title: Neuroendocrine tumor imaging with 68Ga-DOTA-NOC: physiologic and benign variants.
abstract: OBJECTIVE
  Imaging with (68)Ga-labeled 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-octreotide analogs has become an important modality in patients with neuroendocrine tumors (NETs). In addition to high uptake in NET lesions, prominent physiologic radiotracer activity has been reported in the pituitary gland, pancreas, adrenal glands, liver, and spleen, and faint activity has been reported in the thyroid and gastrointestinal tract. This article describes previously unknown sites of 68Ga-DOTA-1-NaI3-octreotide (NOC) uptake unrelated to NETs.
  
  
  METHODS
  One hundred eighty-two patients (96 female and 86 male patients; age range, 4-89 years) with documented (n=156) or suspected (n=26) NETs underwent 207 68Ga-DOTA-NOC PET/CT studies. Studies were retrospectively reviewed for the presence, intensity, and localization of foci of increased uptake that were further correlated with findings on additional imaging studies and clinical follow-up for a period of 4-32 months.
  
  
  RESULTS
  Uptake of 68Ga-DOTA-NOC not identified as NET or known physiologic activity was detected in 297 sites with confirmation in 149 of 207 studies (72%). The most common location of non-NET-related 68Ga-DOTA-NOC-avid sites was in small lymph nodes, followed by prostate, uterus, breasts, lungs, brown fat, musculoskeletal system, and other sites, including oropharynx, pineal body, thymus, aortic plaque, genitalia, surgical bed, and subcutaneous granuloma. Intensity of uptake in non-NET-related 68Ga-DOTA-NOC-avid sites ranged in maximum standardized uptake value from 0.8 to 10.5.
  
  
  CONCLUSIONS
  Previously unreported benign sites of 68Ga-DOTA-NOC uptake were found in the majority of studies, suggesting the presence of somatostatin receptors in physiologic variants or processes with no evidence of tumor. Knowledge of increased tracer uptake in non-NET-related sites is important for accurate interpretation and for avoiding potential pitfalls of 68Ga-DOTA-NOC PET/CT.
authors.affiliation: 1 Department of Nuclear Medicine, Rambam Health Care Campus, POB 9602, Haifa 31096, Israel.
authors.forename: Olga
authors.initials: O
authors.lastname: Kagna
authors.forename: Natalia
authors.initials: N
authors.lastname: Pirmisashvili
authors.forename: Sagi
authors.initials: S
authors.lastname: Tshori
authors.forename: Nanette
authors.initials: N
authors.lastname: Freedman
authors.forename: Ora
authors.initials: O
authors.lastname: Israel
authors.forename: Yodphat
authors.initials: Y
authors.lastname: Krausz
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D004701:Endocrine Gland Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D006801:Humans; D007557:Israel / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D018358:Neuroendocrine Tumors / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D009942:Organometallic Compounds; D049268:Positron-Emission Tomography / Q000706:statistics & numerical data; D015995:Prevalence; D011859:Radiography; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: C504894:68Ga-DOTANOC; D009942:Organometallic Compounds; D019275:Radiopharmaceuticals
keywords: 68Ga-DOTA-NOC; PET/CT; benign variants; neuroendocrine tumor (NET)