Circulation, Vol 73, 551-561, Copyright © 1986 by American Heart Association
AJ Feiring, P Bruch, TS Husayni, PT Kirchner and ML Marcus
The purpose of this study was to develop a clinically applicable system for
quantifying premortem myocardial area at risk. Coronary artery occlusion
was performed in 18 closed-chest dogs (11 left anterior descending and
seven circumflex). 99mTc (15 mCi)-labeled macroaggregated albumin was then
injected through an angiographic catheter into the left main coronary
artery. Gated nuclear images were obtained in the left anterior oblique
view in dogs with left anterior descending occlusions and in right anterior
oblique views in dogs with circumflex artery occlusions. The corresponding
end-diastolic images were analyzed. The percent area at risk was determined
as the planimetric ratio between the hypoperfused area and that of the
total left ventricular myocardium. At the completion of the study the heart
was excised and the autoradiographic area at risk for the left ventricle
was determined. The theoretic advantage of the use of gated acquisition for
determination of area at risk over the use of nongated acquisition was
assessed. For each study a time-integrated nongated image was produced by
summating all frames of the gated study. The area at risk on this composite
image was analyzed in the same manner as for the gated study and compared
with the postmortem area at risk. Studies in five control dogs in which
concomitant left atrial and intracoronary injection of different
radioactive-labeled macroaggregates were used revealed no false-positive
defects and similar and relatively homogenous radionuclide distribution.
Postmortem autoradiographic area at risk ranged from 3.8% to 36.3% of the
left ventricular mass. End- diastolic areas at risk in vivo correlated well
with those determined by the postmortem autoradiographic method (r = .95, y
= 0.86x + 2.7). The regression equations relating interobserver and
intraobserver variance for analysis of the end-diastolic image areas at
risk were small (r = .98, y = 1.06x - 0.66 and r = .96, y = 1.06x - 0.50,
respectively). The interobserver and intraobserver differences for
determinations of autoradiographic area at risk were represented by r =
.99, y = 1.04x - 0.54 and r = .95, y = 0.88x + 2.79. Finally, comparison of
the area at risk in vivo for the nongated image with the postmortem area at
risk yielded a correlation of r = .79, y = 0.80x - 2.2. Nongated imaging
was less sensitive and accurate than gated imaging and resulted in three
false-negative studies, as well as a poorer correlation with results of
postmortem autoradiography.(ABSTRACT TRUNCATED AT 400 WORDS)
ARTICLES
Premortem assessment of myocardial area at risk with the use of intracoronary technetium macroaggregated albumin and gated nuclear imaging