CC BY-NC-ND 4.0 · Endosc Int Open 2017; 05(09): E924-E930
DOI: 10.1055/s-0043-116384
Original article
Eigentümer und Copyright ©Georg Thieme Verlag KG 2017

Incidental colorectal focal 18F-FDG uptake: a novel indication for colonoscopy

Eugénie Rigault1, Laurence Lenoir2, Guillaume Bouguen1, Mael Pagenault1, Astrid Lièvre1, Etienne Garin2, Laurent Siproudhis1, Jean-François Bretagne1
  • 1Service des Maladies de l’Appareil Digestif, Hôpital Pontchaillou, Centre Hospitalo-Universitaire, Rennes
  • 2Service de Médecine Nucléaire, Centre Eugène Marquis, Rennes
Further Information

Publication History

submitted 19 March 2017

accepted after revision 26 June 2017

Publication Date:
13 September 2017 (online)


Background and study aims The relevance of incidental colorectal focal 18F-FDG PET/CT uptake is debatable. All patients who were referred for colonoscopy because of incidental colonic focal FDG uptake were included in this retrospective study.

Patients and methods PET/CT imaging characteristics were reviewed by a nuclear physician who was blinded to endoscopic and histopathological findings to determine the location of FDG uptake sites and to measure the maximum standardized uptake values (SUVmax) and metabolic volume (MV). Endoscopic findings were categorized as malignant lesions (ML), high-risk polyps (HRP), low-risk polyps (LRP) or other non-neoplastic lesions (NNL).

Results Seventy patients with 84 foci of FDG uptake were included. The proportions of true-positive (lesions found at colonoscopy at the same location) and false-positive (no lesion at colonoscopy) PET/CT findings were 65.5 % (n = 55) and 34.5 % (n = 29). Median SUVmax values did not differ between true-positive and false-positive findings (P = 0.27). Median MV30 values differed significantly between true-positive (5.5 cm3, [3.3 – 10.9 cm3]) and false-positive (9.7 cm3, [5.2 – 40.8 cm3]) findings (P = 0.015). Among the 55 true-positive FDG uptake sites, there were 14 (25.5 %) malignant lesions, 30 (54.5 %) HRP, 4 (7.3 %) LRP, and 7 (12.7 %) NNL. Median MV30 values differed significantly between advanced neoplasia (5.0 cm3, [2.9 – 9.7 cm3]) and other endoscopic findings (9.4 cm3, [5.2 – 39.8 cm3]) (P = 0.001); the AUROC was 0.71. By per-colonic segment analysis, the distribution of true-positive, false-negative, false-positive, and true-negative FDG PET/CT findings was as follows: 21.5 %, 14.2 %, 11.5 %, and 52.8 %, respectively.

Conclusion Our study demonstrates that follow-up complete colonoscopy is mandatory in all patients with incidental colorectal focal 18F-FDG PET/CT uptake.