Normal and infarcted myocardium: differentiation with cellular uptake of manganese at MR imaging in a rat model.
OBJECTIVE
To assess whether normal myocardium can be distinguished from infarction at magnetic resonance (MR) imaging with low doses of manganese dipyridoxyl diphosphate (Mn-DPDP).


METHODS
After 1-hour coronary arterial occlusion and 2-hour reperfusion, three groups of eight rats each were injected with 25, 50, or 100 micromol of Mn-DPDP per kilogram of body weight. The longitudinal relaxation rate (R1) in normal myocardium, reperfused infarction, and blood was repeatedly measured at inversion-recovery echo-planar imaging before and for 1 hour after the administration of contrast material. Afterward, several animals from each group were examined at high-spatial-resolution inversion-recovery spin-echo (SE) MR imaging.


RESULTS
Manganese accumulated in normal myocardium but was cleared from reperfused infarction and blood. One hour after the administration of Mn-DPDP, R1 in normal myocardium (1.53 sec(-1) +/- 0.03, 1.73 sec(-1) +/- 0.03, and 1.94 sec(-1) +/- 0.02, respectively, for 25, 50, and 100 micromol/kg) was significantly (P <.05) faster than that of reperfused infarction (0.99 sec(-1) +/- 0.03, 1.11 sec(-1) +/- 0.03, and 1.48 sec(-1) +/- 0.06). Normal myocardium appeared hyperintense on T1-weighted inversion-recovery SE MR images and was clearly distinguishable from reperfused infarction.


CONCLUSIONS
Mn-DPDP-enhanced inversion-recovery echo-planar and SE MR images demonstrated retention of manganese in normal myocardium and clearance of manganese from infarction. Mn-DPDP has characteristics similar to those of widely used thallium and may be useful in the assessment of myocardial viability at MR imaging.
Bremerich
J
J
Department of Radiology, University of California, 505 Parnassus Ave, San Francisco, CA 94143-0628, USA.
Saeed
M
M
Arheden
H
H
Higgins
C B
CB
Wendland
M F
MF
D000704:Analysis of Variance; D000818:Animals; D003287:Contrast Media; D003327:Coronary Disease / Q000150:complications; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D017352:Echo-Planar Imaging; D004492:Edetic Acid / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood; D005260:Female; D005500:Follow-Up Studies; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008345:Manganese / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D008657:Metabolic Clearance Rate; D009203:Myocardial Infarction / Q000209:etiology / Q000378:metabolism*; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000378:metabolism*; D011732:Pyridoxal Phosphate / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood; D051381:Rats; D017207:Rats, Sprague-Dawley
D003287:Contrast Media; D008345:Manganese; D011732:Pyridoxal Phosphate; D004492:Edetic Acid; C060076:N,N'-bis(pyridoxal-5-phosphate)ethylenediamine-N,N'-diacetic acid