Imaging of uterine carcinoma by carbon-11-methionine and PET

L-[methyl-11C]methionine ([11C]methionine) is probably one of the most useful positron-emitting tracers for metabolic imaging of human cancer. In this study, we investigated whether human uterine cancer can be imaged with [11C]methionine and PET.

Fourteen patients with primary uterine malignancy participated in the study. Eight patients had endometrial carcinoma and six had cervical carcinoma. The normal endometrium was analyzed in four additional patients with no uterine malignancy and in one patient with cervical cancer. Tracer uptake was quantitated by calculating both the standardized uptake values (SUVs) and the kinetic influx constants (Ki values) for the tracer.

All patients with either cervical or endometrial carcinoma had increased uptake of [11C]methionine in the PET image. The mean SUV of the carcinomas was 8.4 (n = 13; s.d., 1.5) and the mean Ki was 0.15 min-1 (n = 12; s.d., 0.08 min-1), whereas the mean SUV of the normal endometrium was only 4.6 (n = 5; s.d., 0.8). Histologically poorly (Grade III) or moderately (Grade II) differentiated endometrial carcinomas accumulated more [11C]methionine than the well-differentiated (Grade I) ones (p = 0.04 for the SUVs, and p = 0.05 for the Ki values). There were also variable physiological accumulations of [11C]methionine in the pelvis.

Uterine carcinoma accumulated [11C]methionine more than the normal endometrium. However, the physiological accumulations of [11C]methionine in the pelvis may confuse the interpreter of the PET image; thus, morphological imaging also needs to be performed as a reference to localize the tumor accurately. We conclude that human uterine carcinoma can be effectively imaged with [11C]methionine and PET.