Head-to-head comparison between delayed enhancement and percent infarct mapping for assessment of myocardial infarct size in a canine model

✍ Scribed by Balázs Ruzsics; Pál Surányi; Pál Kiss; Brigitta C. Brott; Ada Elgavish; Tamas Simor; Gabriel A. Elgavish

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 266 KB
• Volume: 28
• Category: Article
• ISSN: 1053-1807
• DOI: 10.1002/jmri.21571

✦ Synopsis

Abstract

Purpose

To compare a novel method, percent‐infarct‐mapping (PIM), with conventional delayed enhancement (DE) of contrast for accurate myocardial viability assessment. Contrary to signal intensity (SI), the longitudinal relaxation‐rate enhancement (ΔR1) is an intrinsic parameter linearly proportional to the concentration of contrast agent (CA). Determining ΔR1 voxel‐by‐voxel, after administering an infarct‐avid CA, allows determination of per‐voxel percentage of infarcted tissue. The feasibility of generating PIM is demonstrated in canine reperfused infarction using an infarct‐avid, persistent‐CA (PCA), (Gd)(ABE‐DTTA). PIM is compared to the DE method using Gd(DTPA), and both to triphenyltetrazolium chloride (TTC) staining histochemistry.

Materials and Methods

In six dogs, 48 hours following closed‐chest, 180‐minute coronary occlusion, DE imaging was carried out. PCA was administered immediately thereafter. Pixel‐by‐pixel R1 maps of the entire left ventricle (LV) were generated 48 hours after PCA using inversion‐recovery with multiple inversion times. R1, ΔR1, and percent‐infarct values were calculated voxel‐by‐voxel.

Results

Significant correlations (P < 0.01, R ≥ 0.8) were obtained for percent‐infarct‐per‐slice (PIS) determined by DE or PIM vs. those from corresponding TTC‐stained slices. Compared to TTC, DE overestimated PIS by 32 ± 18%. PIM underestimated PIS by 2.5 ± 4.9%. Infarction fraction overestimation was 29 ± 6% of LV by DE, but only 1.0 ± 2.3% by PIM. Errors with PIM were significantly smaller than those with DE. Infarct area determined by signal intensity was similarly overestimated whether using Gd(DTPA) or Gd(ABE‐DTTA).

Conclusion

The ΔR1‐based PIM method is highly reproducible and more accurate than DE for quantifying myocardial viability in vivo. J. Magn. Reson. Imaging 2008;28:1386–1392. © 2008 Wiley‐Liss, Inc.