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Liver MRI at 3 T using a respiratory-triggered time-efficient 3D T2-weighted technique: impact on artifacts and image
Andrew B Rosenkrantz1, Jignesh M Patel, James S Babb
1Department of Radiology, NYU Langone Medical Center, 560 First Ave., TCH-HW202, New York, NY 10016, USA. Andrew.Rosenkrantz@nyumc.org
Objective:
The purpose of this retrospective study was to qualitatively and quantitatively compare image quality of a time-efficient 3D T2-weighted sequence-the sampling perfection with application-optimized contrasts using different flip angle evolutions (SPACE) sequence-with a standard 2D T2-weighted turbo spin-echo (TSE) sequence for liver imaging at 3 T.
Materials And Methods:
Twenty patients underwent liver MRI at 3 T using T2-weighted breath-hold 2D TSE and respiratory-triggered SPACE sequences. Two radiologists independently assessed image quality for both sequences during separate sessions, followed by a side-by-side comparison. One reader performed a quantitative analysis of the estimated signal-to-noise ratio (SNR) and the relative contrast between the liver and other tissues.
Results:
Image quality scores for the SPACE sequence were significantly better than those for the 2D TSE sequence for motion (p < 0.0001) and pulsation (p < 0.0001) artifact, flow signal suppression (p = 0.0015), sharpness of intrahepatic vessels (p < 0.0001), and sharpness of liver edge (p = 0.0015), with motion and pulsation artifacts being nearly eliminated using the SPACE sequence. However, the scores for B(1) inhomogeneity artifact were significantly worse for the SPACE sequence (p = 0.0117). Overall, both readers preferred SPACE sequence, although this difference was significant for only one reader (p = 0.025, p = 0.275). There was no significant difference between the sequences for estimated liver SNR (p = 0.1564), but the SPACE sequence showed significantly higher relative contrast between the liver and the kidney (p < 0.0001), gallbladder (p = 0.0476), and spleen (p < 0.0001). Relative contrast between the liver and parenchymal lesions was higher with the SPACE sequence than with the TSE sequence, although this difference was not statistically significant (p = 0.125).
Conclusion:
For T2-weighted liver imaging at 3 T, the respiratory-triggered SPACE sequence shows better image quality with near elimination of motion and pulsation artifacts and improved tissue contrast than the breath-hold 2D TSE sequence, but suffers from increased B(1) inhomogeneity artifact and longer scanning time.
Insights
The SPACE sequence significantly improves T2-weighted liver MRI quality at 3 T by reducing motion and pulsation artifacts. However, it has longer scan times and increased B(1) inhomogeneity artifact compared to 2D TSE.
Area of Science:
- Radiology
- Medical Imaging
- Magnetic Resonance Imaging
Background:
- Standard 2D T2-weighted turbo spin-echo (TSE) sequences are commonly used for liver MRI at 3 Tesla.
- These sequences can be limited by motion and pulsation artifacts, potentially affecting diagnostic accuracy.
- Developing faster and more robust imaging techniques is crucial for improving liver MRI.
Purpose of the Study:
- To compare the image quality of a novel 3D T2-weighted sequence, Sampling Perfection with Application-optimized Contrasts using Different Flip Angle Evolutions (SPACE), with a standard 2D TSE sequence for liver imaging at 3 T.
- To qualitatively and quantitatively assess artifacts, sharpness, signal-to-noise ratio (SNR), and contrast.
Main Methods:
- A retrospective study involving 20 patients who underwent liver MRI at 3 T.
- T2-weighted breath-hold 2D TSE and respiratory-triggered SPACE sequences were acquired.
- Two radiologists independently assessed image quality, followed by a side-by-side comparison.
- Quantitative analysis included estimated SNR and relative contrast between liver and other tissues.
Main Results:
- The SPACE sequence demonstrated significantly better image quality regarding motion and pulsation artifacts, flow signal suppression, and sharpness of intrahepatic vessels and liver edge.
- Motion and pulsation artifacts were nearly eliminated with the SPACE sequence.
- While estimated liver SNR was not significantly different, the SPACE sequence showed significantly higher relative contrast between the liver and surrounding organs (kidney, gallbladder, spleen).
- SPACE sequence exhibited significantly worse B(1) inhomogeneity artifact and longer scanning times.
Conclusions:
- The respiratory-triggered SPACE sequence offers superior image quality for T2-weighted liver imaging at 3 T, effectively minimizing motion and pulsation artifacts and enhancing tissue contrast.
- Despite advantages, SPACE sequence is associated with increased B(1) inhomogeneity artifact and extended scanning duration compared to 2D TSE.
- SPACE sequence is a promising alternative for liver MRI, balancing improved image quality with considerations for artifact and scan time.
