Real-Time Magnetic Resonance-Guided Microwave Coagulation Therapy for Pelvic Recurrence of Rectal Cancer: Initial Clinical Experience Using a 0.5 T Open Magnetic Resonance System

PURPOSE: This study aims to evaluate consecutive cases of recurrent rectal cancer in the pelvic cavity treated with microwave coagulation therapy using real-time navigation by an open magnetic resonance system. METHODS: Nine recurrent pelvic lesions in 8 patients after curative resection of rectal cancer were treated with real-time magnetic resonance-guided microwave coagulation therapy as a palliative local therapy to reduce tumor volume and/or local pain. Clinical and pathological data were collected retrospectively by reviewing medical records and clinical imaging results. RESULTS: Seven patients received other treatments before real-time magnetic resonance-guided microwave coagulation. Six patients had distant synchronous metastases. Three patients underwent surgery under lumbar anesthesia. Microwave coagulation was performed percutaneously in 5 lesions and under laparotomy in 4 lesions. Although adverse events related to microwave coagulation (skin necrosis and nerve injury) were observed, no fatal complications occurred. Local re-recurrence was observed in 2 of 9 ablated lesions. Except for 1 patient who died of chronic renal failure, the remaining 7 patients died of cancer. Median overall survival after microwave coagulation for all patients was 10 months (range, 4–37 mo). Median overall survival after discovery of pelvic recurrence in all patients was 22 months (range, 9–42 mo). CONCLUSIONS: The benefits of using an open magnetic resonance system in the pelvic cavity include the abilities to treat tumors that cannot be visualized by other modalities, to demonstrate internal architectural changes during treatment, to differentiate treated vs untreated areas, and to allow adjustments to the treatment plan during the procedure. Additional studies are required to clarify the efficacy of tumor coagulation for local control.