Comparison of magnetic resonance imaging-fluorodeoxyglucose positron emission tomography fusion with pathological staging in rectal cancer

Background: This study represents an initial experience with combined magnetic resonance imaging (MRI) and [F-18]fluorodeoxyglucose positron emission tomography (FDG PET) (MRI-PET fusion) in the primary staging of rectal carcinoma. Methods: A retrospective analysis of data recorded on patients with rectal cancer was undertaken. Patients requiting long-course radiotherapy were excluded. Chest radiography, abdominal computed tomography and endorectal ultrasonography were performed. In addition, MRI of the pelvis, whole-body FDG PET and MRI-PET fusion were carried out. All patients subsequently underwent anterior resection. Results: Twenty-three patients with rectal carcinoma (15 men), of median age 60 (range 46-75) years, were enrolled. In tumour (T) assessment, AM correctly staged 14 of 22 T2/T3 tumours. In lymph node assessment, MRI-PET fusion had a sensitivity of 44 per cent, with a specificity and positive predictive value of 100 per cent. No additional information was acquired from MRI-PET fusion over MRI plus abdominal computed tomography and chest radiography. Conclusion: MRI-PET fusion adds little to conventional investigations for staging rectal carcinoma.