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Experimental Gd-DTPA polylysine enhanced MR angiography: sequence optimization
G Marchal1, H Bosmans, P Van Hecke
1Department of Radiology, University Hospitals KU Leuven, Belgium.
Abstract:
Most MR angiography (MRA) techniques use macroscopic blood motion to characterize the flowing spins. A different approach is represented by the use of contrast enhancement of blood pooling agents. The intravenous injection of one of these agents, namely Gd-DTPA polylysine, produces a shortening of the blood T1 below the T1 values of fat and soft tissues. In this study on experimental MRA in rabbits, we used an imaging sequence with a 90 degrees saturation pulse and a 180 degrees inversion recovery pulse. Both the saturation and inversion recovery times were adjusted to suppress the signals of soft tissues and fat. The remaining ultrashort T1 blood was imaged with a projective velocity refocused spin echo or gradient echo sequence. Magnetic resonance angiography provided excellent vessel detail with a 30-60 s acquisition time. In addition, there was no need for further processing after image acquisition because the projection was obtained immediately. The disadvantages of the technique are the need for contrast medium injection and the nonselectivity of MRA.
Insights
This study introduces a novel magnetic resonance angiography (MRA) technique using contrast agents to visualize blood vessels. The method offers excellent detail and rapid imaging, overcoming limitations of traditional MRA approaches.
Area of Science:
- Medical Imaging
- Radiology
- Biomedical Engineering
Background:
- Traditional Magnetic Resonance Angiography (MRA) relies on blood flow dynamics.
- Contrast agents offer an alternative MRA approach by altering blood signal properties.
Purpose of the Study:
- To evaluate a novel MRA technique using Gd-DTPA polylysine contrast agent in rabbits.
- To assess the efficacy of this contrast-enhanced MRA for vessel imaging.
Main Methods:
- Intravenous injection of Gd-DTPA polylysine to shorten blood T1 relaxation time.
- Utilized a specialized imaging sequence with saturation and inversion recovery pulses to suppress tissue signals.
- Employed projective velocity refocused spin echo or gradient echo sequences for imaging.
Main Results:
- Achieved excellent vessel detail in experimental MRA of rabbits.
- Acquisition times were rapid, ranging from 30-60 seconds.
- Images required no post-processing, providing immediate projections.
Conclusions:
- Contrast-enhanced MRA with Gd-DTPA polylysine provides high-quality, rapid vascular imaging.
- The technique demonstrates potential for improved MRA visualization.
- Limitations include the necessity of contrast injection and non-specific MRA signal.