Evaluation of (pre-) malignant colonic Abnormalities: endoscopic validation of FDG-PET findings

Department of Nuclear Medicine, University Medical Center St. Radboud, Nijmegen, The Netherlands
European journal of nuclear medicine and molecular imaging (Impact Factor: 5.38). 11/2001; 28(12):1766-1769. DOI: 10.1007/s002590100645


The diagnostic accuracy of 2-[18F]-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) for the detection of (pre-)malignant lesions of the colon was compared with that of endoscopy. We selected a cohort of 39 patients [13 females and 26 males; mean age 62.3 years standard deviation (SD) 9.6 years] who underwent both FDG-PET and endoscopy (total of 44 procedures) in a 2-year period with a maximum interval between the examinations of 3 months (mean 30 days, SD 28 days). The underlying pathology was colorectal malignancies (24 patients), other malignancies (nine patients) and other disorders (six patients). Follow-up of resected colorectal cancer was the most common reason for the performance of endoscopy. In 19 patients FDG bowel uptake was interpreted as non-physiological, and in 18 patients abnormal findings (adenomatous polyps >3 mm or carcinoma) were detected by endoscopy. Compared with colonoscopy, FDG-PET had a sensitivity of 74% and specificity of 84%. The positive predictive value of FDG-PET was 78%. FDG-PET failed to detect small (diameter 3-10 mm) polyps in four patients. In nine cases abnormal FDG accumulation on PET imaging was the sole reason for performance of an endoscopic procedure. In these cases, endoscopy detected large adenomatous polyps in four patients and carcinomas in two patients, but no abnormalities were detected on endoscopy in the other three patients. There was a good correlation between the location of FDG uptake and endoscopy-positive lesions. FDG-PET is able to detect clinically relevant lesions of the colon. Our study suggests that it can be regarded as a useful adjunct in the non-invasive follow-up of patients with colorectal carcinomas.

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    • "In an additional series of 3,210 PET scans performed for screening in asymptomatic patients, focal FDG avid uptakes were found in 20 patients, corresponding to 12 villous adenomas, 6 carcinomas and 2 tubular adenomas in the colonoscopy (4). These results are consistent with other studies showing that FDG PET ± CT is a sensitive tool to detect colonic premalignant lesions (4,6,7,9,10). However, caution must be applied, as the true negative rates are rarely evaluated in studies (9). "
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    ABSTRACT: Fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) is used in the imaging workup of various malignancies. Incidental gastrointestinal observations on FDG PET/CT may be of clinical significance. The aim of the present study was to evaluate endoscopic and histopathological observations in patients referred for colonoscopy due to incidental FDG colonic uptake on a PET/CT study. Fifty-six patients with incidental colonic findings on FDG PET/CT underwent colonoscopy. Normal colonoscopies were observed in 63% of the patients. In 37% of the colonoscopies, we identified an endoscopic observation, including 67% with benign adenomatous polyps, 3% with hyperplastic polyps, 20% with advanced histological lesions and 10% with a malignancy.
    Oncology letters 02/2014; 7(2):479-482. DOI:10.3892/ol.2013.1702 · 1.55 Impact Factor
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    • "The differentiation between clinically relevant and irrelevant incidental gastrointestinal FDG uptake remains difficult. Since early diagnosis is fundamental in many pathological lesions (e.g., asymptomatic malignancies, premalignant lesions, and early stages of inflammatory bowel diseases), further examination, preferably by endoscopy, is strongly recommended in several studies (8-10). "
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    ABSTRACT: Suspicious incidental gastrointestinal FDG uptake during positron-emission tomography/computed tomography (PET/CT) examinations can be caused by different diseases, including malignancies. However, differentiation with PET alone is difficult. The aim of this study was to investigate the potential of PET alone, contrast-enhanced CT (ceCT), and low-dose CT (ldCT) in routine PET/CT protocols for differentiation of incidental gastrointestinal lesions. Sixty patients with incidental gastrointestinal lesions who underwent a routine PET/CT protocol with ldCT and ceCT were retrospectively analysed. The PET lesions were evaluated regarding their FDG uptake patterns and the standard uptake value. The anatomical correlates in both CT protocols were compared in regard to the correct lesion classification with the reference standard endoscopy. Sixty-two lesions were found in 60 patients (17 malignant, 10 premalignant, 5 benign, 13 inflammatory, 17 physiological). The differentiation of the FDG uptake patterns did not enable reliable lesion classification. The positive predictive value for pathology was 0.81 for ceCT in PET/CT and 0.70 for ldCT. Malignancies were detected in 100% of the patients by ceCT vs. 29.4% by ldCT. The false negative rate of ceCT for all pathologies was 31.1%, vs. 68.9% for ldCT. False positive results (17/62) could not be excluded sufficiently by either CT protocol. PET/ceCT protocols provide additional benefit especially in detecting gastrointestinal malignancies as a cause of suspicious incidental gastrointestinal FDG uptake. However, since follow-up endoscopy cannot be forgone due to the considerable false negative rate even with ceCT, the addition of ceCT to a routine PET/ldCT protocol cannot be recommended for this purpose.
    Korean journal of radiology: official journal of the Korean Radiological Society 11/2013; 14(6):951-959. DOI:10.3348/kjr.2013.14.6.951 · 1.57 Impact Factor
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    • "A study of incidental colonic FDG uptake in 15 patients and its correlation with colonoscopic and histopathologic findings [201] concluded that nodular high FDG uptake (on a four-point scale) implies at least a 79% chance of abnormal histopathology. Another evaluation of (pre-)malignant colonic abnormalities in 39 patients for endoscopic validation of FDG-PET [37] found that, compared with colonoscopy, FDG-PET had sensitivity of 74%, specificity of 84%, and positive predictive value of 78%, though it failed to detect small polyps in four patients. Further, in a study of wholebody PET/CT tumor staging with integrated PET/CT colonography [213], PET/CT colonography proved accurate in local lymph node staging and staged nine out of 11 patients correctly. "
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