Interest of electrostimulation of peripheral motor nerves during percutaneous thermal ablation

Microwave ablation combined with percutaneous vertebroplasty for treating painful non-small cell lung cancer with spinal metastases under real-time temperature monitoring

PURPOSE

To retrospectively study the therapeutic effect and safety performance of the combination strategies of the computed tomography (CT)-guided microwave ablation (MWA) and percutaneous vertebroplasty (PVP) as a treatment for painful non-small cell lung cancer (NSCLC) with spinal metastases.

MATERIALS AND METHODS

A retrospective review included 71 patients with 109 vertebral metastases who underwent microwave ablation combined with percutaneous vertebroplasty by the image-guided and real-time temperature monitoring. Treatment efficacy was determined by comparing visual analog scale (VAS) scores, daily morphine equivalent opioid consumption, and Oswestry Disability Index (ODI) scores before treatment and during the follow-up period.

RESULTS

Technical success was achieved in all patients. The mean pre-procedure VAS score and morphine doses were 6.6 ± 1.8 (4-10) and 137.2 ± 38.7 (40-200) mg, respectively. The mean VAS scores and daily morphine doses at 24 h and 1, 4, 12, and 24 weeks postoperatively were 3.3 ± 1.9 and 73.5 ± 39.4 mg; 2.2 ± 1.5 and 40.2 ± 29.8 mg; 1.7 ± 1.2 and 31.3 ± 23.6 mg; 1.4 ± 1.1 and 27.3 ± 21.4 mg; and 1.3 ± 1.1 and 24.8 ± 21.0 mg, respectively (all P < 0.001). ODI scores significantly decreased (P < 0.05). Minor cement leakage occurred in 51 cases (46.8%), with one patient having a grade 3 neural injury. No local tumor progression was observed by follow-up imaging.

CONCLUSIONS

MWA combined with PVP can significantly relieve pain and improve patients' quality of life, which implied this is an effective treatment option for painful NSCLC with spinal metastases. Additionally, its efficacy should be further verified through the mid- and long-term studies.

Palliative Radiofrequency Ablation Therapy for Intractable Cancer-Related Pain Due to Malignant Psoas Syndrome: Case Report

Uncontrollable cancer pain is a highly feared and debilitating symptom. The effectiveness of radiofrequency ablation (RFA) for osseous metastases with intractable cancer-related pain refractory to pharmacological therapy has been reported previously. This case report is the first to demonstrate the use of RFA to achieve pain relief in a patient suffering severe pain caused by para-aortic lymph node metastasis. A 55-year-old male complained of intractable pain in the left groin and perineum due to malignant psoas syndrome caused by metastatic para-aortic lymph nodes. The pain was refractory to medications including opioids and nerve blocks. Considering the dermatome indicating referred pain and the imaging findings, RFA of the area of invasion was performed at the L3 level. The severe pain was relieved within 24 hours without any complications. Opioids were tapered at each postoperative outpatient visit. We discuss the use of RFA for control of intractable cancer-related pain refractory to medication, including opioids.

Clinical guidelines for microwave ablation of spinal metastases

Spinal metastases are the most common source of morbidity in patients with cancer. Recently, microwave ablation has produced satisfactory results in the management of spinal metastases. However, there is still controversy in terms of clinical treatment, such as indication, power, time, and temperature. To standardize the application of microwave ablation technology and reduce the risk of surgical-related complications in spinal metastases, in this report, we aimed to summarize the current evidence and clinical experience of microwave ablation and developed a clinical guideline, initiated by the Musculoskeletal Tumor Group of the Committee for Minimally Invasive Therapy in Oncology of the Chinese Anti-Cancer Association. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used in to rate the quality of evidence and the strength of recommendations, and the Reporting Items for Practice Guidelines in Healthcare (RIGHT) checklist was strictly followed to report the guideline. Finally, 15 evidence-based recommendations were formulated based on the 15 most concerned clinical questions among orthopedic surgeons, oncologists, and interventional radiologists in China. This guideline aims to promote the science-based normalization of microwave ablation for the treatment of spinal metastases.

Microwave ablation combined with cementoplasty under real-time temperature monitoring in the treatment of 82 patients with recurrent spinal metastases after radiotherapy

BACKGROUND

The spine is the most frequently affected part of the skeletal system to metastatic tumors. External radiotherapy is considered the first-line standard of care for these patients with spine metastases. Recurrent spinal metastases after radiotherapy cannot be treated with further radiotherapy within a short period of time, making treatment difficult. We aimed to evaluate the effectiveness and safety of MWA combined with cementoplasty in the treatment of spinal metastases after radiotherapy under real-time temperature monitoring.

METHODS

In this retrospective study, 82 patients with 115 spinal metastatic lesions were treated with MWA and cementoplasty under real-time temperature monitoring. Changes in visual analog scale (VAS) scores, daily morphine consumption, and Oswestry Disability Index (ODI) scores were noted. A paired Student's t-test was used to assess these parameters. Complications during the procedure were graded using the CTCAE version 5.0.

