PET/CT findings in gastric cancer: potential advantages and current limitations

Successful management of gastric cancer depends on early detection and accurate staging of disease as surgery is the only curative treatment method for localized disease. Endoscopic ultrasound has been the most reliable nonsurgical method in evaluation of the primary tumor, however, recent studies comparing the preoperative staging of gastric cancer by endoscopic ultrasound with multidetector CT show that the two modalities demonstrate very close accuracy in determining the individual T and N stage [1,2]. Multidetector CT is currently the staging modality of choice in identifying the primary tumor, assessing the local spread of the tumor, detecting local and distant nodal disease and metastasis [3–5]. Considering that on average 25% of patients with newly diagnosed gastric carcinoma have undetectable intra-abdominal M1 disease (metastasis to peritoneum, liver or nonregional lymph nodes) by current imaging modalities and yet detected at surgical staging [6], there is a need for better imaging to evaluate the extent of disease and avoid unnecessary surgery. The role of F-fluorodeoxyglucose (F-FDG)PET in detection of primary gastric cancer and lymph node metastasis has been controversial. There is limited data on use of PET/CT for preoperative staging of gastric cancer, although there is growing interest in this topic [7]. F-FDGPET can be useful in postoperative follow-up of gastric cancer patients with suspected recurrent gastric cancer, especially when the recurrence is suspected clinically because of its high positive predictive value [8,9]. Treatment decisions were changed in 30.4% patients when PET/CT was introduced to conventional follow-up [10]. Significant correlation was found between F-FDG-PET uptake and patient survival [11]. In this article we review some of the gastric F-FDG uptake patterns and their importance in gastric cancer detection, and describe the additional value of PET/CT on gastric cancer staging illustrated with case examples. The studies were performed in routine setting with dedicated PET/CT system with no special preparation in terms of gastric distention other than oral contrast or water on the table before imaging.