Quantification of late gadolinium enhancement cardiovascular MRI in patients with coronary artery chronic total occlusion

Abstract

Aim: To determine the most accurate and reproducible semi-automated greyscale thresholding technique for quantifying late gadolinium enhancement (LGE) in cardiovascular magnetic resonance imaging (CMRI), by using positron-emission tomography (PET) as the reference standard in patients with coronary artery chronic total occlusion (CTO).

Materials and methods: LGE in CMRI, single-photon-emission computed tomography (SPECT), and PET were performed within 1 week in each of 63 patients with known CTO. The presence and quantity of LGE were determined with greyscale thresholds of 2, 4, 5, 6, and 8 standard deviations (SDs) above the mean signal intensity for normal remote myocardium and full width at half maximum (FWHM). The infarcted myocardium was delineated by PET.

Results: Sixty-three patients and 1,008 segments were analysed. Based on patient analysis, with PET as the reference standard, the 5 SD method yielded the strongest correlation (r=0.85, p<0.0001) compared with the 2 SDs (r=0.42), 4 SDs (r=0.73), 6 SDs (r=0.81), 8 SDs (r=0.71), and FWHM (r=0.69; p<0.001 for all comparisons). The 5 SDs threshold quantification showed high interobserver and intra-observer agreement (intraclass correlation coefficient [ICC]=0.90, p<0.0001; ICC=0.93, p<0.0001, respectively).

Conclusions: Semi-automated LGE CMRI greyscale thresholding with 5 SDs above the mean signal intensity for normal remote myocardium yields the strongest correlation to the extent of LGE identified using PET and is highly reproducible in patients with CTO.