Feasibility of Real-Time Intraprocedural Temperature Control during Bone Metastasis Thermal Microwave Ablation: A Bicentric Retrospective Study

Clinical Analysis of Microwave Ablation Combined with Decompression and Pedicle Screw Fixation in the Treatment of Spinal Metastases

OBJECTIVES

There is still controversy over the choice of treatment for end-stage spinal metastases. With the continuous development of microwave technology in spinal tumors, related studies have reported that microwave combined with techniques such as pedicle screw fixation and percutaneous vertebroplasty can achieve the purpose of tumor ablation, relieving spinal cord compression, enhancing spinal stability, effectively relieving pain, and reducing recurrence rates. This study aimed to analyze the effectiveness of microwave ablation combined with decompression and pedicle screw fixation in the palliative management of spinal metastases with pathological fractures.

METHODS

This retrospective study enrolled 82 patients with spinal metastases and pathological fractures treated between January 2016 and July 2020, with 44 patients undergoing pedicle screw fixation along with laminectomy (fixation group) and the remaining 38 receiving microwave ablation in addition to the treatment provided to group fixation (MWA group). Before surgery, all patients underwent pain assessment using the visual analogue scale (VAS) and evaluation of spinal cord injury using the Frankel classification. After surgery, the patients' prognoses were assessed using the Tomita score, modified Tokuhashi score system, and progression-free survival. Additionally, we compared operative time and blood loss between the two groups. Survival analysis utilized the Kaplan-Meier method with a log-rank test for group comparisons. Paired t-tests and the Mann-Whitney U test were applied to metric and non-normally distributed data, respectively. Neurological function improvement across groups was evaluated using the χ2 test.

RESULTS

All patients were followed up for a median duration of 18 and 20 months in the fixation and MWA groups, respectively, with follow-up periods ranging from 6 to 36 months. Statistically significant reductions in postoperative VAS scores were observed in all patients compared with their preoperative scores. The MWA group exhibited reduced blood loss (t = 2.74, p = 0.01), lower VAS scores at the 1- and 3-month follow-ups (t = 2.34, P = 0.02; t = 2.83, p = 0.006), and longer progression-free survival than the fixation group (p = 0.03). Although the operation times in the MWA group were longer than those in the fixation group, this difference was not statistically significant (t = 6.06, p = 0.12). No statistically significant differences were found regarding improvements in spinal cord function between the two groups (p = 0.77).

CONCLUSION

Compared with decompression and pedicle screw fixation for treating spinal metastases with pathological fractures, microwave ablation combined with decompression and pedicle screw fixation showed better outcomes in terms of pain control, longer progression-free survival, and lower blood loss without increasing operative time, which has favorable implications for clinical practice.

Evaluation of Conditions for the Development of Cryogenic Spinal Cord Injury Using a Canine Model: An Experimental Study on the Safety of Cryoablation for Metastatic Spinal Tumors

BACKGROUND AND PURPOSE

Although the application of cryoablation to metastatic spinal tumors has been attempted, spinal cryoablation has the unique complication of cryogenic spinal cord injury. This study aimed to elucidate the conditions for the development of cryogenic spinal cord injury.

MATERIALS AND METHODS

Fifteen canines were used in this study. A metal probe was inserted into the 13th thoracic vertebral body. Cryoablation was performed for 10 minutes by freezing the probe in liquid nitrogen. The control canine underwent probe insertion only. Spinal cord monitoring, epidural temperature measurement, motor function assessment, and pathologic examination of the spinal cord were performed.

RESULTS

During the 10 minutes of cryoablation, the epidural temperature decreased and reached the lowest epidural temperature (LET) at the end of cryoablation. The LETs (degrees celsius [°C]) of each canine were -37, -30, -27, -8, -3, -2, 0, 1, 4, 8, 16, 18, 20, and 25, respectively. As the epidural temperature decreased, waveform amplitudes also decreased. At the end of cryoablation (10 minutes after the start of cryoablation), abnormal waves were observed in 92.9% (13/14) of canines. With epidural rewarming, the amplitude of the waveforms tended to recover. After epidural rewarming (2 hours after the start of cryoablation), abnormal waves were observed in 28.6% (4/14) of canines. The LETs (°C) of the canines with abnormal waves after epidural rewarming were -37, -30, -27, and -8. None of the canines with normal waves after epidural rewarming had any motor impairment. In contrast, all canines with remaining abnormal waves after epidural rewarming had motor impairment. In the pathologic assessment, cryogenic changes were found in canines with LETs (°C) of -37 -30, -27, -8, 0, and 1.

