title: Iodine-123 metaiodobenzylguanidine scintigraphy for the assessment of cardiac sympathetic innervation and the relationship with cardiac autonomic function in healthy adults using standardized methods.
abstract: BACKGROUND
  Global iodine-123 metaiodobenzylguanidine (I-MIBG) uptake is predictive of cardiovascular events and mortality in patients with heart failure. Normal variations in global and regional uptake, however, are not well defined and few studies have addressed the functional relevance of I-MIBG uptake and distribution in healthy individuals.
  
  
  METHODS
  We performed I-MIBG scintigraphy and cardiac autonomic function testing using the standardized methodology in 15 healthy individuals (mean age 54.6±5.3 years, male : female 10 : 5) with no evidence of previous myocardial infarction or ischaemic heart disease.
  
  
  RESULTS
  Early heart to mediastinum ratio (HMR) was 1.67±0.13, late HMR was 1.73±0.16 and washout rate was 19.09±7.63% (4.20-31.30). Regional analysis showed reduced tracer uptake at the apex, base and inferior wall in all individuals. Early and late HMR correlated negatively with RFa (r=-0.603; P=0.05 and r=-0.644; P=0.033) and expiration and inspiration ratio (r=-0.616; P=0.043 and r=-0.676; P=0.022) and positively with LFa/RFa (r=0.711; P=0.014 and r=0.784; P=0.004). Washout rate correlated only with RFa (r=0.642; P=0.033).
  
  
  CONCLUSIONS
  Healthy adults show a heterogeneous pattern of cardiac innervation with reduced regional uptake of I-MIBG. Furthermore, HMR correlates with indices of cardiac sympathetic function, suggesting that it might not only be a useful prognostic marker but may also provide insight into the functional integrity of the cardiac autonomic nervous system.
authors.affiliation: aInstitute of Cardiovascular Sciences, University of Manchester & Manchester Heart Centre, Central Manchester Foundation Trust bDepartment of Nuclear Medicine, Central Manchester Foundation Trust cNorth West Cardiac Imaging Centre, University Hospital of South Manchester dInstitute of Human Development, University of Manchester, Manchester, UK eDepartment of Medicine, Weill Cornell Medical College, Doha, Qatar.
authors.forename: Omar
authors.initials: O
authors.lastname: Asghar
authors.forename: Parthiban
authors.initials: P
authors.lastname: Arumugam
authors.forename: Ian
authors.initials: I
authors.lastname: Armstrong
authors.forename: Simon
authors.initials: S
authors.lastname: Ray
authors.forename: Matthias
authors.initials: M
authors.lastname: Schmitt
authors.forename: Rayaz A
authors.initials: RA
authors.lastname: Malik
mesh_terms: D019797:3-Iodobenzylguanidine; D000328:Adult; D001341:Autonomic Nervous System / Q000000981:diagnostic imaging* / Q000502:physiology; D005260:Female; D064368:Healthy Volunteers; D006321:Heart / Q000000981:diagnostic imaging* / Q000294:innervation* / Q000502:physiology; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D019275:Radiopharmaceuticals; D012016:Reference Values; D013564:Sympathetic Nervous System / Q000000981:diagnostic imaging* / Q000502:physiology; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods* / Q000706:statistics & numerical data
chemical_list: D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine