Skip to main content

Nikki Dieleman

Followers

5

Following

2

Co-authors

2

Public Views

Jeffrey L Saver

University of California, Los Angeles

Bala Rajaratnam

Nanyang Polytechnic

Vasanthan Rajagopalan

Benito Damasceno

IP Innovative Publication Pvt. Ltd.

Mauro Silvestrini

Università Politecnica delle Marche, Italy

Interests

Uploads

Papers by Nikki Dieleman

Intracranial Atherosclerosis Assessed with 7-T MRI: Evaluation of Patients with Ischemic Stroke or Transient Ischemic Attack

Radiology

Background: Intracranial atherosclerosis is an important cause of ischemic stroke and is associat... more Background: Intracranial atherosclerosis is an important cause of ischemic stroke and is associated with several vascular risk factors. Current imaging is mainly based on the assessment of luminal narrowing rather than abnormalities in the vessel wall. Purpose: To investigate the relationship between vascular risk factors and atherosclerotic lesion burden of intracranial arteries assessed with vessel wall MRI at 7 T in participants with ischemic stroke or transient ischemic attack (TIA). Materials and Methods: In this prospective study (trial identification number: NTR2119; www.trialregister.nl), study participants who presented with ischemic stroke or TIA of the anterior circulation between December 2009 and September 2017 underwent pre-and postcontrast 7-T vessel wall MRI within 3 months of symptom onset. All large arteries of the intracranial circulation were assessed for number, location, and enhancement of vessel wall lesions. Generalized estimating equations for Poisson regression were used to investigate the relationship between vascular risk factors and number or enhancement of vessel wall lesions. Results: Ninety participants (52 men; mean age, 60 years) were evaluated. Increasing age (relative risk [RR], 1.02; 95% confidence interval [CI]: 1.01, 1.03), hypertension (RR, 1.46; 95% CI: 1.06, 2.02), diabetes mellitus (RR, 1.67; 95% CI: 1.20, 2.33), and a higher multivariable vascular risk score (Second Manifestations of Arterial Disease risk score) (RR, 1.01; 95% CI: 1.00, 1.02) were associated with a higher number of vessel wall lesions in the anterior circulation. Contrast material-enhancing vessel wall lesions were associated only with increasing age (RR, 1.03; 95% CI: 1.01, 1.05). No association was found between smoking and the number of vessel wall lesions. Conclusion: Except for smoking, traditional common cardiovascular risk factors were associated with a higher number and enhancement of intracranial vessel wall lesions at 7-T MRI in individuals evaluated after ischemic stroke or transient ischemic attack. Published under a CC BY 4.0 license.

Intracranial arterial wall imaging: Techniques, clinical applicability, and future perspectives

International Journal of Stroke

Purpose To review the current state of the art and future development of intracranial vessel wall... more Purpose To review the current state of the art and future development of intracranial vessel wall imaging. Methods Recent literature review and expert opinion about intracranial arterial wall imaging. Results Intracranial large artery diseases represent an important cause of stroke and vascular cognitive impairment worldwide. Our traditional understanding of intracranial large artery diseases is based on the observation of luminal narrowing or occlusion with angiographic or ultrasound techniques. Recently, novel imaging techniques have made the intracranial artery wall accessible for noninvasive visualization. The main advantage of vessel-wall imaging as compared to conventional imaging techniques for visualization of intracranial arteries is the ability to detect vessel wall changes even before they get to cause any significant luminal stenosis. This diagnostic capacity is provoking a revolutionary change in the way we see the intracranial circulation. In this article, we will revi...

