Evaluation of (pre-)malignant colonic abnormalities: endoscopic validation of FDG-PET findings
ABSTRACT 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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ABSTRACT: In dual-time-point PET/CT, early delayed scanning (D-1) just after the completion of whole body scanning (E) is easy to perform without additional radiation exposure and repositioning. Our aim was to assess the clinical value of D-1 compared with conventional delayed scanning (D-2). Our institutional review board approved this retrospective study. Fifty-four patients with known or suspected colorectal cancer underwent (18)F-FDG PET/CT at our institution. The E scan at 1-h post-injection was followed by D-1 at 85 ± 7 min post-injection and D-2 at 124 ± 7 min post-injection. The clinical value of D-1 was evaluated by comparing diagnostic performance with D-2 for differentiating physiologic from pathological uptake and for staging colorectal cancer. Colonoscopic findings, histopathological results and clinical follow-up including radiological findings were used as reference standards. Thirty-two, eight and 73 focal or short segmental FDG foci by physiologic processes in the colon/rectum, the small intestine and the ureter, respectively, noted in the E scan were evaluated in this study. Using D-1 and D-2, 14/32 (44%) and 17/32 (53%) in the colon/rectum, 5/8 (63%) and 8/8 (100%) in the small intestine, and 55/73 (75%) and 69/73 (95%) in the ureter, respectively, were accurately interpreted as physiologic with the change of intensity and/or shape/location. A significant difference between D-1 and D-2 was observed in the ureter, but not in the bowel. The 55 colorectal cancers were finally diagnosed in 52 patients. In the staging of colorectal cancer, there were no significant differences among the three scans in the lesion-based detectability, the patient-based sensitivity, specificity and accuracy for the identification of primary tumors, nodal and hepatic metastases, and dissemination. Neither D-1 nor D-2 improved staging of colorectal cancer. However, delayed scans yielded information useful for differentiating physiologic uptake from pathological uptake and D-1 may provide comparable efficacy with D-2 in the bowel. Because of the ease of acquisition, the D-1 scan was considered a practical way to reduce false-positives in the abdomen and possibly helpful to avoid unnecessary additional invasive examinations, such as colonoscopy.Annals of Nuclear Medicine 04/2012; 26(6):492-500. · 1.41 Impact Factor
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ABSTRACT: PURPOSE: The aim of this study was to evaluate the interpretations of incidental colonic 18F-FDG uptake made by 10 experienced readers and to more clearly identify the pattern of suspicious colonic FDG uptake. The potential contributions of delayed FDG-PET scanning and of immune fecal occult blood testing (FOBT) in making a diagnosis were also analyzed. MATERIALS AND METHODS: Visual interpretations by 10 readers were made for 147 FDG uptake sites from 126 PET scans (cancer, 38 sites; adenoma, 43 sites; and no abnormality, 66 sites) with colonic FDG uptake. Assessments for the early FDG-PET images were (1) FDG uptake pattern, (2) FDG uptake degree, and (3) likelihood of malignancy. For the delayed images, the assessments were (1) change in the FDG uptake position, (2) change in FDG uptake degree, and (3) likelihood of malignancy. The results of FOBT were analyzed independently of the visual interpretations. RESULTS: Interobserver agreement (κ) was 0.501 for assessing FDG uptake patterns, while agreement on assessing changes in uptake degree and changes in uptake position between early and delayed imaging were low (κ = 0.213-0.229). Logistic regression analysis indicated that 'FDG uptake patterns' and 'FDG uptake degree' were significantly related to decide on the suspicion of malignancy (p < 0.001) and the final result (p < 0.001). "Small localized" and "large irregular localized" types had a high probability of a lesion regardless of either (1) FDG uptake degree or (2) variation in the uptake between the early and the delayed image. The delayed image decreased false-positive cases for some FDG uptake patterns, but it had little impact on distinguishing clearly between "cancer or adenoma" and "normal". The addition of FOBT had little impact on the diagnosis. CONCLUSION: There was highest agreement among readers with respect to the recognition of specified colonic FDG uptake patterns, and this pattern recognition had the most influence on the diagnosis. "Small localized" and "large irregular localized" types had a high probability of a lesion. The addition of delayed imaging and of FOBT results to the early imaging did not have much impact on the diagnosis.Annals of Nuclear Medicine 03/2013; · 1.41 Impact Factor
- Clinical endoscopy. 06/2012; 45(2):109-10.