Integrated cervicocerebral ultrasound-based hemodynamic compensation scoring for anterior-circulation steno-occlusive disease: validation against CT perfusion staging

Introduction

Cerebral perfusion underlies aerobic metabolism in brain tissue and supports normal neuronal function. Cerebral perfusion disruption represents a critical pathological mechanism in the onset and progression of neurological disorders, such as ischemic stroke, cerebral vasospasm, vascular cognitive impairment, and various neurodegenerative diseases. The precise, dynamic assessment of cerebral perfusion serves not only as a vital diagnostic tool for neurological disorders and disease staging, but also provides critical support for formulating clinical intervention strategies, evaluating treatment efficacy, and predicting prognosis. It holds irreplaceable clinical value in neurology practice.

Currently, clinical imaging techniques for cerebral perfusion assessment have evolved into a diversified system. Commonly employed methods include computed tomography perfusion (CTP) imaging, magnetic resonance imaging (MRI), positron emission tomography (PET), and single-photon emission computed tomography (SPECT) (1-3). Among these, CTP imaging enables the quantitative or semi-quantitative acquisition of core hemodynamic parameters such as cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT). It offers rapid scanning speeds and broad applicability. MRI perfusion techniques (e.g., dynamic susceptibility contrast and arterial spin labeling [ASL]) also provide spatially resolved perfusion assessment, with the additional advantage of avoiding ionizing radiation, albeit with longer acquisition times and greater susceptibility to motion and other artifacts in some settings. PET and SPECT are regarded as the gold standard for quantitative CBF assessment. However, these techniques face limitations in long-term monitoring, critical care evaluation, and large-scale screening due to factors such as bulky equipment, extended examination durations, and the nephrotoxicity of contrast agents.

Neurosonography, with its non-invasive, convenient, and readily repeatable bedside application, provides a vital complementary tool for assessing cerebral hemodynamics. Carotid duplex ultrasonography accurately evaluates the degree of stenosis and plaque characteristics in the extracranial segments of the carotid arteries, while transcranial color-coded sonography (TCCS) investigates blood flow velocity, direction, and spectral pattern alterations in major cerebral arteries and their branches. This facilitates the determination of arterial stenosis severity and the presence and patency of collateral circulation. The integrated cervicocerebral ultrasound (ICCUS) protocol combines these two techniques, enabling continuous hemodynamic assessment from the carotid origin to major intracranial vessels (4,5). Notably, ongoing advances in probe technology and signal processing have enabled modern ultrasound systems to more stably acquire hemodynamic signals from intracranial vessels, providing a robust technical foundation for quantitative hemodynamic analysis based on ultrasound-derived parameters.

While neurosonography offers distinct advantages in diagnosing cerebrovascular diseases, it continues to encounter significant challenges in the assessment of cerebral perfusion. The primary limitation stems from the lack of a standardized perfusion evaluation system. Previous studies have largely focused on the correlation between isolated vascular parameters and localized hemodynamic changes, but a systematic assessment framework capable of comprehensively capturing the compensatory status of cerebral perfusion is lacking (6). Further, the quantitative relationship between ultrasound-derived parameters and established perfusion imaging modalities such as CTP remains insufficiently clarified, constraining the standardized application of ultrasound in cerebral perfusion evaluation. Therefore, the development of an ultrasound-based cerebral perfusion assessment system that integrates multiple parameters and the establishment of its correlation with conventional perfusion imaging have emerged as critical issues in the field of neurosonography.

This study aimed to develop a novel ultrasound cerebral perfusion scoring system by systematically analyzing the correlation between CTP perfusion stages [Stage I1–I2, compensated hypoperfusion; Stage II1–II2, decompensated ischemia, defined by characteristic patterns of time-to-peak (TTP)/MTT/regional cerebral blood flow (rCBF)/regional cerebral blood volume (rCBV)] (7), and parameters acquired through ICCUS, including the severity of intracranial and extracranial arterial stenosis, and the status of collateral circulation. This study sought to establish a practical, radiation-free, and reproducible method for monitoring cerebral perfusion in clinical settings. We present this article in accordance with the STROBE reporting checklist (available at https://qims.amegroups.com/article/view/10.21037/qims-2025-1546/rc).

