title: Clinical performance and radiation dosimetry of no-carrier-added vs carrier-added 123I-metaiodobenzylguanidine (MIBG) for the assessment of cardiac sympathetic nerve activity.
abstract: OBJECTIVE
  We hypothesized that assessment of myocardial sympathetic activity with no-carrier-added (nca) (123)I-meta-iodobenzylguanidine (MIBG) compared to carrier-added (ca) (123)I-MIBG would lead to an improvement of clinical performance without major differences in radiation dosimetry.
  
  
  METHODS
  In nine healthy volunteers, 15 min and 4 h planar thoracic scintigrams and conjugate whole-body scans were performed up to 48 h following intravenous injection of 185 MBq (123)I-MIBG. The subjects were given both nca and ca (123)I-MIBG. Early heart/mediastinal ratios (H/M), late H/M ratios and myocardial washout were calculated. The fraction of administered activity in ten source organs was quantified from the attenuation-corrected geometric mean counts in conjugate views. Radiation-absorbed doses were estimated with OLINDA/EXM software.
  
  
  RESULTS
  Both early and late H/M were higher for nca (123)I-MIBG (ca (123)I-MIBG early H/M 2.46 +/- 0.15 vs nca (123)I-MIBG 2.84 +/- 0.15, p = 0.001 and ca (123)I-MIBG late H/M 2.69 +/- 0.14 vs nca (123)I-MIBG 3.34 +/- 0.18, p = 0.002). Myocardial washout showed a longer retention time for nca (123)I-MIBG (p < 0.001). The effective dose equivalent (adult male model) for nca (123)I-MIBG was similar to that for ca (123)I-MIBG (0.025 +/- 0.002 mSv/MBq vs 0.026 +/- 0.002 mSv/MBq, p = 0.055, respectively).
  
  
  CONCLUSIONS
  No-carrier-added (123)I-MIBG yields a higher relative myocardial uptake and is associated with a higher myocardial retention. This difference between nca (123)I-MIBG and ca (123)I-MIBG in myocardial uptake did not result in major differences in estimated absorbed doses. Therefore, nca (123)I-MIBG is to be preferred over ca (123)I-MIBG for the assessment of cardiac sympathetic activity.
authors.affiliation: Department of Nuclear Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. h.j.verberne@amc.uva.nl
authors.forename: Hein J
authors.initials: HJ
authors.lastname: Verberne
authors.forename: Ellinor Busemann
authors.initials: EB
authors.lastname: Sokole
authors.forename: Astrid F
authors.initials: AF
authors.lastname: van Moerkerken
authors.forename: Joop H W M
authors.initials: JH
authors.lastname: Deeterink
authors.forename: Geert
authors.initials: G
authors.lastname: Ensing
authors.forename: Michael G
authors.initials: MG
authors.lastname: Stabin
authors.forename: G Aernout
authors.initials: GA
authors.lastname: Somsen
authors.forename: Berthe L F
authors.initials: BL
authors.lastname: van Eck-Smit
mesh_terms: D019797:3-Iodobenzylguanidine / Q000008:administration & dosage / Q000493:pharmacokinetics*; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging; D006329:Heart Conduction System; D006801:Humans; D007267:Injections; D007457:Iodine Radioisotopes / Q000008:administration & dosage / Q000493:pharmacokinetics*; D007700:Kinetics; D008297:Male; D011877:Radionuclide Imaging; D012016:Reference Values; D013564:Sympathetic Nervous System / Q000000981:diagnostic imaging*; D014018:Tissue Distribution; D014916:Whole-Body Irradiation / Q000379:methods
chemical_list: D007457:Iodine Radioisotopes; D019797:3-Iodobenzylguanidine