Effects of intravenous gadolinium administration and flip angle on the assessment of liver fat signal fraction with opposed-phase and in-phase imaging
✍ Scribed by Takeshi Yokoo; Julie M. Collins; Robert F. Hanna; Mark Bydder; Michael S. Middleton; Claude B. Sirlin
- Publisher
- John Wiley and Sons
- Year
- 2008
- Tongue
- English
- Weight
- 334 KB
- Volume
- 28
- Category
- Article
- ISSN
- 1053-1807
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Purpose
To assess the effects of intravenous gadolinium (Gd) and flip angle (FA) on liver fat quantification by opposed‐phase (OP) and in‐phase (IP) imaging.
Materials and Methods
Our Institutional Review Board (IRB) approved this Health Insurance Portability and Accountability Act (HIPAA)‐compliant, retrospective, clinical study. We identified 79 patients in whom abdominal OP and IP gradient‐echoes were obtained at 1.5T before and after Gd administration. All 79 patients were imaged at high FA (≥70°); 57 were also imaged at low FA (≤20°). Fat signal fraction (FSF) was calculated from pre‐ and post‐Gd liver images for each subject and FA using the formula, FSF = (S~IP~ – S~OP~)/2S~IP~, where S~IP~ and S~OP~ are the OP and IP signal intensities, respectively. The dataset pairs (pre‐Gd vs. post‐Gd; high‐FA vs. low‐FA) were compared using linear regression analysis.
Results
Before Gd, FSF was significantly greater at high FA than at low FA, with regression parameters (slope/intercept) of 1.27*/0.02*, where * indicates P value <0.01. After Gd, FSF was similar at high and low FA (0.99/–0.00). Gd administration caused an FA‐dependent reduction in FSF, larger at high FA (0.68*/–0.03*) than at low FA (0.94, –0.01*).
Conclusion
FSF by OP‐IP imaging is highly dependent on FA before Gd, but this dependency is eliminated after administration of Gd. Gd appears to minimize the effect of T1‐weighting and may improve the accuracy of liver fat quantification. J. Magn. Reson. Imaging 2008;28:246–251. © 2008 Wiley‐Liss, Inc.