RESULTS

Technical success was attained in all patients. The mean VAS score was 6.3 ± 2.0 (range, 4-10) before operation, and remarkable decline was noted in one month (1.7 ± 1.0 [P < .001]), three months (1.4 ± 0.8 [P < .001]), and six months (1.3 ± 0.8 [P < .001]) after the operation. Significant reductions in daily morphine consumption and ODI scores were also observed (P < .05). Cement leakage was found in 27.8% (32/115) of lesions, with no obvious associated symptoms.

CONCLUSION

MWA combined with cementoplasty under real-time temperature monitoring is an effective and safe method for recurrent spinal metastases after radiotherapy.

Interventional Palliation of Painful Extraspinal Musculoskeletal Metastases

The musculoskeletal system is commonly involved by metastases, and skeletal-related events such as intractable pain due to direct osseous tumor involvement, pathologic fracture, and neurologic deficits as a result of nerve compression often adversely affect patient's quality of life. There have been substantial advances in percutaneous minimally invasive musculoskeletal oncologic interventions for the management of patients with musculoskeletal metastases including thermal ablations, cementation with or without osseous reinforcement via implants, osteosynthesis, neurolysis, and palliative injections which are progressively incorporated in clinical practice. These interventions are performed, in conjunction with or supplemented by adjuvant radiation therapy, systemic therapy, surgery, or analgesics, to achieve durable pain palliation, local tumor control, or cure. This article reviews minimally invasive percutaneous image-guided musculoskeletal oncologic interventions for the management of patients with extraspinal musculoskeletal metastases.

Thermal Protection Strategies and Neuromonitoring during Ablation

Advanced interventional pain management approaches seek to lesion neural targets to achieve desirable analgesia; however, equally important is preservation of motor and sensory function for regional bystander nerves. The topic of neuroprotection is also relevant for thermal ablation of metastatic bone tumors in the vicinity of neural structures. This report aims to provide an IR-directed framework of thermoprotective techniques available during thermal ablation.

Radiofrequency Ablation of Spine Metastases: A Clinical and Technical Approach

Percutaneous radiofrequency ablation (RFA) is an integral component of the multidisciplinary treatment algorithm for both local tumor control and palliation of painful spine metastases. This minimally invasive therapy complements additional treatment strategies, such as pain medications, systemic chemotherapy, surgical resection, and radiotherapy. The location and size of the metastatic lesion dictate preprocedure planning and the technical approach. For example, ablation of lesions along the spinal canal, within the posterior vertebral elements, or with paraspinal soft tissue extension are associated with a higher risk of injury to adjacent spinal nerves. Additional interventions may be indicated in conjunction with RFA. For example, ablation of vertebral body lesions can precipitate new, or exacerbate existing, pathologic vertebral compression fractures that can be prevented with vertebral augmentation. This article reviews the indications, clinical work-up, and technical approach for RFA of spine metastases.

Ablation Techniques in Cancer Pain

Painful bone metastases are a frequently encountered problem in oncology practice. The skeletal system is the third most common site of metastatic disease and up to 85% of patients with breast, prostate, and lung cancer may develop bone metastases during the course of their disease.

Bipolar Radiofrequency Ablation of Painful Spinal Bone Metastases Performed under Local Anesthesia: Feasibility Regarding Patient's Experience and Pain Outcome

Background and objectives: To assess the pain relief of bipolar RFA combined or not with vertebroplasty in patients with painful vertebral metastases and to evaluate the feasibility and tolerance of the RFA procedure performed under local anesthesia. Materials and Methods: 25 patients (18 men, 7 women, mean age: 60.X y.o) with refractory painful vertebral metastasis were consecutively included between 2012 and 2019. A total of 29 radiofrequency ablation (RFA) procedures were performed under CT guidance, local anesthesia and nitrous oxide inhalation, including 16 procedures combined with vertebroplasty for bone consolidation purposes. Pain efficacy was clinically evaluated using the visual analogue scale (VAS) at day 1, 1 month, 3 months, 6 months and 12 months, and the tolerance of the procedure was evaluated. Results: Procedure tolerance was graded as either not painful or tolerable in 97% of cases. Follow-up postprocedure mean VAS score decrease was 74% at day 1: 6.6 (p < 0.001), 79% at 1 month: 6.6 (p < 0.001), 79% at 3 months: 6.5 (p < 0.001), 77% at 6 months, and 79% at 12 months: 6.6 (p < 0.001). Conclusions: Bipolar RFA, with or without combined vertebroplasty, appears to be an effective and reliable technique for the treatment of refractory vertebral metastases in patients in the palliative care setting. It is a feasible procedure under local anesthesia which is well tolerated by patients therefore allowing to broaden the indications of such procedures. Field of study: interventional radiology.