Short-term mechanisms influencing volumetric brain dynamics

NeuroImage: Clinical

With the use of magnetic resonance imaging (MRI) and brain analysis tools, it has become possible... more With the use of magnetic resonance imaging (MRI) and brain analysis tools, it has become possible to measure brain volume changes up to around 0.5%. Besides long-term brain changes caused by atrophy in aging or neurodegenerative disease, short-term mechanisms that influence brain volume may exist. When we focus on short-term changes of the brain, changes may be either physiological or pathological. As such determining the cause of volumetric dynamics of the brain is essential. Additionally for an accurate interpretation of longitudinal brain volume measures by means of neurodegeneration, knowledge about the short-term changes is needed. Therefore, in this review, we discuss the possible mechanisms influencing brain volumes on a short-term basis and set-out a framework of MRI techniques to be used for volumetric changes as well as the used analysis tools. 3D T 1-weighted images are the images of choice when it comes to MRI of brain volume. These images are excellent to determine brain volume and can be used together with an analysis tool to determine the degree of volume change. Mechanisms that decrease global brain volume are: fluid restriction, evening MRI measurements, corticosteroids, antipsychotics and short-term effects of pathological processes like Alzheimer's disease, hypertension and Diabetes mellitus type II. Mechanisms increasing the brain volume include fluid intake, morning MRI measurements, surgical revascularization and probably medications like anti-inflammatory drugs and anti-hypertensive medication. Exercise was found to have no effect on brain volume on a short-term basis, which may imply that dehydration caused by exercise differs from dehydration by fluid restriction. In the upcoming years, attention should be directed towards studies investigating physiological short-term changes within the light of long-term pathological changes. Ultimately this may lead to a better understanding of the physiological short-term effects of pathological processes and may aid in early detection of these diseases.

Detecting Intracranial Vessel Wall Lesions With 7T-Magnetic Resonance Imaging

Stroke

Response by Chen et al to Letter Regarding Article, "Magnetic Resonance Imaging of Plaque Morphology, Burden, and Distribution in Patients With Symptomatic Middle Cerebral Artery Stenosis

Stroke; a journal of cerebral circulation, Nov 1, 2016

Qualitative Evaluation of a High-Resolution 3D Multi-Sequence Intracranial Vessel Wall Protocol at 3 Tesla MRI

PloS one, 2016

Intracranial vessel wall imaging using MRI has great potential as a clinical method for assessing... more Intracranial vessel wall imaging using MRI has great potential as a clinical method for assessing intracranial atherosclerosis. The purpose of the current study was to compare three 3T MRI vessel wall sequences with different contrast weightings (T1w, PD, T2w) and dedicated sagittal orientation perpendicular to the middle cerebral artery, to the reconstructed sagittal image from a transverse 3D T1w volumetric isotropically reconstructed turbo spin-echo acquisition (VIRTA), and provide a clinical recommendation. The above-mentioned sequences were acquired in 10 consecutive Chinese ischemic stroke or TIA patients (age: 68 years, sex: 4 females) with angiographic-confirmed MCA stenosis at 3T. Institutional review board approval was obtained. Two raters qualitatively scored all images on overall image quality, presence of artifacts, and visibility of plaques. Data were compared using Repeated measures ANOVA and Sidak's adjusted post hoc tests. All sequences except the T2w sequence w...

Magnetic Resonance Imaging of Plaque Morphology, Burden, and Distribution in Patients With Symptomatic Middle Cerebral Artery Stenosis

Stroke, 2016

Background and Purpose— Intracranial atherosclerosis is a major cause of ischemic stroke worldwid... more Background and Purpose— Intracranial atherosclerosis is a major cause of ischemic stroke worldwide. Intracranial vessel wall imaging is an upcoming field of interest to assess intracranial atherosclerosis. In this study, we investigated total intracranial plaque burden in patients with symptomatic middle cerebral artery stenosis, assessed plaque morphological features, and compared features of symptomatic and asymptomatic lesions using a 3T vessel wall sequence. Methods— Nineteen consecutive Chinese patients with ischemic stroke and transient ischemic attack (mean age: 67 years; 7 females) with a middle cerebral artery stenosis were scanned at 3T magnetic resonance imaging; the protocol included a time-of-flight magnetic resonance angiography and the T1-weighted volumetric isotropically reconstructed turbo spin echo acquisition sequence before and after (83%) contrast administration. Chi-square tests were used to assess associations between different plaque features. Statistical sig...

