Sliding time of flight: sliding time of flight MR angiography using a dynamic image reconstruction method.
OBJECTIVE
To obtain three-dimensional (3D) MR angiography having high contrast between vessel and stationary background tissue, a novel technique called sliding time of flight (TOF) is proposed.


METHODS
The proposed method relies on the property that flow-related enhancement (FRE) is maximized at the blood-entering slice in an imaging slab. For the proposed sliding TOF, a sliding stack-of-stars sampling and a dynamic MR image reconstruction algorithm were developed. To verify the performance of the proposed method, in vivo study was performed and the results were compared with multiple overlapping thin 3D slab acquisition (MOTSA) and sliding interleaved ky (SLINKY).


RESULTS
In MOTSA and SLINKY, the variation of FRE resulted in severe venetian blind (MOTSA) or ghost (SLINKY) artifacts, while the vessel-contrast increased as the flip angle of radiofrequency (RF) pulses increased. On the other hand, the proposed method could provide high-contrast angiograms with reduced FRE-related artifacts.


CONCLUSIONS
The sliding TOF can provide 3D angiography without image artifacts even if high flip angle RF pulses with thick slab excitation are used. Although remains of subsampling artifacts can be present in the reconstructed images, they can be reduced by MIP operation and resolved further by regularization techniques.
Department of Electrical Engineering, Korean Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea.
Joonsung
J
Choi
Hyunseok
H
Seo
Yongwan
Y
Lim
Yeji
Y
Han
HyunWook
H
Park
D000328:Adult; D000465:Algorithms; D016477:Artifacts; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
MOTSA; TOF; sliding slab; stack-of-stars trajectory