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.
Department of Radiology, University of California, 505 Parnassus Ave, San Francisco, CA 94143-0628, USA.
J
J
Bremerich
M
M
Saeed
H
H
Arheden
C B
CB
Higgins
M F
MF
Wendland
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