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

Abstract

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.

Fig 1.

A 59-year-old woman with non-small cell lung cancer and painful osteoblastic L4 vertebral body metastasis. Transaxial CT (A) and FDG PET/CT (B) images demonstrate a hypermetabolic osteoblastic L4 vertebral body metastasis. Transaxial (C) and sagittal (D) intraprocedural CT images demonstrate coaxial placement of a single Ice Rod Plus 17-gauge cryoprobe (Galil) within the L4 sclerotic lesion via a right transpedicular approach. To achieve thermal protection, an 18-ga spinal needle is placed at the right L4–L5 neuroforamen (E), and carbon dioxide is injected in the neuroforamen and epidural space before cryoablation (C–E, arrows). Postablation CT demonstrates a thin rim of hypoattenuating ice ball extending beyond intact vertebral body cortex (F, arrow), marking the margin of the ablation zone.

Fig 2.

A 54-year-old woman with metastatic breast cancer and painful right L2 pedicle and transverse process osteolytic metastasis. Transaxial T1-weighted fat-saturated postcontrast MR (A) and FDG PET/CT (B) images demonstrate right L2 pedicle and transverse process metastasis that demonstrates homogeneous contrast enhancement and marked FDG uptake. Transaxial CT image (C) demonstrates coaxial placement of the Perc-17 Endocare cryoprobe within the right L2 pedicle and transverse process osteolytic lesion. Postcryoablation transaxial CT image (D) demonstrates the hypoattenuating ice ball encompassing the lesion and extending beyond the cortical margin (arrow). A 14-month postcryoablation FDG PET/CT demonstrates complete local tumor control with no evidence of metabolically active tumor (E, arrow).

Fig 3.

A 69-year-old man with metastatic follicular thyroid carcinoma and painful right S1 metastasis. Transaxial iodine-131 SPECT CT image demonstrates increased radiopharmaceutical uptake in the right S1, compatible with metastasis (A). Transaxial intraprocedural CT images demonstrate coaxial placement of 2 Perc-17 Endocare cryoprobes within the right S1 lesion (B and C, short arrow). Thermal protection is performed by placement of a thermocouple and a spinal needle within the right S1 neuroforamen (B, long black arrow) and injection of carbon dioxide into the right S1 neuroforamen with epidural extension (B and C, white arrows). A 24-month postcryoablation FDG PET/CT demonstrates complete local tumor control with no evidence of metabolically active tumor (D, arrow).

Fig 4.

Distribution of NRS scores (A) and morphine-equivalent dosages (B) at study time points. There was a statistically significant decrease in postcryoablation median NRS scores and morphine-equivalent dosages (P < .001 for all).