Scar characteristics derived from two‐ and three‐dimensional reconstructions of cardiac contrast‐enhanced magnetic resonance images: Relationship to ventricular tachycardia inducibility and ablation success

Figures

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  Fig. 1. Representative quantification of scar and scar border zones on 2D CE-MRI. (A) The whole left ventricular (LV) slices of 2D CE-MR images. (B) A region of interest (ROI) in the remote normal myocardium is determined by the reader, and the mean±SD of the signal-intensity (SI) of the ROI are automatically calculated. An algorithm applies SI thresholds of 6 SDs and 2–6 SDs above the SI of the remote normal myocardium to delineate the scar zone (red region) and scar border zone (yellow region), respectively. The total mass of the scar zone and scar border zone (g), and their percentages relative to total myocardium (%scar zone and %scar border zone) are automatically calculated. (C) The LV endocardium is manually outlined, and areas of late gadolinium enhancement (LGE) on all short-axis slices are planimetered and yield the total masses of the scar and scar border zones (g), and the LV endocardial scar zone (g)/total LV myocardial scar zone (g) ratio and LV endocardial scar border zone (g)/total LV myocardial scar border zone (g) ratio are calculated.

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  Fig. 2. Bar graphs showing the (A) %scar zone and %scar border zone in the VT inducible and non-inducible groups and (B) scar zone (g) in the LV endocardium/total LV myocardial scar zone (g) ratio and scar border zone in the LV endocardium (g)/total LV myocardial scar border zone (g) ratio in the patient group with successful ablation via the endocardial side of the LV and the patient group unsuccessful ablation. The bars show the mean percentages and ratios per zone.

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  Fig. 3. Representative examples of 2D CE-MR images and 3D endocardial LV voltage maps obtained from (A) patients in whom ablation via the endocardium was successful and (B) patients in whom it was not successful. In the case of successful ablation (A), the CE-MRI-derived scar zone is widely distributed on the endocardial side of the LV (upper panel), which corresponds to the low voltage area on the 3D endocardial LV voltage map (lower panel). In contrast, in the case of unsuccessful ablation (B), the CE-MRI-derived scar zone is located mainly at the mid portion of the LV myocardium (upper panel), and thus, only a small low voltage area is noted at the apical septal wall on the 3D endocardial LV voltage map. The %scar zones in cases of successful and unsuccessful ablation are similar (35% and 31%, respectively), but the LV endocardial scar zone to total LV myocardial scar zone ratio was significantly greater in the successful ablation group than in the unsuccessful ablation group (0.79 vs. 0.56. respectively).

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  Fig. 4. Representative examples of 3D reconstructed CE-MR images in the cases shown in Fig. 3 wherein ablation via the endocardial side was (A) successful and (B) unsuccessful. The 3D LV reconstructions are derived from short-axis slices of the 2D CE-MRI dataset with the use of custom software. The scar and scar border zones are indicated in blue and yellow, respectively. Note that the distribution of the scar and scar border zones on the 3D CE-MR images can be deduced from the 3D endocardial LV voltage maps shown in Fig. 3.

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  Fig. 5. Electrocardiogram, CE-MR image, and 3D endocardial LV voltage map in a case of sarcoidosis wherein LV ablation was successful via the endocardial approach. The VT morphology on the 12-lead ECG shows positive precordial QRS concordance and a superior axis, suggesting the VT origin at the base of the posterior LV. (A) The scar and scar border zones at the posterior LV are delineated on a short-axis slice of a 2D CE-MR image obtained at the LV base. (B) A successful ablation site is noted at the same place on the 3D endocardial LV voltage map. Dotted line indicates the line corresponding to the short-axis slice of the 2D CE-MR image in (A).