Age-independent myocardial infarct quantification by signal intensity percent infarct mapping in swine.
OBJECTIVE
To test whether signal intensity percent infarct mapping (SI-PIM) accurately determines the size of myocardial infarct (MI) regardless of infarct age.


METHODS
Forty-five swine with reperfused MI underwent 1.5T late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) after bolus injection of 0.2 mmol/kg Gd(DTPA) on days 2-62 following MI. Animals were classified into acute, healing, and healed groups by pathology. Infarct volume (IV) and infarct fraction (IF) were determined by two readers, using binary techniques (including 2-5 standard deviations [SD] above the remote, and full-width at half-maximum) and the SI-PIM method. Triphenyl-tetrazolium-chloride staining (TTC) was performed as reference. Bias (percent under/overestimation of IV relative to TTC) of each quantification method was calculated. Bland-Altman analysis was done to test the accuracy of the quantification methods, while intraclass correlation coefficient (ICC) analysis was done to assess intra- and interobserver agreement.


RESULTS
Bias of the MRI quantification methods do not depend on the age of the MI. Full-width at half-maximum (FWHM) and SI-PIM gave the best estimate of MI volume determined by the reference TTC (P-values for the FWHM and SI-PIM methods were 0.183, 0.26, 0.95, and 0.073, 0.091, 0.73 in Group 1, Group 2, and Group 3, respectively), while using any of the binary thresholds of 2-4 SDs above the remote myocardium showed significant overestimation. The 5 SD method, however, provided similar IV compared to TTC and was shown to be independent of the size and age of MI. ICC analysis showed excellent inter- and intraobserver agreement between the readers.


CONCLUSIONS
Our results indicate that the SI-PIM method can accurately determine MI volume regardless of the pathological stage of MI. Once tested, it may prove to be useful for the clinic.
Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA.|Elgavish Paramagnetics Inc, Birmingham, Alabama, USA.|Medical School, University of Pecs, Hungary.
Zsofia
Z
Lenkey
Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA.|Elgavish Paramagnetics Inc, Birmingham, Alabama, USA.
Akos
A
Varga-Szemes
Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA.|Elgavish Paramagnetics Inc, Birmingham, Alabama, USA.|Medical School, University of Pecs, Hungary.
Tamas
T
Simor
Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands.
Rob J
RJ
van der Geest
Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA.|Elgavish Paramagnetics Inc, Birmingham, Alabama, USA.
Robert
R
Kirschner
Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA.|Elgavish Paramagnetics Inc, Birmingham, Alabama, USA.
Levente
L
Toth
Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA.|Elgavish Paramagnetics Inc, Birmingham, Alabama, USA.
Tamas
T
Bodnar
Department of Medicine, Division of Cardiovascular Disease, University of Alabama at Birmingham, Birmingham, Alabama, USA.
Brigitta C
BC
Brott
Elgavish Paramagnetics Inc, Birmingham, Alabama, USA.|Department of Medicine, Division of Clinical Immunology & Rheumatology, University of Alabama at Birmingham, Birmingham, Alabama, USA.
Ada
A
Elgavish
Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA.|Elgavish Paramagnetics Inc, Birmingham, Alabama, USA.
Gabriel A
GA
Elgavish
D000818:Animals; D001831:Body Temperature; D003287:Contrast Media / Q000737:chemistry; D004569:Electroencephalography; D005682:Gadolinium / Q000737:chemistry; D019786:Gadolinium DTPA / Q000737:chemistry; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D009203:Myocardial Infarction / Q000175:diagnosis*; D015425:Myocardial Reperfusion; D015588:Observer Variation; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D013552:Swine; D013778:Tetrazolium Salts / Q000737:chemistry; D016896:Treatment Outcome
D003287:Contrast Media; D013778:Tetrazolium Salts; C009591:triphenyltetrazolium; D005682:Gadolinium; D019786:Gadolinium DTPA
infarct quantification; late gadolinium enhancement; myocardial infarct; partial volume effect; signal intensity percent infarct mapping