Change in Fat Fraction Quantification Before and After Treatment in Bone Metastases

Bone metastases are a common and serious complication of cancer. Treatment response is currently judged mainly by delayed changes on CT scans or X-rays, a process that can take months and sometimes produces misleading results. The study investigates whether a specialized, radiation-free MRI technique called Dixon imaging can detect early signs of treatment response by measuring fat content within bone metastases before and after chemotherapy or radiotherapy. As tumor tissue within a bone lesion responds to treatment, the lesion is expected to be gradually replaced by fatty marrow, a change that can be quantified using the Dixon MRI method. Adult patients with a solid-tumor cancer and at least one lytic (bone-destroying) metastasis will undergo an MRI scan before starting treatment and a second MRI scan after completing chemotherapy or radiotherapy. Change in fat content within the lesion, and relative to normal marrow, will be measured and compared between patients receiving chemotherapy versus radiotherapy. The study does not involve additional radiation, contrast injection, or invasive procedures beyond standard MRI, and does not influence treatment decisions, which remain under the direction of the treating oncology team.