CONCLUSIONS

This study showed that 10-minute spinal cryoablation with LETs (°C) of -37, -30, -27, -8, 0, and 1 caused cryogenic spinal cord injury. There was no evidence of cryogenic spinal cord injury in canines with LET of ≥4°C. The epidural temperature threshold for cryogenic spinal cord injury is between 1 and 4°C, suggesting that the epidural temperature should be maintained above at least 4°C to prevent cryogenic spinal cord injury.

Microwave ablation versus radiofrequency ablation for treating spinal metastases

BACKGROUND

This study aimed to compare the clinical efficacy and safety of microwave ablation (MWA) and radiofrequency ablation (RFA) for the treatment of spinal metastases.

METHODS

A literature search was performed using the PubMed, Web of Science, and Cochrane Library databases according to the PRISMA statement (as of September 20, 2022). Two independent investigators screened articles based on the inclusion and exclusion criteria and included studies with primary outcomes of pain relief, tumor control, and complications. Article quality was assessed using the Risk Of Bias In Non-randomized Studies of Interventions tool.

RESULTS

Sixteen articles were finally included in this study, including 630 patients with spinal metastases, with ages ranging from 51.4 to 71.3 years. Of these, 393 (62.4%) underwent MWA and 237 (37.6%) underwent RFA. After MWA and RFA treatment, visual analog scale scores significantly decreased, and the local tumor control rates were all above 80%. Complications were reported in 27.4% of patients treated with MWA compared with 10.9% of patients treated with RFA.

CONCLUSION

The results of this systematic review suggest that MWA alone or in combination with surgery and RFA in combination with other modalities may improve pain caused by primary tumor metastasis to the spine, and MWA alone or in combination with surgery may have better local tumor control. However, MWA appears to result in more major complications than RFA in combination with other treatment modalities.

Microwave ablation combined with vertebral augmentation under real-time temperature monitoring for the treatment of painful spinal osteogenic metastases

OBJECTIVE

To evaluate the safety and efficacy of computed tomography (CT)-guided microwave ablation combined with vertebral augmentation under real-time temperature monitoring in the treatment of painful osteogenic spinal metastases.

METHODS

This retrospective study included 38 patients with 63 osteogenic metastatic spinal lesions treated using CT-guided microwave ablation and vertebral augmentation under real-time temperature monitoring. Visual analog scale scores, daily morphine consumption, and Oswestry Disability Index scores were used to evaluate efficacy of the treatment.

RESULTS

Microwave ablation combined with vertebral augmentation reduced the mean visual analog scale scores from 6.40 ± 1.90 preoperatively to 3.32 ± 0.96 at 24 h, 2.24 ± 0.91 at 1 week, 1.92 ± 1.32 at 4 weeks, 1.79 ± 1.45 at 12 weeks, and 1.39 ± 1.12 at 24 weeks postoperatively (all p < 0.001). The mean preoperative daily morphine consumption was 108.95 ± 56.41 mg, which decreased to 50.13 ± 25.46 mg at 24 h, 31.18 ± 18.58 mg at 1 week, 22.50 ± 16.63 mg at 4 weeks, 21.71 ± 17.68 mg at 12 weeks, and 17.27 ± 16.82 mg at 24 weeks postoperatively (all p < 0.001). During the follow-up period, the Oswestry Disability Index scores significantly reduced (p < 0.001). Bone cement leakage occurred in 25 vertebral bodies, with an incidence of 39.7% (25/63).

CONCLUSIONS

The results indicate that microwave ablation combined with vertebral augmentation under real-time temperature monitoring is a feasible, effective, and safe treatment for painful osteoblast spinal metastases.

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.

