Histopathological validation of semi-automated myocardial scar quantification techniques for dark-blood late gadolinium enhancement magnetic resonance imaging

Abstract

Aims To evaluate the performance of various semi-automated techniques for quantification of myocardial infarct size on both conventional bright-blood and novel dark-blood late gadolinium enhancement (LGE) images using histopathology as reference standard. Methods and results In 13 Yorkshire pigs, reperfused myocardial infarction was experimentally induced. At 7 weeks post-infarction, both bright-blood and dark-blood LGE imaging were performed on a 1.5 T magnetic resonance scanner. Following magnetic resonance imaging (MRI), the animals were sacrificed, and histopathology was obtained. The percentage of infarcted myocardium was assessed per slice using various semi-automated scar quantification techniques, including the signal threshold vs. reference mean (STRM, using 3 to 8 SDs as threshold) and full-width at half-maximum (FWHM) methods, as well as manual contouring, for both LGE methods. Infarct size obtained by histopathology was used as reference. In total, 24 paired LGE MRI slices and histopathology samples were available for analysis. For both bright-blood and dark-blood LGE, the STRM method with a threshold of 5 SDs led to the best agreement to histopathology without significant bias (−0.23%, 95% CI [−2.99, 2.52%], P = 0.862 and −0.20%, 95% CI [−2.12, 1.72%], P = 0.831, respectively). Manual contouring significantly underestimated infarct size on bright-blood LGE (−1.57%, 95% CI [−2.96, −0.18%], P = 0.029), while manual contouring on dark-blood LGE outperformed semi-automated quantification and demonstrated the most accurate quantification in this study (−0.03%, 95% CI [−0.22, 0.16%], P = 0.760). Conclusion The signal threshold vs. reference mean method with a threshold of 5 SDs demonstrated the most accurate semi-automated quantification of infarcted myocardium, without significant bias compared to histopathology, for both conventional bright-blood and novel dark-blood LGE.

Quantification of myocardial scar of different etiology using dark- and bright-blood late gadolinium enhancement cardiovascular magnetic resonance

“…Inherently, the measurements may have subjectivity as illustrated by the inter-observer variability, in particular in the NICM and HCM groups. Although the external validity of the present findings is less robust given this single-center nature of this study with a relatively small number of patients for each subgroup, studies at other centers investigating the quantification of ischemic 16 and non-ischemic 33 scar using dark-blood LGE compared to conventional bright-blood LGE found similar results. Finally, high-resolution 3D LGE imaging is increasingly used for accurate substrate detection in the work-up for ablation therapy and implantable cardioverter-defibrillator (ICD) implantation.…”

“…The results of this paper support our study findings even though were obtained with a different dark-blood LGE sequence aimed at achieving the same goal. More recently, Nies et al evaluated the performance of various semi-automated techniques/methods and manual contouring for quantification of MI size using both conventional bright-blood and dark-blood LGE in animal model with histopathology as reference standard 16 . Among the assessed semi-automated quantification methods of signal intensity thresholding (3 to 8 SDs and the FWHM method), they found the best agreement with histopathology using a signal intensity threshold of 5 SD for both bright-blood LGE and dark-blood LGE.…”

“…The volume of enhancement was then derived for signal thresholds of various number of SDs above the average of the remote myocardial signal. In an earlier study, using thresholds of 3–8 SDs and histopathology as reference standard, it was found that a larger number of thresholds (> 6) underestimates the burden of LGE, and 5 SDs was found most accurate for both dark-blood and bright-blood LGE) 16 . However, there is a rationale for trying a lower number of SDs (< 3) as threshold in non-ischemic disease as the scarred tissue might appear less bright than in ischemic disease.…”

Dark-Blood Late Gadolinium Enhancement MRI Is Noninferior to Bright-Blood LGE in Non-Ischemic Cardiomyopathies

“…Further studies, preferably in a multicentre setting and with an even larger patient population, identical sequence protocols, and scanners from different vendors and different field strengths (1.5 and 3 T), may further investigate the performance of darkblood LGE (vs. bright-blood LGE) in non-ischemic cardiomyopathies. Third, although the optimal threshold for semi-automated scar quantification of ischemic scarring using darkblood LGE has recently been investigated using histopathology as a reference standard [37], an optimal threshold for quantification of non-ischemic scarring using dark-blood LGE has not been investigated and is currently unknown [38].…”

An accurate and time-efficient deep learning-based system for automated segmentation and reporting of cardiac magnetic resonance-detected ischemic scar

“…To choose a scar segmentation technique, MIS was assessed on the same set of 56 DB-LGE slices with different techniques (2-SD, 3-SD, 4-SD, 5-SD, 6-SD); the results were then compared against MIS segmented on matching BB-LGE images with the 5-SD technique as the gold standard [28] . Interobserver reproducibility was evaluated on DB-LGE MIS segmentation (all techniques) by Intra Class Correlation (ICC).…”