Shin Takuma

LV volume quantification via spatiotemporal analysis of real-time 3-D echocardiography

This paper presents a method of four-dimensional (4-D) (3-D+Time) space-frequency analysis for directional denoising and enhancement of real-time three-dimensional (RT3D) ultrasound and quantitative measures in diagnostic cardiac ultrasound. Expansion of echocardiographic volumes is performed with complex exponential wavelet-like basis functions called brushlets. These functions offer good localization in time and frequency and decompose a signal into distinct patterns of oriented harmonics, which are invariant to intensity and contrast range. Deformable-model segmentation is carried out on denoised data after thresholding of transform coefficients. This process attenuates speckle noise while preserving cardiac structure location. The superiority of 4-D over 3-D analysis for decorrelating additive white noise and multiplicative speckle noise on a 4-D phantom volume expanding in time is demonstrated. Quantitative validation, computed for contours and volumes, is performed on in vitro balloon phantoms. Clinical applications of this spatiotemporal analysis tool are reported for six patient cases providing measures of left ventricular volumes and ejection fraction.

Suppression of Murine Cardiac Allograft Arteriopathy by Long-Term Blockade of CD40-CD154 Interactions

Background—The interaction between CD40 on antigen-presenting cells and CD40L on T cells is critical in allograft rejection. CD154 blockade suppresses allograft rejection, but the role of this pathway in allograft vasculopathy remains obscure. Methods and Results—A vascularized murine heterotopic cardiac transplant model was used to test whether perioperative CD154 blockade suppresses allograft vasculopathy or whether long-term CD154 blockade is required to suppress allograft vasculopathy. Perioperative CD154 blockade consisted of MR1 given on days −1, 1, and 3; long-term blockade consisted of MR1 given on days −1, 1, and 3 and continued twice weekly for 8 weeks. Allografts treated with perioperative or long-term CD154 blockade survived indefinitely. Perioperative and long-term treatment with control antibody (Ha4/8) resulted in uniform early rejection. Perioperative CD154 blockade transiently reduced early T-cell and macrophage infiltration in parallel with a transient reduction in endothelial adhesion receptor expression. Although perioperative CD154 blockade prevented allograft failure, it did not reduce allograft vasculopathy; mean neointimal cross-sectional area in perioperative MR1-treated and Ha4/8-treated recipients was 43±7% and 50±12%, respectively (P =NS). In contrast, mean neointimal cross-sectional area in long-term, MR1-treated recipients was 19±3% (P <0.001 versus perioperative MR1). Long-term CD154 blockade also suppressed endothelial E-selectin, P-selectin, and intracellular adhesion molecule-1 expression and improved graft function 3.5-fold versus control (P <0.05). Conclusions—These data show that perioperative CD154 blockade mitigates acute rejection but long-term CD154 blockade may result in decreased allograft endothelial activation and is required to suppress allograft arteriopathy.

Directional Representations of 4D Echocardiography for Temporal Quantification of LV Volume

Real-time acquisition via four-dimensional (3D plus time) ultra-sound obviates the need for slice registration and reconstruction, leaving segmentation as the only barrier to an automated, rapid, and clinically applicable calculation of accurate left ventricular cavity volumes and ejection fraction. Speckle noise corrupts ultrasound data by introducing sharp changes in an image intensity profile, while attenuation alters the intensity of equally significant cardiac structures, depending on orientation with respect to the position of the ultrasound beam. These properties suggest that measures based on phase information rather than intensity are appropriate for denoising and boundary (surface) detection. Our method relies on the expansion of temporal volume data on a family of basis functions called Brushlets. These basis functions decompose a signal into distinct patterns of oriented textures. Projected coefficients are associated with distinct “brush strokes” of a particular size (width) and orientation (direction). Brushlet decompositions are invariant to intensity (contrast range) but depend on the spatial frequency content of a signal. Preliminary results of this directional space-frequency analysis applied to both phantoms and clinical data are presented. The method will be used to clinically evaluate 4D data and to extract and quantify heart LV volumes.

Evaluation of Mitral Valve Disease Using TransesophagealEchocardiography

In the past 10 years, clinical application of transesophageal echocardiography (TE) has grown explosively. Intraoperative TE offers a powerful diagnostic and monitoring tool for the physicians in the cardiac operating room. The use of TE revolutionizes the assessment of patients with mitral valve disease. Surgical decisions are often altered based on the information obtained from TE. This review describes the basic features of TE as well as its uses in the intraoperative setting for evaluation of the mitral valve.