IMAGING OF UTERINE CARCINOMA BY CARBON-11-METHIONINE AND PET

L-[methyl-C-11]methionine ([C-11]methionine) is probably one of the mo st useful positron-emitting tracers for metabolic imaging of human can cer. In this study, we investigated whether human uterine cancer can b e imaged with [C-11]methionine and PET. Methods: Fourteen patients wit h 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 m alignancy and in one patient with cervical cancer. Tracer uptake was q uantitated by calculating both the standardized uptake values (SUVs) a nd the kinetic influx constants (Ki values) for the tracer. Results: A ll patients with either cervical or endometrial carcinoma had increase d uptake of [C-11]methionine in the PET image. The mean SUV of the car cinomas was 8.4 (n = 13; s.d., 1.5) and the mean K-i was 0.15 min(-1) (n = 12; s.d., 0.08 min(-1)), whereas the mean SUV of the normal endom etrium was only 4.6 (n = 5; s.d., 0.8). Histologically poorly (Grade I II) or moderately (Grade II) differentiated endometrial carcinomas acc umulated more [C-11]methionine than the well-differentiated (Grade I) ones (p = 0.04 for the SUVs, and p = 0.05 for the Ki values). There we re also variable physiological accumulations of [C-11]methionine in th e pelvis. Conclusions: Uterine carcinoma accumulated [C-11]methionine more than the normal endometrium. However, the physiological accumulat ions of [C-11]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 huma n uterine carcinoma can be effectively imaged with [C-11]methionine an d PET.