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Contrast-to-noise ratio of multiple slice spin lock technique: prospects for liver imaging
J Halavaara1, S Lukkarinen, R Sepponen
1Jorvi Hospital, Department of Radiology, Turuntie 150, 02740 Espoo, Helsinki University of Technology, Helsinki, Finland.
The British Journal of Radiology
|November 19, 2003
Summary
The multiple slice spin lock (SL) MRI technique offers good liver imaging contrast. Optimizing slice number, flip angle, and locking time (TL) maximizes liver-to-spleen contrast-to-noise ratio (CNR) for better visualization.
Area of Science:
- Magnetic Resonance Imaging (MRI)
- Medical Physics
- Radiology
Background:
- Spin lock (SL) MRI provides contrast comparable to conventional MRI techniques for liver imaging.
- The multiple slice SL technique enables rapid data acquisition with reduced motion and susceptibility artifacts due to its short echo time.
Purpose of the Study:
- To evaluate the potential of the multiple slice SL technique for liver imaging at 0.1 Tesla.
- To determine optimal parameters for maximizing liver-to-spleen contrast-to-noise ratio (CNR) using SL MRI.
Main Methods:
- Tissue nuclear magnetic resonance (NMR) information and parameters (T1rho, T1, T2 relaxation times) were measured in 10 healthy volunteers at 0.1 T.
- Liver-to-spleen CNR was calculated using tissue NMR data and literature-derived radiofrequency-attenuation information.
- The effect of varying the number of slices and locking time (TL) on CNR was investigated.
Main Results:
- Increasing the number of slices decreased liver-to-spleen CNR across all locking field durations (TL).
- Minimal CNR difference was observed with small TLs, which is advantageous for achieving wide coverage in liver MRI.
- Higher CNR was achieved with an optimal combination of moderate slices, large flip angle, and TL around 20 ms.
Conclusions:
- The multiple slice SL MRI technique is a viable option for liver imaging, offering good contrast and reduced artifacts.
- Parameter optimization, specifically balancing the number of slices with flip angle and locking time (TL), is crucial for achieving high liver-to-spleen CNR.