REGIONAL VARIATION IN MYOCARDIAL INTENSITY OF THE NORMAL HEART FOLLOWING
INTRAVENOUS CONTRAST MAY AFFECT ASSESSMENT OF MYOCARDIAL PERFUSION D L Prior*, L A Cardon, J A
Odabashian, W A Jaber, A L Klein, J D Thomas. The Cleveland Clinic Foundation, Cleveland, Ohio. Newer generation contrast
agents in combination with Pulse Inversion harmonic imaging may offer a new
modality to assess myocardial perfusion. However, regional variability due to
attenuation by left ventricular cavity contrast may affect the ability to use
signal intensity measurements to quantify myocardial perfusion using Optison contrast. Methods:Two-dimensional
Pulse Inversion echocardiography from the apical 4-chamber and 2-chamber views
was performed on 11 healthy volunteers. One in 4, end-diastolic triggered
images were acquired and digitized at baseline and at the onset of optimal
myocardial contrast effect, after resolution of intracavitary attenuation,
using identical instrument settings. Myocardial intensity was measured from raw
digital data for the basal, mid, and apical segments of the septal, lateral,
anterior, and inferior walls using HDI Lab software. Results:Graph 1 shows an
increase in intensity in all walls, but pre and post contrast intensity levels
varied significantly between walls (P < 0.0001). Graph 2 represents the
anterior wall pre and post contrast and shows significant within wall
variability with higher intensity in apical and mid segments. Conclusions: In subjects with normal perfusion, there is significant
between wall and within wall variability in myocardial intensity both before
and after contrast administration. Incremental attenuation occurs with depth so
that basal segments uniformly demonstrate lower intensities and reduced
contrast effect than apical segments and this phenomenon should be considered
when using acoustic intensity or videodensity to assess myocardial perfusion.
