Abstract 13610: Native T1-based Cardiovascular Magnetic Resonance Imaging for Characterizing Chronic Myocardial Infarctions in Patients

Abstract

Introduction: Late Gadolinium Enhancement (LGE) Cardiovascular Magnetic Resonance (CMR) is the gold standard for characterizing chronic myocardial infarctions (MIs), but it is contraindicated in patients with end-stage chronic kidney disease. Hypothesis: We investigated whether native T1 mapping at 3T can reliably characterize chronic MIs in two pilot patient populations with prior STEMI and NSTEMI. Methods: Patients with prior STEMI (n=15) and NSTEMI (n=17) underwent CMR at a median of 13.6 years after acute MI and native T1 maps and LGE images were acquired. Infarct location, size and transmurality were measured from LGE and T1 maps using standard threshold criterion and compared against one another. Visual conspicuity for detecting chronic MI territories on LGE images and T1 maps were assessed by independent reviewers. Results: LGE images and native T1 maps were not different for measuring infarct size (STEMI: p=0.87; NSTEMI: p=0.93) and transmurality (STEMI: p=0.19; NSTEMI: p=0.24). Statistical analyses showed good agreement between LGE images and T1 maps for measuring infarct size (STEMI: bias = -0.4±2.1%; R2=0.97; NSTEMI: bias = -1.1±3.9%; R2=0.87) and transmurality (STEMI: bias = 1.5±2.9%; R2=0.99; NSTEMI: bias = -2.2±7.4%; R2=0.71). Sensitivity and specificity of native T1 maps for detecting chronic MIs based on threshold criterion were 93% and 97% respectively (STEMI); and 93% and 92% respectively (NSTEMI). Mean visual conspicuity score for detecting chronic MI on LGE images was greater than that of native T1 maps (p<0.001). Sensitivity and specificity of native T1 maps using visual detection were: 61% and 85% (STEMI); and 67% and 90% (NSTEMI). Conclusions: Chronic MIs in STEMI and NSTEMI patients can be reliably characterized using threshold-based detection with native T1 maps when the location of remote myocardium is known. The current visual detectability of remote myocardium on native T1 maps has a certainty of 85% in STEMI and 90% in NSTEMI patients.