Abstract
ObjectiveTo study the influence that the scan percentage tool used in partial k-space acquisition has on the quality of images obtained with magnetic resonance imaging equipment.Materials and MethodsA Philips 1.5 T magnetic resonance imaging scanner was used in order to obtain phantom images for quality control tests and images of the knee of an adult male.ResultsThere were no significant variations in the uniformity and signal-to-noise ratios with the phantom images. However, analysis of the high-contrast spatial resolution revealed significant degradation when scan percentages of 70% and 85% were used in the acquisition of T1- and T2-weighted images, respectively. There was significant degradation when a scan percentage of 25% was used in T1- and T2-weighted in vivo images (p ≤ 0.01 for both).ConclusionThe use of tools that limit the k-space is not recommended without knowledge of their effect on image quality.
Highlights
One way of reducing image acquisition time is to reduce the number of lines to be filled in the k-space
All of the information used in presenting magnetic resonance imaging (MRI) scans is first acquired in the k-space, which represents the spatial frequency domain[2,3]
The technical parameters of the protocols adopted in the imaging process with the phantom were as follows: for axial T1-weighted images—field of view (FOV): 230 mm; reduced field of view (RFOV): 100%; repetition time/echo time (TR/ TE): 638/14 ms; flip angle: 90°; number of excitations (NEX): 2; reconstruction matrix: 512 × 512; acquisition matrix: 256 × 256; interslice gap: 1 mm; slice thickness: 4 mm; spacing: 4.4 mm—and for axial T2-weighted images— FOV: 230 mm; RFOV: 100%; TR/TE: 4986/100 ms; flip angle: 90°; NEX: 2; reconstruction matrix: 512 × 512; acquisition matrix: 256 × 256; interslice gap: 1 mm; slice thickness: 4 mm; spacing: 4.4 mm
Summary
One way of reducing image acquisition time is to reduce the number of lines to be filled in the k-space. Adopting this measure can have a negative effect on image quality[1]. All of the information used in presenting magnetic resonance imaging (MRI) scans is first acquired in the k-space, which represents the spatial frequency domain[2,3]. The peripheral lines contain information on the spatial resolution of the object, whereas the central lines represent the contrast, and the relationship between the k-space and the image can be obtained by the two-dimensional (2D) Fourier transform[1,2,4]
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