title: Recurrent rectal cancer and scar: differentiation with PET and MR imaging.
abstract: The value of positron emission tomography (PET) and magnetic resonance (MR) imaging in differentiating recurrent rectal cancer and scar was investigated. PET with fluorine-18 2-fluoro-2-deoxy-D-glucose (FDG) and MR imaging were performed in 15 patients with suspected recurrence. FDG accumulation in the mass was measured by means of the differential absorption ratio (DAR). All 11 patients with confirmed recurrent rectal cancer had increased accumulation of FDG in the mass (DAR = 4.73 +/- 2.28). Low FDG accumulation in the mass (DAR = 0.97 +/- 0.15) was noted in the remaining four patients, in whom the presence of a scar was proved by means of follow-up observation with or without biopsy. On the MR images, the recurrent tumor could be differentiated from scar in all but one case. The lesion-muscle signal intensity ratios on the T2-weighted images for the recurrent tumor and scar were 2.18 +/- 0.55 and 0.89 +/- 0.30, respectively. PET and MR imaging complement each other in the differential diagnosis between recurrent rectal cancer and scar. PET may also permit the evaluation of the effect of therapy.
authors.affiliation: Department of Radiology, Nagoya University, School of Medicine, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ito
authors.forename: T
authors.initials: T
authors.lastname: Kato
authors.forename: M
authors.initials: M
authors.lastname: Tadokoro
authors.forename: T
authors.initials: T
authors.lastname: Ishiguchi
authors.forename: M
authors.initials: M
authors.lastname: Oshima
authors.forename: T
authors.initials: T
authors.lastname: Ishigaki
authors.forename: S
authors.initials: S
authors.lastname: Sakuma
mesh_terms: D000328:Adult; D000368:Aged; D002921:Cicatrix / Q000175:diagnosis* / Q000000981:diagnostic imaging; D003847:Deoxyglucose / Q000031:analogs & derivatives; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis* / Q000000981:diagnostic imaging; D012004:Rectal Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000628:therapy; D014055:Tomography, Emission-Computed
chemical_list: D019788:Fluorodeoxyglucose F18; D003847:Deoxyglucose