High and typical 18F-FDG bowel uptake in patients treated with metformin.
ABSTRACT This prospective and bi-centric study was conducted in order to determine the impact of antidiabetic treatments (AD) on (18)F-FDG bowel uptake in type 2 diabetic patients.
Fifty-five patients with previously diagnosed and treated type 2 diabetes mellitus (group 1) were divided in two subgroups: AD treatment including metformin (n=32; group 1a) and AD treatment excluding metformin (n=23; group 1b). The 95 patients without diabetes mellitus made up controls (group 2). (18)F-FDG uptake in small intestine and colon was visually graded and semi-quantitatively measured using the maximum standardized uptake value.
(18)F-FDG bowel uptake was significantly increased in AD patients (group 1) as compared to controls (group 2) (p<0.001). Bowel uptake was significantly higher in AD patients including metformin (group 1a) as compared to AD patients excluding metformin (group 1b) (p<0.01), whose bowel uptake was not significantly different from controls (group 2). A metformin treatment was predictive of an increased bowel uptake in the small intestine (odds ratio OR=16.9, p<0.0001) and in the colon (OR=95.3, p<0.0001), independently of the other factors considered in the multivariate analysis. Bowel uptake pattern in the patients treated with metformin was typically intense, diffuse and continuous along the bowel, strongly predominant in the colon, in both the digestive wall and lumen.
This study emphasizes that metformin significantly increases (18)F-FDG uptake in colon and, to a lesser extent, in small intestine. It raises the question of stopping metformin treatment before an (18)F-FDG PET/CT scan is performed for intra-abdominal neoplasic lesion assessment.
[show abstract] [hide abstract]
ABSTRACT: This review aims to provide insight into the factors that influence quantification of glucose metabolism by FDG PET images in oncology as well as their influence on repeated measures studies (i.e. treatment response assessment), offering improved understanding both for clinical practice and research. Structural PubMed searches have been performed for the many factors affecting quantification of glucose metabolism by FDG PET. Review articles and references lists have been used to supplement the search findings. Biological factors such as fasting blood glucose level, FDG uptake period, FDG distribution and clearance, patient motion (breathing) and patient discomfort (stress) all influence quantification. Acquisition parameters should be adjusted to maximize the signal to noise ratio without exposing the patient to a higher than strictly necessary radiation dose. This is especially challenging in pharmacokinetic analysis, where the temporal resolution is of significant importance. The literature is reviewed on the influence of attenuation correction on parameters for glucose metabolism, the effect of motion, metal artefacts and contrast agents on quantification of CT attenuation-corrected images. Reconstruction settings (analytical versus iterative reconstruction, post-reconstruction filtering and image matrix size) all potentially influence quantification due to artefacts, noise levels and lesion size dependency. Many region of interest definitions are available, but increased complexity does not necessarily result in improved performance. Different methods for the quantification of the tissue of interest can introduce systematic and random inaccuracy. This review provides an up-to-date overview of the many factors that influence quantification of glucose metabolism by FDG PET.European Journal of Nuclear Medicine 11/2009; 37(7):1408-25. · 4.53 Impact Factor