Keywords: Blood Vessels, Blood vessels

Motivation: DSC-MRI is vital for diagnosing brain pathologies. Our goal is to harness GESFIDE MR signal evolution through deep learning (DL) to estimate vessel size distribution (VSD), which would allow us to explore deeper into the complexities of tumor vascular microstructure and other pathologies. 

Goal(s): Our objective is to assess the capabilities of GESFIDE in providing voxel-wise VSD estimate. 

Approach: We simulated GESFIDE signals with the FPFDM method. A DL network, VSD estimator (VSDE), was trained to estimate VSDs. 

Results: Our validation demonstrates GESFIDE's promise in assessing VSD as a distinct contrast mechanism, offering insights into tumor microstructure and pathologies. 

Impact: Our study reveals GESFIDE's potential for VSD estimation. Leveraging this unique contrast mechanism allows in-depth exploration of tumor microstructure and other pathologies through histogram analysis. Ongoing research aims to broaden VSD applicability and optimize GESFIDE parameters.

Keywords: Blood Vessels, Blood vessels

Motivation: Arterial pulsatility is used for assessing cerebral vascular dysfunction. However, 2D PC-MRI and 4D flow have limitations including multiple separate scans, prolonged scan time, and flow saturation effects. 

Goal(s): Our study aims to develop a Multi-band Dual-Venc PC-MRI (MB-DV) senquence to measure pulsatility for larger and distal small vessels within short scan time.

Approach: MB-DV scans were performed on 8 subjects to image velocity waveforms from ICA, M2, M3, LSA, and M4 simultaneously. For comparison, multiple standard single-slice PC-MRI were performed.

Results: MB-DV PC-MRI successfully measured flow waveforms and provided reliable PI measurements with no significant difference from PI measured by standard PC-MRI. 

Impact: MD-DV PC-MRI enables simultaneously assessing arterial pulsatility at multiple vessel segments in the brain within a short scan time, which could be a potentially useful imaging tool to study pulsatility in the cerebral vascular tree for cerebrovascular and neurodegenerative diseases.

Keywords: Blood Vessels, Segmentation

Motivation: In this work, we address the challenge of cerebral artery segmentation when time-of-flight (TOF) imaging is unavailable.

Goal(s): Develop an automatic data-driven segmentation of large cerebral arteries.

Approach: Arteries were identified within the fMRI signal by leveraging large pulsation-driven fluctuations. 

Results: In the local subjects with TOF images, the approach displayed high levels of agreement with TOF-derived segmentation. Additionally, the segmentation demonstrated high scan-to-scan reproducibility in 430 subjects with four repeated fMRI scans from the HCP aging cohort. Lastly, the segmentation performed robustly across two different scanning protocols supporting its potential to be used for datasets with various acquisition parameters.

Impact: Our robust data-driven approach reliably automatically segments the large cerebral arteries of fMRI datasets. This work enables more accessible large cerebral artery segmentation in existing MRI datasets, independent of TOF images. 

Keywords: Blood Vessels, Blood vessels, Clustering algorithms, Brain tumor

Motivation: The presence of normal large-blood-vessels(LBV) in tumor region can impact the evaluation of quantitative DCE-MRI parameters and tumor classification.

Goal(s): To develop an automated framework for segmenting LBVs present within or around the tumor region using different clustering algorithms and compare their accuracy in tumor grading.

Approach: LBV masks were generated using three different clustering algorithms on the DCE-MRI derived maps CBV and Slope-2. Generated tumor mask using AI tool on FLAIR images. Statistical analysis was performed.

Results: Overall, k-means clustering based algorithm provided superior performance in segmentation of LBV and tumor grading in less computational time.

Impact: The proposed automatic LBV segmentation algorithm can assist radiologists in objective and accurate assessment of tumor including tumor grading. This will reduce errors in tumor assessment.

Keywords: Blood Vessels, Arterial spin labelling, Sickle Cell Disease, White Matter Perfusion

Motivation: Accurate white matter (WM) perfusion quantification is difficult but likely critical for assessing infarct risk in Sickle Cell Disease (SCD).

Goal(s): To evaluate the feasibility of detecting regional WM perfusion using arterial spin labeling (ASL) under conditions of high perfusion and reduced bolus arrival time (BAT) in SCD patients.

Approach: A multi-inversion time (TI; range=200-3200 ms), pulsed ASL sequence was applied to quantify perfusion detectability in SCD (n=35) and healthy (n=15) participants.

Results: WM perfusion was significantly detected for TI=800-1800 ms in SCD patients. BAT in SCD was more closely related to hematocrit (rho=0.43; p=0.01) than was WM perfusion (rho=-0.13; p=0.47).

