Multiband multislab 3D time-of-flight magnetic resonance angiography for reduced acquisition time and improved sensitivity.

Purpose: To explore the use of multiband (MB) imaging in multislab (MS) 3D time-of-flight-magnetic resonance angiography (TOF-MRA) and to improve acquisition time efficiency (TA), inflow contrast and sensitivity in vessel detection.

Theory and Methods: TOF-MRA is commonly used for imaging intracranial vessels. A MB-MS 3D-TOF-MRA sequence was implemented to excite and acquire multiple slabs simultaneously. Controlled aliasing in parallel imaging results in higher acceleration was used in addition to improve the quality of image reconstruction. Compared to a standard protocol which acquired three slabs in total the MB-MS protocol reduced the thickness by 3 while simultaneously acquiring data from 3 slabs. The total TA was also reduced by a factor 3.

Results: This technique maintains contrast-to-noise ratio while reducing TA, compared to standard single-band/MOTSA acquisitions, leading to an increase in inline image of 1.65 compared to the standard protocol. Furthermore, the strong inflow contrast and increased magnetization transfer contrast caused by the MB excitation pulses improves the sharpness of the vessel borders which is reflected by a 5% higher full width at half maximum of the vessel size and a 17% higher slope of the vessel borders compared to the standard single-band acquisition.

Conclusion: MB-MS 3D-TOF-MRA can appreciably accelerate image acquisition and combines the high spatial resolution of 3D imaging with the additional inflow contrast advantage of thinner slab acquisitions without introducing excessive noise arising from the MB reconstruction.