Biomedical Engineering Reference
In-Depth Information
contrast-enhanced (CE)-MRA was performed [1]. Manual table movements com-
bined with SENSE in the upper station allowed for more rapid overall scan cover-
age such that acquisition of the lower station began 34 sec after aortic contrast ar-
rival. True submillimeter isotropic resolution was achieved in the lower station.
Diagnostic MR angiograms of all three stations were obtained. Venous enhance-
ment did not confound interpretation in any case. Submillimeter lower station
resolution provided excellent vascular details. Decreased delay time between
upper and lower station acquisition in single-bolus peripheral MR angiograms,
now possible using parallel imaging techniques, combined with lower station
submillimeter resolution, may decrease venous contamination and increase
overall interpretability, thus increasing clinical acceptance of peripheral MRA.
3.4.2 Blood Pool Contrast Enhancement
This technique of blood pool contrast-enhanced MRA was used to visualize the
arterial and venous vessel tree and to detect deep venous thrombosis of the
lower extremities. Patients with pulmonary embolism were randomized to eval-
uate various doses of NC100150 by T1-weighted (T1W) 3D gradient recalled
echo sequence. Qualitative assessment of overall MRA image quality and semi-
quantitative vessel scoring revealed good to excellent delineation of venous and
arterial vessel segments independent of the dose of NC100150. However, quan-
titative region of interest analysis revealed a significantly higher signal-to-noise
ratio in the high-dose group than in the mid- and low-dose groups of NC100150.
Between dose groups, the SNR was independent of vessel type (artery or vein)
and vessel segment localization (proximal or distal). Venous thrombi were char-
acterized by very low signal intensity, approximately one tenth the SI in adjacent
venous segments. High-quality MR angiograms of the lower extremities can be
obtained using low concentrations of NC100150 in combination with a strong
T1W 3D GRE sequence. The obvious delineation of venous thrombi suggests that
this technique may be potentially used as a noninvasive “one-stop shopping” tool
in the evaluation of thrombo-embolic disease [2].
3.4.3 Digital Subtraction Angiography
Contrast-magnetic resonance angiography (CE-MRA) MoBI-trak was used in
the evaluation of the peripheral vessels in patients with peripheral vascular
