Bright-Blood T2-Weighted MRI Has Higher Diagnostic Accuracy Than Dark-Blood Short Tau Inversion Recovery MRI for Detection of Acute Myocardial Infarction and for Assessment of the Ischemic Area at Risk and Myocardial Salvage

Abstract

Background-T2-Weighted MRI reveals myocardial edema and enables estimation of the ischemic area at risk and myocardial salvage in patients with acute myocardial infarction (MI). We compared the diagnostic accuracy of a new bright-blood T2-weighted with a standard black blood T2-weighted MRI in patients with acute MI. Methods and Results-A breath-hold, bright-blood T2-weighted, Acquisition for Cardiac Unified T2 Edema pulse sequence with normalization for coil sensitivity and a breath-hold T2 dark-blood short tau inversion recovery sequence were used to depict the area at risk in 54 consecutive acute MI patients. Infarct size was measured on gadolinium late contrast enhancement images. Compared with dark-blood T2-weighted MRI, consensus agreements between independent observers for identification of myocardial edema were higher with bright-blood T2-weighted MRI when evaluated per patient (PϽ0.001) and per segment of left ventricle (PϽ0.001). Compared with bright-blood T2-weighted MRI, dark-blood T2-weighted MRI underestimated the area at risk compared with infarct size (PϽ0.001). The 95% limits of agreement for interobserver agreements for the ischemic area at risk and myocardial salvage were wider with dark-blood T2-weighted MRI than with bright-blood T2-weighted MRI. Bright blood enabled more accurate identification of the culprit coronary artery with correct identification in 94% of cases compared with 61% for dark blood (PϽ0.001). Conclusions-Bright-blood T2-weighted MRI has higher diagnostic accuracy than dark-blood T2-weighted MRI.Additionally, dark-blood T2-weighted MRI may underestimate area at risk and myocardial salvage. (Circ Cardiovasc Imaging. 2011;4:210-219.)

Non-contrast T1-mapping detects acute myocardial edema with high diagnostic accuracy: a comparison to T2-weighted cardiovascular magnetic resonance

“…Bright-blood T2 is excellent for detecting large areas of regional edema when there is obvious normal myocardium to be used as a reference, as shown recently [3] and in this work. The main challenge of extending bright-blood T2 imaging for the detection of diffuse edema was the variability of the image quality of reference skeletal muscle, which was often affected by off-resonance artifacts, bright signals from adjacent fat, bright blood vessels within the muscle or signal dropouts.…”

“…We consider the fact that ShMOLLI T1-mapping has multiple ways for detecting regions with potentially compromised T1 values a strength of the method which makes it more robust, especially to observer bias. ACUT2E is also a relatively novel method that has been validated in acute MIs [3], but not in detecting global edema or non-ischemic pathologies; sometimes, it is unclear whether darker areas within the myocardium are due to SSFP artifacts (as in Figure 2B, middle panel) or whether it is representative of normal myocardium (as in Figure 2B (right panel) versus signal drop-out/artifact in the inferolateral wall (less likely in this case). These reasons contribute to the apparently higher rejection rate of T1-mapping, but do not reflect that the method is artifact-prone; rather, we were strict on selecting only the best segments for the purpose of establishing T1 thresholds with the greatest accuracy.…”

“…It is used for differentiation of acute from chronic MI [2], assessment of the area-at-risk [3,4], myocarditis [5] and increasingly as a surrogate end-point in clinical trials [6]. …”

“…In systemic conditions like viral myocarditis, the reference skeletal muscle may also be inflamed, leading to false negative results [5]. The bright-blood T2-weighted sequence ACUT2E [10] has been shown to be superior to dark-blood STIR in assessing acute myocardial infarction and area-at-risk [3], but has not been tested in subjects with diffuse or patchy edema using reference ROIs outside the myocardium.…”

Coronary Thermodilution Waveforms After Acute Reperfused ST‐Segment–Elevation Myocardial Infarction: Relation to Microvascular Obstruction and Prognosis

“…The extent of myocardial edema was defined as LV myocardium with pixel values (T2) >2 standard deviations from remote myocardium 21, 22, 23, 24, 25, 26. Myocardial salvage was calculated by subtraction of percentage infarct size from percentage area at risk, as reflected by the extent of edema 23, 26, 27.…”