Ultrasound-guided microwave ablation (MWA) is a safe, effective method for treating bone metastases, according to research presented on 9 May at the American Roentgen Ray Society (ARRS) annual meeting.
In his talk, Zirui Zhang from the Sichuan Clinical Research Center for Cancer in China reported a perfect technical success rate with little to no complications in patients with this technique.
“Ultrasound-guided percutaneous MWA can provide short- to medium-term pain relief and functional improvement for patients with bone metastases, which is helpful to improve patients’ quality of life,” Jiang said.
Previous reports indicate that between 30% and 70% of patients with malignant tumors will eventually develop bone metastases. Of the symptoms, pain is the one most observed in patients and is persistent. Current treatment methods include medication, targeted therapy, radiotherapy, and surgery. However, each has its share of tradeoffs.
Thermal ablation has demonstrated its utility as a curative method for benign lesions and a palliative care method for metastatic tumors in the lungs, liver, and breast, among other areas. Jiang however noted that such data on bone metastases is limited.
As a result, the researchers sought to explore the clinical efficiency of ultrasound-guided percutaneous MWA in patients with painful bone metastases. The prospective study included 15 patients with 25 total bone metastases, all of whom underwent MWA.
A case presented at the ARRS annual meeting shows the results of successful microwave ablation (MWA) treatment for a 39-year-old female with metastatic fibrosarcoma of the right axillary sinus.
Metastases were located on the ribs, skull, pelvis, spinal cone, and sternum. Pathological types included sarcomas (32%), adenocarcinomas (32%), squamous carcinomas (24%), and types labeled as “other” (12%).
MWA had a technical success rate of 100%, with no severe complications being reported among the patients.
It also led to pain scores -- as defined by the 0-to-10-point numerical rating scale -- that significantly decreased from pre- to post-operation. Additionally, MWA led to significant increases in the Musculoskeletal Tumor Society (MSTS) scoring system. This scoring system ranges from zero to 30, with lower scores meaning high disability and higher scores indicating no impairment.
Jiang also presented some case reports, including one case that described where a 39-year-old was treated for metastatic fibrosarcoma of the right maxillary sinus. Images taken 12 months after MWA showed that the tumor had disappeared.
In another case, MWA was used for postoperative rib metastasis of a gastric stromal tumor. Ultrasound images acquired after MWA showed no enhancement and the patient reported no pain.
Jiang said that future studies with more patients and longer follow-up periods are needed to confirm the team’s findings.
![Examples of ultrasound findings and techniques. (A) Images in a 39-year-old male patient with a mass in the left thigh. The mass is heterogeneous on the B-mode US image (compared with the patient in D) and showed increased microvascularity (superb microvascular imaging [SMI]) and shear-wave elastography (SWE) values. Undifferentiated pleomorphic sarcoma was diagnosed at biopsy (with pleomorphic rhabdomyosarcoma in surgical specimen). (B) Images in an 18-year-old male patient with a mass in the left leg. The mass is hypoechoic on the B-mode image, with no other findings suggestive of malignancy. The lesion is in contact with the cortex of the tibia, which is slightly irregular. CT revealed a doubtful anteromedial tibial erosion. The microvascular study demonstrated high vascularization, suggestive of malignancy. Periosteal Ewing sarcoma was diagnosed with both histologic and immunohistochemical confirmation. (C) Images in a 69-year-old female patient with a lump growing on the outside of the left leg. Multiple SWE examinations were performed (please note the high values obtained in the measurements, whereas the color map highlights the stiffness relative to adjacent tissues). SMI showed areas of increased vascularization to target for sampling. Undifferentiated spindle cell sarcoma was diagnosed at biopsy, with residual leiomyosarcoma in the surgical specimen after neoadjuvant therapy. (D) Images in a 56-year-old female patient with a mass in the right thigh. The mass is heterogeneous at both B-mode ultrasound (similar to patient A) and MRI (coronal T2-weighted spectral attenuated inversion recovery [SPAIR]; T1-weighted pre-contrast and postcontrast imaging), which even shows uptake after the administration of paramagnetic contrast material, which is traditionally suggestive of malignancy. Low values at SMI and elastography are suggestive of benignity. Spindle cell lipoma was diagnosed at biopsy, with atypical spindle cell lipomatous tumor in the surgical specimen.](https://img.auntminnieeurope.com/mindful/smg/workspaces/default/uploads/2026/08/images-radiol250278fig2.APCFLSvX6p.jpg?auto=format%2Ccompress&fit=crop&h=100&q=70&w=100)
![Examples of ultrasound findings and techniques. (A) Images in a 39-year-old male patient with a mass in the left thigh. The mass is heterogeneous on the B-mode US image (compared with the patient in D) and showed increased microvascularity (superb microvascular imaging [SMI]) and shear-wave elastography (SWE) values. Undifferentiated pleomorphic sarcoma was diagnosed at biopsy (with pleomorphic rhabdomyosarcoma in surgical specimen). (B) Images in an 18-year-old male patient with a mass in the left leg. The mass is hypoechoic on the B-mode image, with no other findings suggestive of malignancy. The lesion is in contact with the cortex of the tibia, which is slightly irregular. CT revealed a doubtful anteromedial tibial erosion. The microvascular study demonstrated high vascularization, suggestive of malignancy. Periosteal Ewing sarcoma was diagnosed with both histologic and immunohistochemical confirmation. (C) Images in a 69-year-old female patient with a lump growing on the outside of the left leg. Multiple SWE examinations were performed (please note the high values obtained in the measurements, whereas the color map highlights the stiffness relative to adjacent tissues). SMI showed areas of increased vascularization to target for sampling. Undifferentiated spindle cell sarcoma was diagnosed at biopsy, with residual leiomyosarcoma in the surgical specimen after neoadjuvant therapy. (D) Images in a 56-year-old female patient with a mass in the right thigh. The mass is heterogeneous at both B-mode ultrasound (similar to patient A) and MRI (coronal T2-weighted spectral attenuated inversion recovery [SPAIR]; T1-weighted pre-contrast and postcontrast imaging), which even shows uptake after the administration of paramagnetic contrast material, which is traditionally suggestive of malignancy. Low values at SMI and elastography are suggestive of benignity. Spindle cell lipoma was diagnosed at biopsy, with atypical spindle cell lipomatous tumor in the surgical specimen.](https://img.auntminnieeurope.com/mindful/smg/workspaces/default/uploads/2026/08/images-radiol250278fig2.APCFLSvX6p.jpg?auto=format%2Ccompress&dpr=2&fit=crop&h=167&q=70&w=250)
