Biomedical Engineering Reference
In-Depth Information
systemic veins and had additional diagnostic data available for comparison with
the MRA findings. The technique did not detect anomalies of the pulmonary veins
that were subsequently diagnosed by MRA. Intervention catheterization proce-
dures and operations followed the 3D MRA diagnoses. 3D MRA either diagnosed
previously unsuspected venous anomalies or added new clinically important in-
formation. The mechanism of pulmonary vein compression in eight patients was
determined by MRA but not by other imaging modalities. Gadolinium-enhanced
3D MRA is rapid and accurate. 3D MRA has been shown to be the premier
noninvasive technique for imaging large blood vessels in the body.
3.4.13 3D Time-Resolved Imaging of Contrast
Kinetics Technique
This technique based on contrast-enhanced MR angiography was used by direct
comparison with the fluoroscopic triggered 3D-elliptical centric view ordering
(3D-ELLIP) technique [13]. 3D-TRICKS and 3D-ELLIP were directly compared
on a 1.5-T MR unit using the same spatial resolution and matrix. In 3D-TRICKS,
the central part of the k-space is updated more frequently than the peripheral
part of the k-space, which is divided in the slice-encoding direction. The carotid
arteries were imaged using 3D-TRICKS and 3D-ELLIP sequentially in 14 pa-
tients. Temporal resolution was 12 sec for 3D-ELLIP and 6 sec for 3D-TRICKS.
The signal-to-noise ratio (S/N) of the common carotid artery was measured
and the quality of MIP images was then scored in terms of venous overlap and
blurring of vessel contours. No significant difference in mean S/N was seen
between the two methods. Significant venous overlap was not seen in any of
the patients examined. Moderate blurring of vessel contours was noted on
3D-TRICKS in five patients and on 3D-ELLIP in four patients. Blurring in the
slice-encoding direction was slightly more pronounced in 3D-TRICKS. How-
ever, qualitative analysis scores showed no significant differences. When the
spatial resolution of the two methods was identical, the performance of 3D-
TRICKS was found to be comparable in static visualization of the carotid arter-
ies with 3D-ELLIP, although blurring in the slice-encoding direction was slightly
more pronounced in 3D-TRICKS. 3D-TRICKS is a more robust technique than
3D-ELLIP, because 3D-ELLIP requires operator-dependent fluoroscopic trigger-
ing. Furthermore, 3D-TRICKS can achieve higher temporal resolution. For the
