Temperature distribution during radiofrequency ablation of spinal metastases in a human cadaver model: Comparison of three electrodes

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.

Percutaneous management of bone metastases: State of the art

Interventional radiology is playing an increasingly important role in the local treatment of bone metastases; this treatment is usually done with palliative intent, although in selected patients it can be done with curative intent. Two main groups of techniques are available. The first group, centered on bone consolidation, includes osteoplasty/vertebroplasty, in which polymethyl methacrylate (PMMA) is injected to reinforce the bone and relieve pain, and percutaneous osteosynthesis, in which fractures with nondisplaced or minimally bone fragments are fixed in place with screws. The second group centers on tumor ablation. tumor ablation refers to the destruction of tumor tissue by the instillation of alcohol or by other means. Thermoablation is the preferred technique in musculoskeletal tumors because it allows for greater control of ablation. Thermoablation can be done with radiofrequency, in which the application of a high frequency (450 Hz-600 Hz) alternating wave to the tumor-bone interface achieves high temperatures, resulting in coagulative necrosis. Another thermoablation technique uses microwaves, applying electromagnetic waves in an approximate range of 900 MHz-2450 MHz through an antenna that is placed directly in the core of the tumor, stimulating the movement of molecules to generate heat and thus resulting in coagulative necrosis. Cryoablation destroys tumor tissue by applying extreme cold. A more recent, noninvasive technique, magnetic resonance-guided focused ultrasound surgery (MRgFUS), focuses an ultrasound beam from a transducer placed on the patient's skin on the target lesion, where the waves' mechanical energy is converted into thermal energy (65 °C-85 °C). Treatment should be planned by a multidisciplinary team. Treatment can be done with curative or palliative intent. Once the patient is selected, a preprocedural workup should be done to determine the most appropriate technique based on a series of factors. During the procedure, protective measures must be taken and the patient must be closely monitored. After the procedure, patients must be followed up.

Radiofrequency ablation and balloon kyphoplasty for palliation of painful spinal metastases

PURPOSE

This study was designed with an aim to assess the safety and early postoperative outcomes of the combined Radiofrequency ablation (RFA) and Balloon Kyphoplasty (BKP) used for the treatment of painful neoplastic spinal lesions palliatively.

PATIENTS AND METHODS

Between December 2015 and December 2018, 60 patients (35 men and 25 women) with spinal metastases were operated using RFA and BKP at our institution. Transpedicular biopsy was performed in all cases. Patients' demographics, lesion characteristics, concurrent palliative therapies and complications were recorded. All patients were clinically (Pain score VAS 0-10) and radiologically evaluated pre- and postoperatively. Retrospective analysis of data for this cohort was performed.

RESULTS

Seventy-five painful spinal metastases (46 in the lumbar spine and 29 in the thoracic region) in 60 patients were operated [transpedicular RFA alone in 5 lesions, and in combination with BKP in 70 lesions (93%)]. The mean pre-procedure and post-procedure VAS for back pain was 7.2/10 and 2.7/10, respectively (p value = 0.0001). No neurological complications related to RFA were found and no cement extravasation into the spinal canal was observed. In two patients, asymptomatic leaks into the needle track, in two patients into draining veins and in one patient into the disk space were detected.

CONCLUSION

Combined RFA and BKP appears to be a safe, practical, effective and reproducible palliative treatment for painful spinal osteolytic metastasis. In carefully indicated cases, it relieves pain and maintains stability in a minimal invasive way without adding significant surgical trauma or complications.

Percutaneous management of bone metastases: state of the art

Interventional radiology is playing an increasingly important role in the local treatment of bone metastases; this treatment is usually done with palliative intent, although in selected patients it can be done with curative intent. Two main groups of techniques are available. The first group, centered on bone consolidation, includes osteoplasty / vertebroplasty, in which polymethyl methacrylate (PMMA) is injected to reinforce the bone and relieve pain, and percutaneous osteosynthesis, in which fractures with nondisplaced or minimally bone fragments are fixed in place with screws. The second group centers on tumor ablation. Tumor ablation refers to the destruction of tumor tissue by the instillation of alcohol or by other means. Thermoablation is the preferred technique in musculoskeletal tumors because it allows for greater control of ablation. Thermoablation can be done with radiofrequency, in which the application of a high frequency (450 Hz-600Hz) alternating wave to the tumor-bone interface achieves high temperatures, resulting in coagulative necrosis. Another thermoablation technique uses microwaves, applying electromagnetic waves in an approximate range of 900MHz to 2450MHz through an antenna that is placed directly in the core of the tumor, stimulating the movement of molecules to generate heat and thus resulting in coagulative necrosis. Cryoablation destroys tumor tissue by applying extreme cold. A more recent, noninvasive technique, magnetic resonance-guided focused ultrasound surgery (MRgFUS), focuses an ultrasound beam from a transducer placed on the patient's skin on the target lesion, where the waves' mechanical energy is converted into thermal energy (65°C-85°C). Treatment should be planned by a multidisciplinary team. Treatment can be done with curative or palliative intent. Once the patient is selected, a preprocedural workup should be done to determine the most appropriate technique based on a series of factors. During the procedure, protective measures must be taken and the patient must be closely monitored. After the procedure, patients must be followed up.

Percutaneous extra-spinal cementoplasty in patients with cancer: A systematic review of procedural details and clinical outcomes

PURPOSE

To perform a systematic review of technical details and clinical outcomes of percutaneous extra-spinal cementoplasty in patients with malignant lesions.