Methods

Patients

This retrospective study enrolled patients who underwent carotid duplex ultrasonography, TCCS, and CTP at Beijing Tiantan Hospital, Capital Medical University between January 2020 and April 2025. The inclusion criteria were as follows: (I) completion of all imaging examinations (carotid ultrasound, TCCS, and CTP) within a maximum interval of 1 month with no revascularization therapy performed during the interval; (II) age >18 years; and (III) availability of complete and diagnostically adequate clinical and imaging data. The exclusion criteria were as follows: (I) a history of neck radiation therapy; (II) impaired consciousness precluding proper ultrasound examination; (III) significant acoustic shadowing due to calcified plaques compromising image quality/measurements; (IV) prior carotid endarterectomy or stenting; (V) prolonged intervals (>1 month) between imaging studies; (VI) acute stroke presentation; and/or (VII) concurrent intracranial space-occupying lesions (e.g., tumors). The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Institutional Board of Beijing Tiantan Hospital, Capital Medical University (No. KY2022-015-04), and informed consent was obtained from all individual participants.

Instruments

All ultrasound examinations were performed by certified sonographers with a minimum of five years of experience in neurosonology. The acquired images were subsequently analyzed by two independent reviewers following a standardized double-blind protocol, both of whom had over five years of specialized expertise in vascular ultrasound assessment. The examinations were conducted using a Philips Epiq 7 ultrasound system (Philips Healthcare, Amsterdam, The Netherlands) equipped with phased-array transducers operating at frequency ranges of 1.0–5.0 MHz for transcranial imaging and 5–14 MHz for extracranial evaluation. During the examinations, the patients were positioned supine with slight neck extension facilitated by a low-profile pillow to optimize acoustic windows. Carotid ultrasound served as a diagnostic tool for evaluating stenotic conditions in the common carotid artery (CCA) and internal carotid artery (ICA). TCCS was employed to evaluate stenotic changes in anterior circulation vessels—specifically the anterior cerebral artery (ACA) and middle cerebral artery (MCA)—as well as the patency of communicating arteries and collateral vessels. These include the anterior communicating artery (ACoA), posterior communicating artery (PCoA), ophthalmic artery (OA), ryACA-MCA leptomeningeal collaterals, and posterior cerebral artery-middle cerebral artery (PCA-MCA) leptomeningeal collaterals. The assessment criteria were based on the Chinese Guidelines for Cerebrovascular Ultrasound in Stroke (Table 1, Figures 1,2) (8,9).

Figure 1 Severe stenosis (arrows) of the (A,B) ICA, (C,D) ACA, and (E,F) MCA. ACA, anterior cerebral artery; EDV, end-diastolic velocity; ICA, internal carotid artery; MCA, middle cerebral artery; PI, pulsatility index; PSV, peak systolic velocity; RI, resistive index; SV depth, sample volume depth; TAMV, time-averaged mean velocity; TAPV, time-averaged peak velocity.

Figure 2 Representative ultrasound images of collateral pathway patency (arrows). (A,B) Patency of the OA; (C,D) leptomeningeal collateral circulation between the PCA-MCA. EDV, end-diastolic velocity; OA, ophthalmic artery; PCA-MCA, posterior cerebral artery-middle cerebral artery leptomeningeal collateral; PI, pulsatility index; PSV, peak systolic velocity; RI, resistive index; SV depth, sample volume depth; TCD, transcranial Doppler.

CTP imaging was performed using a Siemens Sensation 16-slice scanner (Siemens Healthcare, Forchheim, Germany) following non-contrast axial CT acquisition with the following parameters: 120 kVp, 300 mA, 24×24 cm field of view, 512×512 imaging matrix, and 9 mm supratentorial/4.5 mm infratentorial slice thickness. The perfusion protocol involved the intravenous administration of 40 mL of iohexol contrast (300 mgI/mL) at an injection rate of 8 mL per second via an antecubital vein, followed by a 20-mL saline flush, using acquisition parameters of 80 kVp, 209 mA, 1 second per rotation, 12-mm slice thickness, continuous 40-second acquisition (40 time points), with a total scan time of 44 seconds and an effective radiation dose of 3.51 mSv. All images were processed on the Neurosoft picture archiving and communication system (PACS) (Neusoft, Shenyang, China) and independently analyzed by two board-certified neuroradiologists, each with over 5 years of experience. The analysis included assessments of TTP, MTT, rCBF, and rCBV as key metrics. Based on these parameters, cerebral perfusion was classified into four distinct stages according to a previously reported staging scheme (7): Stage I1 (isolated TTP prolongation with normal MTT, rCBF, and rCBV); Stage I2 (prolonged MTT and TTP alongside physiological rCBF and physiological or mildly elevated rCBV); Stage II1 (prolonged MTT and TTP with reduced rCBF and physiological/slightly reduced rCBV); and Stage II2 (prolonged MTT and TTP with both reduced rCBV and rCBF), where Stage I represents compensated hypoperfusion and Stage II indicates decompensated ischemia, with each cerebral hemisphere evaluated separately (Table 2, Figure 3).

