Novel Magnetic Resonance Late Gadolinium Enhancement With Fixed Short Inversion Time in Ischemic Myocardial Scars

Aims Late gadolinium enhancement (LGE) visualizes scar tissue after myocardial infarction. However, in clinically used LGE sequences, subendocardial infarcts can be missed due to low contrast between blood pool and subendocardium. The purpose of his study was to compare scar visibility in a novel 3-dimensional (3D) single breath-hold inversion recovery sequence with fixed, short inversion time (TI = 100 milliseconds) (short LGE) and standard 3D LGE imaging with individually adjusted TI (LGE). Methods Short LGE and LGE (both sequences with the same settings: spatial resolution, 1.2 x 1.2 mm(2); slice thickness, 8 mm; field of view, 350 x 350 mm(2); single breath-hold) were acquired in 64 patients with previous MI (13 female; mean age, 57 +/- 19 years) at 1.5 T. Inversion time was set to 100 milliseconds in short LGE and adjusted individually in LGE according to the Look-Locker sequence. Two independent readers evaluated 1088 segments (17-segment model), identified infarcted segments, and categorized scar visibility (5 = excellent, 1 = poor scar visibility) and scar transmurality (4 = transmural, 0 = no scar) using a 5-point Likert scale. Signal intensity ratios between short LGE and LGE for scar and blood pool, for scar and remote myocardium, and for remote myocardium and blood pool were calculated. Results Short LGE showed 197 infarcted segments out of 1088 (18.1%); LGE revealed 191 segments (17.6%). Short LGE with dark scar and bright blood pool demonstrated better overall scar visibility, especially in subendocardially infarcted segments compared with LGE (4.2 vs 3.0, 5 = excellent visibility;P= 0.01). Signal intensity ratios for short LGE relative to LGE were 1.42 for scar/blood pool, 0.8 for scar/remote myocardium, and 0.22 for remote myocardium/blood. Overall transmurality was not rated higher in short LGE compared with LGE (P= 0.8). More fibrous tissue and total fibrous percentage (P= 0.04) were measured in short LGE compared with LGE, whereas myocardial mass was not significantly different (P= 0.5). Acquisition time was similar between short LGE and LGE (26 +/- 4 seconds vs 25 +/- 9 seconds,P= 0.7). Conclusions Short LGE is a fast, single breath-hold 3D LGE sequence with no need for myocardial nulling due to fixed inversion time with improved scar visibility, especially in subendocardial infarcts.