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Advanced Neurology A novel marker for healthy intracranial arteries

1. Introduction of cardioembolism, extracranial carotid atherosclerosis
(>50% stenosis) assessed through carotid ultrasound,
Intracranial atherosclerotic disease (ICAD) stands as a or non-atherosclerotic stenosis (moyamoya disease,
significant contributor to stroke globally, particularly radiation-induced vasculopathy, infection, dissection,
among patients with Asian, Hispanic, and African or autoimmune disease). Each patient’s bilateral MCAs
ancestry . Recent studies have underscored the pivotal were subject to analysis, with exclusion criteria applied in
[1]
role of hemodynamic characteristics, alongside systemic instances where MRI quality was inadequate for analysis,
risk factors, in the pathophysiology of ICAD [2,3] . Within imaging data were unavailable, or the M1 segment was
a regularly shaped, healthy artery, blood flow typically occluded.
manifests as either parabolic laminar flow, with maximal
flow velocity at the center , or spiral laminar flow, 2.2. Ethics approval and consent
[4]
characterized by relatively low velocity at the rotational
axis [5,6] . Plaque tends to develop in regions where laminar The study protocol was approved by the ethics committee
flow is disrupted, such as arterial bifurcations and of the Peking Union Medical College Hospital (JS-3479D).
curvatures [7-9] . Before participation, written consent was obtained from all
patients or their families.
Signal loss in the center of intracranial and extracranial
internal carotid arteries on time-of-flight magnetic 2.3. The protocol of MRI
resonance angiography (TOF-MRA) is a common The comprehensive vessel wall MRI imaging protocol,
occurrence and is typically considered an artifact . as previously described [13,14] , was employed in this study.
[10]
Bradley et al. have proposed that this signal loss is Patients were imaged using a 3-tesla (3T) magnetic
secondary to a centered high flow velocity producing a resonance scanner (Signa VH/I, GE Medical Systems,
parabolic laminar flow beyond the maximum flow-related USA, from January 2007 to June 2013; GE Discovery
enhancement . Alternative speculations include the MR750, GE Medical Systems, USA, from June 2013 to
[11]
possibility of a truncation artifact or the presence of two August 2015) equipped with a standard 8-channel head
[10]
streams of laminar flow . This phenomenon has raised coil. The imaging protocol comprised conventional
[12]
our interest in its prevalence and its potential association 3-dimensional (3D) TOF-MRA, DWI, and T1- and
with ICAD and strokes. Therefore, our investigation aimed T2-weighted vessel wall imaging of the MCA. From the
to determine the prevalence and associated factors of period of January 2007 to June 2013, the parameters for
this phenomenon in both ICAD patients and a healthy 3D TOF-MRA were as follows: repetition time/echo time
population. We hypothesized that the central signal loss in (TR/TE), 19 – 27 ms/2.7 – 3.3 ms; flip angle, 20°; field-
the intracranial internal carotid artery (ICA) is indicative of-view (FOV), 24 cm × 16 cm; matrix size, 320 × 256;
of a healthy intracranial vasculature. Descriptively, due to slice thickness, 1.6 mm; slab thickness, 8.5 cm; 1 signal
its resemblance to a traditional Chinese food item known average; and scan time, 4 min. Subsequently, a 2D
as the Fried-Breadstick (FB, Figure 1A and B) on maximum T2-weighted vessel wall MRI was acquired perpendicular
intensity projection (MIP) images, we have termed it the to the long axis of the M1 segment of the MCA following
FB sign.
3D TOF-MRA. The parameters for this acquisition were
2. Materials and methods TR/TE, 3000 ms/50 ms; FOV, 13 cm × 13 cm; matrix size,
256 × 256; slice thickness, 2 mm; and 4 signal averages.
2.1. Patients From June 2013 to August 2015, the 3D TOF-MRA
We conducted a comprehensive review of prospectively was obtained with the following parameters: TR/TE,
collected data from vessel wall magnetic resonance 16~22/2.1~2.7ms; flip angle, 20°; FOV, 20 cm × 18 cm;
imaging (MRI) at our institution, spanning from January matrix size, 320 × 288; slice thickness, 1.2 mm; slab
2007 to August 2015. Individuals were eligible for thickness 10 cm; 1 signal averages; and scan time 5 min. 2D
inclusion in this study if they met one of the following T2-weighted vessel wall MRI was obtained using TR/TE,
criteria: (i) exhibited middle cerebral artery (MCA) 4200/60 ms; FOV, 13 × 13 cm; matrix size, 256 × 256; slice
atherosclerosis and experienced an acute first-ever thickness, 2 mm; and 4 signal averages. MIP images were
stroke in the MCA territory, as confirmed by diffusion- reconstructed in axial and coronal planes with a rotation
weighted imaging (DWI); (ii) demonstrated MCA angle interval of 10° or 15°.
atherosclerosis without a history of clinical stroke or
transient ischemic attacks (TIA); and (iii) displayed 2.4. Imaging analysis
no MCA atherosclerosis and had no history of clinical Imaging data were analyzed by two independent evaluators
stroke or TIA. Exclusion criteria encompassed evidence who were blinded to clinical information. To evaluate

Volume 2 Issue 4 (2023) 2 https://doi.org/10.36922/an.1238