Bone Metastases: State of the Art in Minimally Invasive Interventional Oncology

Bone is the third most common site involved by cancer metastases, and skeleton-related events such as intractable pain due to direct osseous tumor involvement, pathologic fracture, and neurologic deficits as a consequence of nerve or spinal cord compression often affect patients' functional independence and quality of life unfavorably. The annual medical-economic burden related to bone metastases is a substantial component of the total direct medical cost estimated by the National Institutes of Health. There have been substantial recent advances in percutaneous image-guided minimally invasive musculoskeletal oncologic interventions for the management of patients with osseous metastatic disease. These advances include thermal ablation, cementation with or without osseous reinforcement with implants, osteosynthesis, thermal and chemical neurolyses, and palliative injections, which are progressively incorporated into the management paradigm for such patients. These interventions are performed in conjunction with or are supplemented by adjuvant radiation therapy, systemic therapy, surgery, or analgesic agents to achieve durable pain palliation, local tumor control, or cure, and they provide a robust armamentarium for interventional radiologists to achieve safe and effective treatment in a multidisciplinary setting. In addition, these procedures are shifting the patient management paradigm in modern-era practice. The authors detail the state of the art in minimally invasive percutaneous image-guided musculoskeletal oncologic interventions and the role of radiologists in managing patients with skeletal metastases. ^©RSNA, 2021.

Complications of Percutaneous Radiofrequency Ablation of Spinal Osseous Metastases: An 8-Year Single-Center Experience

OBJECTIVE. The purpose of this article was to evaluate the complication rate of percutaneous radiofrequency ablation of spinal osseous metastases. MATERIALS AND METHODS. This retrospective HIPAA-compliant study reviewed complications of radiofrequency ablation combined with vertebral augmentation performed on 266 tumors in 166 consecutive patients for management of vertebral metastases between January 2012 and August 2019. Common Terminology Criteria for Adverse Events (CTCAE) was used to categorize complications as major (grade 3-4) or minor (grade 1-2). Local tumor control rate as well as pain palliation effects evaluated by the Brief Pain Inventory scores determined 1 week, 1 month, 3 months, and 6 months after treatment were documented. Wilcoxon signed rank and Mann-Whitney U tests were used for statistical analysis. RESULTS. Among 266 treated tumors, the total complication rate was 3.0% (8/266), the major complication rate was 0.4% (1/266), and the minor complication rate was 2.6% (7/266). The single major (CTCAE grade 3) periprocedural complication was characterized by lower extremity weakness, difficulty in urination, and lack of erection as a result of spinal cord venous infarct. The seven minor complications included four cases of periprocedural transient radicular pain (CTCAE grade 2) requiring transforaminal steroid injections, one case of delayed secondary vertebral body fracture (CTCAE grade 2) requiring analgesics, and two cases of asymptomatic spinal cord edema on routine follow-up imaging (CTCAE grade 1). The local tumor control rate was 78.9%. There were statistically significant pain palliation effects at all postprocedural time intervals (p < .001 for all). CONCLUSION. Radiofrequency ablation of spinal osseous metastases is safe with a 3.0% rate of complications.

Percutaneous cryoablation for advanced and refractory extra-abdominal desmoid tumors

PURPOSE

To assess efficacy and safety of percutaneous cryoablation (CA) for advanced and refractory extra-abdominal desmoid tumors.

MATERIALS AND METHODS

This retrospective study reviewed 30 consecutive patients with symptomatic desmoid tumors evolving after "wait and watch" periods, and despite medical treatment, treated by CA between 2007 and 2019. Progression free survival (PFS), objective response rate, pain reduction (decreased of visual analogic scale pain (VAS)[Formula: see text] 3 or disappearance of pain), total volume lesion (TVL) and complications were documented. Kaplan Meier method was used to outline PFS. Paired sample t test was used to compare volume of tumors before treatment and at 1 and 3 year.

RESULTS

With a median follow-up of 18.5 months (range 6-93 months, interquartile range (IQR): 12-55), the PFS was 85.1% at 1 year and 77.3% at 3 years. Objective response was obtained for 80% of patients with a complete response for 43% patients. Pain reduction was obtained for 96.7% (95% confidence interval (95% CI): 90.3, 100) of patients. Median volume of desmoid tumor before treatment was 124.1cm³ (range 2-1727cm³, IQR: 54-338cm³). Median change of TLV after ablation was 66.6% (95% CI: 37.2, 72.3; p = 0.002) at 1 year and 76.4% (95% CI: 59.1, 89.8; p = 0.002) at 3 year. Adverse events rate was 36.6%, the most common was edema and temporary increase of pain in the days following CA. Four patients experienced a major complication (13.3%): 2 skin necrosis, 1 infection and 1 brachial plexopathy.

CONCLUSION

CA is an effective treatment for advanced and refractory extra-abdominal desmoid tumor, that induces durable responses.

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.

