Visiting Researcher: Shinichi Fujimoto   Towards the Utilization of Computational Biomechanics in the Numerical Analysis of the Left Ventriclar Blood Flow 1. Aim and plan of the study Aim: Studying various image types and their clinical application From the standpoint of clinical medicine, data of various types of images were studied for use in the construction of an endocardial blood flow simulation model. Moreover, the clinical application of this image data was investigated. Plan: The plan of the study was as follows: (1) Cardiac tomogram obtained from transthoracic echocardiogram was studied in order to obtain multiple cross-sectional images and perpendicularly intersecting cross-sectional images. (2) Three-dimensional transesophageal echocardiogram was studied. (3) Three-dimensional transthoracic echocardiogram was studied. (4) Clinical application of the abovementioned echocardiograms was investigated. 2. Summary of this study (A) Studying the various image types (1) Transthoracic echocardiogram In order to construct the shape of the left ventricle for simulation, manual tracing of the endocardium was required, and the time consumed for inputting multiple cross-sectional image data was relatively longer. On the other hand, it was considered that constructing the shape of the left ventricle by using multiple cross-sectional images was not very different from that by using perpendicularly intersecting two cross-sectional images. (2) Three-dimensional transesophageal echocardiogram Since image representation from a transthoracic echocardiogram was occasionally difficult, a method to represent an image from a three-dimensional transesophageal echocardiogram was investigated. However, this method was considered to be inapplicable because it imposed a serious burden on patients. (3) Three-dimensional transthoracic echocardiogram Since image representation from a transthoracic echocardiogram was simple and effective, cases of its application are now being accumulated. (4) Observation of the time course changes in the cardiac wall movement and the endocardial blood flow movement in various cases The accumulated cases are currently being analyzed. Based on the progress of similar previous cases, it is possible that the future image of a new case can be constructed in order to use the image data for attaining a clinical decision and providing explanation to the patient. (B) Clinical application Application of image data for evaluating the human left ventricular function Since supersonic images were used to construct prototype models for computational biomechanics of endocardial blood flow in healthy people and patients with dilated cardiomyopathy, the endocardial blood flow movement could be observed. There was a difference in the blood flow between the center and the limbus of the left ventricle, and the detailed endocardial blood flow movement, which could not be observed by conventional Doppler echocardiography performed from the surface of the body, could be evaluated. In future, we shall construct a database containing sufficient number of cases to enable its application for attaining a clinical decision and providing explanation to patients. 3.****** (1) **** [1] Computational model of left ventricle dynamics and flow based on ultrasonographic data. Hidehito Iwase,H.Liu,Shinichi Fujimoto,and Ryutaro Himeno JSME International Journal,Series C 46 (4);1321-1329,2003. (2) ----- [1] Analysis of the left ventricular diastolic filling dynamics in normal and diseased heart by an image-based,computational fluid dynamic study. Shinichi Fujimoto, Hao Liu, Hidehito Iwase, Ryutaro Himeno, Shinobu Nakamura,Proceeding of The 67 th the Annual Scientific Meeting of Japanese Circulation Society, Circulation Journal 67 Supple; 179, 2003. [2] ******* [3] H. Iwase, H. Liu, S. Fujimoto, and R. Himeno, An efficient, image-based, computational fluid dynamic modeling of leftventricle hemodynamics, Proc. Riken Symposium on Computational Biomechanics, 2002. [4] ******* [5] ******* [6] H. Iwase, H. Liu, S. Fujimoto, R. Himeno, and T. Hayasaka, Non-invasive assessment of left ventricle function with a computational fluid dynamic model, Proc. The 4 th World Congress of Biomechanics, Calgary, Canada, 2002. [7] World Congress of Biomechanics, Calgary, Canada, 2002.H. Iwase, H. Liu, S. Fujimoto and R. Himeno, Numerical analysis of blood flow in leftventricle, Proc. ASME-IMECE, New York, 2001.