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Advanced Neurology A novel marker for healthy intracranial arteries

Arterial bifurcations are the most frequent sites affected be directly applicable to 1.5T scanners or those from other
by atherosclerosis due to complex regional hemodynamics, MRI manufacturers. Additionally, many patients included
a topic extensively studied in coronary and cervical in the plaque-free group presented with multiple stroke risk
carotid arteries but scarcely in intracranial arteries [19,33,34] . factors, potentially leading to an underestimation of the FB
It is reasonable to speculate that intracranial arterial sign’s prevalence in the healthy population. The imaging
bifurcations, such as the terminal ICA bifurcation, share modality used in this study did not visualize intracranial
similar characteristics in hemodynamics and are prone ICA plaque, and though we excluded extracranial carotid
to atherosclerosis, as evidenced by an autopsy study . artery stenosis exceeding 50%, mild extracranial artery
[35]
A smaller bifurcation angle is a geometric feature associated stenosis or other anatomical variation might have affected
with less atherosclerotic burden [19,36] and positive effects on the blood flow in the ICA. Furthermore, we did not
local hemodynamics . This observation further supports analyze the prevalence of the FB sign in other arteries or
[20]
the FB sign as a marker for healthy ICA-MCA vasculature, investigate the coexistence of other vascular abnormalities,
as its presence is independently associated with a smaller such as ICA dolichoectasias or fenestrations. This study
terminal ICA bifurcation angle. did not comprehensively analyze all possible geometric or
plaque-related characteristics. Given the absence of in vivo
TOF-MRA is a routine and non-invasive method for data on intracranial hemodynamics related to the FB sign,
screening ICAD and guiding medical management, but it our proposed mechanisms are speculative and based on
only detects secondary changes of atherosclerosis, such as previous theories. The classification of the FB sign may
luminal narrowing. Considering that the FB sign is more simplify the underlying continuous process. It is important
prevalent in plaque-free MCAs compared to atherosclerotic to note that visualizing the FB sign requires good patient
MCAs without luminal narrowing, the absence of the FB compliance during MRI scanning, and interpreting the
sign may provide additional value in identifying patients FB sign in acute stroke patients should be approached
with early-stage atherosclerosis but without luminal with specific caution. Further investigations, ideally
narrowing. In such cases, further confirmation through incorporating direct evidence from computational fluid
vessel wall imaging or intervention with early prevention dynamics, are warranted to verify our hypotheses.
strategies may be warranted .
[37]
Diagnosing stroke etiology is critical for tailoring the 5. Conclusion
treatment plan for stroke prevention. The FB sign exhibits The phenomenon of central signal loss in ICA is commonly
a distinct distribution in stroke patterns, indicating its considered an artifact observed on TOF-MRA images.
potential for distinguishing ICAD-related strokes from However, this study delves into the association between
non-ICAD-related strokes. In strokes that are likely central signal loss and intracranial atherosclerosis,
attributed to MCA atherosclerosis, the FB sign is more revealing that central signal loss occurs more frequently
frequently observed in small SSI, typically associated with in patients exhibiting healthy ICA-MCAs. Conversely, its
cerebral small vessels [38,39] , and linked to fewer neurological occurrence is less frequent in patients with intracranial
deficits and lower recurrence rates [40,41] . The FB sign is least atherosclerosis, such as ICA or MCA stenosis. This
frequent in the non-SSI stroke pattern, often characterized preliminary investigation suggests that central signal loss
by a territorial infarct, watershed infarct, and mixed in the ICA may serve as an imaging marker indicative
infarct patterns. Non-SSI stroke patterns are considered of healthy ICA-MCA vasculature. To capture its visual
associated with embolic mechanisms , involving resemblance to a traditional Chinese fried breadstick, we
[23]
disrupted laminar flow and the formation of turbulent have aptly named this phenomenon the “Fried-Breadstick
flow in severely stenotic sites of atherosclerotic plaque, sign.”
[42]
leading to subsequent plaque rupture . The prevalence
of the FB sign is intermediate for the large SSI stroke Acknowledgments
pattern, likely due to its mixed etiologies involving branch The authors thank all the participants who gave their time
atheromatous disease , which is associated with large to the study.
[43]
vessel atherosclerosis, and lipohyalinosis , which is
[44]
indicative of small vessel disease. These findings contribute Funding
to a better understanding of the pathophysiology of stroke This study is supported by the National Science Fund for
patterns and hemodynamic disruptions in ICAD patients.
Distinguished Young Scholars (82025013), the National
Our study has several limitations that warrant Natural Science Foundation of China (81671370 and
consideration. Firstly, our study cohort was exclusively 81471207), and the National Key Technologies R&D
scanned with 3T GE scanners, and the findings may not Program of China (2017YFC1307902).

Volume 2 Issue 4 (2023) 7 https://doi.org/10.36922/an.1238