Characterizing radial undersampling artifacts for cardiac applications

The undersampled radial acquisition has been widely employed for accelerated (by a factor R = N r / N p ) 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 N p ), the total artifact is ∼10% for short and long‐axis imaging ( R = 2.1) and ∼15% for coronary MRI ( R = 3.7). For 60 N p , 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 ( N p > 120, R = 2.1). Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.