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.

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Background Coarctation of the aorta accounts for 5-7% of congenital defects of the heart and great vessels. It requires treatment in the form of open surgical or percutaneous repair. Common long-term complications include re-stenosis and aneurysm formation. The formation of a false aneurysm is a complication with a significant morbidity and mortality. Case Summary We reviewed six cases of late false aneurysm after repair of a coarctation of the aorta. Our six cases developed a false aneurysm after an open surgical repair of a coarctation more than 30 years after initial surgical repair. All aneurysms were located at the aortic repair site. Discussion Symptoms or risk factors in the described cases are not uniform and are difficult to include in a general follow-up protocol. Guidelines recommend frequent evaluation, but do not specify duration or intervals of imaging follow-up. Our cases support the necessity of life-long follow-up in patients with open aortic repairs irrespective of symptomatology.