Relations between location and type of intracranial atherosclerosis and parenchymal damage

Journal of Cerebral Blood Flow & Metabolism, 2015

The aim of this study was to assess the relation between location and type of intracranial athero... more The aim of this study was to assess the relation between location and type of intracranial atherosclerosis (ICAS) and cortical microinfarcts (CMIs) and macroinfarcts in 18 patients presenting with ischemic stroke ( n = 12) or transient ischemic attack (TIA) ( n = 6) using 7 tesla MR imaging. The protocol included: 3D T2-weighted FLAIR and 3D T1-weighted Magnetization-Preparation Inversion Recovery Turbo Spin Echo sequence. ICAS lesions and infarcts were scored by two raters. The relation between ICAS lesions, calculated ratios of ICAS lesion characteristics, location, and infarcts were examined using linear regression analyses. A total number of 75 ICAS lesions (all patients), 101 CMIs (78% of patients), and 31 macroinfarcts (67% of patients) were found. Seventy-six and sixty-five percent of the CMIs and macroinfarcts, respectively, were found in the same vascular territory as the ICAS lesions ( p = 0.977, p = 0.167, respectively). A positive correlation existed between the number o...

High-resolution intracranial vessel wall MRI in an elderly asymptomatic population: comparison of 3T and 7T

European Radiology, 2016

Objectives Several intracranial vessel wall sequences have been described in recent literature, w... more Objectives Several intracranial vessel wall sequences have been described in recent literature, with either 3-T or 7-T magnetic resonance imaging (MRI). In the current study, we compared 3-T and 7-T MRI in visualising both the intracranial arterial vessel wall and vessel wall lesions. Methods Twenty-one elderly asymptomatic volunteers were scanned by 3-T and 7-T MRI with an intracranial vessel wall sequence, both before and after contrast administration. Two raters scored image quality, and presence and characteristics of vessel wall lesions. Results Vessel wall visibility was equal or significantly better at 7 T for the studied arterial segments, even though there were more artefacts hampering assessment. The better visualisation of the vessel wall at 7 T was most prominent in the proximal anterior cerebral circulation and the posterior cerebral artery. In the studied elderly asymptomatic population, 48 vesselwall lesions were identified at 3 T, of which 7 showed enhancement. At 7 T, 79 lesions were identified, of which 29 showed enhancement. Seventy-one percent of all 3-T lesions and 59 % of all 7-T lesions were also seen at the other field strength. Conclusions Despite the large variability in detected lesions at both field strengths, we believe 7-T MRI has the highest potential to identify the total burden of intracranial vessel wall lesions. Key Points • Intracranial vessel wall visibility was equal or significantly better at 7-T MRI • Most vessel wall lesions in the cerebral arteries were found at 7-T MRI • Many intracranial vessel wall lesions showed enhancement after contrast administration • Large variability in detected intracranial vessel wall lesions at both field strengths • Seven-tesla MRI has the highest potential to identify total burden of intracranial atherosclerosis

Plaque Characteristics, Burden and Distribution Assessment with High-Resolution Intracranial Vessel Wall Imaging at 3 Tesla MRI

Figure 1. A 57-year-old male patient with a left MCA stenosis. (A) Transverse TOF-MRA shows a ste... more Figure 1. A 57-year-old male patient with a left MCA stenosis. (A) Transverse TOF-MRA shows a stenosis of the right MCA (arrow). Transverse T1w VISTA images show a left MCA plaque (arrows in B) before contrast administration. The plaque enhances after contrast administration (arrow in C). Zoom-box shows sagittal view of the eccentric plaque (black arrow).

Relation between subcortical grey matter atrophy and conversion from mild cognitive impairment to Alzheimer's disease

Journal of neurology, neurosurgery, and psychiatry, Jan 22, 2015

To investigate whether subcortical grey matter atrophy predicts progression from mild cognitive i... more To investigate whether subcortical grey matter atrophy predicts progression from mild cognitive impairment (MCI) to Alzheimer's disease (AD), and to compare subcortical volumes between AD, MCI and controls. To assess the correlation between subcortical grey matter volumes and severity of cognitive impairment. We included 773 participants with three-dimensional T1-weighted MRI at 3 T, made up of 181 controls, who had subjective memory symptoms with normal cognition, 201 MCIs and 391 AD. During follow-up (2.0±0.9 years), 35 MCIs converted to AD (progressive MCI) and 160 MCIs remained stable (stable MCI). We segmented volumes of six subcortical structures of the amygdala, thalamus, caudate nucleus, putamen, globus pallidus and nucleus accumbens, and of the hippocampus, using FMRIBs integrated registration and segmentation tool. Analysis of variances, adjusted for sex and age, showed that all structures, except the globus pallidus, were smaller in AD than in controls. In addition, t...

