Compare image quality of T2-weighted imaging with different phase acceleration factors

Abstract

Previous studies demonstrated that adjusting the phase acceleration (PA) factors could influence image quality. To improve image quality and decrease respiratory artifacts of lesions in the liver on T2-weighted image by adjusting PA factor and number of excitation (NEX). Sixty consecutive patients with hepatic lesions were enrolled in this prospective research between May 2020 and June 2020. All patients had 3.0T magnetic resonance imaging with 4 sequences (combining PA factors and NEXs, the former was 2 and 3, the latter were 1.5 and 2, respectively, with the same other scanning parameters). Two readers used 5-point quality scales to assess image quality. The signal intensity was measured by drawing regions of interest in the liver, spleen, and background on the T2-weighted imaging. Artifacts, overall image impression, and vascular conspicuity were better when the PA factor was 3 than 2. Artifacts and vascular conspicuity were better when NEX was 2 than 1.5. PA factor 3 and NEX 2 got a higher score in 5-point quality scales and less scan time than the other 3 sequences. Meanwhile, the signal-to-noise ratio of PA factor 3 and NEX 2 was best among these 4 sequences. PA factor and NEX could influence the imaging quality and lesion-to-hepatic contrast in detecting hepatic lesions on T2-weighted images. PA factor 3 and NEX 2 may have a positive effect in the clinic, especially for those with irregular respiration, as it decreased artifacts and reduced scan time.

Figure 1.

The images of hepatic lesions in T2-weighted imaging with combinations of different PA factors and NEXs. (A) A2N1.5-T2-weighted imaging, (B) A2N2-T2-weighted imaging, (C) A3N1.5-T2-weighted imaging, and (D) A3N2-T2-weighted imaging. Image (c) and (d) were sharper than (a) and (b). In all 4 images, artifacts were mild or not present. The margins of the liver were blurred in images (a) and (b) (arrows). And the lesion in (d) was larger and clearer, and intrahepatic vascular structures (arrowheads) were more conspicuity than in other sequences. NEX = number of excitation, PA = phase acceleration.

Figure 2.

The images of liver parenchyma in T2-weighted imaging with combinations of different PA factors and NEXs. (A) A2N1.5-T2-weighted imaging, (B) A2N2-T2-weighted imaging, (C): A3N1.5-T2-weighted imaging, and (D) A3N2-T2-weighted imaging. The vascular pulsation artifact was obvious in (a) (arrowhead) and mild in (b) (arrowhead). Intrahepatic vascular structures (arrowheads) were more conspicuity in (d) than in (c). NEX = number of excitation, PA = phase acceleration.