Cardiac iron determines cardiac T2*, T2, and T1 in the gerbil model of iron cardiomyopathy.
BACKGROUND
Transfusional therapy for thalassemia major and sickle cell disease can lead to iron deposition and damage to the heart, liver, and endocrine organs. Iron causes the MRI parameters T1, T2, and T2* to shorten in these organs, which creates a potential mechanism for iron quantification. However, because of the danger and variability of cardiac biopsy, tissue validation of cardiac iron estimates by MRI has not been performed. In this study, we demonstrate that iron produces similar T1, T2, and T2* changes in the heart and liver using a gerbil iron-overload model.


RESULTS
Twelve gerbils underwent iron dextran loading (200 mg . kg(-1) . wk(-1)) from 2 to 14 weeks; 5 age-matched controls were studied as well. Animals had in vivo assessment of cardiac T2* and hepatic T2 and T2* and postmortem assessment of cardiac and hepatic T1 and T2. Relaxation measurements were performed in a clinical 1.5-T magnet and a 60-MHz nuclear magnetic resonance relaxometer. Cardiac and liver iron concentrations rose linearly with administered dose. Cardiac 1/T2*, 1/T2, and 1/T1 rose linearly with cardiac iron concentration. Liver 1/T2*, 1/T2, and 1/T1 also rose linearly, proportional to hepatic iron concentration. Liver and heart calibrations were similar on a dry-weight basis.


CONCLUSIONS
MRI measurements of cardiac T2 and T2* can be used to quantify cardiac iron. The similarity of liver and cardiac iron calibration curves in the gerbil suggests that extrapolation of human liver calibration curves to heart may be a rational approximation in humans.
Wood
John C
JC
Division of Pediatric Cardiology, Department of Pediatrics and Radiology, Children's Hospital of Los Angeles, 4650 Sunset Blvd, Los Angeles, CA 90027, USA. jwood@chla.usc.edu
Otto-Duessel
Maya
M
Aguilar
Michelle
M
Nick
Hanspeter
H
Nelson
Marvin D
MD
Coates
Thomas D
TD
Pollack
Harvey
H
Moats
Rex
R
D000818:Animals; D002138:Calibration; D009202:Cardiomyopathies / Q000378:metabolism*; D005260:Female; D005849:Gerbillinae; D006801:Humans; D007501:Iron / Q000032:analysis* / Q000378:metabolism; D019190:Iron Overload / Q000378:metabolism*; D008099:Liver / Q000737:chemistry; D008279:Magnetic Resonance Imaging; D009206:Myocardium / Q000737:chemistry*; D015203:Reproducibility of Results; D013045:Species Specificity; D013789:Thalassemia / Q000628:therapy*; D065227:Transfusion Reaction
D007501:Iron