RESUMEN
Quantification of regional cardiac function is a central goal of cardiology. Multiple methods, such as Coherent Point Drift (CPD) and Simultaneous Subdivision Surface Registration (SiSSR), have been used to register meshes to the endocardial surface. However, these methods do not distinguish between cardiac chambers during registration, and consequently the mesh may "slip" across the interface between two structures during contraction, resulting in inaccurate regional functional measurements. Here, we present Multilabel-SiSSR (M-SiSSR), a novel method for registering a "labeled" cardiac mesh (with each triangle assigned to a cardiac structure). We compare our results to the original, label-agnostic version of SiSSR and find both a visual and quantitative improvement in tracking of the mitral valve plane.
RESUMEN
BACKGROUND: Modern computed tomographic scanning can produce 4-dimensional images of the left atrial appendage (LAA). LAA function and morphology can then be measured, to plan interventions such as occlusion and to evaluate LAA flow for thrombogenic risk analysis. A current problem here is defining a reproducible boundary between the LAA and the left atrium. METHODS: This study used retrospectively gated 4-dimensional computed tomographic data from 25 implantation and coronary artery imaging patients. In each patient, the LAA ostium was defined at multiple time points during the RR interval. To examine the reproducibility of the definition of the LAA ostium, 3 observers analyzed all time frames in each patient 3 times. Five nonconsecutive time frames from each patient were then compared using intraclass correlation coefficients to quantify the precision of the method across patients. The correlation of LAA volumes for each time frame of each patient was determined across the different observers (interobserver) and within each observer's own data sets (intraobserver). RESULTS: The method was successful in 92% of patients. Two-way random-effect, absolute-agreement, single-measurement intraclass correlation coefficients for interobserver measurements were 0.984, 0.990, and 0.988, with intraobserver intraclass correlation coefficients of 0.989, 0.989, and 0.995. The intraclass correlation coefficient of all observations was 0.988. CONCLUSIONS: Classification of the LAA ostium using a stepwise procedure identifying the coumadin ridge and 2 vascular landmarks in ECG-gated computed tomography provides a viable method of establishing a highly reproducible boundary between the atrium and LAA needed to obtain LAA metrics useful for procedure planning and measuring LAA function.