The surgical management of osteoid osteoma: A systematic review

Background

Osteoid osteoma (OO) comprises approximately 11%-14% of benign bone tumors. The main symptom of OO is localized pain accompanied by nighttime aggravation. Surgical treatment is frequently used in clinic, including open surgery and percutaneous ablation, the latter including radiofrequency ablation, cryoablation, and microwave ablation, but there is no consensus on when and how to choose the best treatment for OO.

Purpose

We did a systematic review of the literature on existing surgical treatments of OO to assess the safety and efficacy of surgical treatments of OO and to evaluate the surgical options for different locations of OO.

Methods

The inclusion criteria in the literature are 1. Patients diagnosed with osteoid osteoma and treated surgically; 2. Include at least five patients; 3. Perioperative visual analogue scale (VAS), postoperative complications, and recurrence were recorded; 4. Literature available in PubMed from January 2014 to December 2021.

Results

In the cohort, 1565 patients (mainly adolescents) with OO received 1615 treatments. And there are 70 patients with postoperative recurrence and 93 patients with postoperative complications (minor: major=84:9). The results of Kruskal-Wallis examination of each experimental index in this experiment were clinical success rate H=14.818, p=0.002, postoperative short-term VAS score H=212.858, p<0.001, postoperative long-term VAS score H=122.290, p<0.001, complication rate H=102.799, p<0.001, recurrence rate H=17.655, p<0.001, the technical success rate was H=45.708, p<0.001, according to the test criteria of α=0.05, H₀ was rejected. The overall means of the outcome index in each group were not completely equal.

Conclusion

Percutaneous ablation and open surgery are safe and reliable for OOs, and the technical success rate of percutaneous ablation is higher than that of open surgery. Open surgery and cryoablation can be selected for OOs close to the nerve and atypical sites, while radiofrequency ablation and microwave ablation can be selected for OOs in most other sites.

The effects of combined microwave ablation and open surgery for the treatment of lung cancer-derived thoracolumbar metastases

OBJECTIVE

To investigate the clinical effects of microwave ablation (MWA) in addition to open surgery for the treatment of lung cancer-derived thoracolumbar metastases.

METHODS

This was a single-institution, retrospective, cohort study. From January 2019 to December 2020, a total of 47 patients with lung cancer-derived thoracolumbar metastases underwent posterior spinal canal decompression and fixation surgery in our hospital. Two independent surgical teams treated these patients. One group underwent open surgery combined with MWA therapy, while the other had open surgery only (control). The pre- and post-operative visual analog scale (VAS) scores and the overall survival (OS) were compared between the MWA and control groups. The Frankel Grade classification was applied for the evaluation of the post-surgical spinal cord function. Improvement was defined as an increase of at least one rank from the pre-operative scores. Each patient was evaluated pre- and post-operatively at 48 h, 1 month, and 3-month intervals. Data on surgical-related complications were recorded.

RESULTS

Thirty men and 17 women were included, with an average age of 57.9 ± 11.4 years (range, 26-81 years). Twenty-eight patients underwent MWA and were in the MWA group, and 19 patients were included in the control group. Post-operatively all patients were followed up regularly; the median follow-up time was 12 months (range, 3-24 months), and their median OS was 14 months. Patients in the MWA group had a lower VAS score than those in the control group at the 48-h (1.75 ± 1.01 vs 2.47 ± 0.96, P = 0.01) and 1-month (1.79 ± 0.92 vs 2.53 ± 1.35, P = 0.048) check-ups. At the 3-month evaluation, the VAS score differences between the two groups were not significant (P = 0.133). After surgery, spinal cord function improvement was not significantly different between the MWA and control groups (P = 0.515). MWA therapy combined with open surgery was not associated with increased OS compared with the control group (P = 0.492).

CONCLUSION

MWA can be an effective and safe pain-relief method but may not extend the OS of patients with lung cancer.

A Multimodal Clinical Approach for the Treatment of Bone Metastases in Solid Tumors

Context

Bone metastasis (BM) is a frequent complication of cancer, representing the third most common site of secondary spread in solid cancers behind the lung and liver. Bone metastasis is found in up to 90% of prostate and breast cancer patients. They can cause significant complications, such as pathological fractures and paralysis of the spine, which decrease daily functioning and quality of life (QoL) and worsen prognosis. The growing life expectancy of cancer patients due to improvements in systemic therapies may further increase BM's eventuality and clinical burden in cancer patients.