Figure 3 Representative CT perfusion maps for Stage I and Stage II. (A) Stage I in CTP. (B) Stage II in CTP. CBF, cerebral blood flow; CBV, cerebral blood volume; CTP, computed tomography perfusion; MTT, mean transit time; tMIP, time-maximum intensity projection; TTP, time-to-peak.

Statistical analysis

The statistical analyses were performed using SPSS 27.0. The continuous variables are expressed as the mean ± standard deviation or median ± standard deviation, and were compared using the t-test or Mann‑Whitney U test depending on the data distribution. The categorical variables are presented as the count or percentage, and were analyzed using the χ² test or Fisher’s exact test as appropriate. A P<0.05 was considered statistically significant. The sonographic variables derived from ICCUS included: (I) stenosis severity of the CCA, ICA, ACA, and MCA (mild/moderate/severe); and (II) collateral pathway status (open vs. closed) assessed via the ACoA, PCoA, OA, ACA-MCA, and PCA-MCA pathways. CTP perfusion staging was dichotomized as compensated (Stage I: I1–I2) or decompensated (Stage II: II1–II2). Univariate logistic regression was performed with CTP Stage II as the outcome. The odds ratio (OR) for each sonographic category represents the relative odds of CTP-defined decompensation compared with the reference category (e.g., an OR of 5 indicates approximately a five-fold increase in the odds of Stage II). To keep the scoring system simple and clinically interpretable, categories with an OR ≤1 were assigned 0 points, whereas those with an OR >1 were assigned integer points equal to the OR rounded to the nearest whole number (e.g., severe ICA stenosis OR =5.05 ≈5 points; severe MCA stenosis OR =8.00 ≈8 points; and open OA OR =2.31 ≈2 points). The total ICCUS-based perfusion scores for both left and right anterior circulation hemispheres were computed, and a receiver operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic capability of the ultrasound-based scoring system in predicting CTP-defined hemodynamic decompensation (Stage II: II1–II2). For the ROC curve analysis, the index test was the total ICCUS-based score calculated for each anterior-circulation hemisphere, and the reference standard was the CTP perfusion stage, dichotomized as decompensated (Stage II: II1–II2, positive) or compensated (Stage I: I1–I2, negative). ROC curves were generated by varying the ICCUS score cut-off; at each cut-off, true positive (TP) was defined as ICCUS-positive with CTP Stage II, false positive (FP) as ICCUS-positive with CTP Stage I, true negative (TN) as ICCUS-negative with CTP Stage I, and false negative (FN) as ICCUS-negative with CTP Stage II. Sensitivity and specificity were computed accordingly, and the area under the curve (AUC) was used to quantify overall discriminative performance.

Results

Demographics

From January 2020 to April 2025, 111 patients were recruited for this study, of whom 91 (82.0%) were male, and 20 (18.0%) were female (Figure 4). No statistically significant association was observed between sex and hemodynamic decompensation on CTP (P=0.624). The patients had a mean age of 64±12.9 years (range, 27–84 years). Similarly, no significant association was observed between age and hypoperfusion (Z=1.666, P=0.096).

Figure 4 Study flow chart. CTP, computed tomography perfusion; TCCS, transcranial color-coded sonography.