Impact: We provide evidence in support of perfusion detection with ASL in SCD patients, which is attributable to higher perfusion and reduced BAT.

Keywords: Vessel Wall, Vessels, Cine Vessel Wall Imaging

Motivation: This research investigates the lesser-explored domain of lumen area changes in intracranial vascular pulsatility, providing insight into cerebral vasculature's mechanical behavior.

Goal(s): To employ cine black-blood MRI for delineating and quantifying intracranial artery pulsatility by monitoring cardiac cycle-induced lumen variations.

Approach: We utilized a sophisticated vessel analysis system to discern pulsatility within the lumen and adjacent tissues, validating our findings with reproducibility scans.

Results: Cine black-blood imaging successfully visualized intracranial vascular pulsatility. The method displayed robust reproducibility in detecting lumen area changes, proving comparable to velocity pulsatility measurements.

Impact: This study illuminates the often-overlooked aspect of lumen area pulsatility, with implications for a holistic assessment of vascular health and disease.

Keywords: Blood Vessels, Blood vessels, Small vessel disease, white matter hyperintensities, 7T MRI, small vessel function, Rotterdam Study

Motivation: Novel 7T MR techniques allow non-invasive assessment of cerebral small vessel function, potentially relevant to small vessel disease (SVD), a common cause of stroke and dementia. 

Goal(s): Assess determinants of small vessel function and its link to SVD lesion burden.

Approach: Perforating artery blood flow velocity and pulsatility were measured with 7T MRI in 200 participants >60 years from a population-based sample and linked to vascular risk factors and white matter hyperintensity (WMH) volume using linear regression.

Results: Age, blood pressure, and BMI were determinants of small vessel function. In turn, vessel function did not relate to WMH burden.

Impact: In the general aging population, perforating artery blood flow velocity and pulsatility do not relate to whole-brain SVD-lesion load. Other complementary small vessel function measures should be investigated as a potential early marker of SVD. 

Keywords: Blood Vessels, Dementia, Black Blood, CADASIL, small vessel disease

Motivation: Cerebral small vessel disease (cSVD) is a leading cause of vascular dementia in the elderly worldwide. No existing MRI methods can directly visualize cerebral small vessels.

Goal(s): Evaluation of a novel pipeline for mapping small blood vessels using high-resolution black-blood MRI in genetic cSVD (CADASIL) patients.

Approach: Small blood vessels were segmented and quantified in 10 CADASIL patients and 10 matched healthy controls.

Results: Significantly lower vessel density has been found in the hippocampus of the patients, whereas the vessel density is significantly higher in cortical white matter of patients compared to the control.

Impact: Visualization and quantification methods of small cerebral blood vessels from high-resolution black blood MRI which would facilitate the study of cSVD mechanisms.

Keywords: Blood Vessels, Vessels, Vessel Wall; Neurovascular; Ultra-high field

Motivation: T2-weighted DANTE-SPACE is a promising sequence for intracranial black-blood vessel wall imaging at 7T. However, it is limited by signal and contrast variations and its performance versus 3T remains unclear. 

Goal(s): To optimize T2-weighted DANTE-SPACE at both 3T and 7T, and to quantitatively compare their performance.

Approach: A recently introduced DANTE-SPACE simulation framework was used for protocol optimization. Data acquired from six healthy volunteers at 3T and 7T were then quantitatively compared.

Results: Optimization of DANTE-SPACE parameters at 7T provides a 24% increase in vessel visibility over a literature protocol. Contrasts at 7T are 90% higher than at 3T.

Impact: Through simulation-based optimization, the vessel wall contrasts from T2-weighted DANTE-SPACE at 7T were improved by 24% versus a literature protocol. When optimized and implemented at 3T, in-vivo data showed a much lower vessel wall contrast-to-noise relative to 7T.

Keywords: Blood Vessels, CEST & MT

Motivation: Exploring the CSVD imaging markers can provide insights into the pathophysiology of CSVD, which is crucial for understanding its etiology, development, and clinical interventions.

Goal(s): To investigate potential variations in hippocampal APT values among individuals with CSVD imaging markers and varying degrees of CSVD total burden.

Approach: All the participants conducted the cognitive assessment and the MRI scans. And statistical analysis was used for evaluation.

Results: The hippocampal APT values among different CSVD total load groups were significantly different (p<0.001). The mediation models demonstrated that the APT values of the hippocampus partially mediated the association between CSVD total load and MoCA score.

Impact: Hippocampal APT values may serve as a biomarker for the early detection of neurodegeneration in CSVD patients.

