Quantitative myocardial infarction on delayed enhancement MRI. Part II: Clinical application of an automated feature analysis and combined thresholding infarct sizing algorithm.
OBJECTIVE
To compare global and regional myocardial infarction (MI) measurements on clinical gadolinium-enhanced magnetic resonance (MR) images using human manual contouring and a computer algorithm previously validated by histopathology, and to study the degree to which visual assessment and human contouring of infarct extent agreed with the computer algorithm.


METHODS
Infarct size in 20 patients was measured by human manual contouring and with an automated feature analysis and combined thresholding (FACT) computer algorithm. Short-axis slices were divided into myocardial sectors for regional analysis. Extent of infarction was also graded visually by consensus of expert readers and compared to human and computer contouring.


RESULTS
Despite good correlations (R = 0.93-0.95) between human contouring and the FACT algorithm, human contouring overestimated infarct size by 3.8% of the left ventricle (23.8% of the MI) area (P < 0.001). Human contouring also overestimated the circumferential extent, transmural extent, and extent of infarction within a sector by 7.1%, 18.2%, and 27.9%, respectively (all P < 0.001). Both consensus reading and human contouring overestimated infarct grades compared with the FACT algorithm (P = 0.002 and P < 0.001).


CONCLUSIONS
Clinically relevant overestimation of MI can occur in visual interpretation and in human manual contouring, particularly with respect to extent of infarction on a regional basis.
Hsu
Li-Yueh
LY
Laboratory of Cardiac Energetics, National Heart Lung and Blood Institute, National Institutes of Health/DHHS, 10 Center Drive, Bethesda, MD 20892, USA.
Ingkanisorn
W Patricia
WP
Kellman
Peter
P
Aletras
Anthony H
AH
Arai
Andrew E
AE
D000328:Adult; D000368:Aged; D000465:Algorithms; D003287:Contrast Media; D003936:Diagnosis, Computer-Assisted; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000473:pathology*; D015588:Observer Variation
D003287:Contrast Media; D019786:Gadolinium DTPA