Percent infarct mapping for delayed contrast enhancement magnetic resonance imaging to quantify myocardial viability by Gd(DTPA).
OBJECTIVE
To demonstrate the advantages of signal intensity percent-infarct-mapping (SI-PIM) using the standard delayed enhancement (DE) acquisition in assessing viability following myocardial infarction (MI). SI-PIM quantifies MI density with a voxel-by-voxel resolution in clinically used DE images.


METHODS
In canines (n= 6), 96 hours after reperfused MI and administration of 0.2 mmol/kg Gd(DTPA), ex vivo DE images were acquired and SI-PIMs calculated. SI-PIM data were compared with data from DE images analyzed with several thresholding levels using SI(remote+2SD), SI(remote+6SD), SI full width half maximum (SI(FWHM)), and with triphenyl-tetrazolium-chloride (TTC) staining. SI-PIM was also compared to R1 percent infarct mapping (R1-PIM).


RESULTS
Left ventricular infarct volumes (IV) in DE images, IV(SIremote+2SD) and IV(SIremote+6SD), overestimated (P < 0.05) TTC by medians of 13.21 mL [10.2; 15.2] and 6.2 mL [3.79; 8.23], respectively. SI(FWHM), SI-PIM, and R1-PIM, however, only nonsignificantly underestimated TTC, by medians of -0.10 mL [-0.12, -0.06], -0.86 mL [-1.04; 1.54], and -1.30 mL [-4.99; -0.29], respectively. The infarct-involved voxel volume (IIVV) of SI-PIM, 32.4 mL [21.2, 46.3] is higher (P < 0.01) than IIVVs of SI(FWHM) 8.3 mL [3.79, 19.0]. SI-PIM(FWHM), however, underestimates TTC (-5.74 mL [-11.89; -2.52] (P < 0.01)). Thus, SI-PIM outperforms SI(FWHM) because larger IIVVs are obtained, and thus PIs both in the rim and the core of the infarcted tissue are characterized, in contradistinction from DE-SI(FWHM), which shows mainly the infarct core.


CONCLUSIONS
We have shown here, ex vivo, that SI-PIM has the same advantages as R1-PIM, but it is based on the scanning sequences of DE imaging, and thus it is obtainable within the same short scanning time as DE. This makes it a practical method for clinical studies.
Simor
Tamás
T
Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama 35294-0005, USA.
Surányi
Pál
P
Ruzsics
Balázs
B
Tóth
Attila
A
Tóth
Levente
L
Kiss
Pál
P
Brott
Brigitta C
BC
Varga-Szemes
Akos
A
Elgavish
Ada
A
Elgavish
Gabriel A
GA
D000818:Animals; D003287:Contrast Media; D004195:Disease Models, Animal; D004285:Dogs; D019786:Gadolinium DTPA; D006352:Heart Ventricles / Q000473:pathology; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000473:pathology*; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000473:pathology*; D013997:Time Factors
D003287:Contrast Media; D019786:Gadolinium DTPA