T2-weighted STIR imaging of myocardial edema associated with ischemia-reperfusion injury: The influence of proton density effect on image contrast
✍ Scribed by Xiangzhi Zhou; Veronica Rundell; Ying Liu; Richard Tang; Rachel Klein; Saurabh Shah; Sven Zuehlsdorff; Sotirios A. Tsaftaris; Debiao Li; Rohan Dharmakumar
- Publisher
- John Wiley and Sons
- Year
- 2011
- Tongue
- English
- Weight
- 367 KB
- Volume
- 33
- Category
- Article
- ISSN
- 1053-1807
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✦ Synopsis
Abstract
Purpose
To investigate the contribution of proton density (PD) in T~2~‐STIR based edema imaging in the setting of acute myocardial infarction (AMI).
Materials and Methods
Canines (n = 5), subjected to full occlusion of the left anterior descending artery for 3 hours, underwent serial magnetic resonance imaging (MRI) studies 2 hours postreperfusion (day 0) and on day 2. During each study, T~1~ and T~2~ maps, STIR (TE = 7.1 msec and 64 msec) and late gadolinium enhancement (LGE) images were acquired. Using T~1~ and T~2~ maps, relaxation and PD contributions to myocardial edema contrast (EC) in STIR images at both TEs were calculated.
Results
Edematous territories showed significant increase in PD (20.3 ± 14.3%, P < 0.05) relative to healthy territories. The contributions of T~1~ changes and T~2~ or PD changes toward EC were in opposite directions. One‐tailed t‐test confirmed that the mean T~2~ and PD‐based EC at both TEs were greater than zero. EC from STIR images at TE = 7.1 msec was dominated by PD than T~2~ effects (94.3 ± 11.3% vs. 17.6 ± 2.5%, P < 0.05), while at TE = 64 msec, T~2~ effects were significantly greater than PD effects (90.8 ± 20.3% vs. 12.5 ± 11.9%, P < 0.05). The contribution from PD in standard STIR acquisitions (TE = 64 msec) was significantly higher than 0 (P < 0.05).
Conclusion
In addition to T~2~‐weighting, edema detection in the setting of AMI with T~2~‐weighted STIR imaging has a substantial contribution from PD changes, likely stemming from increased free‐water content within the affected tissue. This suggests that imaging approaches that take advantage of both PD as well as T~2~ effects may provide the optimal sensitivity for detecting myocardial edema. J. Magn. Reson. Imaging 2011;33:962–967. © 2011 Wiley‐Liss, Inc.