Evidence Acquisition

Four physicians from five different specialties were interviewed and resumed the most relevant literature of the last 20 years focusing on pain treatment in BM patients.

Results

Treatment for BM ideally involves various types of specialists and assessments. The disease status and patient background should be considered, requiring holistic care and expertise from various medical specialties.

Conclusions

Interventional, nuclear medicine, radiotherapy, and mini-invasive techniques can be safe and effective for relieving pain and modifying health-related QoL in BM patients.

Minimally Invasive Interventional Procedures for Metastatic Bone Disease: A Comprehensive Review

Metastases are the main type of malignancy involving bone, which is the third most frequent site of metastatic carcinoma, after lung and liver. Skeletal-related events such as intractable pain, spinal cord compression, and pathologic fractures pose a serious burden on patients’ quality of life. For this reason, mini-invasive treatments for the management of bone metastases were developed with the goal of pain relief and functional status improvement. These techniques include embolization, thermal ablation, electrochemotherapy, cementoplasty, and MRI-guided high-intensity focused ultrasound. In order to achieve durable pain palliation and disease control, mini-invasive procedures are combined with chemotherapy, radiation therapy, surgery, or analgesics. The purpose of this review is to summarize the recently published literature regarding interventional radiology procedures in the treatment of cancer patients with bone metastases, focusing on the efficacy, complications, local disease control and recurrence rate.

Safety of Thermosensor Insertion in the Midline of the Spinal Canal Anterior to the Dura: A Cadaveric Study

OBJECTIVE

To evaluate the safety of the insertion of a blunt-tip thermosensor inside the anterior epidural space using the trans-osseous route in the dorsal spine and the double oblique trans-foraminal approach in the lumbar spine.

MATERIALS AND METHODS

A total of 10 attempts were made on a 91 years old human specimen. Thermosensors were inserted under fluoroscopic guidance in the anterior part of the spinal canal using various oblique angulations. Surgical dissection was then performed to identify the position of the thermosensor and look for any injury to the dural sac or the spinal cord/cauda equina.

RESULTS

Nine thermosensors could be deployed successfully in the anterior part of the spinal canal from Th8 to L5 while one attempt (L5 level) failed due to a technical issue on the coaxial needle. On anteroposterior projection, the tip of thermosensor relative to the midline was classified as centered in 5 cases, overcrossing in 3 cases and undercrossing in 1 case. At surgical dissection, the tip of the thermosensor was epidural posterior to the posterior longitudinal ligament in 8 cases and anterior to the longitudinal ligament in 1 case (the undercrossing case). There were 3 tears to the dura, all in the overcrossing group. There was no case of injury to the spinal cord/cauda equina.

CONCLUSION

Insertion of a thin blunt-tip thermosensor with optimal angulation leads to an epidural post-ligamentous position on the midline without damage to the dural sac. The blunt-tip did not prevent from dural tearing should the insertion overcross the midline.

Temperature Monitoring in Hyperthermia Treatments of Bone Tumors: State-of-the-Art and Future Challenges

Bone metastases and osteoid osteoma (OO) have a high incidence in patients facing primary lesions in many organs. Radiotherapy has long been the standard choice for these patients, performed as stand-alone or in conjunction with surgery. However, the needs of these patients have never been fully met, especially in the ones with low life expectancy, where treatments devoted to pain reduction are pivotal. New techniques as hyperthermia treatments (HTs) are emerging to reduce the associated pain of bone metastases and OO. Temperature monitoring during HTs may significantly improve the clinical outcomes since the amount of thermal injury depends on the tissue temperature and the exposure time. This is particularly relevant in bone tumors due to the adjacent vulnerable structures (e.g., spinal cord and nerve roots). In this Review, we focus on the potential of temperature monitoring on HT of bone cancer. Preclinical and clinical studies have been proposed and are underway to investigate the use of different thermometric techniques in this scenario. We review these studies, the principle of work of the thermometric techniques used in HTs, their strengths, weaknesses, and pitfalls, as well as the strategies and the potential of improving the HTs outcomes.

