Time-resolved 3D MR velocity mapping at 3T: improved navigator-gated assessment of vascular anatomy and blood flow.
OBJECTIVE
To evaluate an improved image acquisition and data-processing strategy for assessing aortic vascular geometry and 3D blood flow at 3T.


METHODS
In a study with five normal volunteers and seven patients with known aortic pathology, prospectively ECG-gated cine three-dimensional (3D) MR velocity mapping with improved navigator gating, real-time adaptive k-space ordering and dynamic adjustment of the navigator acceptance criteria was performed. In addition to morphological information and three-directional blood flow velocities, phase-contrast (PC)-MRA images were derived from the same data set, which permitted 3D isosurface rendering of vascular boundaries in combination with visualization of blood-flow patterns.


RESULTS
Analysis of navigator performance and image quality revealed improved scan efficiencies of 63.6%+/-10.5% and temporal resolution (<50 msec) compared to previous implementations. Semiquantitative evaluation of image quality by three independent observers demonstrated excellent general image appearance with moderate blurring and minor ghosting artifacts. Results from volunteer and patient examinations illustrate the potential of the improved image acquisition and data-processing strategy for identifying normal and pathological blood-flow characteristics.


CONCLUSIONS
Navigator-gated time-resolved 3D MR velocity mapping at 3T in combination with advanced data processing is a powerful tool for performing detailed assessments of global and local blood-flow characteristics in the aorta to describe or exclude vascular alterations.
Markl
Michael
M
Department of Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany. michael.markl@uniklinik-freiburg.de
Harloff
Andreas
A
Bley
Thorsten A
TA
Zaitsev
Maxim
M
Jung
Bernd
B
Weigang
Ernst
E
Langer
Mathias
M
Hennig
Jürgen
J
Frydrychowicz
Alex
A
D000328:Adult; D000368:Aged; D001012:Aorta, Abdominal / Q000033:anatomy & histology / Q000473:pathology / Q000502:physiology*; D001013:Aorta, Thoracic / Q000033:anatomy & histology / Q000473:pathology / Q000502:physiology*; D001018:Aortic Diseases / Q000473:pathology / Q000503:physiopathology; D001783:Blood Flow Velocity / Q000502:physiology; D004562:Electrocardiography; D005260:Female; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged