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Motion related artifacts in spin-echo MR imaging: effects of sequence parameters on image quality at 1.5 Tesla
O N Adjei1, H Sugimura, S Tamura
1Department of Radiology, Miyazaki Medical College, Japan.
Purpose:
The purpose of this study was to evaluate the effects of selected parameters in a conventional spin-echo MRI sequence on image quality in a phantom undergoing periodic motion.
Methods:
Images of a composite oil/copper sulfate phantom moving in a 1.5 Tesla magnet were acquired. The CuSO4 ghost signal-to-noise ratio (SNR) and distances between corresponding points on the phantom image and adjacent ghosts were evaluated.
Results:
Increasing time to repeat (TR) and number of acquisitions (NAq) improved image quality. Ghost SNR was near unity at TR = 500 msec and at NAq around 4. Increasing TR and NAq resulted in increased distance between images. The effects of field of view (FOV) and matrix size on image quality were relatively less significant.
Conclusion:
Increasing NAq appeared to have a comparatively greater effect on ghost SNR and image quality under our experimental conditions. However, the effect of increasing NAq on image quality appeared to be definite since a saturation point was reached after a particular NAq. Increasing NAq above this point resulted in a relatively smaller improvement in image quality.
Insights
Optimizing magnetic resonance imaging (MRI) sequences for moving phantoms involves adjusting parameters like time to repeat (TR) and number of acquisitions (NAq). Increasing NAq significantly enhances ghost signal-to-noise ratio (SNR) and overall image quality.
Area of Science:
- Medical Imaging
- Physics
Background:
- Periodic motion in patients can degrade MRI image quality.
- Spin-echo sequences are commonly used but susceptible to motion artifacts.
Purpose of the Study:
- To assess how specific parameters in spin-echo MRI affect image quality in a moving phantom.
- To identify optimal settings for reducing motion artifacts.
Main Methods:
- A composite phantom with oil and copper sulfate was imaged in a 1.5 Tesla MRI scanner.
- The study evaluated ghost signal-to-noise ratio (SNR) and inter-image distances.
- Parameters varied included time to repeat (TR), number of acquisitions (NAq), field of view (FOV), and matrix size.
Main Results:
- Increasing TR and NAq improved image quality and increased the distance between ghost images.
- Optimal ghost SNR was achieved around TR = 500 msec and NAq = 4.
- FOV and matrix size had less impact on image quality compared to TR and NAq.
Conclusions:
- Increasing NAq demonstrated a significant positive effect on ghost SNR and image quality.
- A saturation point exists for NAq, beyond which improvements in image quality diminish.
- Careful selection of NAq is crucial for optimizing MRI in the presence of motion.