Etiology and significance of incidentally detected focal colonic uptake on FDG PET/CT

Purandare, Nilendu; Gawade, Sachin K; Puranik, Ameya; Agrawal, Archi; Shah, Sneha; Rangarajan, Venkatesh

doi:10.4103/0971-3026.111476

Cited by 16 publications

(9 citation statements)

References 19 publications

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“…concluded that malignancy could not be ruled out based on SUVmax alone because the differences of SUVmax between the premalignant adenomatous polyps and the malignant lesions was not significant. [ 10 13 ] This is consistent with our observation of the SUVmax in our study. A comparison between benign and malignant SUVmax values by Roh et al .…”

Section: Discussionsupporting

confidence: 93%

Focal Colonic FDG Activity with PET/CT: Guidelines for Recommendation of Colonoscopy

et al. 2015

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Focal 18F-fluorodeoxyglucose (FDG) colonic activity can be incidentally seen in positron emission tomography/computed tomography (PET/CT) scans. Its clinical significance is still unclear. The purpose of this study was to assess the significance of focal FDG activity in PET/CT scans by correlating the imaging findings to colonoscopy results, and come up with some guidelines for recommendation of follow-up colonoscopy. A total of 133 patients who underwent both 18F-FDG PET/CT for different oncological indications and colonoscopy within 3 months were retrospectively studied. Imaging, colonoscopy and pathology results were analyzed. Of the 133 FDG-PET/CT scans, 109/133 (82%) did not show focal colonic FDG activity, and 24/133 (18%) did. Of the 109/133 PET/CTs without focal colonic FDG activity, 109/109 (100%) did not have evidence of colon cancer after colonoscopy and histology. Of the 24/133 PET/CTs with focal colonic FDG activity, 10/24 (42%) had pathologic confirmation of colon cancer and 14/24 (58%) did not have evidence of colon cancer after colonoscopy and histological analysis. Sensitivity was 10/10 (100%), specificity 109/123 (89%), positive predictive value (PPV) 10/24 (42%) and negative predictive value (NPV) 109/109 (100%). Incidental focal 18FDG activity in PET/CT imaging shows a high sensitivity, specificity and NPV for malignancy, with a not so high PPV of 42%. Although some people would argue that a 42% chance of malignancy justifies colonoscopy, this maybe is not possible in all cases. However, the high sensitivity of the test does not allow these studies to be overlooked. We provide our recommendations as per when to send patients with focal FDG colonic activity to have further characterization with colonoscopy.

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Section: Discussionsupporting

confidence: 93%

Focal Colonic FDG Activity with PET/CT: Guidelines for Recommendation of Colonoscopy

et al. 2015

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“…No significant difference in SUVmax was observed the two groups with focal or diffuse incidental GIT uptake, and no significant difference in SUVmax, SUVpeak, SUV50 and SUV41 was observed between the four diagnosis groups, confirming previously published data [ 13 , 14 , 18 – 20 , 23 , 35 , 36 ]. In our study, the mean SUVmax of diffuse FDG uptake was slightly higher than the mean SUVmax of focal FDG uptake, although diffuse FDG uptake was generally associated with a benign diagnosis.…”

Section: Discussionsupporting

confidence: 90%

“…Colorectal cancer was detected incidentally in 3 of a series of 230 (1.3 %) patients, which is higher than the rate observed in various FDG PET/CT cancer screening studies, such as that reported by Chen et al with a colorectal cancer incidence of 0.19 % (6/3210), Terauchi et al with an incidence of 0.96 % (28/2911), and Purandare et al with an incidence of 0.055 % (5/9000) [ 33 – 35 ] probably related to potential common risk factors between colon cancer and lung cancer in our series.…”

Section: Discussionmentioning

confidence: 78%

Incidental gastrointestinal 18F-Fluorodeoxyglucose uptake associated with lung cancer

et al. 2015

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BackgroundF-Fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) is increasingly used for the initial staging and restaging of lung cancer. Incidental gastrointestinal findings are often observed on 18F-FDG PET/CT. The objective of this study was to assess incidental 18F-FDG uptake by the gastrointestinal tract (GIT) in patients with lung cancer.MethodsTwo hundred thirty consecutive 18F-FDG PET/CT examinations performed for lung cancer over a 3-year period were retrospectively reviewed for the presence of incidental FDG uptake in the GIT. The charts of patients with positive FDG uptake were then reviewed and analysed to determine the GIT uptake sites, the standardized uptake value (SUV) max and the final clinical diagnosis.ResultsFifty-two patients (52/230, 23 %) demonstrated incidental FDG uptake in the GIT. Thirty-three patients (63.5 %) had diffuse uptake (oesophagus, n = 2, colon, n = 31) and 19 patients (36.5 %) had focal uptake (oesophagus, n = 1, small bowel, n = 1, ascending colon, n = 5, descending colon, n = 4, sigmoid, n = 4, rectum, n = 3, and anal margin, n = 1). Twelve of the 52 patients with GIT uptake were further investigated, revealing, a diagnosis of malignancy in 4 patients with focal FDG uptake. No significant differences in mean SUVmax were observed between patients with malignant and benign GIT diseases.ConclusionThis study demonstrates a high incidence of FDG uptake in the GIT associated with lung cancer. Focal GIT uptake was frequently associated with malignant disease. These results suggest that further GIT investigations should be performed in patients with focal GIT uptake.

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“…In contrast, focal FDG uptake, which is observed in 0.4 % to 16.3 % of patients undergoing PET/CT examinations, is usually associated with the discovery of malignant and pre-malignant lesions in almost 68 % of patients 6 . Consequently, false-positive findings have been reported in 9.3 % to 63 % of these cases 9 10 11 12 13 14 15 16 17 18 19 20 21 22 . Although the mechanisms of FDG uptake in the large bowel are unclear, false-positive uptake is thought to be the consequence of the physiological accumulation of FDG 23 24 .…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2017

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Background and study aims The relevance of incidental colorectal focal 18 F-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 cm 3 , [3.3 – 10.9 cm 3 ]) and false-positive (9.7 cm 3 , [5.2 – 40.8 cm 3 ]) 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 cm 3 , [2.9 – 9.7 cm 3 ]) and other endoscopic findings (9.4 cm 3 , [5.2 – 39.8 cm 3 ]) ( 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 18 F-FDG PET/CT uptake.

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Etiology and significance of incidentally detected focal colonic uptake on FDG PET/CT

Cited by 16 publications

References 19 publications

Focal Colonic FDG Activity with PET/CT: Guidelines for Recommendation of Colonoscopy

Focal Colonic FDG Activity with PET/CT: Guidelines for Recommendation of Colonoscopy

Incidental gastrointestinal 18F-Fluorodeoxyglucose uptake associated with lung cancer

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

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