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RingTag: ring-shaped tagging for myocardial centerline assessment
Marcus A Spiegel1, Roger Luechinger, Jueg Schwitter
1Institute for Biomedical Engineering, University and ETH, Zurich, Switzerland.
Investigative Radiology
|September 23, 2003
Summary
Magnetic resonance tagging accurately assesses midwall myocardial mechanics in hypertrophied hearts. This method reveals normal circumferential fiber shortening (cFS) despite apparent hypercontractility, offering a better tool for studying heart function.
Area of Science:
- Cardiovascular imaging
- Cardiac mechanics
- Magnetic resonance imaging
Background:
- Endocardial ejection indexes can overestimate contractility in hypertrophied hearts due to increased wall thickness.
- Circumferential fiber shortening (cFS) at the midwall is less influenced by wall thickness, providing a more accurate measure of myocardial contractility.
Purpose of the Study:
- To directly assess circumferential fiber shortening (cFS) at the midwall in normal and hypertrophied hearts using magnetic resonance tagging.
- To evaluate the utility of a novel tagging procedure for studying myocardial mechanics in conditions like hypertensive cardiomyopathy.
Main Methods:
- A novel magnetic resonance tagging technique was developed to generate and track freely definable, convex saturation bands on the myocardium.
- Fast, single breath-hold echo-planar imaging with slice-following and navigator-guided breath-holding was employed for reproducible data acquisition.
Main Results:
- The tagging procedure successfully created trackable saturation structures on the myocardium.
- While endocardial shortening (FSendo) was significantly higher in hypertrophied hearts (43.9%) compared to normal hearts (30.7%), midwall cFS showed no significant difference (18.1% vs. 17.2%).
Conclusions:
- The developed magnetic resonance tagging approach enables accurate assessment of midwall myocardial mechanics.
- This technique offers a valuable tool for studying contractile function in hypertrophied hearts, overcoming limitations of traditional ejection indexes.