ICCUS evaluations

The left and right cerebral hemispheres of the 111 patients enrolled in the study were observed separately with 222 observations ultimately obtained. The degree of stenosis of the CCA, ICA, ACA, and MCA was analyzed univariately in relation to CTP staging (Table 3). The results revealed that stenosis severity of the ICA, ACA, and MCA was significantly associated with CTP perfusion staging. Specifically, the ORs increased with stenosis severity: moderate ICA stenosis (OR =1.57) and severe ICA stenosis (OR =5.05) were assigned 2 and 5 points, respectively; severe ACA stenosis (OR =3.92) was assigned 4 points; moderate MCA stenosis (OR =1.11) and severe MCA stenosis (OR =8.00) were assigned 1 and 8 points, respectively. In addition, the collateral and patency variables were evaluated, and an open OA (OR =2.31) and an open PCA-MCA leptomeningeal collateral (OR =2.28) were each assigned 2 points. Point values were determined by rounding the ORs to the nearest whole number (Tables 3,4, Figure 5). Based on these assigned values, ICCUS scoring was performed on the 222 observations (Table 5). The ROC curve analysis demonstrated an AUC of 0.845. Using a cut-off value of >4 points to diagnose the phase of anterior circulation reserve loss, the sensitivity was 74.58% and the specificity was 81.60% (Figure 6).

Figure 5 Scoring criteria for the ICCUS. ACA, anterior cerebral artery; ACoA, anterior communicating artery; CCA, common carotid artery; ICA, internal carotid artery; ICCUS, integrated cervicocerebral ultrasound; MCA, middle cerebral artery; OA, ophthalmic artery; PCA, posterior cerebral artery; PCoA, posterior communicating artery; TCCS, transcranial color-coded sonography.

Figure 6 ROC curve analysis of the ICCUS scoring system. The dashed purple lines indicate the 95% confidence interval of the AUC. AUC, area under curve; ICCUS, integrated cervicocerebral ultrasound; ROC, receiver operating characteristic.

Discussion

Cerebral hypoperfusion represents the common pathophysiological end-point in nearly all ischemic encephalopathies. Thus, the early and precise staging of perfusion status is critical for timely clinical intervention and accurate prognostication. CTP imaging is currently the most commonly used imaging method for the evaluation of cerebral perfusion, providing quantitative parameters, including rCBV, rCBF, MTT, and TTP, that enable detailed characterization of perfusion abnormalities (10). The widely adopted CTP staging system distinguishes critical pathophysiological states: Stages I1–I2 reflect compensated hypoperfusion where cerebral autoregulation maintains microcirculatory homeostasis through arteriolar and capillary vasomodulation, while Stages II1–II2 indicate decompensated ischemia with exhausted cerebrovascular reserve and emerging neuronal metabolic dysfunction (9,11). Despite its diagnostic utility, the clinical application of CTP faces significant limitations, including ionizing radiation exposure, requirements for nephrotoxic contrast agents, a prolonged acquisition time, and high operational costs. These constraints render it unsuitable for acute or critically ill patients, for individuals with renal insufficiency, and for the longitudinal monitoring of perfusion changes—a particular challenge in stroke and chronic cerebrovascular disease management.

In this context, ICCUS has gained increasing recognition as a valuable non-invasive tool for cerebrovascular assessment. Its advantages include real-time hemodynamic evaluation, the absence of radiation, bedside applicability, and excellent patient tolerance, making it particularly suitable for serial examinations. Recent advances have demonstrated the potential of ICCUS to evaluate both cervical and intracranial vessels, with growing evidence supporting its role in cerebral perfusion assessment (12,13). The present study built upon these developments by establishing a novel ICCUS-based scoring system that translates hemodynamic parameters into a standardized hemodynamic risk stratification framework.

Previous preliminary studies have largely used CT perfusion as the reference standard for perfusion assessment and ischemia and hypoperfusion stratification, and thus as a benchmark to validate bedside ultrasound-based approaches for detecting cerebral perfusion abnormalities. In acute anterior circulation ischemia, contrast-enhanced ultrasound perfusion imaging has been shown to delineate normally perfused, hyperperfused, and non-perfused regions, with region-level findings compared against CTP [or magnetic resonance (MR) perfusion], suggesting potential advantages for rapid, bedside, and repeatable dynamic monitoring (14). Further comparative work evaluating different ultrasound quantification strategies against CTP/MR perfusion indicates that while ultrasound offers real-time acquisition and practical bedside deployment, its overall diagnostic performance and semi-quantitative agreement can vary with methodological choices and patient heterogeneity—supporting its role as a complementary approach to CTP rather than a replacement (15).