Keywords: Blood Vessels, Permeability

Motivation: Evaluating intracranial aneurysm (IA) risk holds significant clinical importance. Recent studies have proposed wall permeability (K^trans) as a significant risk predictor, but its validity in non-saccular aneurysms remains unclear.

Goal(s): Our study aims to predict non-saccular IA rupture by K^trans from DCE-MRI.

Approach: K^trans was derived from the extended Kety/Tofts model. We analyzed correlation between K^trans and IA size, the Population, Hypertension, Age, Size, Earlier Subarachnoid Hemorrhage, and Site (PHASES) score and other clinical factors.

Results: K^trans significantly related to IA size and PHASES score, but there was no correlation between K^trans and intramural hematoma (IMH) and wall enhancement index (WEI).

Impact: By analyzing correlation between aneurysm wall permeability (K^trans) and other risk factors of non-saccular aneurysms rupture, we found that K^trans might be a risk indicator for rupture of non-saccular IAs.

Keywords: Blood Vessels, Blood vessels, 5.0-T magnetic resonance angiography

Motivation: Moyamoya disease necessitates precise visualization of cerebral vessels for management, but current imaging may be inadequate.

Goal(s): To ascertain if 5.0-T 4D NCEMRA offers superior imaging of collateral circulation in Moyamoya disease compared to traditional TOF MRA.

Approach: Utilized 5.0-T MRI to compare 4D NCEMRA and TOF MRA in visualizing leptomeningeal collateral anastomoses in 19 patients.

Results: 5.0-T 4D NCEMRA outperformed TOF MRA, particularly in identifying leptomeningeal collaterals, with significant statistical support.

Impact: The study underscores 5.0-T 4D NCEMRA's potential to enhance cerebral vascular mapping in Moyamoya disease, prompting advancements in diagnostic and therapeutic strategies, possibly leading to more personalized patient care.

Keywords: Blood Vessels, DSC & DCE Perfusion, GRASP technique, Moyamoya disease

Motivation: To better understand the hemodynamics in moyamoya disease (MMD), high temporal and spatial resolution DCE-MRI using GRASP technique could estimate bolus arrival time (BAT) in MMD.

Goal(s): To find optimal condition for measuring BAT and to elucidate clinical value of BAT on MMD.

Approach: Thirty-seven MMD patients were included. Images with 5, 8, 13, and 21 spokes/frame were post-processed to derive time-intensity curves and estimate BATs.

Results: Using the optimal 13 spokes/frame, BATs were delayed on the side with severe stenosis/occlusion and were in the order of MCA M2, basal ganglia, thalamus, and choroid plexus.

Impact: Bolus arrival time in moyamoya disease estimated by using high temporal and spatial resolution 3D dynamic contrast-enhanced MR imaging using GRASP technique facilitates our understanding of the hemodynamics in moyamoya disease by elucidating regional difference.

Keywords: Blood Vessels, Atherosclerosis, Vascular Territories

Motivation: Internal carotid artery stenosis (ICAS) accounts for ≈10% of strokes. Individual watershed areas (iWSA) are especially susceptible to hemodynamic impairments. Currently, iWSA are segmented from contrast agent-based time-to-peak (TTP), limiting applicability.

Goal(s): We aimed towards non-invasive iWSA segmentation based on arterial transit time (ATT) from Hadamard-encoded pseudo-continuous ASL.

Approach: Overlap of iWSA from ATT and TTP was investigated and agreement of extracted hemodynamic parameter values such as cerebrovascular reactivity (CVR) was evaluated and ICAS-induced parameter-lateralization was investigated.

Results: ATT-based and TTP-based iWSAs overlapped well, with excellent agreement in quantitative parameters and significant lateralization of hemodynamic parameters in ICAS within both iWSA delineation approaches.

Impact: We successfully segmented iWSA from non-invasive ATT and demonstrated sensitivity to ICAS-related impairments, in agreement with TTP-based iWSA segmentation. ATT-based iWSAs facilitate longitudinal investigation without contrast application in cerebrovascular diseases such as ICAS or Moyamoya.

Keywords: Vessel Wall, Atherosclerosis, mechanical constitutive property, inverse problem

Motivation: Beyond structural features of carotid plaque and hemodynamic parameters, the hemodynamic and structural metrics were determined by image-based computer simulations and the constitutive characteristics of carotid plaques were ignored.

Goal(s): We aimed to propose a method for identification of carotid plaque constitutive parameters using CINE MR images.

Approach: A novel MRI-based method to identify constitutive parameters of carotid plaque compositions was proposed and the calculated values from the proposed method were compared with the reference and ex-vivo validation.

