Study of myocardial fiber pathway using magnetic resonance diffusion tensor imaging.
The purpose of this study was to investigate myocardial fiber pathway distribution in order to provide supplemental information on myocardial fiber architecture and cardiac mechanics. Diffusion tensor imaging (DTI) with medium diffusion resolution (15 directions) was performed on normal canine heart samples (N=6) fixed in formalin. With the use of diffusion tensor fiber tracking, left ventricle (LV) myocardial fiber pathways and helix angles were computed pixel by pixel at short-axis slices from base to apex. Distribution of DTI-tracked fiber pathway length and number was analyzed quantitatively as a function of fiber helix angle in step of 9 degrees . The long fiber pathways were found to have small helix angles. They are mostly distributed in the middle myocardium and run circumferentially. Fiber pathways tracked at the middle and upper LV are generally longer than those near the apex. Majority of fiber pathways have small helix angles between -20 degrees and 20 degrees , dominating the fiber architecture in myocardium. Likely, such myocardial fiber pathway measurement by DTI may reflect the spatial connectiveness or connectivity of elastic myofiber bundles along their preferential pathway of electromechanical activation. The dominance of the long and circumferentially running fiber pathways found in the study may explain the circumferential predominance in left ventricular contraction.
Wu
Ed X
EX
Department of Electrical and Electronic Engineering, Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong, China. ewu@eee.hku.hk
Wu
Yin
Y
Tang
Haiying
H
Wang
Jie
J
Yang
Jian
J
Ng
Man C
MC
Yang
Edward S
ES
Chan
Carmen W
CW
Zhu
Shuguang
S
Lau
Chu-Pak
CP
Tse
Hung-Fat
HF
D000818:Animals; D038524:Diffusion Magnetic Resonance Imaging; D004285:Dogs; D006321:Heart / Q000033:anatomy & histology*; D021621:Imaging, Three-Dimensional; D018485:Muscle Fibers, Skeletal; D010210:Papillary Muscles / Q000033:anatomy & histology*