Head-to-head comparison between delayed enhancement and percent infarct mapping for assessment of myocardial infarct size in a canine model.
OBJECTIVE
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 (DeltaR1) is an intrinsic parameter linearly proportional to the concentration of contrast agent (CA). Determining DeltaR1 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.


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, DeltaR1, and percent-infarct values were calculated voxel-by-voxel.


RESULTS
Significant correlations (P < 0.01, R >or= 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).


CONCLUSIONS
The DeltaR1-based PIM method is highly reproducible and more accurate than DE for quantifying myocardial viability in vivo.
Ruzsics
Balázs
B
University of Alabama at Birmingham, Department of Biochemistry & Molecular Genetics MCLM 556, Birmingham, AL 35294-0005, USA.
Surányi
Pál
P
Kiss
Pál
P
Brott
Brigitta C
BC
Elgavish
Ada
A
Simor
Tamas
T
Elgavish
Gabriel A
GA
D000704:Analysis of Variance; D000818:Animals; D003287:Contrast Media; D004195:Disease Models, Animal; D004285:Dogs; D019786:Gadolinium DTPA; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009203:Myocardial Infarction / Q000175:diagnosis*; D009942:Organometallic Compounds; D004369:Pentetic Acid; D012044:Regression Analysis
D003287:Contrast Media; D009942:Organometallic Compounds; C120791:gadolinium N-(2-butyryloxyethyl)-N'-(2-ethyloxyethyl)-N,N'-bis(N'',N''-bis(carboxymethyl)acetamido)-1,2-ethanediamine; D004369:Pentetic Acid; D019786:Gadolinium DTPA