Between Stenosis and Scar: A 1.5T CMR Study Using MOLLI T1 Mapping and PSIR-LGE in Iraqi CAD Patients

Abstract

This study aimed to assess the agreement between MOLLI T1 mapping and PSIR-LGE for myocardial scar assessment at 1.5T in Iraqi patients with coronary artery disease confirmed by coronary CT angiography. This prospective pilot study included 33 adult patients with significant coronary stenosis or complete occlusion on CCTA. All patients underwent cardiac MRI at 1.5T. The protocol included cine imaging, native and post-contrast MOLLI T1 mapping, extracellular volume calculation, and PSIR-LGE. MOLLI was considered abnormal when native T1, ECV, or both were elevated. Agreement between MOLLI and PSIR-LGE was assessed at patient level and segment level using the AHA 17-segment model. CMR showed myocardial scar in 26 of 33 patients. Seven patients had no visible scar on PSIR-LGE, despite having significant coronary disease on CCTA. PSIR-LGE identified scar in all 26 scar-positive patients, while MOLLI showed abnormal native T1 and/or ECV in 25 of them. Patient-level agreement was strong, with κ = 0.85, p < 0.001. At segment level, PSIR-LGE identified 84 scar-positive segments, and MOLLI showed corresponding abnormality in 81 segments, with κ = 0.82, p < 0.001. In the scar-negative subgroup, mean native T1 was 982 ± 24 ms and mean ECV was 27.1 ± 2.4%. The best visual myocardial nulling on PSIR-LGE was observed at inversion times of about 300–320 ms. MOLLI T1 mapping showed strong agreement with PSIR-LGE for myocardial scar assessment at 1.5T. PSIR-LGE remains more suitable for direct visual scar detection, while MOLLI adds quantitative tissue information through native T1 and ECV. The findings also show that significant coronary stenosis on CCTA does not always mean visible myocardial scar on CMR. Larger local studies are needed to validate Iraqi 1.5T T1 and ECV values and to refine PSIR-LGE acquisition practice.