Imaging intracranial vessel wall pathology with magnetic resonance imaging: current prospects and future directions

by Anja Van Der Kolk and Nikki Dieleman

Circulation, Jan 8, 2014

MORE ATROPHY OF DEEP GRAY MATTER STRUCTURES IN BEHAVIORAL VARIANT FRONTOTEMPORAL DEMENTIA COMPARED TO ALZHEIMER'S DISEASE

Alzheimer's & Dementia, 2014

DEEP GRAY MATTER ATROPHY DOES NOT PREDICT SHORT-TERM CONVERSION FROM MILD COGNITIVE IMPAIRMENT TO ALZHEIMER'S DISEASE

Alzheimer's & Dementia, 2014

and scrubbing level on connectivity was estimated with a t-test false-discovery rate (FDR) correc... more and scrubbing level on connectivity was estimated with a t-test false-discovery rate (FDR) corrected. Group differences (ECN, MCI and DAT) were investigated using t -tests for ten point-to-point connections selected based on a literature review (false-positive rate p<0.05). To test the robustness of group differences, the t -tests were replicated 1000 times for random subsamples including 70% of each group. Results: A wide range of motion level was observed in the sample. An arbitrary cut-off was used to separate the population into "moderate" and "high" motion groups". A bias in connectivity measures was observed between the "moderate" and "high" motion groups ( ). The 0.5 scrubbing significantly improve connectivity strength for both groups in the network and reduce connectivity with anticorrelated regions ( . Despite a moderate loss of subjects using the 0.5 scrubbing due to insufficient remaining data < 50 frames, the gain in data quality translated into an increased detection rate for group differences in all tested connections. Conclusions: Motion introduces a systematic bias in the measures of resting-state connectivity in elderly population. The 0.5 scrubbing procedure mitigated motion artifacts and improved the statistical power of group-level analysis.

Patterns of intracranial vessel wall changes in relation to ischemic infarcts

by Anja Van Der Kolk and Nikki Dieleman

Neurology, 2014

In this retrospective case series study, we used 7.0 tesla MRI to describe patterns of intracrani... more In this retrospective case series study, we used 7.0 tesla MRI to describe patterns of intracranial vessel wall abnormalities in relation to ischemic infarcts in 9 patients with different intracranial vessel wall pathologies. A patient-specific clinical imaging protocol was obtained after regular clinical workup, including a fluid-attenuated inversion recovery and an intracranial vessel wall sequence before and after contrast administration using 7.0 tesla MRI. An attempt was made to describe patterns by grouping the patients by intracranial vessel wall abnormalities (eccentric or concentric; enhancing or nonenhancing), then on the presence of macroinfarcts and cortical microinfarcts (CMIs), and lastly on type of macroinfarct (lacunar, small macroinfarct, or large macroinfarct). Intracranial vessel wall abnormalities were identified in all patients, totaling 45 lesions, 12 of which enhanced after contrast administration. CMIs were found in 5 patients. Two patients had eccentric, enhancing wall thickening but differed based on presence or absence of CMIs. Four patients also had eccentric but nonenhancing wall thickening, 2 of whom showed CMIs. The 2 patients lacking CMIs could be subdivided based on the type of macroinfarct. Concentric, enhanced wall thickening was observed in 2 patients with CMIs who differed regarding macroinfarct types. One patient with previous vasculitis showed concentric, nonenhancing wall thickening. Our results suggest that the combination of intracranial vessel wall abnormalities and infarct type is related to different stroke etiologies.

More atrophy of deep gray matter structures in frontotemporal dementia compared to Alzheimer's disease

Journal of Alzheimer's disease : JAD, 2015

The involvement of frontostriatal circuits in frontotemporal dementia (FTD) suggests that deep gr... more The involvement of frontostriatal circuits in frontotemporal dementia (FTD) suggests that deep gray matter structures (DGM) may be affected in this disease. We investigated whether volumes of DGM structures differed between patients with behavioral variant FTD (bvFTD), Alzheimer's disease (AD), and subjective complaints (SC) and explored relationships between DGM structures, cognition, and neuropsychiatric functioning. For this cross-sectional study, we included 24 patients with FTD and matched them based on age, gender, and education at a ratio of 1:3 to 72 AD patients and 72 patients with SC who served as controls. Volumes of hippocampus, amygdala, thalamus, caudate nucleus, putamen, globus pallidus, and nucleus accumbens were estimated by automated segmentation of 3D T1-weighted MRI. MANOVA with Bonferroni adjusted post-hoc tests was used to compare volumes between groups. Relationships between volumes, cognition, and neuropsychiatric functioning were examined using multivari...

