Biomedical Engineering Reference
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by repeated imaging of the same slices during free breathing. Each spiral interleaf
from the breath-held data set was used as a standard for comparison with corre-
sponding acquisitions at the same interleaf angle during free breathing. The most
closely matched acquisitions are incorporated into a multi-slice, multi-average
data set with increasing SNR over time. In-plane translations of the coronary
artery could be measured and compensated for each accepted acquisition before
combination with the other acquisitions. CMRA was performed with improved
SNR and minimal motional blurring. BACSPIN provided a promising method for
CMRA with improved SNR and limited breath-holding requirements [32].
3.4.33 Motion-Adapted Gating Window in
Coronary MRA
An acquisition technique was reported that used subject-specific acquisition win-
dows in the cardiac cycle and a motion-adapted gating window for respiratory
navigator gating. Cardiac acquisition windows and trigger delays were deter-
mined individually from a coronary motion scan. Motion-adapted gating used a
2-mm acceptance window for the central 35% of k-space and a 6-mm window
for the outer 65% of k-space. The adaptive technique was applied in patients
who underwent coronary radiographic angiography. Scanning times with the
adaptive technique were reduced for the right coronary artery and left coronary
artery system compared with the conventional technique, due to the use of longer
subject-specific acquisition windows in patients with low heart rates. Subjective
and objective measurements of image quality showed no significant differences
between the two techniques. Coronary MR angiography with subject-specific
acquisition windows and motion-adapted respiratory gating reduced scanning
times while maintaining image quality and provided high diagnostic accuracy
for the detection of coronary artery stenosis [33].
3.4.34 Attenuated Coronary Blood—Myocardium
In-Flow Contrast 3D Coronary Magnetic
Resonance Angiography (CMRA)
The in-flow contrast between the coronary blood and the surrounding my-
ocardium
was
attenuated
as
compared
to
thin-slab
2D
techniques.
The
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