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.

Oncological applications of positron emission tomography with fluorine-18 fluorodeoxyglucose

“…Patients with presacral masses and suspected local recurrences were first studied by the group from the German Cancer Research Centre in Heidelberg. In several successive studies, these investigators [91,144] demonstrated the value of PET in differentiating scar tissue and tumour in this setting, a finding later confirmed by Ito et al and Schiepers et al [145,146] (Table 3). In contrast, when a presacral mass is identified on CT, it is very difficult to diagnose its origin: scar, fibrotic tissue or tumoral recurrence.…”

Monoclonal antibody A7-superparamagnetic iron oxide as contrast agent of MR imaging of rectal carcinoma

“…MR imaging in the differential diagnosis between recurrent tumour and postoperative scar (Ito et al, 1992;Takeuchi et al, 1999). The values of CEA scintigraphy and dynamic MR imaging have also been evaluated (Muller-Schimpfle et al, 1993;Blomqvist et al, 1996;Jarv et al, 2000;Torricelli et al, 2003).…”

Positron Emission Tomography in the Diagnosis and Staging of Urinary Bladder Cancer

“…In their rat model, the bladder was irrigated before measurement of the uptake of '*FDG in the tumour, and they reported a higher "FDG concentration in urine than in tumour tissue. There are also reports that suggest that 18FDG is useful in diagnosis of recurrences of colorectal tumours (4). In these reports, the patient was instructed to urinate before transmission and emission scanning when a single image was performed.…”