Computed tomography-guided microwave ablation combined with percutaneous vertebroplasty for treatment of painful high thoracic vertebral metastases

PURPOSE

To retrospectively evaluate the efficacy and safety of computed tomography (CT)-guided microwave ablation (MWA) combined with percutaneous vertebroplasty (PVP) as a treatment for painful high thoracic vertebral metastases (T1-T4).

MATERIALS AND METHODS

In this retrospective study, 23 adult patients (33 high thoracic vertebral metastases) with moderate to severe pain were treated with CT-guided MWA and PVP. The procedural effectiveness was evaluated using a Visual Analog Scale (VAS), daily morphine consumption, and the Oswestry Disability Index (ODI) before and immediately after the procedure and during follow-up.

RESULTS

Technical success was achieved in all patients. The mean pre-procedure VAS score and morphine doses were 6.7 ± 1.7 (5-10) and 105.2 ± 32.7 (30-150) mg, respectively. The mean VAS scores and daily morphine doses at 24 h and 1, 4, 12, and 24 weeks post-operatively were 3.2 ± 1.4 and 41.3 ± 9.6 mg; 1.8 ± 1.0 and 31.5 ± 12.2 mg; 1.4 ± 1.3 and 19.6 ± 12.4 mg; 1.1 ± 0.8 and 14.5 ± 9.6 mg; and 1.0 ± 0.7 and 13.9 ± 9.3 mg, respectively (all p < 0.001). ODI scores significantly decreased (p < 0.05). Minor cement leakage occurred in 10 patients (30.30%) with no symptoms. Follow-up imaging showed no local tumor progression.

CONCLUSIONS

Preliminary results suggest MWA combined with PVP is an effective and safe treatment for painful high thoracic vertebral metastases (T1-T4) and can significantly relieve pain and improve the quality of life of patients. However, its efficacy should be confirmed by mid- and long-term studies.

Musculoskeletal Oncologic Interventions: Proceedings from the Society of Interventional Radiology and Society of Interventional Oncology Research Consensus Panel

Musculoskeletal interventions are increasingly used with palliative and curative intent in the multidisciplinary treatment of oncology patients with bone and soft-tissue tumors. There is an unmet need for high-quality evidence to guide broader application and adoption of minimally invasive interventional technologies to treat these patients. Therefore, the Society of Interventional Radiology Foundation and the Society of Interventional Oncology collaborated to convene a research consensus panel to prioritize a research agenda addressing the gaps in the current evidence. This article summarizes the panel's proceedings and recommendations for future basic science and clinical investigation to chart the course for interventional oncology within the musculoskeletal system. Key questions that emerged addressed the effectiveness of ablation within specific patient populations, the effect of combination of ablation with radiotherapy and/or immunotherapy, and the potential of standardization of techniques, including modeling and monitoring, to improve the consistency and predictability of treatment outcomes.

Feasibility and Clinical Value of CT-Guided 125I Brachytherapy for Pain Palliation in Patients With Breast Cancer and Bone Metastases After External Beam Radiotherapy Failure

Objectives: To evaluate the feasibility and clinical value of CT-guided iodine-125 (¹²⁵I) brachytherapy for pain palliation in patients with breast cancer and bone metastases after external beam radiotherapy failure. Methods: From January 2014 to July 2016, a total of 90 patients, who had received the standard therapies for bone metastases but still suffered moderate-to-severe pain, were retrospectively studied. About 42 patients were treated with both ¹²⁵I brachytherapy and bisphosphonates (Group A), and 48 patients were treated with bisphosphonates alone (Group B). Results: In Group A, 45 ¹²⁵I brachytherapy procedures were performed in 42 patients with 69 bone metastases; the primary success rate of ¹²⁵I seed implantation was 92.9%, without severe complications. Regarding pain progression of the two groups, Group A exhibited significant relief in "worst pain," "least pain," "average pain," and "present pain" 3-day after treatment and could achieve a 12-week-remission for "worst pain," "least pain," "average pain," and "present pain." The morphine-equivalent 24-h analgesic dose at 3 days, 4 weeks, 8 weeks, and 12 weeks was 91 ± 27, 53 ± 13, 31 ± 17, and 34 ± 12 mg for Group A, and 129 ± 21, 61 ± 16, 53 ± 15, and 105 ± 23 mg for Group B. Group A experienced a lower incidence of analgesic-related adverse events and better quality of life than Group B. Conclusion: The CT-guided ¹²⁵I brachytherapy is a feasible and an effective treatment for the palliation of pain caused by bone metastases from breast cancer after external beam radiotherapy failure.

