title: Frequency and characteristics of extremely low accumulation of 123I-metaiodobenzylguanidine (MIBG) in patients with and without cardiovascular diseases.
abstract: OBJECTIVE
  Very low accumulation of 123I-metaiodobenzylguanidine (LoMIBG) in the human heart has been reported. This study assessed the frequency and characteristics of LoMIBG in the human heart.
  
  
  METHODS
  A total of 2212 patients (male/female ratio 1442/770, mean age 64 +/- 12 years) who underwent MIBG imaging were included. LoMIBG was defined as an initial heart-to-mediastinum (H/M) ratio of less than 1.4.
  
  
  RESULTS
  Of the 114 patients with LoMIBG, 2 patients were excluded because of taking imipramine. Patients with LoMIBG were older than those without LoMIBG (P < 0.0001). The main diagnosis and the number of patients with each disease were as follows: 28 of 410 coronary artery disease patients, 13 of 371 vasospastic angina patients, 3 of 86 various arrhythmias patients, 4 of 23 valvular heart disease patients, 9 of 101 dilated cardiomyopathy patients, 13 of 512 essential hypertension patients, 2 of 20 hypertrophic cardiomyopathy patients, 24 of 511 subjects without any definite disease (control), and 16 of 176 patients with miscellaneous diseases. When compared with patients without LoMIBG in each cardiovascular disease, LoMIBG patients had left ventricular function and frequency similar to critically ill patients. In the control group, the subjects with LoMIBG were significantly older (P < 0.0001) and had significantly higher HF (P < 0.03) and lower LF/HF (P < 0.001) than those without LoMIBG. In addition, the incidence of LoMIBG was significantly elevated in the elderly (P < 0.002).
  
  
  CONCLUSIONS
  LoMIBG occurred in patients both with various diseases and without obvious diseases. Aging may be one of the mechanisms contributing to LoMIBG, especially in patients without obvious diseases.
authors.affiliation: Division of Cardiology, Shizuoka Cancer Center Hospital, 1007 Shimonagakubo, Sunto, Shizuoka, 411-8777, Japan. k.sakata@scchr.jp
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Sakata
authors.forename: Kei
authors.initials: K
authors.lastname: Iida
authors.forename: Nao
authors.initials: N
authors.lastname: Motiduki
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Nakaya
mesh_terms: D019797:3-Iodobenzylguanidine / Q000493:pharmacokinetics*; D000375:Aging / Q000378:metabolism*; D002318:Cardiovascular Diseases / Q000000981:diagnostic imaging* / Q000378:metabolism*; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism*; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014018:Tissue Distribution
chemical_list: D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine