Radiation Monitoring/Original Articles
ZHAI Hezheng, ZHANG Jin, WU Xiangjun, YIN Handong, WANG Xin, WANG Manyao, HUANG Ziqi, WU Quan
Objective This paper discusses the process of MRI image quality testing index, establishes the baseline value of MRI equipment image quality index, and provides the certain basis for improving the relevant national standards.Methods On the basis of the current domestic and foreign standard test conditions at home and abroad, and with the help of SMR 170 magnetic resonance image quality control phantom, newly installed MAGNETOM Skyra type magnetic resonance signal-to-noise ratio, image uniformity, layer thickness, uniformity of layer thickness, spatial resolution, geometric distortion rate, low contrast resolution, resonant frequency, aspect ratio and other indicators were tested, and the corresponding baseline values of each indicator were obtained, and combined with relevant materials, discussing the impact of magnetic resonance imaging quality testing;Results The spin echo sequence (SE), head coil, pulse echo time of 20 ms, pulse recovery time of 250 ms, field of view (FOV) of 250 mm×250 mm and acquisition twice were used to collect the images. The preset layer thickness was 5 mm, 8 mm and 10 mm, respectively. The measured layer thickness and nonuniformity were 5.2 mm/1.3%, 8.3 mm/2.0% and 10.4 mm/3.2%, respectively; When the matrix was 256 mm×256 mm, the results of signal-to-noise ratio and image uniformity were 103.2/98.3%, 105.6/96.0% and 110.2/96.4%, respectively. The signal-to-noise ratios were 102.6, 104.8 and 106.2, respectively, when the matrix was 512 mm×512 mm; The spatial resolution was 1 mm when the matrix was 256 mm×256 mm, and the results were 0.556 mm, 0.556 mm and 0.5 mm, respectively when the matrix was 512 mm×512 mm; The low contrast resolution was circular holes with a diameter of 4 mm and a hole depth of 0.5 mm. Meanwhile, the measurement results of geometric distortion rate were 20.0 mm, 40.3 mm, 80.5 mm and 100.8 mm at the hole spacing of 20 mm, 40 mm, 80 mm and 100 mm, respectively.Conclusion Using SMR 170 phantom to detect the parameter setting and baseline value of the MRI indexes could provide certain basis for the follow-up state detection. The key point of MRI quality control work in the future is to improve the MRI image quality detection index, develop the matching MRI image quality test phantom and update the relevant standards.
