Characterizing radial undersampling artifacts for cardiac applications

Abstract

The undersamplsd radial acquisition has been widely employed for accelerated (by a factor R = Nr/NP) cardiac imaging, but the resulting reduction in image quality has not been well characterized. This investigation presents a method of measuring these artifacts through synthetic undersampling of high SNR images (SNR > 30). After validating the method in phantoms, the method was applied to a study of short-axis, long-axis, and coronary MRI imaging in healthy subjects. For 60 projections (60 Np), the total artifact is ∼10% for short and long-axis imaging (R = 2.1) and ∼15% for coronary MRI (R = 3.7). For 60 Np, the SD of artifact in the region of the heart is 2% for short- and long-axis imaging (R = 2.1) and 3.5% for coronary MRI (R = 3.7). The artifact content is less in the region of the heart than in the periphery. The artifact is very reproducible among subjects for standard views. A study of coronary MRI at progressively fewer projections (at constant scan time) showed that right coronary MRI images were acceptable if total artifact was <6.5% of image content (Np > 120, R = 2.1). © 2006 Wiley-Liss, Inc.