Bone metastases: Diagnosis and monitoring on imaging methods, interventional radiology

Abstract

Skeletal metastases in cancer patients are quite common (in 70 % of cases) and cause significant morbidity. Mostly they are asymptomatic, but if they are not, they are a source of severe complications, pain and compromised quality of life. When metastasis is suspected, the primary imaging modality in long bones and skull is the X-ray imaging. However, in the spine and pelvis, the radiograph is often false negative and magnetic resonance imaging (MRI) is used. If this is not available, then computerized tomography (CT) can be regarded as an option. If dissemination is suspected, scintigraphy, SPECT, or whole-body MR is the method of choice. Expensive hybrid modalities, like positron emission tomography (PET-CT and PET-MR) are typically used in patients already treated with clinical suspicion of dissemination. Biopsy (either percutaneous or peroperative) is only recommended if origin is unclear or additional histological, immunological or genetic testing is required. In the case of a known cancer diagnosis, verification is usually not performed. When assessing the risk of pathological fracture, the location and nature of the lesion, pain, bone destruction, and bone quality are assessed. The Mirels score can be used in long bones, Spinal Instability Neoplastic Score (SIN score) is an alternative for spine lesions, which can give guidance on whether to perform surgical or other stabilization. In solitary or oligometastatic disease (maximum of five foci under 3 cm), curative treatment in the form of radiotherapy, surgery or some of the methods of interventional radiology, or a combination of all, can be considered an addition to the oncological treatment itself. With more extensive disease, palliative therapy aims to maintain mobility and the highest possible quality of life for the patient, to analgesize and prevent pathological fractures. In the case of painful lesions insufficiently responding to medication, especially in the axial skeleton, the first choice is classic external radiotherapy or recently stereatactic radiation therapy. Surgical solutions - splints, nailing, implantation of tumor endoprostheses, vertebral somatectomy with stabilization, resection, amputation can be considered in indicated cases. From minimally invasive methods transarterial embolisation, percutaneous ablation (radiofrequency, microwave, cryoablation, high-intensity focused ultrasound, cementoplasty, neurolysis, pharmacological blocks) are used. The minimally invasive possibilities of interventional radiology are sometimes inadequately used in treatment of painful conditions. Certainly, the treatment of patients in complex oncology centers with sufficient human and technical background is advantageous. Indications for more advanced interventions should in principle be subject to discussion at multidisciplinary boards in collaboration with an oncologist, orthopedic surgeon, surgeon, radiotherapist, diagnostic and interventional radiologist, algesiologist, pathologist, or other specialist as appropriate.