In aneurysmal subarachnoid hemorrhage, ultrasound perfusion imaging has been applied to detect cerebral hypoperfusion with direct comparison to CTP, underscoring its feasibility for serial bedside follow-up in critically ill patients. In parallel, studies combining transcranial Doppler with perfusion CT for delayed cerebral ischemia/vasospasm monitoring have emphasized that CTP provides tissue-level perfusion “end-point” information, while ultrasound modalities are better suited for high-frequency, trend-based monitoring, and early detection in time-sensitive clinical workflows (16).

The anterior cerebral circulation, comprising the ICA and its major branches (the ACA and MCA), represents a hemodynamically interdependent system in which the stenosis or occlusion of these vessels triggers complex compensatory mechanisms. Our study focused on this critical vascular territory due to its predominant role in clinical ischemic events and the well-characterized pathophysiology of its collateral pathways, which include both primary (ACoA and PCoA) and secondary (leptomeningeal anastomoses) compensatory routes. The univariate analysis in our study identified significant perfusion alterations associated with three key factors: (I) stenosis severity in the ICA, ACA, and MCA; (II) patency and flow characteristics of the OA; and (III) the development of PCA-MCA leptomeningeal collaterals. These findings align with established neurovascular physiology, in which increasing stenosis severity progressively compromises perfusion pressure, while collateral recruitment serves as the principal compensatory mechanism. The developed ICCUS perfusion scoring system innovatively weights these parameters according to their ORs, reflecting their relative contribution to perfusion compromise. This approach demonstrated robust diagnostic performance for anterior circulation decompensation, with the optimal cut-off value (>4 points) achieving balanced sensitivity and specificity. The model’s performance characteristics suggest strong clinical utility for detecting hemodynamic compromise, particularly in settings in which CTP is unavailable or contraindicated. Importantly, the scoring system captures the continuum of perfusion states, enabling the identification of patients in the critical transition from compensated to decompensated hypoperfusion—a clinical decision point for therapeutic intervention.

ICCUS has several advantages, including bedside accessibility, the absence of ionizing radiation and nephrotoxic contrast, and suitability for serial monitoring. The proposed scoring system provides a structured and standardized framework for interpreting ICCUS-derived hemodynamic parameters, thereby enhancing the consistency and clinical utility of ICCUS in assessing cerebral perfusion compromise. This standardized approach may facilitate its application in scenarios such as high-risk population screening, longitudinal follow-up of subacute stroke patients, and treatment response evaluation in chronic cerebrovascular disease.

It should be noted that the autonomic regulation of CBF constitutes a key mechanism for maintaining perfusion homeostasis, and its status may influence the interpretation of ICCUS perfusion parameters. During compensatory hypoperfusion phases (e.g., CTP Stages I1/I2), intact autonomic regulation can sustain CBF through vasodilation; conversely, impaired regulation may accelerate progression to decompensated states (e.g., CTP Stages II1/II2), and compromise the correlation between ultrasound hemodynamic parameters and actual perfusion status (14). Therefore, any clinical application must account for individual variations in autonomic regulation capacity based on patient-specific circumstances. Spatial perfusion imaging techniques such as CTP and MRI (including ASL) offer high-resolution whole-brain coverage, volumetric analysis, and direct detection of infarct core and small lesions, capabilities not provided by ICCUS (17-21). The present study did not seek to compare ICCUS with these modalities, but rather to propose a standardized scoring framework that enhances the interpretability and reproducibility of ICCUS-derived hemodynamic information. By referencing CTP-defined decompensation staging, the scoring system translates multi-parameter ultrasound findings into an intuitive integer score, facilitating risk stratification in settings where advanced perfusion imaging is unavailable or impractical for serial use.

The proposed scoring system is not intended to replace CTP. CTP remains the reference standard for spatial perfusion mapping, infarct core delineation, and the detection of small or distributed ischemic lesions—capabilities not offered by ICCUS. Rather, the scoring system was designed to provide a pragmatic, CTP-referenced hemodynamic risk stratification tool in settings where advanced perfusion imaging is unavailable, contraindicated, or impractical for repeated follow-up.

This study had several limitations that should be acknowledged. First, as a single-center study, the results may be subject to bias due to the relatively small sample size. Second, the scoring system has not yet been validated in a prospective cohort. Third, although the three imaging modalities were completed within a maximum interval of 1 month, temporal separation between ICCUS and CTP may introduce hemodynamic variability. Finally, the accuracy of this scoring method may require further refinement in cases where posterior circulation compensatory mechanisms dominate. Therefore, the ICCUS scoring system proposed in this study is positioned as a pragmatic framework for stenosis-related hemodynamic stratification, rather than a set of definitive or universally applicable parameter values. Future research should seek to expand the sample size through multicenter collaborations and explore the integration of other non-invasive perfusion assessment techniques to improve diagnostic efficacy. To enable the effective integration of this scoring system into routine clinical practice, future efforts should focus on developing standardized protocols for image acquisition and scoring, as well as conducting multicenter operator training to ensure the consistency of results. Initial clinical implementation is recommended in neurointensive care units, stroke follow-up clinics, and emergency departments, with a primary focus on serving patient populations who cannot immediately undergo advanced imaging assessments. It is important to note that the results of this ultrasound scoring system should always be interpreted as an integral component of comprehensive clinical evaluation, and synergistically analyzed alongside patients’ symptoms, physical signs, and other imaging findings to collectively guide treatment decisions.

Conclusions

This study developed and validated a novel ICCUS-based scoring system for anterior circulation perfusion assessment that demonstrated good diagnostic accuracy and clinical practicality. This system is not intended to replace CTP in all scenarios; however, it provides a valuable complementary tool in clinical settings in which perfusion imaging is unavailable or contraindicated. By standardizing the integration of multi-parametric ultrasound information, it improves the consistency and interpretability of hemodynamic assessment. With further validation and refinement, this approach has the potential to substantially enhance cerebrovascular evaluation across a range of clinical contexts.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://qims.amegroups.com/article/view/10.21037/qims-2025-1546/rc

Data Sharing Statement: Available at https://qims.amegroups.com/article/view/10.21037/qims-2025-1546/dss

