Cardiac magnetic resonance parallel imaging at 3.0 Tesla: Technical feasibility and advantages

Abstract

Purpose: To quantify changes in signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), specific absorption rate (SAR), RF power deposition, and imaging time in cardiac magnetic resonance imaging with and without the application of parallel imaging at 1.5 T and 3.0 T. Materials and Methods:Phantom and volunteer data were acquired at 1.5 T and 3.0 T with and without parallel imaging.Results: Doubling field strength increased phantom SNR by a factor of 1.83. In volunteer data, SNR and CNR values increased by factors of 1.86 and 1.35, respectively. Parallel imaging (reduction factor ϭ 2) decreased phantom SNR by a factor of 1.84 and 2.07 when compared to the full acquisition at 1.5 T and 3.0 T, respectively. In volunteers, SNR and CNR decreased by factors of 2.65 and 2.05 at 1.5 T and 1.99 and 1.75 at 3.0 T, respectively. Doubling the field strength produces a nine-fold increase in SAR (0.0751 to 0.674 W/kg). Parallel imaging reduced the total RF power deposition by a factor of two at both field strengths. Conclusions:Parallel imaging decreases total scan time at the expense of SNR and CNR. These losses are compensated at higher field strengths. Parallel imaging is effective at reducing total power deposition by reducing total scan time.

Evaluation of motion correction effect and image quality with the periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) (BLADE) and parallel imaging acquisition technique in the upper abdomen

“…This was because of the dense and extensive sampling of the central region of the k-space to overcome undersampling even if parallel imaging was used, i.e., overcoming motion artifact, as reported in a previous work (20). The deteriorated results for L/C(1) compared with those for L/C(2) indicated that for the same values of matrix size, blade width, and number of blades, the advantage of shorter ETL could not overcome the effect of k-space undersampling (21). The streak artifact arises in the process of gridding acquired data to the parallel k-space from the oblique trajectory, and the undersampling of kspace was shown to increase the artifact (13,20).…”

“…Therefore, increasing blade coverage was expected to improve not only motion correction effects but also the signal-to-noise ratio (SNR), as a result of oversampling, as was shown in the L/C(3) compared with other scan conditions. Although reduced ETL was expected to decrease image blurring and improve the overall image quality, the L/C(1) image gave the worst score because of an increase in image artifacts due to k-space undersampling, which was found to be unrecoverable with iPAT (21).…”

Prostate MR imaging at high-field strength: evolution or revolution?

“…Despite these potential difficulties, it is now clear that high field strength is beneficial for many applications such as brain [10][11][12], heart [4,13,14], or musculoskeletal imaging [1,15].…”

“…Chemical shift and susceptibility artifacts also increase linearly with B 0 , resulting in difficulties in analyzing water-fat transitions and in signal losses in regions of susceptibility differences. Increasing the sampling bandwidth can reduce chemical shift artifacts, but at the expense of SNR [1,2,4]. The applied RF has to be adapted to higher Larmor frequencies, making its penetration into tissues more difficult [1,2].…”

The year in cardiac imaging

“…McGee et al (9) showed increasing the field strength from 1.5-T to 3-T resulted in a 1.83 increase in signal-tonoise ratio in five volunteers. They also tested parallel imaging at 3-T.…”