Musculoskeletal interventional oncology: current and future practices

Management of musculoskeletal (MSK) tumours has traditionally been delivered by surgeons and medical oncologists. However, in recent years, image-guided interventional oncology (IO) has significantly impacted the clinical management of MSK tumours. With the rapid evolution of relevant technologies and the expanding range of clinical indications, it is likely that the impact of IO will significantly grow and further evolve in the near future.

In this narrative review, we describe well-established and new interventional technologies that are currently integrating into the IO armamentarium available to radiologists to treat MSK tumours and illustrate new emerging IO indications for treatment.

French Multidisciplinary Approach for the Treatment of MSK Tumors

Several interventional treatments have recently been integrated into the therapeutic armamentarium available for the treatment of bone tumors. In some scenarios (e.g., osteoid osteoma), interventional treatments represent the sole and definitive applied treatment. Due to the absence of widely shared protocols and the complex multivariate scenarios underlying the clinical presentation of the remaining bone tumors including metastases, therapeutic strategies derived from a multidisciplinary tumor board are essential to provide effective treatments tailored to each patient. In the present review, we present the multidisciplinary therapeutic strategies commonly adopted for the most frequent bone tumors.

Percutaneous image-guided ablation: From techniques to treatments

Image-guided ablation is performed by percutaneously introducing ablation probes to deliver energy into a tumor to destroy it in a controlled and localized fashion. Ablation modalities can be broadly classified as thermal or non-thermal based on the mechanism of tumor destruction and are performed using different types of image guidance for planning, delivering and follow-up of the treatment. Ablation is performed in a minimally invasive fashion, providing greater residual organ preservation with minimal morbidity to the patient. Image-guided ablation is being used in the clinic for the treatment of primary and metastatic tumors, and this article reviews state of the art for the treatment of malignancies in the liver, lung, kidney and musculoskeletal tissue.

Complications of Percutaneous Bone Tumor Cryoablation: A 10-year Experience

Background Percutaneous cryoablation has been shown to be effective in the management of painful bone tumors. However, knowledge of the complication rate and risk factors for complication is currently lacking. Purpose To report the complication rate and associated risk factors for bone tumor cryoablation. Materials and Methods This retrospective study reviewed complications in 239 consecutive patients (131 men and 108 women; median age, 64 years; age range, 6-86 years) who underwent cryoablation of 320 primary or metastatic bone tumors between January 2008 and November 2017. Common Terminology Criteria for Adverse Events was used to categorize complications as major (grade 3-4) or minor (grade 1-2). Multivariable analysis was performed for variables with P values less than .20, including age, tumor location, adjacent critical structures, number of cryoprobes, and Eastern Cooperative Oncology Group performance status (ECOG-PS). Results Among the 320 tumors, the total complication rate was 9.1% (29 of 320; 95% confidence interval [CI]: 6%, 12.2%). The major complication rate was 2.5% (eight of 320; 95% CI: 0.8%, 4.2%), with secondary fracture the most frequent complication (1.2% [four of 320]; mean delay, 71 days); cryoablation site infection, tumor seeding, bleeding, and severe hypotension were each observed in 0.3% (one of 320) of procedures. Minor complications included postprocedural pain (2.2% [seven of 320]), peripheral neuropathy (0.9% [three of 320]), and temporary paresthesia (0.9% [three of 320]). For all complications, associated risk factors included ECOG-PS greater than 2 (odds ratio [OR], 3.1 [95% CI: 3, 7.6]; P = .01), long-bone cryoablation (OR, 17.8 [95% CI: 2.3, 136.3]; P = .01), and use of more than three cryoprobes (OR, 2.5 [95% CI: 1.0, 6.0]; P = .04); for major complications, associated risk factors included age greater than 70 years (OR, 7.1 [95% CI: 1.6, 31.7]; P = .01) and use of more than three cryoprobes (OR, 23.6 [95% CI: 2.8, 199.0]; P = .01). Conclusion Bone tumor cryoablation is safe, with a 2.5% rate of major complications, most commonly secondary fracture (1.2%). Major complications are associated with age greater than 70 years and use of more than three cryoprobes. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Jennings in this issue.

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.

Integrated CT-Fluoroscopy Equipment: Improving the Interventional Radiology Approach and Patient Experience for Treatment of Musculoskeletal Malignancies

Integrated CT-fluoroscopy equipment augments the comprehensive approach to the treatment of musculoskeletal (MSK) malignancy by interventional radiology techniques. As the role of minimally invasive treatment expands to meet the highly variable presentation of MSK malignancy, creative solutions to treatment challenges are required to improve locoregional tumor control and durability of pain palliation. Challenges to effective treatment can often be attributed to a combination of aggressive tumor biology, large size, forbidding location, and adverse vascularity. In these cases, a tailored treatment approach may necessitate the application of multiple interventional radiology (IR) techniques that require different image guidance capabilities. Integrated CT-fluoroscopy equipment provides the means to leverage both imaging modalities within the same procedural setting to facilitate the simultaneous application of multiple synergistic treatments and protective measures. This article examines the potential role of hybrid units in the IR treatment of challenging MSK malignancies as a means to empower a paradigm transition for a more comprehensive and patient-tailored approach.

