title: Incidental focal uptake in colorectal location on oncologic ¹⁸FDG PET and PET/CT studies: histopathological findings and clinical significances.
abstract: OBJECTIVE
  Unexpected focal colonic or rectal radiotracer activity is an usual finding in patients subjected to a PET study. The aim of this work has been to evaluate the clinical significance of this finding in the prediction of an existing colorectal malignancy.
  
  
  METHODS
  During the last three years, all patients studied with (18)F-FDG PET/CT and PET for oncologic work-up purposes were prospectively surveyed for focal colorectal radiotracer activity. Colonoscopy was performed in all patients with this incidental finding in order to exclude colonic malignancy. CEA level, maximum standardized uptake value (SUVmax), CT findings, colonoscopy findings and histopathological results were prospectively analyzed in all patients.
  
  
  RESULTS
  A total of 2290 patients were evaluated, 158 of whom were studied with PET and the remainder with a hybrid PET/CT. Focal FDG colorectal activity was incidentally detected in 27 patients with no previous history of colorectal cancer. Colorectal adenocarcinoma was diagnosed in seven (25.9%) patients. A pre-cancerous lesion was found in eleven patients (40.7%). Eight patients (29.6%) had no macroscopic lesions. One patient was diagnosed with a benign lesion. Any focal activity found in the colon by (18)F-FDG PET/CT examination predicts a probability greater than 50% of an underlying malignant or premalignant lesion in the histopathological analysis (logistic regression, p=0.01), independently of the calculated SUVmax.
  
  
  CONCLUSIONS
  According to the results of the present study, we recommend the performance of a colonoscopy and biopsy of any suspicious lesions, in all patients with unexpected focal FDG activity found in colon or rectum during a (18)F-FDG PET/CT examination.
authors.affiliation: Nuclear Medicine Department, Hospital Universitari Sant Joan, Reus, Tarragona, Spain. Electronic address: jfm35709@yahoo.es.
authors.forename: Jordi
authors.initials: J
authors.lastname: Fuertes
authors.affiliation: Medical Oncology Department, University Hospital del Mar-IMIM, Universitat Pompeu Fabra, Parc de Salut Mar, Barcelona, Spain. Electronic address: cmontagut@parcdesalutmar.cat.
authors.forename: Clara
authors.initials: C
authors.lastname: Montagut
authors.affiliation: Molecular Imaging Centre, Barcelona Biomedical Research Park, Barcelona, Spain. Electronic address: sbullich@gmail.com.
authors.forename: Santi
authors.initials: S
authors.lastname: Bullich
authors.affiliation: Pathology Department, University Hospital del Mar-IMIM, Universitat Pompeu Fabra, Parc de Salut Mar, Barcelona, Spain. Electronic address: miglesias@parcdesalutmar.cat.
authors.forename: Mar Iglesias
authors.initials: MI
authors.lastname: Coma
authors.affiliation: Nuclear Medicine Department, University Hospital del Mar, Parc de Salut Mar, Barcelona, Spain. Electronic address: tonimefu@hotmail.com.
authors.forename: Antoni
authors.initials: A
authors.lastname: Mestre-Fusco
authors.affiliation: Nuclear Medicine Department, University Hospital del Mar, Parc de Salut Mar, Barcelona, Spain. Electronic address: marina.suarez@crccorp.es.
authors.forename: Marina
authors.initials: M
authors.lastname: Suárez-Piñera
authors.affiliation: Molecular Imaging Centre, Barcelona Biomedical Research Park, Barcelona, Spain. Electronic address: carlostrampal@gmail.com.
authors.forename: Carlos
authors.initials: C
authors.lastname: Trampal
authors.affiliation: Medical Oncology Department, University Hospital del Mar-IMIM, Universitat Pompeu Fabra, Parc de Salut Mar, Barcelona, Spain. Electronic address: jbellmunt@parcdesalutmar.cat.
authors.forename: Joaquim
authors.initials: J
authors.lastname: Bellmunt
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D018253:Adenoma, Villous / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D003106:Colon / Q000737:chemistry* / Q000473:pathology; D003111:Colonic Polyps / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D005260:Female; D005462:Fluorine Radioisotopes / Q000493:pharmacokinetics*; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D000072078:Positron Emission Tomography Computed Tomography; D049268:Positron-Emission Tomography; D011230:Precancerous Conditions / Q000378:metabolism / Q000473:pathology; D011446:Prospective Studies; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics*; D012007:Rectum / Q000737:chemistry* / Q000473:pathology
chemical_list: D005462:Fluorine Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: Actividad focal; Adenocarcinoma; Benign colorectal lesion; CT; Colorectal cancer; Cáncer colorectal; FDG; Focal activity; Lesión colorectal benigna; Neoplasia sincrónica; PET/CT; PET/TAC; Second neoplasm; Segunda neoplasia; Synchronous neoplasm; TAC