Four-Dimensional Flow MRI Analysis of Cerebral Blood Flow Before and After High-Flow Extracranial–Intracranial Bypass Surgery With Internal Carotid Artery Ligation

Orita, Erika; Murai, Yasuo; Sekine, Tetsuro; Takagi, Ryo; Amano, Yasuo; Ando, Takahiro; Iwata, Kotomi; Obara, Makoto; Kumita, Shin‐ichiro

doi:10.1093/neuros/nyy192

Cited by 17 publications

(18 citation statements)

References 28 publications

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“…However, limitations of the study included no comparison to a ‘gold-standard’ technique, uniform v enc , long scan times and poor flow extraction of small vessels. A similar study was carried out by the same group in 2019 to assess arterial blood flow before and after carotid bypass surgery, 39 in which undersampling techniques reduced the scan time to just six minutes, yet issues with low spatial resolution continued to limit the evaluation of small arteries.…”

Section: Resultsmentioning

confidence: 98%

“…Several studies demonstrated the use of 4D flow in the context of surgical operations. 38,39 These are useful in highlighting and summarising the main concerns in using 4D flow in disease research, and the solutions that will likely address these concerns in the future: including (but not limited to) high-field MRI, advanced acceleration techniques (ideally using correlations in space and time), increased resolution and multi- v enc acquisition. A summary of the range of popular imaging parameters used in current, state-of-the-art cerebral 4D flow studies is presented in Figure 4.…”

Section: Discussionmentioning

confidence: 99%

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4D flow MRI for non-invasive measurement of blood flow in the brain: A systematic review

Morgan

Thrippleton

Marshall

2020

J Cereb Blood Flow Metab

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The brain’s vasculature is essential for brain health and its dysfunction contributes to the onset and development of many dementias and neurological disorders. While numerous in vivo imaging techniques exist to investigate cerebral haemodynamics in humans, phase-contrast magnetic resonance imaging (MRI) has emerged as a reliable, non-invasive method of quantifying blood flow within intracranial vessels. In recent years, an advanced form of this method, known as 4D flow, has been developed and utilised in patient studies, where its ability to capture complex blood flow dynamics within any major vessel across the acquired volume has proved effective in collecting large amounts of information in a single scan. While extremely promising as a method of examining the vascular system’s role in brain-related diseases, the collection of 4D data can be time-consuming, meaning data quality has to be traded off against the acquisition time. Here, we review the available literature to examine 4D flow’s capabilities in assessing physiological and pathological features of the cerebrovascular system. Emerging techniques such as dynamic velocity-encoding and advanced undersampling methods, combined with increasingly high-field MRI scanners, are likely to bring 4D flow to the forefront of cerebrovascular imaging studies in the years to come.

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Section: Resultsmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

4D flow MRI for non-invasive measurement of blood flow in the brain: A systematic review

Morgan

Thrippleton

Marshall

2020

J Cereb Blood Flow Metab

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“…Their work importantly characterized the limitations of 4D flow to evaluate small arteries (<2.4 mm in their study) and illustrated the feasibility of the technique in this patient population. In addition, Orita et al continued to expand the scope of 4D flow in EC‐IC bypass by characterizing the hemodynamic changes that occurred after bypass, by measuring both preoperative and postoperative flow measurements in bypass patients who also underwent ICA ligation 19 . Using 4D flow, they were able to quantify the degree to which the bypass graft could compensate for the sacrificed ICA in these patients.…”

Section: Discussionmentioning

confidence: 99%

The Effect of Extracranial‐to‐Intracranial Bypass on Cerebral Vasoreactivity: A 4D Flow MRI Pilot Study

Callen

Caton

Rutledge

et al. 2020

Journal of Neuroimaging

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BACKGROUND AND PURPOSE: Extracranial-to-intracranial (EC-IC) surgical bypass improves cerebral blood flow (CBF) and cerebrovascular vasoreactivity (CVR) for patients with carotid occlusion. Bypass graft patency and contribution of the graft to the postoperative increase in CVR are challenging to assess. To assess the effectiveness of 4D flow magnetic resonance imaging (MRI) to evaluate bypass graft patency and flow augmentation through the superficial temporal artery (STA) before and after EC-IC bypass. METHODS: Three consecutive patients undergoing EC-IC bypass for carotid occlusion were evaluated pre-and postoperatively using CVR testing with pre-and poststimulus 4D flow-MRI for assessment of the bypass graft and intracranial vasculature. RESULTS: Preoperatively, 2 patients (patients 1 and 3) did not augment flow through either native STA. The third, who had evidence of extensive native EC-IC collateralization on digital subtraction angiography (DSA), did augment flow through the STA preoperatively (CVR = 1). Postoperatively, all patients demonstrated CVR > 1 on the side of bypass. The patient who had CVR > 1 preoperatively demonstrated the greatest increase in resting postoperative graft flow (from 40 to 130 mL/minute), but the smallest CVR, with a poststimulus graft flow of 160 mL/minute (CVR = 1.2). The 2 patients who did not demonstrate augmentation of graft flow preoperatively augmented postoperatively from 10 to 20 mL/minute (CVR = 2.0) and 10-80 mL/minute (CVR = 8.0), respectively. Intracranial flow was simultaneously interrogated. Two patients demonstrated mild reductions in resting flow velocities in all interrogated vessels immediately following bypass. The patient who underwent CVR testing on postoperative day 48 demonstrated a stable or increased flow rate in most intracranial vessels. CONCLUSION: Four-dimensional flow MRI allows for noninvasive, simultaneous interrogation of the intra-and extracranial arterial vasculature during CVR testing, and reveals unique paradigms in cerebrovascular physiology. Observing these flow patterns may aid in improved patient selection and more detailed postoperative evaluation for patients undergoing EC-IC bypass.

