Intrinsic signal amplification in the application of 2D SENSE parallel imaging to 3D contrast‐enhanced elliptical centric MRA and MRV

Abstract

The relative signal‐to‐noise ratio (SNR) provided by 2D sensitivity encoding (SENSE) when applied to 3D contrast‐enhanced MR angiography (CE‐MRA) is studied. If an elliptical centric phase‐encoding order is used to map the waning magnetization of the contrast bolus to k‐space, the application of SENSE will reduce the degree of k‐space signal modulation, providing a signal amplification A over corresponding nonaccelerated acquisitions. This offsets the SNR loss in R‐accelerated SENSE due to and the geometry (g ) factor. The theoretical bound on A is R and is reduced from this depending on the properties of the bolus profile and the duration over which it is imaged. In this work a signal amplification of 1.14–1.23 times that of nonvascular background tissue is demonstrated in a study of 20 volunteers using R = 4 2D SENSE whole‐brain MR venography (MRV). The effects of a nonuniform g‐factor and inhomogeneity of background tissue are accounted for. The observed amplification compares favorably with the value of 1.31 predicted numerically from a measured bolus curve. Magn Reson Med 58:855–864, 2007.