Influence of age and gender on iodine-123 MIBG kinetics in normal lung.
Iodine-123 MIBG is a biochemical marker that can be used to monitor pulmonary norepinephrine (NE) metabolism. The purpose of this study was to characterize pulmonary I-123 MIBG kinetics in relation to age and gender.


METHODS
Seventeen healthy volunteers and 14 patients with no cardiac or pulmonary disorders were included in this study (age range: 24 to 88 years, mean age 50.2 +/- 17.6 years; 16 males, 15 females). Planar images were obtained 15 min (early) and 3 h (delayed) after injection of I-123 MIBG (111 MBq). Pulmonary uptake of I-123 MIBG was quantified based on the lung-to-mediastinum ratio (LMR) on early and delayed images. The lung clearance rate (LCR) was calculated form both the early and delayed images.


RESULTS
Both early and delayed LMR values increased slightly, although they showed no significant correlations with age. There was a significant inverse correlation between LCR and age (r = -0.57, p < 0.001). Neither LCR nor LMR differed significantly between male and female patients, but the mean age of the men was lower than that of the women.


CONCLUSIONS
Pulmonary I-123 MIBG kinetics may reflect age-dependent changes in NE metabolism. The effects of age should be taken into account when assessing pulmonary NE metabolism with I-123 MIBG.
Kanzaki
N
N
Department of Radiology, Okayama University School of Medicine, Japan.
Soda
R
R
Takahashi
K
K
Sato
K
K
Hayabara
T
T
Kibata
M
M
Takeda
Y
Y
Hiraki
Y
Y
D019797:3-Iodobenzylguanidine / Q000493:pharmacokinetics*; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008168:Lung / Q000000981:diagnostic imaging / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics*; D012737:Sex Factors
D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine