Keywords: Vessel Wall, Data Analysis, Vessel Wall Morphological Measurements; Whole-Body Fat Distribution

Motivation: Obesity is associated with cardiovascular diseases. However, its effect on cerebrovascular disease remains unclear.

Goal(s): To investigate the correlation between morphological measurements of intra- and extracranial arterial vessel walls and whole-body fat distribution characteristics.

Approach: A total of 98 volunteers underwent three-dimensional high-resolution MR vessel wall imaging and whole-body MR proton density fat fraction (PDFF) imaging on a 3.0T MRI scanner.

Results: The results indicate that the vessel wall thickness of both the extracranial carotid artery and vertebral artery is positively correlated with visceral adipose tissue and the liver-PDFF.

Impact: The assessment of vascular health in individuals with central obesity necessitates a comprehensive evaluation of both extracranial carotid arteries and vertebral arteries. This paradigm shift may have far-reaching implications for the prevention and treatment of cerebrovascular diseases associated with obesity.

Keywords: Flow, Vessels

Motivation: Local stiffness of intracranial arteries may provide regional assessment of vessel changes and information about vessel pathologies, but so far there is no reliable method to measure it.

Goal(s): To propose a black-blood MRI technique with submillimeter isotropic resolution and multiple cardiac phases, and to explore its feasibility of measuring local stiffness of intracranial arteries.

Approach: A novel time-resolved 3D black-blood cine MRI was proposed combining MERGE, golden-angle radial, retrospective gating, and GRASP reconstruction. MOCHA pipeline was used to measure cardiac-driven lumen changes.

Results: Images obtained with our proposed technique can capture cardiac-driven lumen area changes that are essential for local stiffness measurement.

Impact: The proposed method, after validation, can serve as a unique local stiffness measurement tool for intracranial arteries that will highly benefit vascular imaging studies.

Keywords: Vessel Wall, Vessels

Motivation: In this retrospective observational cohort study, we found that both CAWE pattern and aspect ratio were independent predictors of aneurysm recurrence after stent-assisted coil embolization.

Goal(s): To explore the baseline clinical and imaging characteristics which can predict aneurysm recurrence after stent-assisted coil embolization.

Approach: 3D high-resolution MRI vessel wall imaging

Results: Among the 155 patients, 26 patients (16.7%) got aneurysm recurrence after stent-assisted coil embolization during the 2-year follow-up.  Multivariate logistic regression analysis revealed that the CAWE pattern (OR 3.87, 95% CI 1.2–10.4, p=0.02) and aspect ratio (OR 2.1, 95% CI 0.6-4.2, p=0.03) were independently associated with aneurysm recurrence after stent-assisted coil embolization.

Impact: If validated in future larger-scale studies, preoperative imaging characteristics, especially vessel wall enhancement patterns on 3D HR-VWI could be a potential tool for identifying patients at elevated risk of recurrence after stent-assisted coil embolization.

Keywords: Vascular, Blood vessels, vessels; TOF; Angiography

Motivation: Clinicians express concerns about false-positive findings, leading to uncertainties in the reliable interpretation of TOF-MRA.

Goal(s): This study focuses on improving the reliability of TOF-MRA for cerebrovascular imaging.

Approach: By incorporating a small flip-angle spatially-selective fat-suppression and utilizing the shortest echo-time, signal loss is minimized, and uniform fat-suppression is achieved.

Results: The results, compared to conventional protocols, demonstrate superior quality and reliability by reducing spin-dephasing and achieving uniform fat-suppression without compromising blood signal quality or requiring extensive post-processing. This approach effectively mitigates the risk of false-positive findings and overestimation of stenosis, potentially establishing it as a more effective routine clinical examination for MRA.

Impact: By improving the reliability of TOF-MRA through optimized fat-suppression and echo-time reduction, it enhances the accuracy of evaluating cerebrovascular abnormalities. This advancement enables clinicians to have greater confidence in interpreting TOF-MRA images and reduces the risk of false-positive findings.

Keywords: Vascular, Vessels

Motivation: Time-of-flight MRA (TOF-MRA) is sensitive to abnormal blood flow and result in susceptibility artifact signal and signal loss in distal small artery.

Goal(s): To investigate whether zero echo time MRA (zTE-MRA) could improve the image quality in intracranial artery with the same scan time.

Approach: Recruiting healthy subjects and taking zTE-MRA and TOF-MRA scanning.

Results: Compared with TOF-MRA using the same scan time, zTE-MRA could reduce susceptibility artifact signal in intracranial curved artery and suppress tissue signal intensity surrounding artery to better show ophthalmic artery.

Impact: Providing a non-invasive method to better reduce susceptibility artifact signal in intracranial curved artery and suppress tissue signal intensity surrounding artery to better show distal small artery.

