title: I-123-MIBG cardiac uptake imaging, in familial dilated cardiomyopathy.
abstract: The pathological significance of myocardial adrenergic activity in patients with heart failure is well documented. No previous study has assessed the usefulness of I123-metaiodobenzylguanidine (123I-MIBG) cardiac uptake imaging for the evaluation of familial dilated cardiomyopathy (DCM).
  
  
  OBJECTIVE
  To evaluate cardiac adrenergic activity, using 123I-MIBG cardiac uptake imaging, in members of a genotyped family with DCM.
  
  
  METHODS
  Clinical evaluation, 12-lead ECG, 2D echocardiogram, heart rate variability analysis by 24h Holter, plasma B-type natriuretic peptide (BNP) measurements and 123I-MIBG cardiac imaging were performed in all participants. Anterior projection planar images and single photon emission computed tomographies of the thorax were obtained 20 min and 4 hours after the intravenous administration of 370 MBq of 123I-MIBG (early and late images). Heart/mediastinal (H/M) ratio and myocardial washout (MW) rate were obtained based on the anterior planar images. In polar maps, segmental uptake of 123I-MIBG was evaluated using a 4-grade visual score: grade 1 - uptake > 75% of maximum myocardial uptake (MMU); grade 2 - uptake 51-75% of MMU; grade 3 - uptake 26-50% of MMU; grade 4 - uptake < or = 25% of MMU.
  
  
  RESULTS
  Eleven adults were included: 4 with DCM, 4 with isolated left ventricular enlargement (LVE), and 3 with normal echocardiogram. Patients with DCM and LVE presented higher MW rates, lower H/M ratios and higher visual score grades than those with normal 2D echocardiograms. One patient with a normal echocardiogram but carrying the disease locus also presented an abnormal MIBG cardiac scintigram.
  
  
  CONCLUSIONS
  Patients with the phenotypic expression of the disease (DCM and LVE) and even carriers of the DCM gene with normal echocardiograms may present an abnormal MIBG cardiac scintigram, probably reflecting cardiac adrenergic hyperactivity. If confirmed in larger numbers, this method may be useful for the evaluation of DCM families.
authors.affiliation: Faculdade de Medicina do Porto, Serviço de Cardiologia, Hospital de São João, Porto, Portugal. elisabetemartins09@gmail.com
authors.forename: Elisabete
authors.initials: E
authors.lastname: Martins
authors.forename: Teresa
authors.initials: T
authors.lastname: Faria
authors.forename: J
authors.initials: J
authors.lastname: Silva-Cardoso
authors.forename: Ana
authors.initials: A
authors.lastname: Oliveira
authors.forename: Manuel
authors.initials: M
authors.lastname: Campelo
authors.forename: Sandra
authors.initials: S
authors.lastname: Amorim
authors.forename: Brenda
authors.initials: B
authors.lastname: Moura
authors.forename: F
authors.initials: F
authors.lastname: Rocha-Gonçalves
authors.forename: Jorge G
authors.initials: JG
authors.lastname: Pereira
authors.forename: M Júlia
authors.initials: MJ
authors.lastname: Maciel
mesh_terms: D019797:3-Iodobenzylguanidine / Q000378:metabolism; D000328:Adult; D000368:Aged; D002311:Cardiomyopathy, Dilated / Q000000981:diagnostic imaging* / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism; D010865:Pilot Projects; D011877:Radionuclide Imaging
chemical_list: D019797:3-Iodobenzylguanidine