Metastatic Osseous Pain Control: Bone Ablation and Cementoplasty

Nociceptive and/or neuropathic pain can be present in all phases of cancer (early and metastatic) and are not adequately treated in 56 to 82.3% of patients. In these patients, radiotherapy achieves overall pain responses (complete and partial responses combined) up to 60 and 61%. On the other hand, nowadays, ablation is included in clinical guidelines for bone metastases and the technique is governed by level I evidence. Depending on the location of the lesion in the peripheral skeleton, either the Mirels scoring or the Harrington (alternatively the Levy) grading system can be used for prophylactic fixation recommendation. As minimally invasive treatment options may be considered in patients with poor clinical status or limited life expectancy, the aim of this review is to detail the techniques proposed so far in the literature and to report the results in terms of safety and efficacy of ablation and cementoplasty (with or without fixation) for bone metastases. Percutaneous image-guided treatments appear as an interesting alternative for localized metastatic lesions of the peripheral skeleton.

Percutaneous Image-Guided Cryoablation in Vascular Anomalies

Understanding and management of vascular anomalies has always been intriguing. These disorders exhibit an expected pattern of clinical presentation and progression, and characteristic imaging findings. Significant progress in understanding and treating patients with vascular anomalies has been made in the past quarter century. Newer multidisciplinary domains for treating these disorders with medical drugs and less invasive image-guided or surgical procedures are constantly evolving. Vascular anomalies can exhibit aggressive tumor-like behavior resulting in recurrence or persistent symptoms after treatment. Thermal ablation has been widely used in tumor treatment. This has generated interest on using thermal ablation for treating vascular anomalies. Percutaneous image-guided cryoablation is increasingly used for this purpose as compared with other ablation technologies. Availability of small caliber cryoprobes and the ability to monitor the freeze zone in real time have made this an attractive option to interventional radiologists. These experiences are relatively new and limited. It is helpful to understand the emerging role of this technology in the treatment of vascular anomalies.

Increasing Role of Image-Guided Ablation in the Treatment of Musculoskeletal Tumors

In the last decade, percutaneous treatment of musculoskeletal (MSK) tumors has become more established in routine clinical care while also undergoing a number of advancements. Ablative techniques to palliate painful skeletal metastases have gained wide acceptance, while goals for ablation have evolved to include local control of oligometastases and desmoid tumors. Bone consolidation or augmentation is now frequently used in conjunction with or instead of ablation of skeletal tumors to stabilize pathologic fractures or prevent further morbidity that could result from fractures caused by tumor progression. These procedures have traditionally been performed with cement injection, although additional percutaneous consolidation or stabilization devices have been developed. Techniques to monitor the ablation zone and adjacent structures intraprocedurally are now applied to increase the number of tumors amenable to treatment. These include methods to depict, displace, or monitor critical structures adjacent to targeted MSK tumors. Finally, the role of ablation in the comprehensive care of patients with MSK tumors continues to change with the evolving triage of patients between radiation therapy, surgical resection and stabilization, and percutaneous ablative and consolidative management.

Percutaneous Spinal Ablation in a Sheep Model: Protective Capacity of an Intact Cortex, Correlation of Ablation Parameters with Ablation Zone Size, and Correlation of Postablation MRI and Pathologic Findings

BACKGROUND AND PURPOSE

Despite the growing use of percutaneous ablation therapy for the treatment of metastatic spine disease, several issues have yet to be fully addressed. Our aims were to determine whether the vertebral body cortex protects against ablation-induced spinal cord injury; correlate radiofrequency, cryo-, and microwave ablation parameters with resulting spinal ablation zone dimensions and describe normal spinal marrow postablation changes on MR imaging.

MATERIALS AND METHODS

Ten thoracolumbar vertebrae in 3 sheep were treated with radiofrequency ablation, cryoablation, or microwave ablation under fluoroscopic guidance. Technique parameters were chosen to produce ablation zones that exceeded the volume of the vertebral bodies in sheep 1 and were confined to the vertebrae in sheep 2 and 3. Expected ablation zone dimensions were based on data provided by the device manufacturers. Postablation MR imaging was performed at 48 hours (sheep 1) or 7 days (sheep 2 and 3).

RESULTS

In sheep 1, cryoablation and microwave ablations extended into the spinal canal and caused histologically confirmed neurologic injury, but radiofrequency ablation did not. The mean difference between the lengths of the radiofrequency ablation zone dimensions measured on gross pathology compared with those expected was 9.6 ± 4.1 mm. The gross pathologic cryo- and microwave ablation zone dimensions were within 1 mm of those expected. All modalities produced a nonenhancing ablation zone with a rim of enhancement, corresponding histologically to marrow necrosis and hemorrhagic congestion.

