristics. A sensitivity analysis was performed to evaluate the effect of severe fibrosis/cirrhosis. In addition, we performed exploratory analyses to determine the effectiveness of RFA and SBRT in clinically relevant patient subsets. Results Overall, 3,684 (92.6%) and 296 (7.4%) nonsurgically managed patients with stage I or II HCC received RFA or SBRT, respectively. After propensity matching, 5-year overall survival was 29.8% (95% CI, 24.5% to 35.3%) in the RFA group versus 19.3% (95% CI, 13.5% to 25.9%) in the SBRT group ( P < .001). Inverse probability-weighted analysis yielded similar results. The benefit of RFA was consistent across all subgroups examined and was robust to the effects of severe fibrosis/cirrhosis. Conclusion Our study suggests that treatment with RFA yields superior survival compared with SBRT for nonsurgically managed patients with stage I or II HCC. Even though our results are limited by the biases related to the retrospective study design, we believe that, in the absence of a randomized clinical trial, our findings should be considered when recommending local ablative therapy for localized unresectable HCC.

Outcomes of Ultrasound-Guided Thrombin Injection of Nongroin Arterial Pseudoaneurysms

PURPOSE

To evaluate success and complication rates of percutaneous ultrasound-guided thrombin injection of nongroin pseudoaneurysms (PSAs).

MATERIALS AND METHODS

Retrospective review of a prospectively maintained institutional database yielded 39 cases of arterial PSAs occurring at nongroin sites that were treated with percutaneous ultrasound-guided thrombin injection between 2000 and 2016 (average patient age 69.2 y ± 14.0). Of PSAs, 74.4% (29/39) arose in the upper extremities, and 92.3% (36/39) were iatrogenic. The brachial artery was the most commonly affected vessel (51.3% [20/39]), and arterial access was the most common cause (56.4% [22/39]). Average overall PSA size was 2.4 cm (range, 0.5-7.2 cm); average amount of thrombin injected was 320 IU (range, 50-2,000 IU). Technical success was defined as absence of flow within the PSA immediately after thrombin injection. Treatment success was defined as sustained thrombosis on follow-up imaging obtained at 1-3 days after treatment.

RESULTS

Technical and treatment success rates of thrombin injections were 100% (39/39) and 84.8% (28/33), respectively. Longer term follow-up imaging (average 71 d; range, 12-201 d) was available for 7 of the treatment successes with 100% (7/7) showing sustained thrombosis. Comparing treatment successes and failures, there was no significant difference in average PSA size (2.3 cm vs 2.0 cm, P = .51) or average amount of thrombin injected (360 IU vs 180 IU, P = .14). There were no complications.

CONCLUSIONS

Ultrasound-guided thrombin injection is a safe, efficacious treatment option for PSAs arising in nongroin locations.

Evaluation of infectious complications following percutaneous liver ablation in patients with bilioenteric anastomoses

PURPOSE

Prior bilioenteric anastomosis (BEA) has been associated with elevated risk of abscess formation after thermal ablation of hepatic tumors. We assessed the incidence of hepatic abscess after thermal ablation in a BEA cohort treated with extended antibiotic regimens following ablation.

MATERIALS AND METHODS

Retrospective review was performed to identify patients with BEA who underwent percutaneous hepatic thermal ablation between January 1, 2003-September 1, 2016. Fifteen patients with BEA underwent 18 percutaneous thermal ablation procedures. Patient and procedural characteristics were reviewed, as well as the antibiotic regiment utilized post ablation. Complications were characterized via standardized nomenclature [Common Terminology for Clinically Adverse Events (CTCAE) v4.03].

RESULTS

Fifteen patients with BEA underwent treatment of 49 liver lesions during 18 ablation sessions. Mean follow-up in these patients was 39 months (range 3-138 months). Two patients (11%) developed hepatic abscesses, both of which occurred within 45 days of the ablation procedure while the patients were still on extended prophylactic antibiotic therapy. No additional CTCAE clinically significant complications were observed.

CONCLUSION

Thermal ablation of hepatic tumors can be accomplished safely in patients with BEA. Long-term post-procedural antibiotics may mitigate the risk of hepatic abscess formation. Due to the high number of patients who are deemed surgically unresectable, patients with BEA may have limited alternate treatment modalities and percutaneous hepatic thermal ablative treatments warrant consideration.

Retrospective Review of Percutaneous Image-Guided Ablation of Oligometastatic Prostate Cancer: A Single-Institution Experience

PURPOSE

To retrospectively review and report the efficacy and safety of percutaneous image-guided ablation (cryoablation or radiofrequency ablation) in the treatment of oligometastatic prostate cancer.

