Stephenson Cardiovascular MR Centre, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada.
J Magn Reson Imaging. 2013 Feb;37(2):382-90. doi: 10.1002/jmri.23814. Epub 2012 Sep 25.
To assess the Otsu-Auto-Threshold (OAT) for accuracy and reproducibility for sizing irreversible injury in late gadolinium enhancement (LGE) images of patients with acute heart disease. The OAT method automatically identifies high signal intensity areas using a cutoff derived from the signal intensity histogram and therefore is user-independent.
LGE was performed in 28 patients with acute myocardial infarction (MI) and 30 patients with acute myocarditis. LGE mass was compared between OAT and thresholds using 2 standard deviations (SD), 3SD, and 5SD above remote myocardium, and full-width-at-half-maximum (FWHM). A separate, blinded visual assessment served as the standard of truth.
In patients with acute MI, OAT and 5SD did not differ (26.1 ± 11.4 g vs. 25.4 ± 11.1 g, P = 0.088), but thresholds of 2SD and 3SD overestimated LGE mass by 37% and 20%, respectively, and FWHM underestimated by 15%. In acute myocarditis, OAT was not different from a visual quantification, but thresholds of 2SD and 3SD overestimated LGE mass by 46% and 19%, respectively, and thresholds of 5SD and FWHM underestimated LGE mass by 17% and 26%, respectively. OAT and FWHM showed the best intraobserver and interobserver reproducibility.
Automatic thresholding using OAT may serve as an accurate and reproducible method to quantify irreversible myocardial injury in acute heart disease.
评估 Otsu-Auto-Threshold（OAT）在急性心脏病患者晚期钆增强（LGE）图像中测量不可逆损伤的准确性和可重复性。OAT 方法使用来自信号强度直方图的截断值自动识别高信号强度区域，因此不受用户影响。
对 28 例急性心肌梗死（MI）患者和 30 例急性心肌炎患者进行 LGE。使用 2 个标准差（SD）、3SD 和 5SD 以上的远程心肌以及半峰全宽（FWHM）将 OAT 和阈值之间的 LGE 质量进行比较。单独的、盲目的视觉评估作为标准。
在急性 MI 患者中，OAT 和 5SD 没有差异（26.1 ± 11.4 g 比 25.4 ± 11.1 g，P = 0.088），但 2SD 和 3SD 的阈值高估了 LGE 质量分别为 37%和 20%，而 FWHM 低估了 15%。在急性心肌炎患者中，OAT 与视觉定量无差异，但 2SD 和 3SD 的阈值高估了 LGE 质量分别为 46%和 19%，而 5SD 和 FWHM 的阈值低估了 LGE 质量分别为 17%和 26%。OAT 和 FWHM 显示出最佳的观察者内和观察者间可重复性。
使用 OAT 的自动阈值处理可能是一种准确且可重复的方法，可用于量化急性心脏病中的不可逆心肌损伤。