CONCLUSIONS

An intact cortex appears to protect against radiofrequency ablation-induced spinal cord injury, but not against non-impedance-based modalities. Ablation dimensions produced by microwave and cryoablation are similar to those expected, while radiofrequency ablation dimensions are smaller. Ablation of normal marrow produces a rim of enhancement at the margin of the ablation zone on MR imaging.

Benign Spine Lesions: Advances in Techniques for Minimally Invasive Percutaneous Treatment

Minimally invasive percutaneous imaging-guided techniques have been shown to be safe and effective for the treatment of benign tumors of the spine. Techniques available include a variety of tumor ablation technologies, including radiofrequency ablation, cryoablation, microwave ablation, alcohol ablation, and laser photocoagulation. Vertebral augmentation may be performed after ablation as part of the same procedure for fracture stabilization or prevention. Typically, the treatment goal in benign spine lesions is definitive cure. Painful benign spine lesions commonly encountered in daily practice include osteoid osteoma, osteoblastoma, vertebral hemangioma, aneurysmal bone cyst, Paget disease, and subacute/chronic Schmorl node. This review discusses the most recent advancement and use of minimally invasive percutaneous therapeutic options for the management of benign spine lesions.

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.

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

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

Image-Guided Spinal Ablation: A Review

The image-guided thermal ablation procedures can be used to treat a variety of benign and malignant spinal tumours. Small size osteoid osteoma can be treated with laser or radiofrequency. Larger tumours (osteoblastoma, aneurysmal bone cyst and metastasis) can be addressed with radiofrequency or cryoablation. Results on the literature of spinal microwave ablation are scarce, and thus it should be used with caution. A distinct advantage of cryoablation is the ability to monitor the ice-ball by intermittent CT or MRI. The different thermal insulation, temperature and electrophysiological monitoring techniques should be applied. Cautious pre-procedural planning and intermittent intra-procedural monitoring of the ablation zone can help reduce neural complications. Tumour histology, patient clinical-functional status and life-expectancy should define the most efficient and least disabling treatment option.

Feasibility of Intraoperative Nerve Monitoring in Preventing Thermal Damage to the "Nerve at Risk" During Image-Guided Ablation of Tumors

PURPOSE

To assess feasibility of intraoperative neurophysiologic monitoring (IONM) during image-guided, percutaneous thermal ablation of tumors.

MATERIALS AND METHODS

From February 2009 to October 2013, a retrospective review of all image-guided percutaneous thermal ablation interventions using IONM was performed and data was compiled using electronic medical records and imaging studies.

RESULTS

Twelve patients were treated in 13 ablation interventions. In 4 patients, real-time feedback from the monitoring neurologist was used to adjust applicator placement and ablation settings. IONM was technically feasible in all procedures and there were no complications related to monitoring or ablation. All nerves at risk remained intact and of the 11 patients who could be followed, none developed new nerve deficit up to a minimum of 2 months after ablation.

CONCLUSION

IONM is safe and feasible for use during image-guided thermal ablation of tumors in the vicinity of nerves. Outcomes in this study demonstrate its potential utility in image-guided ablation interventions.

Spine Cryoablation: Pain Palliation and Local Tumor Control for Vertebral Metastases

BACKGROUND AND PURPOSE

Percutaneous cryoablation has emerged as a minimally invasive technique for the management of osseous metastases. The purpose of this study was to assess the safety and effectiveness of percutaneous imaging-guided spine cryoablation for pain palliation and local tumor control for vertebral metastases.

MATERIALS AND METHODS

Imaging-guided spine cryoablation was performed in 14 patients (31 tumors) with vertebral metastases refractory to conventional chemoradiation therapy or analgesics, to achieve pain palliation and local tumor control in this retrospective study. Spinal nerve and soft-tissue thermal protection techniques were implemented in all ablations. Patient response was evaluated by a pain numeric rating scale administered before the procedure and 1 week, 1 month, and 3 months after the procedure. Pre- and postprocedural analgesic requirements (expressed as morphine-equivalent dosages) were also analyzed at the same time points. Pre- and postprocedural cross-sectional imaging was evaluated in all patients to assess local control (no radiographic evidence of disease at the treated sites). Complications were monitored. Analysis of the primary end points was undertaken via paired-comparison procedures by using the Wilcoxon signed rank test.

RESULTS

Thirty-one tumors were ablated in 14 patients (9 women and 5 men; 20-73 years of age; mean age, 53 years). The most common tumor location was in the lumbar spine (n = 14, 45%), followed by the thoracic spine (n = 8, 26%), sacrum (n = 6, 19%), coccyx (n = 2, 6%), and cervical spine (n = 1, 3%). There were statistically significant decreases in the median numeric rating scale score and analgesic usage at 1-week, 1-month, and 3-month time points (P < .001 for all). Local tumor control was achieved in 96.7% (30/31) of tumors (median follow-up, 10 months). Two patients had transient postprocedural unilateral lower extremity radiculopathy and weakness.