MATERIALS AND METHODS

PUBMED, MEDLINE, MEDLINE in-process, EMBASE and the Cochrane databases were searched between January 1990 and February 2019 using the keywords «percutaneous cementoplasty», «percutaneous osteoplasty» and «extra-spinal cementoplasty». Inclusion criteria were: retrospective/prospective cohort with more than 4 patients, published in English language, reporting the use of percutaneous injection of cement inside an extra-spinal bone malignant tumour using a dedicated bone trocar, as a stand-alone procedure or in combination with another percutaneous intervention, in order to provide pain palliation and/or bone consolidation.

RESULTS

Thirty articles involving 652 patients with a total of 761 lesions were reviewed. Mean size of lesion was 45mm (range of mean size among publications: 29-73mm); 489 lesions were located in the pelvis, 262 in the long bones of the limbs and 10 in other locations. Cementoplasty was reported as a stand-alone procedure for 60.1% of lesions, and combined with thermal ablation for 26.2% of lesions, implant devices for 12.3% of lesions, and balloon kyphoplasty for 1.4% of lesions. The mean volume of injected cement was 8.8mL (range of mean volume among publications: 2.7-32.2mL). The preoperative visual analogic scores ranged between 3.2 and 9.5. Postoperative scores at last available follow-up ranged from 0.4 to 5.6. Thirteen papers reported a reduction of the visual analogic scores of 5 points or more. Nerve injury was the most frequent symptomatic leakage (0.6%).

CONCLUSION

Percutaneous extra-spinal cementopasty is predominantly performed as a stand-alone procedure and for lesions in the bony pelvis. It appears to be an effective tool to manage pain associated with malignant bone tumours. There is however a lack of standardization of the technique among the different publications.

Renal cell carcinoma metastasis involving vertebral hemangioma: dual percutaneous treatment by navigational bipolar radiofrequency ablation and high viscosity cement vertebroplasty

The case of a 70-year-old woman with progressive renal cell carcinoma (RCC) metastatic invasion of a L3 vertebral hemangioma treated by dual percutaneous radiofrequency ablation (RFA) and vertebroplasty is reported. The patient was surgically treated for RCC in 2001. Chemotherapy and immunotherapy were introduced in 2013 for ovarian, bladder and cerebral metastatic disease. An asymptomatic L3 benign hemangioma was noticed at this time. One-year CT and MRI follow-up studies demonstrated a nodular isolated soft tissue lesion involving the anterior edge of the hemangioma. Percutaneous treatment consisted of a L3 vertebral body unipedicular approach to perform a biopsy, RFA with a navigational bipolar RFA device and vertebroplasty using high viscosity cement. Histopathological examination confirmed metastasis of RCC. The 5-month spinal MRI and CT examinations demonstrated complete disappearance of the tumor.

Renal cell carcinoma metastasis involving vertebral hemangioma: dual percutaneous treatment by navigational bipolar radiofrequency ablation and high viscosity cement vertebroplasty

The case of a 70-year-old woman with progressive renal cell carcinoma (RCC) metastatic invasion of a L3 vertebral hemangioma treated by dual percutaneous radiofrequency ablation (RFA) and vertebroplasty is reported. The patient was surgically treated for RCC in 2001. Chemotherapy and immunotherapy were introduced in 2013 for ovarian, bladder and cerebral metastatic disease. An asymptomatic L3 benign hemangioma was noticed at this time. One-year CT and MRI follow-up studies demonstrated a nodular isolated soft tissue lesion involving the anterior edge of the hemangioma. Percutaneous treatment consisted of a L3 vertebral body unipedicular approach to perform a biopsy, RFA with a navigational bipolar RFA device and vertebroplasty using high viscosity cement. Histopathological examination confirmed metastasis of RCC. The 5-month spinal MRI and CT examinations demonstrated complete disappearance of the tumor.

Fracture risk of vertebral bodies after cryosurgery using a miniature cryoprobe: A biomechanical in-vitro analysis on human bones

INTRODUCTION

Due to spinal instability and compressive neurologic deficits surgical management is sometimes necessary in patients with metastatic spinal lesions. However, in some cases open surgery is not possible and minimally invasive procedures, like cryoablation, are needed. The aim of the current study was to investigate whether a miniature cryoprobe provides adequate tissue cooling in vertebrae and to evaluate the direct impact of cryosurgery on vertebral body stability.

MATERIALS AND METHODS

Twelve thoracic vertebral bodies were harvested from fresh cadavers. After documenting bone density cryoablation was performed in six vertebral bodies according to a standardized procedure. Afterwards temperature inside the vertebral body and maximum breaking force were measured in the control and experimental groups.

RESULTS

Required temperature of -50° was reached in all areas. There was a significant correlation between maximum breaking force and measured bone density (p= 0.001). Mean breaking force within the experimental group was 5047 N (SD = 2955 N) compared to 4458 N (SD = 2554 N) in the control group. There were no observable differences in maximum breaking force between both groups.

CONCLUSION

Miniature cryoprobe can deliver adequate tissue cooling to -50°C in vertebral bodies. The procedure does not seem to influence breaking force of the treated bones in-vitro. Therefore, using miniature probes cryosurgery may provide a valuable alternative to conventional surgical resection of neoplastic diseases as well as of benign locally aggressive bone tumors.