Hyaluronan accumulation and arrested oligodendrocyte progenitor maturation in vanishing white matter disease

by Nikki Dieleman and I. Boor

Brain, 2013

High-Resolution Postcontrast Time-of-Flight MR Angiography of Intracranial Perforators at 7.0 Tesla

by Anja Van Der Kolk and Nikki Dieleman

PloS one, 2015

Different studies already demonstrated the benefits of 7T for precontrast TOF-MRA in the visualiz... more Different studies already demonstrated the benefits of 7T for precontrast TOF-MRA in the visualization of intracranial small vessels. The aim of this study was to assess the performance of high-resolution 7T TOF-MRA after the administration of a gadolinium-based contrast agent in visualizing intracranial perforating arteries. Ten consecutive patients (7 male; mean age, 50.4 ± 9.9 years) who received TOF-MRA at 7T after contrast administration were retrospectively included in this study. Intracranial perforating arteries, branching from the parent arteries of the circle of Willis, were identified on all TOF-MRA images. Provided a TOF-MRA before contrast administration was present, a direct comparison between pre- and postcontrast TOF-MRA was made. It was possible to visualize intracranial perforating arteries branching off from the entire circle of Willis, and their proximal branches. The posterior cerebral artery (P1 and proximal segment of P2) appeared to have the largest number of...

Intracranial Atherosclerosis Assessed with 7-T MRI: Evaluation of Patients with Ischemic Stroke or Transient Ischemic Attack

Radiology

Background: Intracranial atherosclerosis is an important cause of ischemic stroke and is associat... more Background: Intracranial atherosclerosis is an important cause of ischemic stroke and is associated with several vascular risk factors. Current imaging is mainly based on the assessment of luminal narrowing rather than abnormalities in the vessel wall. Purpose: To investigate the relationship between vascular risk factors and atherosclerotic lesion burden of intracranial arteries assessed with vessel wall MRI at 7 T in participants with ischemic stroke or transient ischemic attack (TIA). Materials and Methods: In this prospective study (trial identification number: NTR2119; www.trialregister.nl), study participants who presented with ischemic stroke or TIA of the anterior circulation between December 2009 and September 2017 underwent pre-and postcontrast 7-T vessel wall MRI within 3 months of symptom onset. All large arteries of the intracranial circulation were assessed for number, location, and enhancement of vessel wall lesions. Generalized estimating equations for Poisson regression were used to investigate the relationship between vascular risk factors and number or enhancement of vessel wall lesions. Results: Ninety participants (52 men; mean age, 60 years) were evaluated. Increasing age (relative risk [RR], 1.02; 95% confidence interval [CI]: 1.01, 1.03), hypertension (RR, 1.46; 95% CI: 1.06, 2.02), diabetes mellitus (RR, 1.67; 95% CI: 1.20, 2.33), and a higher multivariable vascular risk score (Second Manifestations of Arterial Disease risk score) (RR, 1.01; 95% CI: 1.00, 1.02) were associated with a higher number of vessel wall lesions in the anterior circulation. Contrast material-enhancing vessel wall lesions were associated only with increasing age (RR, 1.03; 95% CI: 1.01, 1.05). No association was found between smoking and the number of vessel wall lesions. Conclusion: Except for smoking, traditional common cardiovascular risk factors were associated with a higher number and enhancement of intracranial vessel wall lesions at 7-T MRI in individuals evaluated after ischemic stroke or transient ischemic attack. Published under a CC BY 4.0 license.

