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771 Rapid Segmentation of Myocardial Scar From 3-Dimensional Late Gadolinium Enhancement Magnetic Resonance Imaging
S395
Abstracts
Canadian Cardiovascular Society (CCS) CCS357 Oral CARDIOMYOPATHY Tuesday, October 30, 2012 771 RAPID SEGMENTATION OF MYOCARDIAL SCAR FROM 3DIMENSIONAL LATE GADOLINIUM ENHANCEMENT MAGNETIC RESONANCE IMAGING M Rajchl, J Stirrat, TM Peters, JA White London, Ontario BACKGROUND: High-resolution, 3D late gadolinium enhancement (LGE) scar imaging is feasible using 3T MRI, and is emerging as a preferred approach for imaging complex scar. However, these datasets pose substantial challenges for manual scar segmentation. An efficient and reliable scar segmentation technique would allow for accurate scar volume quantification while providing anatomic scar models relevant to procedural navigation, such as for ablative therapies to eliminate ventricular tachycardia (VT). In this study we test the feasibility of a novel semi-automated algorithm to isolate scar signal from isotropic LGE MRI. METHODS: A total of 25 patients with LV scar (ischemic, N⫽10) or RV scar (Tetralogy of Fallot repair, N⫽15) underwent high-resolution 3D LGE using a 3T MRI system (Siemens Trio®, Germany) using a respiratory navigated IR-GRE sequence 30 minutes following 0.2 mmol/kg Gadovist® (Bayer, Canada). Voxel dimensions were 1.3x1.3x1.3mm. Datasets were blindly segmented using proposed convex flow maximization (CFM) principals that use the spatial consistency of cardiac structures as a geometric constraint to limit the search of scar signal to the myocardium. Resulting scar volumes were compared to a blinded expert manual segmentation using the Dice Similarity Coefficient (DSC) and a root mean squared surface error (RMSE). A second interpreter performed CFMbased segmentation in 10 cases to provide inter- and intraoperator reproducibility. RESULTS: Image quality was adequate for scar segmentation in 24 of 25 cases (respiratory motion in one patient with RV scar). Expert manual segmentation of RV scar took 46⫾13 min. In patients with LV scar the CFM-based software segmented all scar in 9⫾2 minutes and provided a DSC of 0.78⫾0.03. The RMS surface error (RMSE) was excellent at 1.05⫾0.15mm. In patients with RV scar the CFM-based software segmented all scar in 10⫾2 minutes and provided a DSC of 0.71⫾0.04. The RMSE was 0.80⫾0.2mm. Inter- and intra-observer reproducibility was excellent with total scar volume measurements within (r⫽0.982, bias⫽0.37, 95% CI -2.894 to 3.628) and between users (r⫽0.975, bias⫽2.04, 95% CI -3.479 to 7.563). CONCLUSION: We demonstrate feasibility of a novel segmentation algorithm for the identification of myocardial scar from high-resolution 3D LGE-MRI. The technique provides accurate quantification of scar and generation of cardiac models for procedural navigation.
CIHR, ORF, CFI
Featured Research 772 GENOTYPE-PHENOTYPE CORRELATIONS ACCORDING TO CLINICAL AND ECHOCARDIOGRAPHIC CHARACTERISTICS IN HYPERTROPHIC CARDIOMYOPATHY C Henri, P Garceau, L Robb, J Lavoie, LA Mercier, P Romeo, MS Phillips, Y Renaud, C Barahona-Dussault, I Fillion, P L’Allier, F Marcotte, M Talajic Montréal, Québec BACKGROUND: Many mutations among genes encoding sarcomeric proteins have been identified in hypertrophic cardiomyopathy (HCM) leading to a heterogenic phenotype. Studies demonstrate negative outcomes associated with positive genetic testing but data on specific genotype-phenotype correlations are limited and highly variable. METHODS: Identified mutations in genes TNNI3 (troponin I), TNNT2 (troponin T), MYBPC3 (myosin-binding protein C) and MYH7 (myosin heavy chain) were screened in 284 patients at the Cardiovascular Genetic Clinic of the Montréal Heart Institute. Mutations were identified in 113 patients (40%) and 84 patients (74%) were included for analysis. Five cardiac transplant recipients without previous echocardiographic images available were analysed according to clinical characteristics only. We excluded 16 patients without HCM phenotype and 13 patients with follow-up outside of our center. RESULTS: MYH7 (40%) and MYBPC3 (40%) mutations were the most common (Table 1). Only one patient was identified with a TNNI3 (1%) mutation and was excluded from further analysis. Patients with MYH7 mutations were younger at diagnosis and presented more often with a familial history of sudden cardiac death (76%) and defibrillator implantation (59%). Patients with MYH7 mutations were also more likely to progress to “burn-out” HCM (ejection fraction less than 50%) (27%) and cardiac transplantation (18%). Significant mitral insufficiency was more prevalent in patients with MYBPC3 mutations (33%). Patients with TNNT2 (18%) mutations showed an increased probability of having a signif-
