title: In Vivo Measurement and Characterization of a Novel Formulation of [177Lu]-DOTA-Octreotate.
abstract: OBJECTIVE
  Lutetium-177 can be made with high specific activity and with no other isotopes of lutetium present, referred to as "No Carrier Added" (NCA)177Lu. We have radiolabelled DOTA-conjugated peptide DOTA-(Tyr3)-octreotate with NCA177Lu ("NCA-LuTATE") and used it in nearly 40 therapeutic administrations for subjects with neuroendocrine tumours or meningiomas. In this paper, we report on our initial studies on aspects of the biodistribution and dosimetry of NCA-LuTATE from gamma camera 2D whole body (WB) and quantitative 3D SPECT (qSPECT)177Lu imaging.
  
  
  METHODS
  Thirteen patients received 39 NCA-LuTATE injections. Extensive WB planar and qSPECT imaging was acquired at approximately 0.5, 4, 24 and 96 h to permit estimates of clearance and radiation dose estimation using MIRD-based methodology (OLINDA-EXM).
  
  
  RESULTS
  The average amount of NCA-Lutate administered per cycle was 7839±520 MBq. Bi-exponential modelling of whole body clearance showed half lives for the fast & slow components of t½=2.1±0.6 h and t½=58.1±6.6 h respectively. The average effective dose to kidneys was 3.1±1.0 Gy per cycle. In eight patients completing all treatment cycles the average total dose to kidneys was 11.7±3.6 Gy.
  
  
  CONCLUSIONS
  We have shown that NCA-LuTATE has an acceptable radiation safety profile and is a suitable alternative to Carrier-Added177Lu formulations. The fast component of the radiopharmaceutical clearance was closely correlated with baseline renal glomerular filtration rate, and this had an impact on radiation dose to the kidneys. In addition, it has less radioactive waste issues and requires less peptide per treatment.
authors.affiliation: Department of Nuclear Medicine, Royal North Shore Hospital, Sydney, Australia.
authors.forename: Dale L
authors.initials: DL
authors.lastname: Bailey
authors.affiliation: Department of Nuclear Medicine, Prince of Wales Hospital Randwick, Sydney Australia.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Hennessy
authors.affiliation: Institute of Medical Physics, University of Sydney, Sydney, Australia.
authors.forename: Kathy P
authors.initials: KP
authors.lastname: Willowson
authors.affiliation: Institute of Medical Physics, University of Sydney, Sydney, Australia.
authors.forename: E Courtney
authors.initials: EC
authors.lastname: Henry
authors.affiliation: Department of Nuclear Medicine, Royal North Shore Hospital, Sydney, Australia.
authors.forename: David Lh
authors.initials: DL
authors.lastname: Chan
authors.affiliation: Department of Nuclear Medicine, Royal North Shore Hospital, Sydney, Australia.
authors.forename: Alireza
authors.initials: A
authors.lastname: Aslani
authors.affiliation: Department of Nuclear Medicine, Royal North Shore Hospital, Sydney, Australia.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Roach
keywords: Neuroendocrine tumour; Peptide receptor radionuclide therapy (PRRT); Quantification; SPECT