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“…Assessment of vessel patency and blood flow direction is critical in various medical situations, including diagnosis and treatment monitoring of ischemic diseases [1][2][3][4][5][6][7][8] and image-guided vascular surgeries. [9][10][11][12][13][14][15][16][17][18][19][20][21] Ischemic diseases are typically characterized by the disruption of the blood flow, such as changes in blood flow speed and blood flow direction. 11 In the treatment of ischemic diseases, the natural and procedurally promoted vascular remodeling of existing arterial interconnections to form adequate collateral development for restoration of perfusion to the organs that have suffered ischemia is closely related to the patient outcomes.…”

Section: Introductionmentioning

confidence: 99%

“…[2][3][4][5][6][7] Non-invasive monitoring of blood flow direction and occasional flow direction reversal in the treatment of ischemic diseases can provide important information to assess therapeutic effectiveness. [1][2][3][4][5] In various vascular surgeries such as vascular bypass, [13][14][15][16][17] vascular shunt, 5,[18][19][20][21] and aneurysm surgery, 9,10,14,17 blood flow characteristics such as blood flow path and blood flow direction are intentionally modified. Imaging the blood flow direction during the surgeries that confirms the intended changes of the paths and directions of the blood flow while avoiding any unintended alteration in vessel patency and blood flow direction is highly desirable for monitoring of the immediate effects of the surgery and for quality control of the vascular intervention.…”

Section: Introductionmentioning

confidence: 99%

Visualization of two-dimensional transverse blood flow direction using optical coherence tomography angiography

Shin

2020

J. Biomed. Opt.

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. Significance: Evaluation of vessel patency and blood flow direction is important in various medical situations, including diagnosis and monitoring of ischemic diseases, and image-guided vascular surgeries. While optical coherence tomography angiography (OCTA) is the most widely used functional extension of optical coherence tomography that visualizes three-dimensional vasculature, inability to provide information of blood flow direction is one of its limitations. Aim: We demonstrate two-dimensional (2D) transverse blood flow direction imaging in en face OCTA. Approach: A series of triangular beam scans for the fast axis was implemented in the horizontal direction for the first volume scan and in the vertical direction for the following volume scan, and the inter A-line OCTA was performed for the blood flow direction imaging while the stepwise pattern was used for each slow axis scan. The decorrelation differences between the forward and the backward inter A-line OCTA were calculated for the horizontal and the vertical fast axis scans, and the ratio of the horizontal and the vertical decorrelation differences was utilized to show the 2D transverse flow direction information. Results: OCTA flow direction imaging was verified using flow phantoms with various flow orientations and speeds, and we identified the flow speed range relative to the scan speed for reliable flow direction measurement. We demonstrated the visualization of 2D transverse blood flow orientations in mouse brain vascular networks in vivo . Conclusions: The proposed OCTA imaging technique that provides information of 2D transverse flow direction can be utilized in various clinical applications and preclinical studies.

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Four-Dimensional Flow MRI Analysis of Cerebral Blood Flow Before and After High-Flow Extracranial–Intracranial Bypass Surgery With Internal Carotid Artery Ligation

Abstract: After high-flow EC-IC bypass with permanent ICA ligation, the bypass artery could partially compensate for the loss of BFV of the sacrificed ICA. The increased flow of the contralateral ICA and BA supply collateral blood flow. Clinically irrelevant hyperperfusion was observed.

Cited by 17 publications

References 28 publications

4D flow MRI for non-invasive measurement of blood flow in the brain: A systematic review

4D flow MRI for non-invasive measurement of blood flow in the brain: A systematic review

The Effect of Extracranial‐to‐Intracranial Bypass on Cerebral Vasoreactivity: A 4D Flow MRI Pilot Study

Visualization of two-dimensional transverse blood flow direction using optical coherence tomography angiography

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