Keywords: Flow, Fat, time-of-flight, phase-sensitive, water-fat separation, fat suppression

Motivation: Efficient fat suppression can improve flow visualization in time-of-flight (TOF) MRA. We hypothesize that the phase difference of water and fat may be used for efficient fat suppression for out-of-phase (OP) TOF MRA.

Goal(s): To demonstrate the feasibility of fat suppression for spiral TOF with sliding-slice localized quadratic (ssLQ) encoding using the phase-sensitive approach.

Approach: After the general reconstruction of ssLQ OP TOF, the global slowly varying phase was estimated and removed. Water and fat voxels were then identified according to their phase.

Results: Background suppression was substantially improved with the proposed method, resulting in enhanced visualization of small vessels.

Impact: The proposed phase-sensitive approach requires no changes of pulse sequence and negligible computational cost. It might be implemented with a wide range of OP TOF MRA for fat suppression.

Keywords: Atherosclerosis, Atherosclerosis, High-resolution magnetic resonance vessel wall imaging; Systemic Inflammatory Response Index

Motivation: The activation of inflammation can aggravate plaque rupture, thrombosis and cause brain tissue ischemia and infarction. Looking for reliable inflammatory markers might provide potential targets for the treatment of atherosclerosis patients.

Goal(s): We investigated the relationship between systemic inflammatory response index (SIRI)and intracranial plaque features, as well as the risk factors related to the severity of cerebral ischemic events. 

Approach: Compare the differences in imaging features and SIRI among patients with transient ischemic attack, mild stroke, and moderate-severe stroke.

Results: SIRI levels were significantly associated with plaque vulnerable characteristics and burden. Higher SIRIlevels and plaque featureswere independently related to moderate-severe stroke.

Impact: Our study suggested that immune inflammation may have adverse effects on intracranial atherosclerosis, and link to the severity of cerebral ischemic events. Therefore, the regulation of immune inflammation may be a potential therapeutic target for sICAD.

Keywords: Flow, Velocity & Flow, aneurysm

Motivation: The research aims to investigate the changes in hemodynamics in intracranial aneurysms before and after treatment with blood flow shunt stents treatment.

Goal(s): The technical goal is to quantify common hemodynamic parameters, and use statistical comparison to analyze the variation patterns.

Approach: A set of program was utilized to separate aneurysms from complex environments, calculate hemodynamic values within the region, and analyze the trend of changes in preoperative and postoperative data.

Results: The results of simple statistical analysis showed that the average flow velocity, average WSS and OSI at the aneurysm presented a decreasing trend in different degrees after the shunt stent treatment.

Impact: In this study, the number of subjects and hemodynamic parameters can be increased to obtain more comprehensive experimental results. Researchers can also focus on the relationship between aneurysm stability and hemodynamics, and establish corresponding prediction and evaluation models.

Keywords: Flow, Cardiovascular, neuroprotection in cardiac surgery

Motivation: Cerebral injury following deep hypothermic circulatory arrest (HCA) remains an important clinical problem in cardiac surgery.  Investigating mechanisms of neuroprotection and establishing clinically efficient means to assess acute brain injury following HCA has been the cornerstone of our laboratory's work. 

Goal(s): Identify mechanism of cerebral injury following HCA. Establish accurate and efficient mechanisms for diagnosing acute brain injury following HCA.

Approach: Double blinded, prospective, randomized large animal study using canines and multiple neurobehavioral testing instruments including clinically validated methods and pCASL MR imaging.

Results: Cerebral blood flow corroborates with clinically validated neurobehavioral scoring instruments in a canine model of HCA.

Impact: By employing highly effective mechanisms for acute brain injury diagnosis and matching these with ongoing RO1-funded mechanism of neuroprotection following HCA, we aim to impact all cardiac patients in the world who may need deep hypothermic circulatory arrest.

Keywords: Atherosclerosis, Atherosclerosis, High resolution magnetic resonance vascular wall imaging, Middle cerebral artery, Acute ischemic stroke

Motivation: The occurrence of acute ischemic stroke (AIS) in patients with middle cerebral artery (MCA) atherosclerosis is related to the status of atherosclerotic plaque itself and level of homocysteine (Hcy) and glycated hemoglobin (HbA1c).

Goal(s): To analyze wall characteristics and clinical indicators in patients with MCA atherosclerosis with a view to finding predictors of AIS events.

Approach: We gathered data from 38 participants, segregated them into the AIS and transient ischemic attack (TIA) groups, and subjected the data from both groups to statistical analysis.

Results: Combined stenosis rate and Hcy have higher value for predicting AIS events.