MATERIALS AND METHODS

An institutional registry was retrospectively reviewed and revealed 16 patients with oligometastatic prostate cancer (median age, 67 y; range, 50-86 y) who underwent percutaneous image-guided ablation to treat 18 metastatic sites. A subgroup of 7 patients with 8 metastases were androgen-deprivation therapy (ADT)-naïve and underwent ablation to delay initiation of ADT. Local tumor control, progression-free survival (PFS), ADT-free survival, and procedural complications were analyzed.

RESULTS

Local tumor control was achieved in 15 of 18 metastases (83%) at a median follow-up of 27 months (range, 5-56 mo). Local tumor recurrence was found in 3 of 18 metastases (17%), with a median time to local recurrence of 3.5 months (range, 3-38 mo). Estimated PFS rates at 12 and 24 months were 56% (95% confidence interval [CI], 30%-76%) and 43% (95% CI, 19%-65%), respectively. In the 7 ADT-naïve patients, local tumor control was achieved in all metastases, and the median ADT-free survival period was 29 months. There were no major procedural complications.

CONCLUSIONS

In this cohort of patients with oligometastatic prostate cancer, percutaneous image-guided ablation was feasible and well tolerated and achieved acceptable local tumor control rates. Percutaneous ablation may be of particular utility in patients who wish to delay initiation of ADT.

Expanding role of percutaneous ablative and consolidative treatments for musculoskeletal tumours

Interventional approaches to musculoskeletal tumours have significantly changed over the last several years, and new treatments continue to be developed. All ablative modalities are currently applied to the treatment of bone tumours, including radiofrequency, cryo-, microwave, and laser ablation devices. Indications for ablation of bone and soft-tissue tumours have expanded beyond palliation of painful bone metastases and eradication of osteoid osteomas to the local control of oligometastatic disease from a number of primary tumours and ablation of desmoid tumours. In addition, tools for consolidation of bone tumours at risk of pathological fracture have also expanded. With these developments, ablation has become the primary treatment for osteoid osteomas and, at some institutions, desmoid tumours. It may be the primary or secondary treatment for palliation of painful bone tumours, frequently used in patients with pain refractory to or recurrent after radiation therapy. It is used as a treatment for limited metastatic disease or for metastases that grow disproportionately in patients with multifocal metastases, either in combination with systemic therapy or to reserve systemic therapy and its toxicity for more widespread disease progression. Moreover, percutaneous methods to consolidate bone at risk of fracture have become more commonplace, aided by techniques using materials beyond typical bone cement.

Effects of Aspirin Therapy on Ultrasound-Guided Renal Allograft Biopsy Bleeding Complications

PURPOSE

To determine if patient aspirin exposure and timing affect bleeding risk after renal allograft biopsy.

MATERIALS AND METHODS

Review of 6,700 renal allograft biopsies (in 2,362 unique patients) was performed. Median patient age was 53.0 years [interquartile range 43.0, 62.0]; 56.2% of patients were male. Of biopsies, 4,706 (70.2%) were performed in patients with no aspirin exposure within 10 days of biopsy; 664 (9.9%), were performed within 8-10 days of aspirin exposure; 855 (12.8%), within 4-7 days; and 475 (7.1%), within 0-3 days. Follow-up to 3 months after the procedure was completed in all patients. Biopsies were categorized as protocol or indication; 19.7% were indication biopsies. Bleeding complications were graded based on SIR criteria. Logistic regression models examined the association between aspirin use and bleeding events.

RESULTS

Rate [95% confidence interval] of major bleeding complications was 0.24% [0.14, 0.39], and rate of any bleeding complication was 0.66% [0.46, 0.90]. Bleeding events were significantly associated with patients undergoing indication biopsies compared with protocol biopsies (odds ratio [OR] 2.27, P = .012). Patient factors associated with major bleeding complications in multivariate models included estimated glomerular filtration rate (OR 0.61, P = .016) and platelet count (OR 0.64, P = .033). Aspirin use was not significantly associated with increased risk of bleeding complication except for use of 325 mg of aspirin within 3 days of biopsy (any complication OR 3.87 [1.12, 13.4], P = .032; major complication OR 6.30 [1.27, 31.3], P = .024).

CONCLUSIONS

Renal allograft biopsy bleeding complications are very rare, particularly for protocol biopsies. Use of 325 mg of aspirin within 3 days of renal allograft biopsy was associated with increased bleeding complications.

Recurrence and Survival Outcomes After Percutaneous Thermal Ablation of Oligometastatic Melanoma

OBJECTIVES

To evaluate focal treatment of melanoma metastases and to explore whether any potential extended survival benefit exists in a select patient population.

PATIENTS AND METHODS

All patients who underwent image-guided local thermal ablation of metastatic melanoma over an 11-year period (January 1, 2002, to December 31, 2013) were retrospectively identified using an internally maintained clinical registry. Only patients with oligometastatic stage IV disease amenable to complete ablation of all clinical disease at the time of ablation were included in the analysis. Overall survival and median progression-free survival periods were calculated.