Funding: This work was supported by the National Natural Science Foundation of China (Nos. 82271995 and 81730050).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-2025-1546/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Institutional Board of Beijing Tiantan Hospital, Capital Medical University (No. KY2022-015-04), and informed consent was obtained from all individual participants.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Fan X, Li Z, Han G, Sun G, Han H, Hong Y, Chen S, You H, Ni J, Li G, Li M, Feng F. Whole-cerebrum three-dimensional pseudo-continuous arterial spin labeling at 5T: reproducibility and preliminary application in moyamoya. Quant Imaging Med Surg 2025;15:3824-38. [Crossref] [PubMed]
2. Rao MR, Stewart NJ, Griffiths PD, Norquay G, Wild JM. Imaging Human Brain Perfusion with Inhaled Hyperpolarized (129)Xe MR Imaging. Radiology 2018;286:659-65. [Crossref] [PubMed]
3. Larsson HBW, Law I, Andersen TL, Andersen FL, Fischer BM, Vestergaard MB, Larsson TSW, Lindberg U. Brain perfusion estimation by Tikhonov model-free deconvolution in a long axial field of view PET/CT scanner exploring five different PET tracers. Eur J Nucl Med Mol Imaging 2024;51:707-20. [Crossref] [PubMed]
4. Zhao J, Hou C, He W, Zhang W. Independent predictors of ischemic stroke: a comprehensive scan of the internal carotid and vertebrobasilar systems. Quant Imaging Med Surg 2025;15:2827-38. [Crossref] [PubMed]
5. Liu WJ. The diagnosis of intracranial artery stenosis in patients with stroke by transcranial Doppler ultrasound: A meta-analysis. Technol Health Care 2024;32:639-49. [Crossref] [PubMed]
6. Gunda ST, Ng TKV, Liu TY, Chen Z, Han X, Chen X, Pang MY, Ying MT. A Comparative Study of Transcranial Color-Coded Doppler (TCCD) and Transcranial Doppler (TCD) Ultrasonography Techniques in Assessing the Intracranial Cerebral Arteries Haemodynamics. Diagnostics (Basel) 2024;14:387. [Crossref] [PubMed]
7. Yin H, Liu X, Zhang D, Zhang Y, Wang R, Zhao M, Zhao J. A Novel Staging System to Evaluate Cerebral Hypoperfusion in Patients With Moyamoya Disease. Stroke 2018;49:2837-43. [Crossref] [PubMed]
8. Hua Y, Meng XF, Jia LY, Ling C, Miao ZR, Ling F, Liu JB. Color Doppler imaging evaluation of proximal vertebral artery stenosis. AJR Am J Roentgenol 2009;193:1434-8. [Crossref] [PubMed]
9. Chinese Society of Neurology. Neuroimaging Cooperative Group of Chinese Society of Neurology. Chinese guidelines for the clinical application of cerebrovascular ultrasound. Chin J Neurol 2016;49:507-18.
10. Pallesen LP, Lambrou D, Eskandari A, Barlinn J, Barlinn K, Reichmann H, Dunet V, Maeder P, Puetz V, Michel P. Perfusion computed tomography in posterior circulation stroke: predictors and prognostic implications of focal hypoperfusion. Eur J Neurol 2018;25:725-31. [Crossref] [PubMed]
11. Feil K, Reidler P, Kunz WG, Küpper C, Heinrich J, Laub C, Müller K, Vöglein J, Liebig T, Dieterich M, Kellert L. Addressing a real-life problem: treatment with intravenous thrombolysis and mechanical thrombectomy in acute stroke patients with an extended time window beyond 4.5 h based on computed tomography perfusion imaging. Eur J Neurol 2020;27:168-74. [Crossref] [PubMed]
12. Zhang L, Pu T, Xu X. Raynald, Zheng S, Fu J, Yong Q, Zhang W, He W. Diagnostic feasibility of middle cerebral artery stenosis or occlusion evaluated by TCCS and CEUS: Repeatability, reproducibility, and diagnostic agreement with DSA. J Stroke Cerebrovasc Dis 2024;33:107575. [Crossref] [PubMed]
13. Rossi S, Paolucci M, Arnone G, Bigliardi G, Longoni M, Pulito G, et al. Prognostic Value of Cerebral Hemodynamics Assessment on 24-h Transcranial Color-Coded Doppler Following a Successful Thrombectomy. Eur J Neurol 2025;32:e70224. [Crossref] [PubMed]
14. Reitmeir R, Eyding J, Oertel MF, Wiest R, Gralla J, Fischer U, Giquel PY, Weber S, Raabe A, Mattle HP. Z’Graggen WJ, Beck J. Is ultrasound perfusion imaging capable of detecting mismatch? A proof-of-concept study in acute stroke patients. J Cereb Blood Flow Metab 2017;37:1517-26. [Crossref] [PubMed]
15. Eyding J, Reitmeir R, Oertel M, Fischer U, Wiest R, Gralla J, Raabe A, Zubak I, Z, Graggen W, Beck J. Ultrasonic quantification of cerebral perfusion in acute anterior circulation occlusive stroke-A comparative challenge of the refill- and the bolus-kinetics approach. PLoS One 2019;14:e0220171. [Crossref] [PubMed]
16. Fung C, Heiland DH, Reitmeir R, Niesen WD, Raabe A, Eyding J, Schnell O, Rölz R. Z Graggen WJ, Beck J. Ultrasound Perfusion Imaging for the Detection of Cerebral Hypoperfusion After Aneurysmal Subarachnoid Hemorrhage. Neurocrit Care 2022;37:149-59. [Crossref] [PubMed]
17. Small C, Lucke-Wold B, Patel C, Abou-Al-Shaar H, Moor R, Mehkri Y, Still M, Goldman M, Miller P, Robicsek S. What are we measuring? A refined look at the process of disrupted autoregulation and the limitations of cerebral perfusion pressure in preventing secondary injury after traumatic brain injury. Clin Neurol Neurosurg 2022;221:107389. [Crossref] [PubMed]
18. Alberts A, Lucke-Wold B. Updates on Improving Imaging Modalities for Traumatic Brain Injury. J Integr Neurosci 2023;22:142. [Crossref] [PubMed]
19. Chen JQ, Li CY, Wang W, Yao DQ, Jiang RF, Wáng YXJ. Diffusion-derived vessel density (DDVD) for penumbra delineation in brain acute ischemic stroke: initial proof-of-concept results using single NEX DWI. Quant Imaging Med Surg 2024;14:9533-42. [Crossref] [PubMed]
20. Yu H, Feng Y, Shao X, Zhen X, Zhang L, Yu Y, Xie S. Analysis of perfusion in patients with vertebrobasilar dolichoectasia through use of multidelay arterial spin labeling magnetic resonance imaging. Quant Imaging Med Surg 2025;15:7246-58. [Crossref] [PubMed]
21. Havsteen I, Damm Nybing J, Christensen H, Christensen AF. Arterial spin labeling: a technical overview. Acta Radiol 2018;59:1232-8. [Crossref] [PubMed]