From: Intracranial vessel wall MRI: a review of current indications and future applications
Pulse sequence | Advantages | Disadvantages |
---|---|---|
3D time of flight (TOF) MRA (non-contrast) | Flow-related enhancement allows identification of luminal abnormality or aneurysm for measurement and placement of IVWM sequences | Luminal imaging alone may not identify non-stenotic vessel abnormalities (outwardly remodeling plaque, non-stenotic dissection, etc.). TOF overestimates stenosis secondary to flow dephasing artifact. It also shows diminished flow in slow flow or in-plane flow states. These are overcome with contrast-enhanced TOF MRA |
2D turbo spin echo (TSE) or fast spin echo (FSE) | Wide availability, good in-plane resolution, flexible tissue contrast, reduced sensitivity to magnetic field inhomogeneities, high SNR, can image focused area of interest in rapid acquisition to limit motion artifact | Low spatial resolution in the slice-select direction leading to partial volume effect that can hide subtle findings, poor reproducibility, inability to create multiplanar reformats. Requires multi-planar scanning which is time consuming |
3D variable refocusing flip angle (VRFA) sequences (VISTA, Philips; SPACE, Siemens; CUBE, GE) | High SNR with excellent spatial resolution, superior anatomic coverage, T1/T2/PD weightings available, ability to reformat into multiplanar images that allow viewing of vessel wall, plaque, or aneurysm from any aspect. Shorter overall scan time | Requires research preparation prepulse sequence for blood suppression, longer acquisition times for slab can result in motion artifact, more susceptible to magnetic field inhomogeneities |
Blood suppression prepulse:  • Double inversion-recovery | Available as a commercial pulse, negligible effect on image contrast weighting | Blood-suppression difficult after contrast administration, does not work with 3D techniques |
Blood suppression prepulse:  • Motion-sensitive driven equilibrium (MSDE) | 3D blood suppression technique, robust to large slab size acquisition, in-flow/outflow independent | Can lead to loss of signal with T2 weighting, inability to implement 180° pulse due to high specific absorption rate, B1 inhomogeneity |
Blood suppression prepulse:  • Delay alternating with nutation for tailored excitation (DANTE) | Best blood suppression, robust to large slab size acquisition, in-flow/outflow independent, no loss of T2 signal, performs well at 7T, available on research sequences from most vendors | Longer imaging time than MSDE may create artifact from vessel wall motion |
Gradient-echo 3D T1-weighted without blood suppression (MP-RAGE, FLASH) | Can identify intraplaque hemorrhage in atherosclerosis, intramural hematoma in dissection, and aneurysmal wall hematoma | Lack of blood suppression can hide pathologic findings, unclear significance of intracranial intraplaque hemorrhage. MP-RAGE is preferred sequence |