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Respiratory gating in magnetic resonance imaging: improved image quality over non-gated images for equal scan time
M W Groch1, D A Turner, W D Erwin
1Department of Diagnostic Radiology and Nuclear Medicine, Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois 60612.
Abstract:
Magnetic resonance image quality is adversely affected by respiratory (RESP) motion during the scan. Respiratory gating improves magnetic resonance image (MRI) quality and removes artifacts, but has not been widely used, as RESP gating increases scan time. Our RESP-gating device was used to study scan time versus improvement in image quality using various gating modes; with and without combined electrocardiographic (ECG) gating. When RESP scans were acquired for the same time as non-gated scans, by using a wide RESP-gating window bracketing end expiration and a reduced number of pulse sequence repetitions, substantial improvement in image quality (over non-gated scans) resulted, despite the inferior statistical content of the acquisition.
Insights
Respiratory gating significantly enhances magnetic resonance image (MRI) quality by reducing motion artifacts. This technique can be implemented without increasing scan time, offering a practical solution for improved diagnostic imaging.
Area of Science:
- Medical Imaging
- Biomedical Engineering
- Radiology
Background:
- Respiratory motion is a major cause of artifacts in magnetic resonance imaging (MRI), degrading image quality.
- Respiratory gating (RESP gating) can mitigate these artifacts but often increases scan duration, limiting its clinical adoption.
- Electrocardiographic (ECG) gating is sometimes combined with RESP gating.
Purpose of the Study:
- To evaluate the trade-off between scan time and image quality improvement using a novel RESP-gating device.
- To investigate the impact of various gating modes, including combined ECG gating, on MRI quality.
- To determine if substantial image quality enhancement is achievable without extending scan time.
Main Methods:
- Utilized a RESP-gating device to acquire MRI scans under different gating conditions.
- Compared scan times and image quality metrics between gated and non-gated acquisitions.
- Employed a wide RESP-gating window at end-expiration and reduced pulse sequence repetitions to maintain scan duration.
Main Results:
- Substantial improvements in MRI image quality were observed with RESP gating compared to non-gated scans.
- These quality enhancements were achieved even when acquiring gated scans for the same duration as non-gated scans.
- The strategy of using a wide gating window and fewer repetitions yielded better image quality despite reduced statistical content.
Conclusions:
- Optimized respiratory gating protocols can significantly improve MRI quality without increasing overall scan time.
- This approach offers a viable method to reduce motion-induced artifacts in clinical MRI.
- The findings suggest that RESP gating can be more widely implemented by addressing the scan time limitation.