PROCEEDINGS ARTICLE | March 15, 2011
Proc. SPIE. 7962, Medical Imaging 2011: Image Processing
KEYWORDS: Digital image processing, Visualization, Imaging systems, Magnetic resonance imaging, Image processing, Linear filtering, Arteries, Image quality, Image filtering, Magnetic resonance angiography
Whole-heart coronary magnetic resonance angiography (WH-MRA) is useful noninvasive examination. Its signal
acquisition is performed during very short still timing in each cardiac motion cycle, and therefore the adequate still
timing selection is important to obtain the better image quality. However, since the current available selection method is
only manual one using visual comparison of cine MRI images with different phases, the selected timings are often
incorrect and their reproducibility is not sufficient. We developed an automated selection method to detect the best still
timing for the WH-MRA and compared the automated method with conventional manual one. Cine MRI images were
used for the analysis. In order to extract the high-speed cardiac cine image, each phase directional pixel set at each pixel
position in all cine images were processed by a high-pass filtering using the Fourie transform. After this process, the cine
images with low speed timing became dark, and the optimal timing could be determined by a threshold processing. We
took ten volunteers' WH-MRA with the manually and automatically selected timings, and visually assessed image
quality of each image on a 5-point scale (1=excellent, 2=very good, 3=good, 4=fair, 5=poor). The mean scores of the
manual and automatic methods for right coronary arteries (RCA), LDA left anterior descending arteries (LAD) and LCX
left circumflex arteries (LCX) were 4.2±0.38, 4.1±0.44, 3.9±0.52 and 4.1±0.42, 4.1±0.24, 3.2±0.35 respectively. The
score were increased by our method in the RCA and LCX, and the LCX was significant (p<0.05). As the results, it was
indicated that our automated method could determine the optimal cardiac phase more accurately than or equally to the
conventional manual method.
