Parallel Imaging of the Cervical Spine at 3T: Optimized Trade-Off between Speed and Image Quality

Abstract

Patients with cervical spine syndrome often experience pain during the MR examination. Our aim was to compare the quality of cervical spine MR images obtained by parallel imaging with those of nonaccelerated images, with the goal of shortening the examination time while preserving adequate image quality. A phantom study and examinations of 10 volunteers and 26 patients were conducted on a clinical 3T scanner. Acquisitions included axial T2WI, sagittal T2WI, T1WI, and T2TIRM sequences. Nonaccelerated sequences and accelerated sequences with different numbers of averages and different accelerations, with a scanning time reduction of 67%, were performed. For quantitative analysis, the SNR was obtained from the phantom measurements, and the NU was calculated from the volunteer measurements. For qualitative analysis, 3 independent readers assessed the delineation of anatomic structures in volunteers and the visibility of degenerative disease in patients. In the phantom study, as expected, the SNR of the nonaccelerated images was higher than the SNR of the same sequence with parallel imaging. In vivo, the NU was higher when applying fewer averages or parallel imaging, compared with the nonaccelerated images. The analysis of the subjective parameters in the volunteers and patients showed that a scanning time of 48% of the original protocol could be obtained by combining the following sequences: sagittal T1WI with 1 average; sagittal T2WI with acceleration factor 3; sagittal T2TIRM with acceleration factor 2; and axial T2* GRE with acceleration factor 2. Parallel imaging of the cervical spine at 3T allows shortening of the examination time by 52%, preserving adequate image quality.