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Intracranial simultaneous noncontrast angiography and intraplaque hemorrhage (SNAP) MRA: Analyzation, optimization, and extension for dynamic MRA
Author(s) -
Xiong Yuhui,
Zhang Zhe,
He Le,
Ma Yu,
Han Hualu,
Zhao Xihai,
Guo Hua
Publication year - 2019
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.27855
Subject(s) - medicine , snap , flip angle , magnetic resonance angiography , blood flow , angiography , magnetic resonance imaging , radiology , dynamic contrast , hemodynamics , computer science , cardiology , computer graphics (images)
Purpose Simultaneous noncontrast angiography and intraplaque (SNAP) imaging, as a noncontrast‐enhanced MRA technique, may not provide consistent vessel visualization for intracranial artery imaging among subjects. This study aims to investigate the underlying mechanism and extend SNAP to dynamic MRA. Methods The cause of the instability of intracranial SNAP‐MRA was investigated through theoretical analysis and simulations. The scan parameters, including TI and flip angle, were optimized for reliable imaging. In vivo experiments were conducted to validate the simulation results. The simulation results were correlated with real intracranial blood flow by introducing the concept of blood travel time, and intracranial SNAP‐MRA was revealed to reflect the cerebral blood expanse region in 5 TI. A new noncontrast‐enhanced dynamic MRA technique, termed 4D SNAP‐MRA , was proposed and demonstrated through in vivo scans. Results The cause of the instability of intracranial SNAP‐MRA was proved to be the slow or fast blood flow in the imaging slab. This instability can be mitigated by adjusting TI and flip angle in the SNAP sequence. The proposed 4D SNAP‐MRA can provide dynamic visualization of the cerebral blood circulation and cerebral hemodynamic information such as blood travel time. Conclusion The 3D SNAP‐MRA with optimal imaging parameters can generate cerebral angiography with hemodynamic information, and the 4D SNAP‐MRA provides dynamic visualization of the cerebral blood circulation.