An analysis of the physiological FDG uptake pattern in the stomach

Abstract

The purpose of this study was to clarify the normal gastric FDG uptake pattern to provide basic information to make an accurate diagnosis of gastric lesions by FDG PET. We examined 22 cases, including 9 of malignant lymphoma, 8 of lung cancer, 2 of esophageal cancer, and 3 of other malignancies. No gastric lesions were observed in any of the 22 cases on upper gastrointestinal examinations using either barium meal or endoscopic techniques. The intervals between FDG PET and the gastrointestinal examination were within one week in all cases. The stomach regions were classified into the following three areas: U (upper)-area, M (middle)-area, and L (lower)-area. The degree of FDG uptake in these three gastric regions was qualitatively evaluated by visual grading into 4 degrees, and then a semiquantitative evaluation was carried out using the standardized uptake value (SUV). Based on a visual grading evaluation, the mean FDG uptake score in the U-, M-, and L-areas was 1.14 +/- 0.96, 0.82 +/- 0.96, and 0.36 +/- 0.49 (mean +/- S.D.), respectively. The FDG uptake scores obtained in the three areas were significantly different (Friedman test, p < 0.05). Furthermore, the rank order of the FDG uptake score in each case (U > or = M > or = L) was found to be statistically significant (Cochran-Armitage trend test, p < 0.05). The mean SUVs of 11 cases in the three areas were 2.38 +/- 1.03, 1.91 +/- 0.71, and 1.34 +/- 0.44 (mean +/- S.D.), respectively. The SUV in the U-area was significantly higher than that in the L-area (Friedman test, p < 0.05). A significant difference in FDG uptake was observed among the three gastric areas, and the FDG uptake extent in all cases was U > M > L. In conclusion, the physiological gastric FDG uptake was significantly higher at the oral end. A stronger gastric FDG uptake at the anal end may therefore be suggestive of a pathological uptake.

Imaging in assessing lymph node status in gastric cancer

“…On the other hand, FDG uptake of the primary tumor may mimic involvement of adjacent LNs, thereby decreasing specifi city. Similarly, physiological FDG uptake of the stomach [73] may also mask or mimic metastatic perigastric LNs. FDG-PET/CT fusion provides both anatomic and functional information, and allows more accurate localization of foci with increased FDG uptake than stand-alone PET; this may reduce the problems of missing metastatic LNs with low FDG uptake, physiological FDG uptake being misinterpreted as pathological, and false localization of disease [74].…”

Japanese Gastric Cancer Association Task Force for Research Promotion: clinical utility of 18F-fluoro-2-deoxyglucose positron emission tomography in gastric cancer. A systematic review of the literature

“…Furthermore, a significant difference in FDG uptake was observed among the three portions of the stomach: upper third [ middle third [ lower third; the physiological gastric FDG uptake was significantly higher at the oral end. Therefore, stronger gastric FDG uptake at the anal end would suggest pathological uptake [2,3].…”

“…For gastric cancer screening, the usefulness of PET is limited because of physiological FDG uptake in the normal gastric wall and differences of FDG uptake according to the histological type of the tumor [1,2]. Physiological FDG deposits in the stomach may increase false-positive findings, although these deposits can be decreased by expanding the gastric wall by the patient consuming water or milk just before imaging acquisition [4,5].…”

Evaluation of 18F-2-deoxy-2-fluoro-glucose positron emission tomography for gastric cancer screening in asymptomatic individuals undergoing endoscopy

“…PET findings were assessed according to the criteria, which we defined, due to lack of established criteria. The main difficulty in FDG-PET diagnosis of stomach cancer is physiological uptake in the stomach (Cook et al, 1996;Gordon et al, 1997;Shreve et al, 1999;Koga et al, 2003), but there was no cancer subject in whom we had difficulty in differentiating physiological uptake from cancer lesions. Nevertheless, it is possible that there were tiny cancers overlooked due to significant FDG background uptake.…”

“…Because there are no established criteria for assessing FDG-PET findings, we determined the following criteria based on previous reports (Cook et al, 1996;Gordon et al, 1997;Shreve et al, 1999;Koga et al, 2003): (1) positive pattern 1 -spotty or focal accumulation that was stronger than the uptake in the liver ( Figure 1A); positive pattern 2 -any accumulation in the area of the lower stomach ( Figure 1B). This category was based on a report by Koga et al (2003), suggesting that physiological gastric FDG uptake is significantly higher at the oral end than the anal end, and that a stronger gastric FDG uptake at the anal end might therefore be suggestive of a pathological uptake. (2) negative pattern 1 -no definite accumulation in the stomach ( Figure 1C); negative pattern 2 -diffuse accumulation in the stomach, considered to be a normal physiological uptake ( Figure 1D).…”