Related Experiment Videos
Background suppression using magnetization preparation for contrast-enhanced MR projection angiography
C Bos1, C J Bakker, M A Viergever
1Department of Radiology, Image Sciences Institute, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands. C.Bos@azu.nl
Abstract:
In contrast-enhanced MR projection angiography, vessel conspicuity is determined by the T(1)-weighted signal difference between blood and surrounding tissues. For slice-selective excitation pulses, the excitation angle varies across the slice, leading to poor saturation of the background signal at the slice edge and reducing the blood-background signal difference. This work reports on the use of magnetization preparation to enhance the T(1)-weighted contrast between blood and background tissue. Applying the prepulse nonselectively reduces the influence of the slice profile imperfections of the excitation pulse by keeping the background tissue at the slice edge saturated. Analytical calculations and in vitro experiments show that a prepulse angle of 110 degrees -130 degrees and a delay time of 20-25 ms enhance the contrast between contrast-enhanced blood (T(1) < 50 ms) and background tissues (T(1) > 200 ms), and improve the slice weighting profile. Magnetization preparation is shown to effectively suppress signal from background tissue, resulting in a threefold increase of the vessel-to-background signal ratio. Magnetization preparation eliminates the need for subtraction at the cost of a slight increase in scan time. Possible applications, such as projection MRA, detection of contrast arrival, and test-bolus tracking are demonstrated in a pig model. Magn Reson Med 46:78-87, 2001.
Insights
Magnetization preparation improves MR angiography contrast by saturating background tissue. This technique enhances vessel conspicuity and signal ratio without needing subtraction, aiding in contrast arrival detection.
Area of Science:
- Magnetic Resonance Imaging (MRI)
- Medical Imaging Techniques
Background:
- Contrast-enhanced MR projection angiography relies on T(1)-weighted signal difference between blood and tissue.
- Slice-selective excitation pulses cause imperfect background signal saturation, reducing vessel conspicuity.
Purpose of the Study:
- To enhance T(1)-weighted contrast between blood and background tissue in MR angiography.
- To improve vessel conspicuity by suppressing background signal.
Main Methods:
- Utilized nonselective magnetization preparation pulses prior to imaging.
- Optimized prepulse angle (110-130 degrees) and delay time (20-25 ms).
- Evaluated technique using analytical calculations, in vitro experiments, and a pig model.
Main Results:
- Magnetization preparation effectively saturated background tissue, improving slice weighting.
- Achieved enhanced contrast between contrast-enhanced blood and background tissues.
- Demonstrated a threefold increase in vessel-to-background signal ratio.
- Eliminated the need for subtraction imaging.
Conclusions:
- Magnetization preparation is an effective method to enhance MR angiography contrast and vessel conspicuity.
- The technique improves signal-to-noise ratio and simplifies imaging protocols.
- Applicable to projection MRA, contrast arrival detection, and bolus tracking.