Background Gradient Correction using Excitation Pulse Profile for Fat and T2* Quantification in 2D Multi-Slice Liver Imaging
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Purpose : The objective of this study was to develop background gradient correction method using excitation pulse profile compensation for accurate fat and T2* quantification in the liver. Materials and Methods: In liver imaging using gradient echo, signal decay induced by linear background gradient is weighted by an excitation pulse profile and therefore hinders accurate quantification of T2* and fat. To correct this, a linear background gradient in the slice-selection direction was estimated from a B0 field map and signal decays were corrected using the excitation pulse profile. Improved estimation of fat fraction and T2* from the corrected data were demonstrated by phantom and in vivo experiments at 3 Tesla magnetic field. Results: After correction, in the phantom experiments, the estimated T2* and fat fractions were changed close to that of a well-shimmed condition while, for in vivo experiments, the background gradients were estimated to be up to approximately 120 μT/m with increased homogeneity in T2* and fat fractions obtained. Conclusion: The background gradient correction method using excitation pulse profile can reduce the effect of macroscopic field inhomogeneity in signal decay and can be applied for simultaneous fat and iron quantification in 2D gradient echo liver imaging.
Abstract
Purpose : The objective of this study was to develop background gradient correction method using excitation pulse profile compensation for accurate fat and T2* quantification in the liver. Materials and Methods: In liver imaging using gradient echo, signal decay induced by linear background gradient is weighted by an excitation pulse profile and therefore hinders accurate quantification of T2* and fat. To correct this, a linear background gradient in the slice-selection direction was estimated from a B0 field map and signal decays were corrected using the excitation pulse profile. Improved estimation of fat fraction and T2* from the corrected data were demonstrated by phantom and in vivo experiments at 3 Tesla magnetic field. Results: After correction, in the phantom experiments, the estimated T2* and fat fractions were changed close to that of a well-shimmed condition while, for in vivo experiments, the background gradients were estimated to be up to approximately 120 μT/m with increased homogeneity in T2* and fat fractions obtained. Conclusion: The background gradient correction method using excitation pulse profile can reduce the effect of macroscopic field inhomogeneity in signal decay and can be applied for simultaneous fat and iron quantification in 2D gradient echo liver imaging.
참고문헌 (19)
- Hussain HK, "Hepatic fat fraction: MR imaging for quantitative measurement and display--early experience", Radiology, 237, pp.1048~1055 (2005)
- 박혜영, "Detection of Hepatic Lesion: Comparison of Free- Breathing and Respiratory-Triggered Diffusion- Weighted MR imaging on 1.5-T MR system", 대한자기공명의과학회지, 15(1), pp.22~31 (2011), 대한자기공명의과학회
- Dixon WT, "Simple proton spectroscopic imaging", Radiology, 153, pp.189~194 (1984)
- Glover GH, "Three-point Dixon technique for true water", fat decomposition with B0 inhomogeneity correction, 1991, pp.18, 371~383
- Wood JC, "MRI R2 and R2* mapping accurately estimates hepatic iron concentration in transfusion-dependent thalassemia and sickle cell disease patients", Blood, 106, pp.1460~1465 (2005)
- O’Regan DP, "Liver fat content and T2*: simultaneous measurement by using breathhold multiecho MR imaging at 3.0 T--feasibility", Radiology, 247, pp.550~557 (2008)
- Reeder SB, "Iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL): application with fast spin-echo imaging", Magn Reson Med, 54, pp.636~644 (2005)
- Yu H, "Multiecho reconstruction for simultaneous water-fat decomposition and T2* estimation", J Magn Reson Imaging, 26, pp.1153~1161 (2007)
- Haacke EM, "Reduction of T2* dephasing in gradient field-echo imaging", Radiology, 170, pp.457~462 (1989)
- 조상흠, "나선주사영상에서 모델 기반 경사자계 보상", 대한자기공명의과학회지, 13(1), pp.15~21 (2009), 대한자기공명의과학회
- 노용만, "REDUCTION OF SUSCEPTIBILITY ARTIFACT IN GRADIENT-ECHO IMAGING", MAGNETIC RESONANCE IN MEDICINE, 23(1), pp.193~200, WILLIAMS WILKINS
- Fernandez-Seara MA, "Postprocessing technique to correct for background gradients in image-based R*(2) measurements", Magn Reson Med, 44, pp.358~366 (2000)
- Dahnke H, "Limits of detection of SPIO at 3.0 T using T2 relaxometry", Magn Reson Med, 53, pp.1202~1206 (2005)
- Pauly JM, "New approach to selective excitation for magnetic resonance imaging", 박사, pp.1990
- Chebrolu VV, "Independent estimation of T*2 for water and fat for improved accuracy of fat quantification", Magn Reson Med, 63, pp.849~857 (2010)
- Yu H, "Field map estimation with a region growing scheme for iterative 3- point water-fat decomposition", Magn Reson Med, 54, pp.1032~1039 (2005)
- Jenkinson M, "Fast, automated, N-dimensional phase-unwrapping algorithm", Magn Reson Med, 49, pp.193~197 (2003)
- Lu W, "Multiresolution field map estimation using golden section search for water-fat separation", Magn Reson Med, 60, pp.236~244 (2008)
- Bydder M, "Assessment of liver fat quantification in the presence of iron", Magn Reson Imaging, 28, pp.767~776 (2010)