ABSTRACT
PURPOSE: In patients undergoing (18)F-FDG PET/CT, incidental colonic focal lesions can be indicative of inflammatory, premalignant or malignant lesions. The maximum standardized uptake value (SUVmax) of these lesions, representing the FDG uptake intensity, might be helpful in differentiating malignant from benign lesions, and thereby be helpful in determining the urgency of colonoscopy. The aim of our study was to assess the incidence and underlying pathology of incidental PET-positive colonic lesions in a large cohort of patients, and to determine the usefulness of the SUVmax in differentiating benign from malignant pathology. METHODS: The electronic records of all patients who underwent FDG PET/CT from January 2010 to March 2013 in our hospital were retrospectively reviewed. The main indications for PET/CT were: characterization of an indeterminate mass on radiological imaging, suspicion or staging of malignancy, and suspicion of inflammation. In patients with incidental focal FDG uptake in the large bowel, data regarding subsequent colonoscopy were retrieved, if performed within 120 days. The final diagnosis was defined using colonoscopy findings, combined with additional histopathological assessment of the lesion, if applicable. RESULTS: Of 7,318 patients analysed, 359 (5 %) had 404 foci of unexpected colonic FDG uptake. In 242 of these 404 lesions (60 %), colonoscopy follow-up data were available. Final diagnoses were: adenocarcinoma in 25 (10 %), adenoma in 90 (37 %), and benign in 127 (53 %). The median [IQR] SUVmax was significantly higher in adenocarcinoma (16.6 [12 - 20.8]) than in benign lesions (8.2 [5.9 - 10.1]; p < 0.0001), non-advanced adenoma (8.3 [6.1 - 10.5]; p < 0.0001) and advanced adenoma (9.7 [7.2 - 12.6]; p < 0.001). The receiver operating characteristic curve of SUVmax for malignant versus nonmalignant lesions had an area under the curve of 0.868 (SD ± 0.038), the optimal cut-off value being 11.4 (sensitivity 80 %, specificity 82 %, positive predictive value 34 %, negative predictive value 98 %). CONCLUSION: In these patients with incidental colonic focal activity undergoing PET/CT (the largest series published to date), malignancies had significantly higher SUVmax values than all other types of lesions. However, SUVmax could not distinguish between benign lesions and adenomas. In conclusion, all incidental findings in the colon should be further evaluated and lesions with SUVmax ≥11.4 should be evaluated without delay.
Subject(s)
Colonic Neoplasms/diagnostic imaging , Colonoscopy , Incidental Findings , Positron-Emission Tomography , Tomography, X-Ray Computed , Aged , Colonic Neoplasms/pathology , Diagnosis, Differential , Female , Fluorodeoxyglucose F18 , Humans , Male , Middle Aged , Multimodal Imaging , RadiopharmaceuticalsABSTRACT
Three patients with hepatic cirrhosis and ascites, a 65-year-old man, a 17-year-old woman and a 49-year-old man, were admitted to hospital for progressive drowsiness, increased ascites, and melaena, respectively. An elevated number of polymorphonuclear leukocytes was found in the ascites. The three patients became more and more seriously ill. On the basis of the laboratory findings, a diagnosis of 'spontaneous bacterial peritonitis' was made. The patients recovered after administration of antibiotics. The signs and symptoms of spontaneous bacterial peritonitis can range from subtle, renal dysfunction or an altered mental state to the signs ofan acute abdomen. The common signs of infection such as fever and an elevated leukocyte count are present in only 50% of the patients. Gram-negative bacteria are most frequently isolated from cultures of the ascites fluid. The 1-year mortality is still 50-70% and is partly a result of the underlying liver disease. Prophylactic oral administration of a quinolone decreases the risk of spontaneous bacterial peritonitis in patients with gastrointestinal haemorrhage and in patients with a prior episode of spontaneous bacterial peritonitis. Long-term prophylaxis has been associated with the development of infections with quinolone-resistant microorganisms.