Abstracts
Canadian Cardiovascular Society (CCS) CCS357 Oral CARDIOMYOPATHY Tuesday, October 30, 2012 771 RAPID SEGMENTATION OF MYOCARDIAL SCAR FROM 3DIMENSIONAL LATE GADOLINIUM ENHANCEMENT MAGNETIC RESONANCE IMAGING M Rajchl, J Stirrat, TM Peters, JA White London, Ontario BACKGROUND: High-resolution, 3D late gadolinium enhancement (LGE) scar imaging is feasible using 3T MRI, and is emerging as a preferred approach for imaging complex scar. However, these datasets pose substantial challenges for manual scar segmentation. An efficient and reliable scar segmentation technique would allow for accurate scar volume quantification while providing anatomic scar models relevant to procedural navigation, such as for ablative therapies to eliminate ventricular tachycardia (VT). In this study we test the feasibility of a novel semi-automated algorithm to isolate scar signal from isotropic LGE MRI. METHODS: A total of 25 patients with LV scar (ischemic, N⫽10) or RV scar (Tetralogy of Fallot repair, N⫽15) underwent high-resolution 3D LGE using a 3T MRI system (Siemens Trio®, Germany) using a respiratory navigated IR-GRE sequence 30 minutes following 0.2 mmol/kg Gadovist® (Bayer, Canada). Voxel dimensions were 1.3x1.3x1.3mm. Datasets were blindly segmented using proposed convex flow maximization (CFM) principals that use the spatial consistency of cardiac structures as a geometric constraint to limit the search of scar signal to the myocardium. Resulting scar volumes were compared to a blinded expert manual segmentation using the Dice Similarity Coefficient (DSC) and a root mean squared surface error (RMSE). A second interpreter performed CFMbased segmentation in 10 cases to provide inter- and intraoperator reproducibility. RESULTS: Image quality was adequate for scar segmentation in 24 of 25 cases (respiratory motion in one patient with RV scar). Expert manual segmentation of RV scar took 46⫾13 min. In patients with LV scar the CFM-based software segmented all scar in 9⫾2 minutes and provided a DSC of 0.78⫾0.03. The RMS surface error (RMSE) was excellent at 1.05⫾0.15mm. In patients with RV scar the CFM-based software segmented all scar in 10⫾2 minutes and provided a DSC of 0.71⫾0.04. The RMSE was 0.80⫾0.2mm. Inter- and intra-observer reproducibility was excellent with total scar volume measurements within (r⫽0.982, bias⫽0.37, 95% CI -2.894 to 3.628) and between users (r⫽0.975, bias⫽2.04, 95% CI -3.479 to 7.563). CONCLUSION: We demonstrate feasibility of a novel segmentation algorithm for the identification of myocardial scar from high-resolution 3D LGE-MRI. The technique provides accurate quantification of scar and generation of cardiac models for procedural navigation.
CIHR, ORF, CFI
Featured Research 772 GENOTYPE-PHENOTYPE CORRELATIONS ACCORDING TO CLINICAL AND ECHOCARDIOGRAPHIC CHARACTERISTICS IN HYPERTROPHIC CARDIOMYOPATHY C Henri, P Garceau, L Robb, J Lavoie, LA Mercier, P Romeo, MS Phillips, Y Renaud, C Barahona-Dussault, I Fillion, P L’Allier, F Marcotte, M Talajic Montréal, Québec BACKGROUND: Many mutations among genes encoding sarcomeric proteins have been identified in hypertrophic cardiomyopathy (HCM) leading to a heterogenic phenotype. Studies demonstrate negative outcomes associated with positive genetic testing but data on specific genotype-phenotype correlations are limited and highly variable. METHODS: Identified mutations in genes TNNI3 (troponin I), TNNT2 (troponin T), MYBPC3 (myosin-binding protein C) and MYH7 (myosin heavy chain) were screened in 284 patients at the Cardiovascular Genetic Clinic of the Montréal Heart Institute. Mutations were identified in 113 patients (40%) and 84 patients (74%) were included for analysis. Five cardiac transplant recipients without previous echocardiographic images available were analysed according to clinical characteristics only. We excluded 16 patients without HCM phenotype and 13 patients with follow-up outside of our center. RESULTS: MYH7 (40%) and MYBPC3 (40%) mutations were the most common (Table 1). Only one patient was identified with a TNNI3 (1%) mutation and was excluded from further analysis. Patients with MYH7 mutations were younger at diagnosis and presented more often with a familial history of sudden cardiac death (76%) and defibrillator implantation (59%). Patients with MYH7 mutations were also more likely to progress to “burn-out” HCM (ejection fraction less than 50%) (27%) and cardiac transplantation (18%). Significant mitral insufficiency was more prevalent in patients with MYBPC3 mutations (33%). Patients with TNNT2 (18%) mutations showed an increased probability of having a signif-