Techniques for Temperature Monitoring of Myocardial Tissue Undergoing Radiofrequency Ablation Treatments: An Overview

Cardiac radiofrequency ablation (RFA) has received substantial attention for the treatment of multiple arrhythmias. In this scenario, there is an ever-growing demand for monitoring the temperature trend inside the tissue as it may allow an accurate control of the treatment effects, with a consequent improvement of the clinical outcomes. There are many methods for monitoring temperature in tissues undergoing RFA, which can be divided into invasive and non-invasive. This paper aims to provide an overview of the currently available techniques for temperature detection in this clinical scenario. Firstly, we describe the heat generation during RFA, then we report the principle of work of the most popular thermometric techniques and their features. Finally, we introduce their main applications in the field of cardiac RFA to explore the applicability in clinical settings of each method.

Microwave Ablation as a Treatment for Spinal Metastatic Tumors: A Systematic Review

BACKGROUND

Microwave ablation (MWA) is a novel technique that offers several potential advantages over existing ablation systems, which include production of larger ablation zones, shorter procedural times, and more effective heating through high impedance tissues such as bone.

METHODS

A systematic review was performed using inclusion criteria defined as follows: 1) metastatic spinal tumors treated with open or percutaneous MWA alone or in combination with other treatments, 2) available data on pain palliation and/or local tumor control, and 3) retrospective or prospective studies with at least 1 patient.

RESULTS

A total of 156 patients harboring 196 spinal lesions underwent MWA in the 8 included studies. Most studies employed the use of additional interventions, which included minimally invasive open surgery with pedicle screw fixation, traditional open surgical intervention, and cement augmentation. Despite the variability in time intervals for pain assessment, postoperative pain scores decreased considerably in both percutaneous and open MWA studies. No evidence of tumor progression was additionally seen in >80% of patients at the last follow-up across 5 studies. Complications were reported in 6.5% of all patients who underwent percutaneous MWA and in 12.2% of patients who underwent open MWA.

CONCLUSIONS

This review showed that MWA can be effective in achieving analgesia for up to 6 months in select cases, although most procedures were performed in combination with augmentation and/or open surgery. Local tumor control was additionally successful in most patients, suggestive of a potential curative role for MWA.

Multipoint Temperature Monitoring of Microwave Thermal Ablation in Bones through Fiber Bragg Grating Sensor Arrays

Bones are a frequent site of metastases that cause intolerable cancer-related pain in 90% of patients, making their quality of life poor. In this scenario, being able to treat bone oncology patients by means of minimally invasive techniques can be crucial to avoid surgery-related risks and decrease hospitalization times. The use of microwave ablation (MWA) is gaining broad clinical acceptance to treat bone tumors. It is worth investigating temperature variations in bone tissue undergoing MWA because the clinical outcomes can be inferred from this parameter. Several feasibility studies have been performed, but an experimental analysis of the temperature trends reached into the bone during the MWA has not yet been assessed. In this work, a multi-point temperature study along the bone structure during such treatment is presented. The study has been carried out on ex vivo bovine femur and tibia, subjected to MWA. An overall of 40 measurement points covering a large sensing area was obtained for each configuration. Temperature monitoring was performed by using 40 fiber Bragg grating (FBGs) sensors (four arrays each housing 10 FBGs), inserted into the bones at specific distances to the microwave antenna. As result, the ability of this experimental multi-point monitoring approach in tracking temperature variations within bone tissue during MWA treatments was shown. This study lays the foundations for the design of a novel approach to study the effects of MWA on bone tumors. As consequence, the MWA treatment settings could be optimized in order to maximize the treatment effects of such a promising clinical application, but also customized for the specific tumor and patient.