RESULTS

Thirty-three patients with primary ocular or nonocular melanoma had 66 metastases treated in the lungs, liver, bones, or soft tissues. Eleven (33%) patients were on systemic medical therapy at the time of the procedure. The median survival time was 3.8 years (range, 0.5-10.5 years), with a 4-year estimated survival of 44.1% (95% CI, 28%-68%). Local recurrence at the ablation site developed in 15.1% (5 of 33) of the patients and 13.6% of the tumors (9 of 66). The median progression-free survival time was 4.4 months (95% CI, 1.4 months to 10.5 years), with an estimated 1-year progression-free survival of 30.3% (95% CI, 18%-51%). A subgroup analysis identified 11 patients with primary ocular melanoma and 22 with nonocular melanoma, with a median survival time of 3.9 years (range, 0.9-4.7 years) and 3.8 years (range, 0.5-10.5 years), respectively (P=.58). There were no major complications and no deaths within 30 days of the procedure.

CONCLUSION

Selective use of image-guided thermal ablation of oligometastatic melanoma may provide results similar to surgical resection in terms of technical effectiveness and oncologic outcomes with minimal risk.

Bleeding Rate for Ultrasound-Guided Paracentesis in Thrombocytopenic Patients

OBJECTIVES

The purpose of this study was to determine the rate of major bleeding complications for ultrasound-guided paracentesis performed in thrombocytopenic patients.

METHODS

We retrospectively reviewed the electronic medical records of patients with platelet counts of less than 50,000/μL who had ultrasound-guided paracenteses performed in the Department of Radiology without correcting preprocedural platelet transfusions between 2005 and 2011. Medical records were evaluated for evidence of major bleeding complications (grade 3 or higher as defined by the National Institutes of Health's Common Terminology Criteria for Adverse Events, version 4.03) and their clinical sequelae. Platelet count and bleeding complications were evaluated for an association, and a sensitivity analysis was performed to determine whether analysis of a control group of patients without thrombocytopenia would yield added confidence in this assessment.

RESULTS

Among 304 procedures in 205 thrombocytopenic patients (69% male; mean age ± SD, 56.6 ± 11.9 years), the mean platelet count was 38,400 ± 9300/μL (range, 9000-49,000/μL). Three major bleeding complications requiring red blood cell transfusion were observed in patients with platelet counts of 41,000 to 46,000/μL, for a complication rate of 0.99% (95% confidence interval, 0.3%-2.9%). No patient required an additional procedure or died because of the bleeding complication. There was no association of platelet count with bleeding complications. The sensitivity analysis showed that further evaluation of patients with normal platelet counts would not add to the conclusion.

CONCLUSIONS

The risk of major bleeding after ultrasound-guided paracentesis in thrombocytopenic patients is very low. In most patients, routine assessment of the preprocedural serum platelet concentration is not necessary, and correction of such an abnormal laboratory value is not indicated.

Evaluation of the charges, safety, and mortality of percutaneous renal thermal ablation using the nationwide inpatient sample

PURPOSE

To perform a national analysis of safety, charges, complications, and mortality of percutaneous image-guided renal thermal ablation and compare outcomes by hospital volume.

MATERIALS AND METHODS

Using the Nationwide Inpatient Sample, trends in the proportion of inpatient percutaneous renal thermal ablation procedures performed at high-volume centers in the United States from 2007-2011 were evaluated. In-hospital mortality, discharge to long-term care facility, length of stay, hospitalization charges, and postoperative complications were compared between high-volume and low-volume ablation centers. High volume was set at the 90th percentile for renal thermal ablation volume, which equated to seven or more patients per year. A multivariate logistic regression analysis adjusting for hospital volume, age, sex, Charlson Comorbidity Index, obesity, race, and insurance status was performed to analyze the influence of hospital volume on the above-listed outcomes.

RESULTS

This study included 874 patients. The number of hospitals ranged from 59-77 depending on year. Overall, 328 patients (37.5%) were treated at high-volume ablation centers. The proportion of patients treated at high-volume centers decreased from 42.0% in 2007-2009 to 28.5% in 2010-2011. High-volume hospitals also performed significantly more partial nephrectomies than low-volume hospitals. On multivariate logistic regression analysis, increasing hospital volume was associated with lower odds of in-hospital mortality (odds ratio [OR] = 0.31, 95% confidence interval [CI] = 0.02-0.95) and lower odds of discharge to a long-term care facility (OR = 0.00, 95% CI = 0.00-0.66). Increasing hospital volume was also associated with lower odds of blood transfusion (OR = 0.84, 95% CI = 0.72-0.94). Length of stay decreased with increasing hospital volume (P = .03).

CONCLUSIONS

Patient safety may be maximized when renal ablation is performed at high-volume centers as a result of both greater procedural experience and potentially multidisciplinary triage and periprocedural management.

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.

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.

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.

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.