Impact: Hcy and stenosis rate were independent risk factors for AIS events in patients with MCA atherosclerosis; combined Hcy and stenosis rate had a higher predictive value of AIS events.

Keywords: Vessel Wall, Blood vessels

Motivation: Manual centerline Extraction based on black-blood Magnetic resonance vessel wall imaging is a difficult and time-consuming but important step for further analysis of plaques. 

Goal(s): To propose a method for quickly, automatically and accurately extracting the centerline and label the segments of the target arteries.

Approach: This study proposes a method that combines deep learning and traditional graphics method for the automatic and accurate centerline extraction and even segments labeling, which is applicable to flexible MR sequences (only black-blood images, only bright-blood images, or both).

Results: Compared with the ground truth, the proposed method achieved excellent completeness and accuracy in a short time.

Impact: This study introduces a flexible (MRVWI or/and TOF-MRI), swift, and precise approach for extracting and labeling the centerline of target vessel. With this method, radiologists can more conveniently and efficiently observe potential abnormal areas around vessel and diagnose vessel-related diseases.

Keywords: Vascular, Brain

Motivation: There is limited understanding regarding the physiological mechanisms underlying the impact of coronary artery disease (CAD) on brain health.

Goal(s): In this study, we sought to explore the influence of CAD on vascular and metabolic biomarkers.

Approach: Specifically examining Cerebrovascular Reactivity (CVR), Cerebral Blood Flow (CBF), and Oxygen Extraction Fraction (OEF) in the brain, and how these factors relate to cognitive performance.

Results: Our initial findings, based on a preliminary dataset, indicate that individuals with CAD exhibit reduced CBF and CVR, with increased OEF across several brain regions. Low CVR and high OEF are also associated with poorer executive function in these regions.

Impact: The influence of coronary artery disease (CAD) on brain health remains unclear. We show that CAD is associated with elevated OEF and reduced CVR and CBF. High OEF and low CVR are linked to poorer cognition, especially executive functions.

Keywords: Vessel Wall, Vessels, Vessel wall imaging, blood suppression

Motivation: The intrinsic “black-blood (BB)” property in 3D TSE is insufficient for vessel wall imaging and other neuroimaging applications. Additional blood suppression preparations can diminish T1 weighting and SNR.

Goal(s): To develop and validate a new approach compatible with 3D TSE to enhance BB effects while minimizing sacrifice in T1 weighting and overall SNR.

Approach: An interleaved flow-sensitive dephasing scheme was developed, and verified in healthy volunteers and assessed in 32 patients with one of four neurological diseases.

Results:  iFSD-SPACE achieved the lowest lumen SNR and the highest wall-lumen CNR. iFSD-SPACE yielded significantly higher white-matter SNR and gray-to-white matter CNR than DANTE and MSDE.

Impact: iFSD is a 3D TSE-compatible blood flow suppression technique that overcomes the limitations of existing BB magnetization preparation methods and holds the potential to greatly enhance the performance of 3D TSE in several neuroimaging applications.

Keywords: Vessel Wall, Vessels, GRASP, MRA

Motivation: The mortality and disability rates following cerebral aneurysm rupture remain significantly high. Recently, pulsation of aneurysms has been suggested as a novel risk factor of rupture.

Goal(s): To harness the ultra-high temporal resolution and signal-to-noise ratio of the modified GRASP technique with 7T MRI to visualize pulsatile motions of cerebral aneurysms.

Approach: A pulsatile aneurysm phantom and aneurysm patient were scanned using a 3D-cine MRI technique, aiming to capture dynamic aneurysmal wall movements at high spatial and ultra-high temporal resolution.

Results: The new imaging technique successfully depicted pulsatile movements in the aneurysm phantom and subject, suggesting a novel predictor for aneurysm rupture.

Impact: This study presents a 3D-cine MRI method at 7T, capturing aneurysm pulsations with ultra-high frame rates in the tens of milliseconds range, promising to refine rupture risk assessments and potentially reducing adverse outcomes in cerebral aneurysm management.

Keywords: Vessel Wall, Cardiovascular

Motivation: Atherosclerotic proteins have been implicated with inflammation and remodeling of aneurysm wall. Both aneurysm wall enhancement (AWE) and irregular pulsation have been suggested as potential candidates for intracranial aneurysms (IAs) instability. 

Goal(s): To explore the association between atherosclerotic proteins and AWE and irregular pulsation. 

Approach: Using vessel wall MRI and four-dimensional computed tomography angiography

Results: We found higher level of serum Lp(a) (Lipoprotein[a]) was significantly associated with increased wall enhancement and irregular pulsation of IAs (both p<0.05)

Impact: This study established a link between atherosclerotic proteins and AWE and irregular pulsation, inflammation and wall remodeling.