CONCLUSIONS

Percutaneous imaging-guided spine cryoablation is a safe and effective treatment for pain palliation and local tumor control for vertebral metastases.

Percutaneous Image-guided Laser Photocoagulation of Spinal Osteoid Osteoma: A Single-Institution Series

PURPOSE

To retrospectively evaluate the safety and efficacy of percutaneous image-guided laser photocoagulation for the treatment of spinal osteoid osteoma (OO) in proximity to neural structures.

MATERIALS AND METHODS

This study was institutional review board-approved with waivers of informed consent. From January 1994 until October 2014, 58 patients with spinal OO (mean age, 25 years; 40 men, 17 women) were treated in one institution by using laser photocoagulation with combined computed tomographic (CT) and fluoroscopic guidance. One patient was excluded because of less than 3 months of follow-up. All patients had typical clinical and imaging findings. Clinical features, radiologic data, and procedure-related data were reviewed, and limitations, complications, and failure rate were evaluated. All data were expressed as means ± standard deviation. P values of less than .05 were indicative of statistical significance.

RESULTS

OO was in the vertebral body for 18 of 57 patients, the neural arch for 21 of 57 patients, and the articular process for 18 of 57 patients. Mean nidal diameter was 8 mm, and the mean distance from the closest neural structure was 6.6 mm (minimum distance, ≤5 mm in 35 of 57 patients). In 35 of 57 patients, no cortical coverage was present between the nidus and neural structure in danger. Mean total energy delivered was 1271 J (2-watt continuous power mode). Thermal insulation (carbon dioxide and/or hydrodissection), temperature monitoring, and electrostimulation were used in 42, 24, and one patient, respectively. Primary clinical success at 1 month was 98.2%. Total recurrence rate was 5.3%. All recurrences were addressed percutaneously. Secondary success rate was 100%. One-year follow-up is available in 54 of 57 patients. No major complications were noted.

CONCLUSION

Spinal OO can be safely and effectively treated with percutaneous laser photocoagulation. In cases that are less than 8 mm to 10 mm distance and in the absence of cortical coverage, thermal protection techniques of the neural structures should be used.

Initial Results of Image-Guided Percutaneous Ablation as Second-Line Treatment for Symptomatic Vascular Anomalies

PURPOSE

The purpose of this study was to determine the feasibility, safety, and early effectiveness of percutaneous image-guided ablation as second-line treatment for symptomatic soft-tissue vascular anomalies (VA).

MATERIALS AND METHODS

An IRB-approved retrospective review was undertaken of all patients who underwent percutaneous image-guided ablation as second-line therapy for treatment of symptomatic soft-tissue VA during the period from 1/1/2008 to 5/20/2014. US/CT- or MRI-guided and monitored cryoablation or MRI-guided and monitored laser ablation was performed. Clinical follow-up began at one-month post-ablation.

RESULTS

Eight patients with nine torso or lower extremity VA were treated with US/CT (N = 4) or MRI-guided (N = 2) cryoablation or MRI-guided laser ablation (N = 5) for moderate to severe pain (N = 7) or diffuse bleeding secondary to hemangioma-thrombocytopenia syndrome (N = 1). The median maximal diameter was 9.0 cm (6.5-11.1 cm) and 2.5 cm (2.3-5.3 cm) for VA undergoing cryoablation and laser ablation, respectively. Seven VA were ablated in one session, one VA initially treated with MRI-guided cryoablation for severe pain was re-treated with MRI-guided laser ablation due to persistent moderate pain, and one VA was treated in a planned two-stage session due to large VA size. At an average follow-up of 19.8 months (range 2-62 months), 7 of 7 patients with painful VA reported symptomatic pain relief. There was no recurrence of bleeding at five-year post-ablation in the patient with hemangioma-thrombocytopenia syndrome. There were two minor complications and no major complications.

CONCLUSION

Image-guided percutaneous ablation is a feasible, safe, and effective second-line treatment option for symptomatic VA.

Interstitial ultrasound ablation of vertebral and paraspinal tumours: parametric and patient-specific simulations

PURPOSE

Theoretical parametric and patient-specific models are applied to assess the feasibility of interstitial ultrasound ablation of tumours in and near the spine and to identify potential treatment delivery strategies.

METHODS

3D patient-specific finite element models (n = 11) of interstitial ultrasound ablation of tumours associated with the spine were generated. Gaseous nerve insulation and various applicator configurations, frequencies (3 and 7 MHz), placement trajectories, and tumour locations were simulated. Parametric studies with multilayered models investigated the impacts of tumour attenuation, tumour dimension, and the thickness of bone insulating critical structures. Temperature and thermal dose were calculated to define ablation (>240 equivalent minutes at 43 °C (EM43 °C)) and safety margins (<45 °C and <6 EM43 °C), and to determine performance and required delivery parameters.