Use of percutaneous microwave ablation for the treatment of bone tumors: a retrospective study of clinical outcomes in 47 patients

Objective

The present study aimed to evaluate the short-term clinical performance and safety of percutaneous microwave ablation (MWA) techniques for the treatment of bone tumors.

Methods

This single-institution retrospective study investigated 47 cases of bone tumors treated by MWA from June 2015 to June 2018. The study included 26 patients (55.3%) with benign bone tumors and 21 patients (44.7%) with malignant bone tumors. The tumors were located in the spine or sacrum (15, 31.9%), the upper extremities (6, 12.8%), the lower extremities (17, 36.2%) and the pelvis (9, 19.1%). Outcomes regarding clinical efficacy, including pain relief, quality of life, and intervention-related complications, were evaluated before and after MWA using the visual analog scale (VAS) and the 36-item Short-Form Health Survey (SF-36) scoring system.

Results

Of the 47 patients included in this study, all of them completed follow-up examinations, with a mean follow-up duration of 4.8 ± 1.6 months (range, 2–9 months). Significantly improved VAS and SF-36 scores were recorded after the initial treatment (P<0.001), suggesting that almost 100% of patients experienced pain relief and an improved quality of life following surgery. No major intervention-related complications (e.g., serious neurovascular injury or infection) occurred during or after the treatment. We recorded only three minor posttreatment complications (6.4%, 3/47), which were related to thermal injury that caused myofasciitis and affected wound healing.

Conclusion

In our study, the short-term efficacy of MWA was considerably favorable, with a relatively low rate of complications. Our results also showed that MWA was effective for pain relief and improved patients’ quality of life, making it a feasible treatment alternative for bone tumors.

Transforaminal Insertion of a Thermocouple on the Posterior Vertebral Wall Combined with Hydrodissection during Lumbar Spinal Radiofrequency Ablation

The purpose of the present article is to describe the technique of transforaminal insertion of an ultrathin thermosensor in the anterior epidural space in 13 patients treated by radiofrequency ablation. The mean time taken to position the thermosensor was 10.6 minutes (range, 5-38 minutes). Technical success was 93% (correct positioning in 13/14 levels). Additional hydrodissection was performed through the same access in 11 cases. No postoperative neural deficit was elicited in any of the cases.

The clinical efficacy of ultrasound-guided percutaneous microwave ablation for rib metastases with severe intractable pain: a preliminary clinical study

Purpose: To retrospectively evaluate the clinical efficacy of ultrasound-guided percutaneous microwave ablation (US-PMWA) for patients with rib metastases that caused severe intractable pain.

Materials and methods: From Jan 2016 to Apr 2018, 9 rib metastases from 7 solid tumor patients were treated with US-PMWA. The visual analogue scale (VAS), daily opiate intake doses, local tumor control and complications were recorded and analyzed.

Results: The follow-up period ranged from 6 to 33 months (median: 16 months). The procedures were successfully performed in all of the patients by one ablation. The ablation power ranged from 30 to 60 W, and the ablation time was 610.0±317.5 s. The mean preablation VAS pain score was 8.1±0.7, whereas the mean VAS pain score at 72 h postablation was 3.3±0.5 (P<0.001). All of the patients needed to apply oral and/or intravenous injection opiates to relieve severe intractable pain before ablation, with daily opiate intake doses of 61.4±30.8 mg. After ablation, five patients did not need to apply any opiate treatments 72 h after ablation, and only two patients needed oral opiates (daily opiate intake doses: 30 mg and 20 mg). Recurrence was detected in three lesions at 6, 11 and 9 months after ablation, with the maximum diameter observed being more than 4 cm. All of the patients were alive during the follow-up period. No minor or major complications occurred.

Conclusion: US-PMWA appears to be feasible, convenient, safe and effective in the palliative management of refractory pain caused by rib metastases. This treatment can improve the quality of life of patients and may also achieve promising local control of tumors.

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.