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Quality Assurance for Diffusion Tensor Imaging Using an ACR Phantom KCI 등재
- 언어ENG
- URLhttps://db.koreascholar.com/Article/Detail/340724
p.219
Pulpose : Although diffusion tensor imaging (DTI) has been widely used for the quantitative analyses of the integrity of white matter in the brain in clinical and research fields, quality assurance (QA) for DTI has not been fully established. The purpose of this study suggests a QA guideline for DTI using the American College of Radiology (ACR) Magnetic resonance imaging (MRI) head phantom.
Materials and Methods : All experiments were performed using 1.5T and 3.0T scanners (InteraAchiva 1.5T and AchivaTx 3.0T; Philips Medical Systems, Netherlands) equipped with an 8-channel SENSE head coil. The standard axial SE T1-weighted MR images with 6, 15 and 32 directions of DTI were obtained using the standard scanning protocol “Phantom Test Guidance for the ACR MRI Accreditation Program” . Slice thickness and slice gap were set at 5 mm for standard axial SE T1 images and echo planar images, and then both images were compared. Reproducibility was tested with 7 repeat scans in 1.5T scanner and 10 repeat scans in 3.0T scanner. Between the scanning, the ACR MRI phantom was completely removed from coil and was repositioned for each new trial. Parameters for the QA protocol are shown in Table 1. The ACR MRI phantom was stored in the scanner room for at least 24 hours before an experiment, and the room temperature was measured before scanning for DTI.
Results : There were statistically significant differences in the geometric accuracy between the 1.5T and 3.0T two scanners across all scan directions. The top-to-bottom diameters had a 11.3 mm error in 1.5T scanner and a 7.2 mm error in 3.0T scanner. Image intensity uniformity tests were significant in 6, 15, and 32 directions at 1.5T and 3.0T comparative analysis (p < 0.001). Additionally, percent signal-ghosting tests were significant in all directions, such as 6, 15 and 32 directions, in both 1.5T and 3.0T scanners (p < 0.001). The DTI images from 1.5T scanner had a ghosting ratio less than 0.025 at 1.5T scanner while 3.0T scanner had a ghosting ratio greater than 0.045. The low-contrast object detectability had a significant differences in 6, 15, 32 directions at 1.5T and 3.0T systems (p < 0.001). The DTI images from 1.5T system showed 2.85 spokes in 6 directions, 14.00 spokes in 15 directions, and 26.14 spokes in 32 directions. The DTI images from 3.0T system had 7.80 spokes in 6 directions, 32.20 spokes in 15 directions, and 37.30 spokes in 32 directions. Image distortion was significant in the anteriorposterior (AP) direction (p <0.001), but was not significant in right-left (RL) direction (p = 0.359). Image distortions in 1.5T scanner were 6.93 mm for the AP direction and 0.26 mm for the RL direction while the same for 3.0T system were 8.55 mm for the AP direction and 0.28 mm for the RL direction. For the FA and the ADC values, we acquired significant results in 6, 15, and 32 directions for 1.5T and 3.0T scanners (p < 0.001). The FA values were relatively lower for 3.0T system than for 1.5T system, and 32 directions for 3.0T scanner had the lowest value. The ADC values of 3.0T system were lower than those of 1.5T system, and 15 and 32 directions had the lowest values.
Conclusion : This study is the first trial using the ACR MRI phantom that is easily accessible in most clinical MR centers. Also, the present study using the ACR MRI phantom suggests a QA method for DTI with high reproducibility and easy accessibility.
