Angiographic contrast mechanism comparison between Simultaneous Non-contrast Angiography and intraPlaque hemorrhage (SNAP) sequence and Time of Flight (TOF) sequence for intracranial artery

2020 ◽  
Vol 66 ◽  
pp. 199-207
Author(s):  
Qiang Zhang ◽  
Zhensen Chen ◽  
Shuo Chen ◽  
Xinke Liu ◽  
Jia Ning ◽  
...  
Keyword(s):  
Time Of Flight ◽  
Intraplaque Hemorrhage ◽  
Intracranial Artery ◽  
Contrast Mechanism ◽  
Contrast Angiography

MR angiography

2018 ◽  
pp. 34-37
Author(s):  
Sebastian Kozerke ◽  
Redha Boubertakh ◽  
Marc Miquel
Keyword(s):  
Spin Echo ◽  
Time Of Flight ◽  
Flow Quantification ◽  
Black Blood ◽  
Blood Flows ◽  
Contrast Enhanced ◽  
Stationary Signals ◽  
Contrast Mechanism ◽  
Contrast Angiography ◽  
Spin Echo Sequences

The appearance of blood on magnetic resonance (MR) images is directly linked to its flowing nature. The contrast mechanism relies on the time-of-flight mechanism. In spin echo sequences, the excited blood flows out before the echo is created, resulting in black blood images, whereas in gradient echo images, the rapid succession of radiofrequency pulses saturates stationary signals, while fresh blood continuously flows in, leading to bright blood images. This phenomenon can be exploited to create inflow or time-of-flight angiography. It is also possible to encode the movement by using gradients that create phase differences between stationary and moving tissues. This technique, known as phase contrast angiography, can be used to image the venous and arterial phases separately. It also forms the basics of blood flow quantification. Finally, it is possible to use gadolinium-based agents to acquire contrast-enhanced angiographies.

scholarly journals Identification of Intraplaque Hemorrhage on MR Angiography Images: A Comparison of Contrast-Enhanced Mask and Time-of-Flight Techniques

2011 ◽  
Vol 32 (3) ◽  
pp. 454-459 ◽  
Author(s):  
Y. Qiao ◽  
M. Etesami ◽  
S. Malhotra ◽  
B.C. Astor ◽  
R. Virmani ◽  
...  
Keyword(s):  
Mr Angiography ◽  
Time Of Flight ◽  
Intraplaque Hemorrhage ◽  
Contrast Enhanced

Intraplaque high-intensity signal on time-of-flight magnetic resonance angiography and restenosis after carotid artery stenting

2021 ◽  
pp. 1-6
Author(s):  
Keisuke Tokunaga ◽  
So Tokunaga ◽  
Kenta Hara ◽  
Masahiro Yasaka ◽  
Yasushi Okada ◽  
...  
Keyword(s):  
Carotid Artery ◽  
High Intensity ◽  
Carotid Artery Stenting ◽  
Time Of Flight ◽  
Peak Systolic Velocity ◽  
Intraplaque Hemorrhage ◽  
Tof Mra ◽  
Increased Risk ◽  
High Intensity Signal

OBJECTIVE To test the hypothesis that intraplaque hemorrhage is a predictor of restenosis after carotid artery stenting (CAS), the association between intraplaque high-intensity signal (HIS) on time-of-flight MR angiography (TOF-MRA), as a marker of intraplaque hemorrhage, and restenosis after CAS was assessed in the present observational study. METHODS Consecutive patients who underwent initial CAS for atherosclerotic stenosis in the cervical internal carotid artery in the authors’ department were enrolled. Of these, patients without preprocedural cervical TOF-MRA were excluded. Outcome measures were ≥ 50% restenosis, defined as a peak systolic velocity of > 1.3 m/sec; or occlusion and ≥ 70% restenosis, defined as a peak systolic velocity of > 2.1 m/sec; or occlusion on carotid duplex ultrasound. RESULTS Of 230 consecutive patients who underwent initial CAS, 22 without preprocedural cervical TOF-MRA were excluded. Of the remaining 208 patients (mean age 73 years; 33 women), 46 had intraplaque HIS. Ultrasound follow-up was not performed in 4 patients. The median follow-up duration was 3.2 years (interquartile range 1.7–5.1 years). During the follow-up period, 102 patients had ≥ 50% restenosis and 36 had ≥ 70% restenosis. Intraplaque HIS was significantly associated with increased risk of ≥ 50% restenosis (adjusted hazard ratio 2.18; 95% CI 1.28–3.68) and ≥ 70% restenosis (adjusted hazard ratio 3.12; 95% CI 1.32–7.52). CONCLUSIONS Intraplaque HIS on TOF-MRA was associated with increased risk of restenosis after CAS. The present results indicate that intraplaque hemorrhage is a predictor of restenosis after CAS.

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