Contrast-enhanced intracranial magnetic resonance angiography with a spherical shells trajectory and online gridding reconstruction.
OBJECTIVE
To evaluate the feasibility of applying the shells trajectory to single-phase contrast-enhanced magnetic resonance angiography.


METHODS
Several methods were developed to overcome the challenges of the clinical implementation of shells including off-resonance blurring (eg, from lipid signal), aliasing artifacts, and long reconstruction times. These methods included: 1) variable TR with variable readout length to reduce fat signal and off-resonance blurring; 2) variable sampling density to suppress aliasing artifacts while minimizing acquisition time penalty; and 3) an online 3D gridding algorithm that reconstructed an 8-channel, 240(3) image volume set. Both phantom and human studies were performed to establish the initial feasibility of the methods.


RESULTS
Phantom and human study results demonstrated the effectiveness of the proposed methods. Shells with variable TR and readout length further suppressed the fat signal compared to the fixed-TR shells acquisition. Reduced image aliasing was achieved with minimal scan time penalty when a variable sampling density technique was used. The fast online reconstruction algorithm completed in 2 minutes at the scanner console, providing a timely image display in a clinical setting.


CONCLUSIONS
It was demonstrated that the use of the shells trajectory is feasible in a clinical setting to acquire intracranial angiograms with high spatial resolution. Preliminary results demonstrate effective venous suppression in the cavernous sinuses and jugular vein region.
Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905, USA. Shu.Yunhong@mayo.edu
Yunhong
Y
Shu
Matt A
MA
Bernstein
John
J
Huston
Dan
D
Rettmann
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001158:Arteries / Q000473:pathology; D001921:Brain / Q000473:pathology*; D003287:Contrast Media / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008638:Mesenteric Arteries / Q000473:pathology; D008875:Middle Aged
D003287:Contrast Media