Results: We found that calculated values were consistent with the reference and experimental results. The constant D₂ could identify plaque compositions with different stiffness.

Impact: Our study proposed a novel MRI-based method for identifying constitutive parameters of carotid plaque compositions. The constant D2 could indicate different components of carotid plaques.

Keywords: Blood Vessels, Blood vessels

Motivation: To improve non-invasive visualization of the superior cerebellar artery (SCA) for better clinical outcomes.

Goal(s):  To assess the feasibility of using 3D-TOF MRA at 5.0 T MR for detailed imaging of the SCA.

Approach: Retrospective analysis of high-resolution 5.0T MR images from patients with suspected cerebrovascular diseases, focusing on the SCA's anatomical details.

Results: The study confirmed that 5.0T MRA provides accurate SCA imaging, consistent with anatomical and CTA results, crucial for diagnosing and managing related cerebrovascular conditions.

Impact: The study provides a new non-invasive benchmark for SCA imaging, potentially reducing iatrogenic risks in neurosurgery and informing the etiology of trigeminal neuralgia, paving the way for safer surgical practices and targeted treatments.

Keywords: Blood Vessels, Velocity & Flow

Motivation: The distribution pattern of blood flow velocity in venous sinus stenosis is worth exploring, and its screening value for venous stenting is unknown yet.

Goal(s): To explore velocity distribution pattern in idiopathic intracranial hypertension (IIH) patients with venous stenosis and its relationships with clinical characteristics.

Approach: Fifteen IIH patients with venous stenosis were scanned through 4D flow MRI with 7.0T scanner, and data was processed for the velocity distribution patterns.

Results: Steady, ascending, and descending distribution patterns were identified. TPG, CSF pressure and stenosis rate were significantly different among three patterns, with significantly higher value in ascending velocity group.

Impact: As a noninvasive imaging technique, 4D flow MRI may provide some support from a hemodynamic perspective for screening IIH patients who would benefit from venous manometry and venous stenting.

Keywords: Blood Vessels, Blood vessels, 4D flow, cerebral hyperperfusion syndrome

Motivation: Little is known about cerebral hemodynamics after bypass surgery in patients with chronic arterial stenosis (CAS) and its role in the development of cerebral hyperperfusion syndrome (CHS).

Goal(s): The purpose of this study was to explore the hemodynamic characteristics of patients with CAS and occlusion before and after surgery and its relationship with CHS.

Approach: We used 4D flow MRI sequence to obtain the hemodynamic characteristics of patients with CAS and occlusion before and after bypass surgery.

Results: Postoperative total cerebral blood flow increased and resistance index and pulsatility index decreased maybe a higher risk factor of CHS events in bypass surgery patients.

Impact: This study provides a new insight into the hemodynamic characteristics of patients with chronic arterial stenosis, and holds a promising marker for marker for identifying CHS patients.

Keywords: Multiple Sclerosis, Multiple Sclerosis

Motivation:  This study investigates the complex pathology of multiple sclerosis (MS), focusing on the relationship between cerebral perfusion and myelin integrity. 

Goal(s):  Utilizing selective inversion recovery (SIR) to determine myelin content through the macromolecular (PSR), and a combined spin- and gradient-echo (SAGE) sequence to assess micro- and macrovascular perfusion,

Approach: This study aims to uncover the interplay of hemodynamic impairments and myelin repair in MS.
 
 

Results: In a cohort of individuals with RRMS and healthy controls, we found significant correlations between PSR and microvascular perfusion within lesions, suggesting a possible link between myelin integrity and cerebral blood flow. 

Impact: Uncovering specific pathological changes in MS lesions may enhance diagnostic accuracy and disease monitoring. Such insights could also drive the creation of new therapies focused on remyelination and neuroprotection, potentially altering the treatment landscape for MS. 

Keywords: Blood Vessels, Neuro

Motivation: To clear the depicting ability for the lenticulostriate arteries at 7 Tesla in patients with unruptured the middle cerebral artery aneurysm.

Goal(s): MRA at 7 Tesla can depict the lenticulostriate arteries more than that at 3 Tesla in assessment using the intraoperative video.

Approach: Comparison of accuracy of identification of LSAs at standard 3D TOF imaging at 3T, standard 3D TOF imaging at 7Tand high-resolution 3D TOF at 7T, using the findings of intraoperative video as the reference.

Results: LSAs were identified more accurately by HR7T 3D TOF than by S3T 3D TOF.

Impact: In patients with an unruptured MCA aneurysm, LSAs were identified more accurately by HR7T 3D TOF than by S3T 3D TOF; however, the ability to depict the vessels could depend on the resolution rather than the signal-to-noise ratio.