Locally focused 3D coronary imaging using volume-selective RF excitation

• Published in: Magnetic resonance in medicine Vol. 41; no. 1; pp. 171 - 178
• Main Authors: Yang, G.Z., Burger, P., Gatehouse, P.D., Firmin, D.N.
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 01.01.1999; Williams & Wilkins
• Subjects: 2D RF excitation; 3D coronary angiography; Biological and medical sciences; Cardiovascular system; Coronary Vessels - anatomy & histology; Echo-Planar Imaging - standards; echoplanar imaging; Fourier Analysis; Humans; Image Processing, Computer-Assisted; image reconstruction; Investigative techniques, diagnostic techniques (general aspects); Magnetic Resonance Angiography - methods; Magnetic Resonance Angiography - standards; Medical sciences; Motion; Observer Variation; Phantoms, Imaging; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Random Allocation; Reproducibility of Results; Respiration; respiratory motion; 3D imaging; Volume; Echo time; Coronary arteriography; Excitation; Technique; Radiofrequency; Nuclear magnetic resonance imaging; Spatial resolution; Image reconstruction; Test object
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/(SICI)1522-2594(199901)41:1<171::AID-MRM24>3.0.CO;2-5

This paper describes a locally focused magnetic resonance (MR) imaging method for three‐dimensional (3D) zonal echoplanar coronary angiography using volume‐selective radiofrequency (RF) excitation. Spatially variable resolution was used for delineating coronary arteries and reducing the effect of residual signals caused by the imperfect excitation profile of the RF pulse. The use of variable resolution enabled the derivation of basis functions having different spatial characteristics pertaining to regional object details, and a significantly smaller number of phase‐encoded signal measurements was needed for image reconstruction. Based on the relative significance of each required phase‐encoding step, real‐time phase‐encode reordering was used to minimize the effect of respiratory motion during coronary imaging. To eliminate Nyquist ghosting in oblique echoplanar imaging, the echoplanar data acquired during forward and reverse echoes were reconstructed separately and then averaged with spatial registration for improving the signal‐to‐noise ratio. The technique was evaluated with phantom experiments and right coronary artery images of 11 asymptomatic volunteers using a 0.5 T MR system. A marked improvement in image quality has been achieved despite a 30% reduction in imaging time. Magn Reson Med 41:171‐178. © 1999 Wiley‐Liss, Inc.