## 4 Results
### Myocardial Scar Segmentation and Quantification
#### 4.2.3 Microvascular Obstruction Inclusion  
In Table 6, the sensitivity of the different methods for detecting MVO areas are shown. Our proposal achieved the highest performance values and showed statistical significance when compared with all reference methods with exception of the 1-SD one. A MVO segmentation example can be appreciated in Figure 6, where our proposal's capability for the task is exposed. It can be highlighted the accurate segmentation of the hyper-enhanced area provided by the coarse pre-segmentation, with its improvement and MVO inclusion after the refinement approach. For the shown image, only our approach was able to deal with the no-reflow area.  
\begin{table}
\begin{tabular}{l c c c c c c c c c} \hline \hline
**FWHM** & **GMM** & **Otsu** & **1-SD** & **2-SD** & **3-SD** & **4-SD** & **5-SD** & **6-SD** & **Proposed** \\ \hline
18.8 * & 54.6 * & 57.7 * & 63.6 & 46.5 * & 27.9 * & 14.1 * & 5.7 * & 2.8 * & **66.9** \\ (23.0) & (37.1) & (35.0) & (36.4) & (38.9) & (34.0) & (25.1) & (14.6) & (9.1) & **(40.5)** \\ \hline \hline \end{tabular}  
* FWHM: Full-width at half-maximum; GMM: Gaussian mixture model; n-SD: n-standard deviation thresholding from remote myocardium.
* \(p<0.05\) by means of Mann–Whitney U test.  
\end{table}
Table 6: Mean (standard-deviation) sensitivity for detecting microvascular obstruction areas per method.  
Figure 6: Segmentation results for the microvascular obstruction areas per method. **(a)** Ground-truth. **(b)** Full-width at half-maximum. **(c)** Gaussian mixture model. **(d)** Otsu. **(e)** 1-SD. **(f)** 2-SD. **(g)** 3-SD. **(h)** 4-SD. **(i)** 5-SD. **(j)** 6-SD. **(k)** Proposed coarse segmentation. **(l)** Full proposed method. The arrow indicates the microvascular obstruction area.  
\begin{table}
\begin{tabular}{l c c c c c c c c} \hline \hline  & & \multicolumn{3}{c}{**Scar Volume (cm\({}^{3}\))**} & \multicolumn{4}{c}{\% **Infracted Myocardial Volume**} \\
**Method** & **Value** & \(\rho\) & **BA Bias** & \(p\)**-Value** & **Value** & \(\rho\) & **BA Bias** & \(p\)**-Value** \\ \hline Manual & 25.7 (19.4) & & & & 18.5 (12.7) & & & \\ FWHM & 17.6 (12.9) & 0.937 & \(-8.1\) (8.7) & \(<0.001\) & 12.7 (8.1) & 0.934 & \(-5.8\) (5.9) & \(<0.001\) \\ GMM & 32.7 (17.2) & 0.807 & 7.1 (14.6) & \(<0.001\) & 24.2 (11.0) & 0.777 & 5.6 (9.5) & \(<0.001\) \\ Otsu & 39.3 (20.8) & 0.907 & 13.6 (10.1) & \(<0.001\) & 28.6 (12.1) & 0.885 & 10.1 (6.6) & \(<0.001\) \\
1-SD & 44.0 (24.4) & 0.932 & 18.3 (10.8) & \(<0.001\) & 32.3 (15.8) & 0.923 & 13.8 (7.2) & \(<0.001\) \\
2-SD & 28.6 (18.7) & 0.927 & 3.0 (9.4) & \(<0.01\) & 21.1 (13.0) & 0.916 & 2.6 (6.4) & \(<0.001\) \\
3-SD & 18.4 (14.5) & 0.875 & \(-7.2\) (12.6) & \(<0.001\) & 13.7 (10.4) & 0.847 & \(-4.9\) (7.7) & \(<0.001\) \\
4-SD & 11.2 (11.1) & 0.756 & \(-14.5\) (15.3) & \(<0.001\) & 8.4 (8.0) & 0.723 & \(-10.2\) (9.4) & \(<0.001\) \\
5-SD & 6.4 (8.4) & 0.567 & \(-19.3\) (17.0) & \(<0.001\) & 4.8 (6.0) & 0.565 & \(-13.7\) (10.6) & \(<0.001\) \\
6-SD & 3.7 (6.4) & 0.458 & \(-21.9\) (17.7) & \(<0.001\) & 2.8 (4.4) & 0.471 & \(-15.8\) (11.3) & \(<0.001\) \\
**Proposed** & **26.6 (18.5)** & **0.945** & **1.0 (6.9)** & **0.196** & **19.1 (11.0)** & **0.945** & **0.5 (4.6)** & **0.314** \\ \hline \hline \end{tabular}  
* Mean (standard deviation). FWHM: Full-width at half-maximum; GMM: Gaussian mixture model; n-SD: n-standard deviation thresholding from remote myocardium; BA: Bland–Altman; \(\rho\): Spearman correlation coefficient; \(p\)-values obtained by a paired t-Student test.  
\end{table}
Table 5: Agreement between methods and the manual delineations by means of clinical markers.