Intracranial arterial wall imaging: Techniques, clinical applicability, and future perspectives

International Journal of Stroke

Purpose To review the current state of the art and future development of intracranial vessel wall... more Purpose To review the current state of the art and future development of intracranial vessel wall imaging. Methods Recent literature review and expert opinion about intracranial arterial wall imaging. Results Intracranial large artery diseases represent an important cause of stroke and vascular cognitive impairment worldwide. Our traditional understanding of intracranial large artery diseases is based on the observation of luminal narrowing or occlusion with angiographic or ultrasound techniques. Recently, novel imaging techniques have made the intracranial artery wall accessible for noninvasive visualization. The main advantage of vessel-wall imaging as compared to conventional imaging techniques for visualization of intracranial arteries is the ability to detect vessel wall changes even before they get to cause any significant luminal stenosis. This diagnostic capacity is provoking a revolutionary change in the way we see the intracranial circulation. In this article, we will revi...

Short-term mechanisms influencing volumetric brain dynamics

NeuroImage: Clinical

With the use of magnetic resonance imaging (MRI) and brain analysis tools, it has become possible... more With the use of magnetic resonance imaging (MRI) and brain analysis tools, it has become possible to measure brain volume changes up to around 0.5%. Besides long-term brain changes caused by atrophy in aging or neurodegenerative disease, short-term mechanisms that influence brain volume may exist. When we focus on short-term changes of the brain, changes may be either physiological or pathological. As such determining the cause of volumetric dynamics of the brain is essential. Additionally for an accurate interpretation of longitudinal brain volume measures by means of neurodegeneration, knowledge about the short-term changes is needed. Therefore, in this review, we discuss the possible mechanisms influencing brain volumes on a short-term basis and set-out a framework of MRI techniques to be used for volumetric changes as well as the used analysis tools. 3D T 1-weighted images are the images of choice when it comes to MRI of brain volume. These images are excellent to determine brain volume and can be used together with an analysis tool to determine the degree of volume change. Mechanisms that decrease global brain volume are: fluid restriction, evening MRI measurements, corticosteroids, antipsychotics and short-term effects of pathological processes like Alzheimer's disease, hypertension and Diabetes mellitus type II. Mechanisms increasing the brain volume include fluid intake, morning MRI measurements, surgical revascularization and probably medications like anti-inflammatory drugs and anti-hypertensive medication. Exercise was found to have no effect on brain volume on a short-term basis, which may imply that dehydration caused by exercise differs from dehydration by fluid restriction. In the upcoming years, attention should be directed towards studies investigating physiological short-term changes within the light of long-term pathological changes. Ultimately this may lead to a better understanding of the physiological short-term effects of pathological processes and may aid in early detection of these diseases.

Detecting Intracranial Vessel Wall Lesions With 7T-Magnetic Resonance Imaging

Stroke

Response by Chen et al to Letter Regarding Article, "Magnetic Resonance Imaging of Plaque Morphology, Burden, and Distribution in Patients With Symptomatic Middle Cerebral Artery Stenosis

Stroke; a journal of cerebral circulation, Nov 1, 2016

Qualitative Evaluation of a High-Resolution 3D Multi-Sequence Intracranial Vessel Wall Protocol at 3 Tesla MRI

PloS one, 2016

Intracranial vessel wall imaging using MRI has great potential as a clinical method for assessing... more Intracranial vessel wall imaging using MRI has great potential as a clinical method for assessing intracranial atherosclerosis. The purpose of the current study was to compare three 3T MRI vessel wall sequences with different contrast weightings (T1w, PD, T2w) and dedicated sagittal orientation perpendicular to the middle cerebral artery, to the reconstructed sagittal image from a transverse 3D T1w volumetric isotropically reconstructed turbo spin-echo acquisition (VIRTA), and provide a clinical recommendation. The above-mentioned sequences were acquired in 10 consecutive Chinese ischemic stroke or TIA patients (age: 68 years, sex: 4 females) with angiographic-confirmed MCA stenosis at 3T. Institutional review board approval was obtained. Two raters qualitatively scored all images on overall image quality, presence of artifacts, and visibility of plaques. Data were compared using Repeated measures ANOVA and Sidak's adjusted post hoc tests. All sequences except the T2w sequence w...

