title: Predictive value of 68Ga-DOTANOC PET/CT in patients with suspicion of neuroendocrine tumors: is its routine use justified?
abstract: OBJECTIVE
  The objective of this study was to evaluate the predictive value of Ga-DOTANOC PET/CT in patients with suspected neuroendocrine tumor (NET).
  
  
  METHODS
  Data of 164 patients (mean age, 42.5 ± 17.3 years; 54.8% male) who underwent Ga-DOTANOC PET/CT for suspected NET were retrospectively analyzed. Neuroendocrine tumor was suspected based on clinical features (n = 94) and/or raised biochemical markers (n = 83, serum chromogranin A, gastrin, serum/urinary catecholamines, insulin/C-peptide, and 5-hydroxytrytophan/5-hydroxyindoleacetic acid) and/or imaging findings (n = 93). PET/CT images were reviewed by 2 experienced nuclear medicine physicians, and any nonphysiological Ga-DOTANOC uptake was taken as positive for NET. Histopathology (n = 55) and clinical/imaging follow-up (n = 109; median, 11 months) was used as reference standard.
  
  
  RESULTS
  Based on the reference standard, 97 of 164 patients had NET. Ga-DOTANOC PET/CT was positive for NET in 101 and negative in 63 patients. Primary tumor was demonstrated in 90 patients (commonest site-pancreas) and metastasis in 30 (commonest site-liver). PET/CT was true positive in 92 patients, true negative in 58, false positive in 9, and false negative in 5. The overall sensitivity was 94.8%, specificity was 86.5%, positive predictive value was 91%, negative predictive value was 92%, and accuracy was 91.4%. The accuracy of PET-CT in patients with clinical features of NET was 90.4%, with raised biochemical markers was 86.7%, and with imaging findings suggestive of NET was 93.5%. No difference was seen in the accuracy in patients with or without clinical symptoms (P = 0.794), raised versus those with normal/unknown biochemical markers (P = 0.094), and suggestive imaging versus those with negative/unavailable imaging (P = 0.420).
  
  
  CONCLUSIONS
  Ga-DOTANOC PET-CT shows high positive and negative predictive values in patients with suspected NET and can be routinely used for this purpose.
authors.affiliation: From the Departments of *Nuclear Medicine, †Surgical Gastroenterology, ‡Gastroenterology and Human Nutrition, §Endocrinology and Metabolism, and ¶Radiodiagnosis, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Punit
authors.initials: P
authors.lastname: Sharma
authors.forename: Saurabh
authors.initials: S
authors.lastname: Arora
authors.forename: Anirban
authors.initials: A
authors.lastname: Mukherjee
authors.forename: Sujoy
authors.initials: S
authors.lastname: Pal
authors.forename: Peush
authors.initials: P
authors.lastname: Sahni
authors.forename: Pramod
authors.initials: P
authors.lastname: Garg
authors.forename: Rajesh
authors.initials: R
authors.lastname: Khadgawat
authors.forename: Sanjay
authors.initials: S
authors.lastname: Thulkar
authors.forename: Chandrasekhar
authors.initials: C
authors.lastname: Bal
authors.forename: Rakesh
authors.initials: R
authors.lastname: Kumar
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D018358:Neuroendocrine Tumors / Q000000981:diagnostic imaging* / Q000378:metabolism; D009942:Organometallic Compounds; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D055815:Young Adult
chemical_list: C504894:68Ga-DOTANOC; D009942:Organometallic Compounds