The value of 18F-FDG PET in patients with elevated CEA levels

In clinical fields, it is important to detect the location of malignant tumors before and/or after operation. Here we report seven cases, in which F-18-FDG PET was performed, whose carcinoernbryonic antigen (CEA) levels were higher than normal, but the location of the malignant tumor could not be detected by computed tomography (CT). Methods. A total of 288 patients with suspected malignant tumors underwent F-18-FDG PET examinations at our hospital between June 1998 and May 1999. All patients fasted at least 12 h before undergoing PET, F-18-FDG (185-370 MBq) was injected 1 h before scanning. All scans were performed with 3-D collection. Attenuation correction was not performed. This study includes seven patients with elevated CEA levels (11.6-10,000 ng/ml) but the location of the tumor could not be detected by CT. Results. The location of tumor could be detected by F-18-FDG PET in six patients. After undergoing PET, CT scans were repeated and the tumors were detected in the same position as in the PET scan. The location of the tumor could not be detected in only one patient who was operated on for rectal carcinoma (CEA 23.3 ng/ml). Conclusion. F-18-FDG PET is useful in examination when the location of the malignant tumors is unknown but the tumor market level is higher than the normal range.