The potential of contrast-enhanced magnetic resonance imaging for predicting left ventricular remodeling.
OBJECTIVE
To determine whether the myocardial injury size on day 2 measured after gadolinium (Gd)-mesoporphyrin and Gd-diethylenetriamine-pentaacetic acid (DTPA) administration can be used for predicting left ventricular (LV) remodeling 8 weeks later, and to monitor the structural and functional changes in the infarct, peri-infarct rim, and remote myocardium in reperfused infarction using contrast-enhanced and functional magnetic resonance imaging (MRI) MATERIALS AND METHODS: Myocardial infarction (MI) was induced in 27 rats by 1 hour of coronary occlusion/reperfusion. Rats were imaged 2 days and 8 weeks after MI using MRI to determine LV function and size of myocardial injury. All animals received 0.05 mmol/kg Gd-mesoporphyrin 12 hours before the first MRI. A subgroup of 13 rats received 0.3 mmol/kg Gd-DTPA in addition to Gd-mesoporphyrin, and seven rats received 0.05 mmol/kg Gd-mesoporphyrin 12 hours before the second MRI for detection of healed MI. True infarct size (IS) and LV mass were measured postmortem. LV volumes, mass, function, and wall thickness were determined in both imaging sessions.


RESULTS
A close correlation was found between contrast-enhanced MRI and postmortem measurements for IS (r = 0.94, P < 0.001 for Gd-mesoporphyrin; r = 0.91, P < 0.001, N = 13 for Gd-DTPA). IS measured on Gd-mesoporphyrin-enhanced images correlated well with end-systolic LV volumes (r = 0.68, P < 0.001) and ejection fraction (r = -0.75, P < 0.001) 8 weeks after MI. Similar correlation with parameters of LV remodeling were found on Gd-DTPA-enhanced MRI. Healed infarcts showed no enhancement on Gd-mesoporphyrin-enhanced MRI.


CONCLUSIONS
Contrast-enhanced MRI can be used as a noninvasive method for determining the initial size of myocardial injury and predicting later LV remodeling. MRI demonstrates the structural and functional changes in infarct, peri-infarct rim, and remote non-infarcted myocardium. The complementary use of functional and contrast-enhanced MRI may provide reliable assessment of therapeutic interventions to reduce IS and LV remodeling.
Watzinger
Norbert
N
Department of Radiology, University of California San Francisco, San Francisco, California 94143-0628, USA.
Lund
Gunnar K
GK
Higgins
Charles B
CB
Wendland
Michael F
MF
Weinmann
Hanns-Joachim
HJ
Saeed
Maythem
M
D000704:Analysis of Variance; D000818:Animals; D003287:Contrast Media; D019786:Gadolinium DTPA; D007091:Image Processing, Computer-Assisted; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008652:Mesoporphyrins; D009203:Myocardial Infarction / Q000473:pathology*; D011237:Predictive Value of Tests; D051381:Rats; D017207:Rats, Sprague-Dawley; D018709:Statistics, Nonparametric; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis*; D020257:Ventricular Remodeling
D003287:Contrast Media; D008652:Mesoporphyrins; D019786:Gadolinium DTPA