Myocardial area at risk and salvage measured by T2-weighted cardiovascular magnetic resonance: Reproducibility and comparison of two T2-weighted protocols

Abstract

BackgroundLate Gadolinium Enhancement (LGE) and T2-weighted cardiovascular magnetic resonance (CMR) provides a means to measure myocardial area at risk (AAR) and salvage. Several T2-weighted CMR sequences are in use, but there is no consensus in terms of which sequence to be the preferred. Therefore, the aim of the present study was to: (1) Assess the reproducibility and (2) compare the two most frequently used T2-weighted CMR protocols for measuring AAR and salvage.Methods91 patients with ST-elevation myocardial infarction treated with primary percutaneous coronary intervention underwent a CMR scan 1-7 days after initial treatment. Two different T2-weighted protocols, varying in slice thickness and echo time (TE), were applied covering the entire left ventricle (LV) (protocol 1: TE 65 msec and slice thickness 15 mm; protocol 2: TE 100 msec and slice thickness of 8 mm). On a second scan performed 3 months later, infarct size was assessed with a standard LGE sequence. The two protocols were compared in terms of AAR and salvage index. Furthermore, intra- and interobserver reproducibility were assessed.ResultsProtocol 1 measures a larger AAR and salvage index than protocol 2 with a mean difference in AAR of 1 ± 8%LV (p < 0.01) and 6 ± 12 g (p < 0.01) and salvage index of 0.04 ± 0.12 (p < 0.01). Both protocols had a high intra- and interobserver reproducibility with acceptable limits of agreement (6-8%LV and 6-12 g in AAR and 0.06-0.08 in salvage index).ConclusionsWe report acceptable reproducibility for AAR and salvage index measured by T2-weighted images. Thus CMR is a reliable tool for measuring AAR and salvage index. Protocol 2 (8 mm slice thickness and 100 msec TE) measures slightly smaller AAR than protocol 1 (15 mm slice thickness and 65 msec TE), but the present study does not allow for a clear recommendation of either of the protocols.

Left Ventricular Hypertrophy Is Associated With Increased Infarct Size and Decreased Myocardial Salvage in Patients With ST‐Segment Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention

“…Myocardial salvage assessed by CMR has also been shown to be a reproducible tool with excellent agreement with single‐photon emission computed tomography and angiography 18, 41. However, T 2 ‐weighted images can be technically challenging, with a sufficient diagnostic quality obtainable in only 88% to 95% of patients with STEMI 16. Fourth, given the nature of the study, we did not have continuous data on heart rate and blood pressure.…”

“…Cardiovascular magnetic resonance (CMR) provides an accurate method for in vivo assessment of infarct size,14, 15 area at risk,16, 17, 18, 19 myocardial salvage index,20, 21 MVO,22 LV mass, and LV ejection fraction (LVEF) 23…”

Exenatide Reduces Final Infarct Size in Patients With ST-Segment–Elevation Myocardial Infarction and Short-Duration of Ischemia

“…25 However, T2-weighted images may be technically problematic and have a sufficient diagnostic quality in only 88% to 95% of patients with STEMI. 26,27 Furthermore, the CMR scans are performed after reperfusion, and it may be speculated that exenatide or any other effective treatment modality per se leads to a decrease in edema and hence a smaller myocardial area at risk. In turn, this will result in an underestimation of salvage index and thus the effect of a given therapy.…”

A Novel Prehospital Electrocardiogram Score Predicts Myocardial Salvage in Patients with ST-Segment Elevation Myocardial Infarction Evaluated by Cardiac Magnetic Resonance

“…The salvage index was calculated as follows: (AAR - IS)/AAR. Several experienced CMR readers validated the method used to assess the salvage index, and intra- and interobserver variability was 0.00 ± 0.03 and 0.01 ± 0.04, respectively [26]. The final IS was evaluated on the second scan with delayed-enhancement CMR.…”