Small Bowel

In the absence of a corresponding CT abnormality, nearly all FDG uptake in the small bowel uptake, focal or diffuse, is considered normal. 

PET/CT evaluation of small bowel uptake is identical to that for the colon. Unlike the colon, however, the small bowel is not readily amenable to further endoscopic evaluation, and the clinician may have to rely on a follow up PET/CT exam to re-evaluate a “potential” lesion.

Generally, small bowel uptake should be considered normal unless:

• There is an accompanying CT abnormality (e.g. focal bowel wall thickening or focal mass); or
• A solitary focus of intense uptake presents in an otherwise non-avid (or minimally avid) small bowel.  Although this focal uptake may still represent normal physiologic uptake, it is reasonable to raise the possibility of a small lesion and recommend follow up.  If there is no associated CT abnormality, we often report, “While this may represent normal physiologic uptake, a neoplastic process cannot be entirely excluded. Follow up may be of diagnostic value, if clinically warranted.”

Metformin: 

This very popular medication is notorious for causing extensive and extremely intense bowel uptake (colon > small bowel).  As this uptake can occasionally limit interpretation, we ask our patients to discontinue Metformin 24-hours prior to their exam.