Radiation therapy alone versus radiation therapy plus radiofrequency ablation/vertebral augmentation for spine metastasis: study protocol for a randomized controlled trial

Hidden blood loss and its influencing factors after cement augmentation for vertebral metastasis

Introduction

Few studies have focused on the risk factors for hidden blood loss (HBL) during cement augmentation surgery for pathologic vertebral compression fraction (PVCFs).

Method

From January 2014 to December 2020, the clinical data of 169 PVCF patients (283 levels) who underwent cement augmentation were retrospectively analysed. HBL was calculated according to the linear Gross formula using the patient's average Hct during the perioperative course and PBV. Multivariate linear regression analysis was performed to evaluate the independent factors associated with HBL.

Results

The mean HBL was 448.2 ± 267.2 ml, corresponding to 10.8% ± 6.2% of the patient blood volume (PBV). There were significant differences between pre- and postoperative haematocrit (Hct) (P < 0.001) and Hb (P < 0.001), and 132 patients developed anaemia postoperatively, while 79 patients had anaemia preoperatively (P < 0.001). Multivariate linear regression revealed that bone lesion quality (p = 0.028), number of PVCFs (p = 0.002), amount of bone cement (p = 0.027), bone cement leakage (p = 0.001), and percentage of vertebral height loss (VHL) (p = 0.011) were independent risk factors for HBL.

Conclusion

In conclusion, patients with lytic vertebral destruction, larger amounts of bone cement, greater amounts of bone cement leakage, more PVCF(s), and greater percentages of VHL may be more prone to HBL.

Development and validation of a radiofrequency ablation treatment planning system for vertebral metastases

PURPOSE

Bone-targeted radiofrequency ablation (RFA) is widely used in the treatment of vertebral metastases. While radiation therapy utilizes established treatment planning systems (TPS) based on multimodal imaging to optimize treatment volumes, current RFA of vertebral metastases has been limited to qualitative image-based assessment of tumour location to direct probe selection and access. This study aimed to design, develop and evaluate a computational patient-specific RFA TPS for vertebral metastases.

METHODS

A TPS was developed on the open-source 3D slicer platform, including procedural setup, dose calculation (based on finite element modelling), and analysis/visualization modules. Usability testing was carried out by 7 clinicians involved in the treatment of vertebral metastases on retrospective clinical imaging data using a simplified dose calculation engine. In vivo evaluation was performed in a preclinical porcine model (n = 6 vertebrae).

RESULTS

Dose analysis was successfully performed, with generation and display of thermal dose volumes, thermal damage, dose volume histograms and isodose contours. Usability testing showed an overall positive response to the TPS as beneficial to safe and effective RFA. The in vivo porcine study showed good agreement between the manually segmented thermally damaged volumes vs. the damage volumes identified from the TPS (Dice Similarity Coefficient = 0.71 ± 0.03, Hausdorff distance = 1.2 ± 0.1 mm).

CONCLUSION

A TPS specifically dedicated to RFA in the bony spine could help account for tissue heterogeneities in both thermal and electrical properties. A TPS would enable visualization of damage volumes in 2D and 3D, assisting clinicians in decisions about potential safety and effectiveness prior to performing RFA in the metastatic spine.

Radiofrequency Ablation and Augmentation in the Management of Spinal Metastases: Clinical Experience in 41 Patients

OBJECTIVE

To evaluate functional outcome after combined radiofrequency ablation and vertebral augmentation in patients with metastatic spinal tumors using visual analog scale and Oswestry Disability Index scores.

METHODS

This retrospective study included 41 patients with metastatic spinal tumors. There were 19 women and 22 men with a mean age of 67 years (range, 45-87 years). Visual analog scale and Oswestry Disability Index were used to assess the intensity of pain and quality of life. The assessments were performed before the procedure and at 1 week and 1, 2, 3, and 6 months after the procedure.

RESULTS

No serious complications were seen in the periprocedural period. Two patients (4.8%) had transient neurological motor deficits without cement leakage, and 1 patient had a pulmonary embolism with transient mild symptoms. The comparison of preprocedural visual analog scale and Oswestry Disability Index scores with postprocedural scores up to 6 months after treatment revealed significant pain control and good functional state.

CONCLUSIONS

Spinal metastasis is a frequent entity in the growing population of patients with cancer. A multidisciplinary approach using several nonsurgical and minimally invasive methods (e.g., radiofrequency ablation, vertebroplasty, balloon kyphoplasty) is key to successful management, and combining these procedures is effective against spinal metastatic pain.

Percutaneous bipolar radiofrequency ablation for spine metastatic lesions

PURPOSE

The purpose of this review is to become familiar with the most common indications for imaging guided percutaneous bipolar radiofrequency ablation, to learn about different technical considerations during performance providing the current evidence. Controversies concerning products will be addressed.

METHODS

We performed a literature review excluding non-English studies and case reports. All references of the obtained articles were also evaluated for any additional information.

RESULTS

RFA achieves cytotoxicity by raising target area temperatures above 60 °C, and may be used to achieve total necrosis of lesions smaller than 3 cm in diameter, to debulk and reduce the pain associated with larger lesions, to prevent pathological fractures due to progressive osteolysis or for cavity creation aiming for targeted cement delivery in case of posterior vertebral wall breaching. Protective ancillary techniques should be used in order to increase safety and augment efficacy of RFA in the spine.

CONCLUSION

Percutaneous radiofrequency ablation of vertebral lesions is a reproducible, successful and safe procedure. Ablation should be combined with vertebral augmentation in all cases. In order to optimize maximum efficacy a patient- and a lesion-tailored approach should both be offered focusing upon clinical and performance status along with life expectancy of the patient as well as upon lesion characteristics.