title: T(2) -weighted STIR imaging of myocardial edema associated with ischemia-reperfusion injury: the influence of proton density effect on image contrast.
abstract: OBJECTIVE
  To investigate the contribution of proton density (PD) in T(2) -STIR based edema imaging in the setting of acute myocardial infarction (AMI).
  
  
  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).
  
  
  CONCLUSIONS
  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.
authors: Department of Radiology, Northwestern University, Chicago, IL, USA.
authors: Xiangzhi
authors: X
authors: Zhou
authors: Veronica
authors: V
authors: Rundell
authors: Ying
authors: Y
authors: Liu
authors: Richard
authors: R
authors: Tang
authors: Rachel
authors: R
authors: Klein
authors: Saurabh
authors: S
authors: Shah
authors: Sven
authors: S
authors: Zuehlsdorff
authors: Sotirios A
authors: SA
authors: Tsaftaris
authors: Debiao
authors: D
authors: Li
authors: Rohan
authors: R
authors: Dharmakumar
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000494:pharmacology; D004285:Dogs; D004487:Edema; D005260:Female; D005682:Gadolinium / Q000494:pharmacology; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008954:Models, Biological; D015233:Models, Statistical; D009203:Myocardial Infarction / Q000473:pathology; D009206:Myocardium / Q000473:pathology*; D011522:Protons; D015427:Reperfusion Injury / Q000473:pathology*
chemical_list: D003287:Contrast Media; D011522:Protons; D005682:Gadolinium