RESULTS

Osteolytic tumours (≤44 mm) encapsulated by bone could be successfully ablated with 7 MHz interstitial ultrasound (8.1-16.6 W/cm(2), 120-5900 J, 0.4-15 min). Ablation of tumours (94.6-100% volumetric) 0-14.5 mm from the spinal canal was achieved within 3-15 min without damaging critical nerves. 3 MHz devices provided faster ablation (390 versus 930 s) of an 18 mm diameter osteoblastic (high bone content) volume than 7 MHz devices. Critical anatomy in proximity to the tumour could be protected by selection of appropriate applicator configurations, active sectors, and applied power schemas, and through gaseous insulation. Preferential ultrasound absorption at bone surfaces facilitated faster, more effective ablations in osteolytic tumours and provided isolation of ablative energies and temperatures.

CONCLUSIONS

Parametric and patient-specific studies demonstrated the feasibility and potential advantages of interstitial ultrasound ablation treatment of paraspinal and osteolytic vertebral tumours.

Treatment of a spinal aneurysmal bone cyst using combined image-guided cryoablation and cementoplasty

The authors describe the case of a 6.6-cm symptomatic spinal aneurysmal bone cyst (ABC) in a 17-year-old athlete treated percutaneously. Surgical treatment was not considered as the first option owing to its invasiveness and associated morbidity. CT-guided cryoablation of the expansile part of the ABC was performed for tumour shrinkage and nerve decompression. Thermal insulation, temperature monitoring and functional control/electrostimulation of the neural structures at risk were applied. Finally, the bony defect was cemented. No complications occurred during the procedure. Complete resolution of the ABC on imaging and clinical improvement were achieved. Percutaneous cryoablation should be considered as an alternative treatment option, especially when tumour size reduction is desired.

Percutaneous bone lesion ablation

Benign tumors and metastatic bone lesions can be treated by ablation techniques performed either alone or in combination with other percutaneous techniques. Ablation techniques include ethanol or acetic acid injection and thermal ablation by means of energy deposition [including laser, radiofrequency, microwave, cryoablation, radiofrequency ionization and magnetic resonance (MR)-guided high-intensity focused ultrasound (HIFU)]. Goal definition of the therapy is crucial: ablation techniques can be proposed as curative treatments in benign bone tumors or oligometastatic disease (<3 lesions). Alternatively, these techniques can be proposed as palliative treatments aiming at reduction of pain, local control of the disease and tumor decompression. Depending on the lesion's location ablation can be combined with cementation with or without further metallic augmentation; local tumor control can be enhanced by combining ablation with transarterial bland embolization or chemoembolization. Thermal ablation of bone and soft tissues is characterized by high success and relatively low rates of potential complications, mainly iatrogenic thermal damage of surrounding sensitive structures. Successful thermal ablation requires a sufficient ablation volume and thermal protection of the surrounding vulnerable structures. This article will describe the general principles governing ablation and the mechanism of action for each technique and in addition will review the literature about safety and effectiveness of percutaneous imaging-guided ablation for benign and malignant (primary and metastatic) lesions.

Percutaneous image-guided ablation of bone and soft tissue tumours: a review of available techniques and protective measures

Background

Primary or metastatic osseous and soft tissue lesions can be treated by ablation techniques.

Methods

These techniques are classified into chemical ablation (including ethanol or acetic acid injection) and thermal ablation (including laser, radiofrequency, microwave, cryoablation, radiofrequency ionisation and MR-guided HIFU). Ablation can be performed either alone or in combination with surgical or other percutaneous techniques.

Results

In most cases, ablation provides curative treatment for benign lesions and malignant lesions up to 3 cm. Furthermore, it can be a palliative treatment providing pain reduction and local control of the disease, diminishing the tumour burden and mass effect on organs. Ablation may result in bone weakening; therefore, whenever stabilisation is undermined, bone augmentation should follow ablation depending on the lesion size and location.

Conclusion

Thermal ablation of bone and soft tissues demonstrates high success and relatively low complication rates. However, the most common complication is the iatrogenic thermal damage of surrounding sensitive structures. Nervous structures are very sensitive to extremely high and low temperatures with resultant transient or permanent neurological damage. Thermal damage can cause normal bone osteonecrosis in the lesion’s periphery, surrounding muscular atrophy and scarring, and skin burns. Successful thermal ablation requires a sufficient ablation volume and thermal protection of the surrounding vulnerable structures.

Teaching points

• Percutaneous ablations constitute a safe and efficacious therapy for treatment of osteoid osteoma.

• Ablation techniques can treat painful malignant MSK lesions and provide local tumour control.

• Thermal ablation of bone and soft tissues demonstrates high success and low complication rates.

• Nerves, cartilage and skin are sensitive to extremely high and low temperatures.

• Successful thermal ablation occasionally requires thermal protection of the surrounding structures.