Assessment of Reproducibility of Geometric Distortion in MRI using Phantom Measurements
Publish place: Iranian Journal of Medical Physics، Vol: 2، Issue: 3
Publish Year: 1384
نوع سند: مقاله ژورنالی
زبان: English
View: 269
This Paper With 8 Page And PDF Format Ready To Download
- Certificate
- من نویسنده این مقاله هستم
استخراج به نرم افزارهای پژوهشی:
شناسه ملی سند علمی:
JR_IJMP-2-3_001
تاریخ نمایه سازی: 20 مهر 1398
Abstract:
Introduction: Image distortion is one of the major problems of magnetic resonance imaging (MRI) for use in 3DMRI, velocity MRI, FMRI and radiotherapy treatment planning (RTTP). It is widely known that the most obvious effect of the inhomogenity of the magnetic fields and the nonlinearity of the gradient is the Geometric Distortion of MR tomograms. In this study, the accuracy of MR images was considered by the phantom study and the reproducibility of images was evaluated by repeating the phantom measurements. Materials and Methods: MRI scans of the phantom with grid pattern inside it were performed using head coil in two 1.5 Tesla MRI systems (Picker VISTA TM HPQ, USA & GE Signa Echo Speed, USA). For the Geometric Distortion reproducibility evaluation the T1W, T2W and PDW SE protocols were repeated three times. The Geometric Distortion was measured by an edge detection program in MATLAB. Results: The geometric distortion in the peripheral area of the images tends to be generally larger than it in the central area in all images. The average displacement in Picker MRI was 3 pixels in the y and 1 pixel in the x direction and in GE MRI it was 1 pixel in both x and y direction for 24 cm FOV (pixel = 0.9 mm). Discussion and Conclusions: Since the positional variation was within 1 to 3 pixels for the head coil, it will be possible to use this MR system in 3DMRI, velocity MRI, FMRI and RTTP. To decrease the geometric distortion the use of suitable coil and protocol are expected.
Keywords:
Authors
M. Ashkanmehr
M.Sc. in Nuclear Engineering Dept., Islamic Azad University, Tehran, Iran.
N. Riyahi Alam
Associate Professor, Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran. Research Center for Science & Technology in Medicine, Imam Khomeini Hospital, Tehran. Iran.
M.A. Oghabian
Associate Professor, Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran. Research Center for Science & Technology in Medicine, Imam Khomeini Hospital, Tehran. Iran.
A. Ghasemzadeh
M. Sc. in Research Center for Science & Technology in Medicine, Imam Khomeini Hospital, Tehran. Iran.