title: Measured human dosimetry of 68Ga-DOTATATE.
abstract: Measured human dosimetry of the (68)Ga-labeled synthetic somatostatin analog (68)Ga-DOTATATE has not been reported in the peer-reviewed literature. (68)Ga-DOTATATE is an investigational PET/CT imaging agent that binds with high affinity to somatostatin receptor subtype 2, found on many human cancers, most classically neuroendocrine tumors but also others. Reporting of measured dosimetry of (68)Ga-DOTATATE could be useful for investigations for diagnosis, staging, and restaging of somatostatin receptor-expressing tumors.
  
  
  METHODS
  We performed measured dosimetry with (68)Ga-DOTATATE PET/CT scanning in 6 volunteer human subjects as part of an Institutional Review Board-approved biodistribution investigation of the use of this radiopharmaceutical for possible future use in the diagnosis of indeterminate lung nodules or lung cancer. Five subjects were imaged at 3 time points, and 1 subject was imaged at 2 time points. Dosimetry was then measured for the whole body and for specific organs.
  
  
  RESULTS
  There were no observed adverse events to the radiopharmaceutical in the immediate or delayed time frames, with a follow-up of 1 y. One patient had stage IV non-small cell lung cancer and remains alive but with disease progressing on treatment. For the other 5 patients, it was ultimately proven that they had benign nodules. The measured dosimetry shows that the critical organ with (68)Ga-DOTATATE is the spleen, followed by the uroepithelium of the bladder, the kidneys, and the liver, in that order. Organ-specific and whole-body dosimetries for (68)Ga-DOTATATE were similar to but often slightly greater than those for (68)Ga-DOTATOC or (68)Ga-DOTANOC but less than those for (111)In-diethylenetriaminepentaacetic acid-octreotide.
  
  
  CONCLUSIONS
  No toxicity was observed in our 6 patients, and no adverse events occurred. The measured human dosimetry of (68)Ga-DOTATATE is similar to that of other (68)Ga-labeled somatostatin receptor analogs.
authors.affiliation: Medical Imaging Service, Veterans Affairs Tennessee Valley Healthcare System, Nashville, Tennessee 37232-2675, USA. ronald.walker@vanderbilt.edu
authors.forename: Ronald C
authors.initials: RC
authors.lastname: Walker
authors.forename: Gary T
authors.initials: GT
authors.lastname: Smith
authors.forename: Eric
authors.initials: E
authors.lastname: Liu
authors.forename: Brandon
authors.initials: B
authors.lastname: Moore
authors.forename: Jeff
authors.initials: J
authors.lastname: Clanton
authors.forename: Michael
authors.initials: M
authors.lastname: Stabin
mesh_terms: D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis; D008297:Male; D009942:Organometallic Compounds / Q000009:adverse effects / Q000493:pharmacokinetics*; D011874:Radiometry
chemical_list: D009942:Organometallic Compounds; C513399:gallium Ga 68 dotatate
keywords: 68Ga-DOTATATE; dosimetry; neuroendocrine tumors