Abstract 2124: Accuracy of T2-weighted Cardiac Magnetic Resonance in Detecting Myocardial Edema in Acute Myocardial Infarction is Strongly Influenced by Microvascular Obstruction.
Background: High signal intensity (SI) on T2-weighted Cardiac Magnetic Resonance (CMR) indicates infarct-associated myocardial edema in patients with acute myocardial infarction (MI). However, erythrocytes leaking from capillaries in infarct tissue may result in reduced signal on T2W CMR due to T2 shortening. The purpose of this study was to determine if detection of myocardial edema with T2-weighted CMR is influenced by microvascular obstruction (MO- ).
Methods: Thirty-seven patients underwent black blood T2 weighted MRI with a spectral presaturation with inversion recovery fat saturation method, rest perfusion MRI and late gadolinium enhanced (LGE) MRI 5.4±3.1 days after onsets. The presence and transmural extent of LGE and MO were analyzed based on a 16-segment model. The relative SI compared with remote normal myocardium was determined in the infarction and peri-infarction zones on T2 weighted MRI, by using the mean + 2SD of the SI in normal segments as a threshold.
Results: LGE was observed in 37 (100%) of 37 patients and MO in 19 (51%) of 37 patients. The SI in LGE segments without MO and the SI in periinfarct zones were significantly higher than those in normal segments (relative SI 1.84±0.5, p<0.001 and 1.69±0.18, p<0.001, respectively). However, no significant difference was found between the SI in MO segments and the SI in normal segments (relative SI 1.12±0.24, p=N.S.). The sensitivity of T2 weighted MRI for detecting edema in acute MI was 95% (73/77) in the LGE segments without MO, but was reduced to 30% (22/73) in the segments with MO. Myocardial edema was completely missed on T2 weighted MRI in 2 patients with severe MO.
Conclusions: Although T2-weighted CMR is highly sensitive in detecting myocardial edema in the segments without MO, reduced T2 signal intensity in MO segments can be an important pitfall in characterizing the area of the acute event.