Myocardial edema as detected by pre-contrast T1 and T2 MRI delineates area at risk associated with acute myocardial infarction
Published Date:Jun 2012
Source:JACC Cardiovasc Imaging. 2012; 5(6):596-603.
Disease Models, Animal
Image Interpretation, Computer-Assisted
Magnetic Resonance Imaging
Myocardial Perfusion Imaging
Myocardium At Risk
Predictive Value Of Tests
Reproducibility Of Results
Pubmed Central ID:PMC3769169
Funding:1 Z01 HL004607-08 CE/CE/NCIPC CDC HHS/United States
HL-CR-05-004/HL/NHLBI NIH HHS/United States
ZIA HL004607-14/Intramural NIH HHS/United States
ZIA HL006136-01/Intramural NIH HHS/United States
ZIA HL006136-02/Intramural NIH HHS/United States
To determine whether cardiac magnetic resonance (CMR) in vivo T1-mapping can measure myocardial area at risk (AAR) compared with microspheres or T2-mapping CMR.
If T2-weighted CMR is abnormal in the AAR due to edema related to myocardial ischemia, then T1-weighted CMR should also be able to detect and accurately quantify AAR.
Dogs (n=9) underwent a 2 hour coronary occlusion followed by 4 hours of reperfusion. CMR of the left ventricle was performed for mapping of T1 and T2 prior to any contrast administration. AAR was defined as regions which had a T1 or T2 value (ms) greater than 2SD from remote, and regions with microsphere blood flow (ml/min/g) during occlusion less than 2SD from remote. Infarct size was determined by triphenyltetrazolium chloride staining.
The relaxation parameters T1 and T2 were increased in the AAR compared to remote myocardium (T1: 1133±55 vs. 915±33ms, T2: 71±6 vs. 49±3 ms; mean±SD). On a slice-by-slice basis (n=78 slices), AAR by T1- and T2-mapping correlated (R2=0.95, p<0.001) with good agreement (0.4±16.6 % of slice, mean±2SD). On a whole-heart analysis, T1 measurements of left ventricular mass, AAR and myocardial salvage correlated to microsphere measures (R2=0.94) with good agreement (−1.4±11.2 g of myocardium; mean±2SD). Corresponding T2 measurements of left ventricular mass, AAR, and salvage correlated to microsphere analysis (R2=0.96, agreement 1.6±9.2 g of myocardium; mean±2SD). Median infarct size was 30% of the AAR (range 12–52).
For determining area at risk after acute myocardial infarction, non-contrast T1-mapping and T2-mapping sequences yield similar quantitative results, and both agree well with microspheres. The relaxation properties T1 and T2 both change in a way that is consistent with the presence of myocardial edema following myocardial ischemia/reperfusion.
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