Magnetic Resonance Imaging of Plaque Morphology, Burden, and Distribution in Patients With Symptomatic Middle Cerebral Artery Stenosis

Stroke, 2016

Background and Purpose— Intracranial atherosclerosis is a major cause of ischemic stroke worldwid... more Background and Purpose— Intracranial atherosclerosis is a major cause of ischemic stroke worldwide. Intracranial vessel wall imaging is an upcoming field of interest to assess intracranial atherosclerosis. In this study, we investigated total intracranial plaque burden in patients with symptomatic middle cerebral artery stenosis, assessed plaque morphological features, and compared features of symptomatic and asymptomatic lesions using a 3T vessel wall sequence. Methods— Nineteen consecutive Chinese patients with ischemic stroke and transient ischemic attack (mean age: 67 years; 7 females) with a middle cerebral artery stenosis were scanned at 3T magnetic resonance imaging; the protocol included a time-of-flight magnetic resonance angiography and the T1-weighted volumetric isotropically reconstructed turbo spin echo acquisition sequence before and after (83%) contrast administration. Chi-square tests were used to assess associations between different plaque features. Statistical sig...

Relations between location and type of intracranial atherosclerosis and parenchymal damage

Journal of Cerebral Blood Flow & Metabolism, 2015

The aim of this study was to assess the relation between location and type of intracranial athero... more The aim of this study was to assess the relation between location and type of intracranial atherosclerosis (ICAS) and cortical microinfarcts (CMIs) and macroinfarcts in 18 patients presenting with ischemic stroke ( n = 12) or transient ischemic attack (TIA) ( n = 6) using 7 tesla MR imaging. The protocol included: 3D T2-weighted FLAIR and 3D T1-weighted Magnetization-Preparation Inversion Recovery Turbo Spin Echo sequence. ICAS lesions and infarcts were scored by two raters. The relation between ICAS lesions, calculated ratios of ICAS lesion characteristics, location, and infarcts were examined using linear regression analyses. A total number of 75 ICAS lesions (all patients), 101 CMIs (78% of patients), and 31 macroinfarcts (67% of patients) were found. Seventy-six and sixty-five percent of the CMIs and macroinfarcts, respectively, were found in the same vascular territory as the ICAS lesions ( p = 0.977, p = 0.167, respectively). A positive correlation existed between the number o...

High-resolution intracranial vessel wall MRI in an elderly asymptomatic population: comparison of 3T and 7T

European Radiology, 2016

Objectives Several intracranial vessel wall sequences have been described in recent literature, w... more Objectives Several intracranial vessel wall sequences have been described in recent literature, with either 3-T or 7-T magnetic resonance imaging (MRI). In the current study, we compared 3-T and 7-T MRI in visualising both the intracranial arterial vessel wall and vessel wall lesions. Methods Twenty-one elderly asymptomatic volunteers were scanned by 3-T and 7-T MRI with an intracranial vessel wall sequence, both before and after contrast administration. Two raters scored image quality, and presence and characteristics of vessel wall lesions. Results Vessel wall visibility was equal or significantly better at 7 T for the studied arterial segments, even though there were more artefacts hampering assessment. The better visualisation of the vessel wall at 7 T was most prominent in the proximal anterior cerebral circulation and the posterior cerebral artery. In the studied elderly asymptomatic population, 48 vesselwall lesions were identified at 3 T, of which 7 showed enhancement. At 7 T, 79 lesions were identified, of which 29 showed enhancement. Seventy-one percent of all 3-T lesions and 59 % of all 7-T lesions were also seen at the other field strength. Conclusions Despite the large variability in detected lesions at both field strengths, we believe 7-T MRI has the highest potential to identify the total burden of intracranial vessel wall lesions. Key Points • Intracranial vessel wall visibility was equal or significantly better at 7-T MRI • Most vessel wall lesions in the cerebral arteries were found at 7-T MRI • Many intracranial vessel wall lesions showed enhancement after contrast administration • Large variability in detected intracranial vessel wall lesions at both field strengths • Seven-tesla MRI has the highest potential to identify total burden of intracranial atherosclerosis

Plaque Characteristics, Burden and Distribution Assessment with High-Resolution Intracranial Vessel Wall Imaging at 3 Tesla MRI

Figure 1. A 57-year-old male patient with a left MCA stenosis. (A) Transverse TOF-MRA shows a ste... more Figure 1. A 57-year-old male patient with a left MCA stenosis. (A) Transverse TOF-MRA shows a stenosis of the right MCA (arrow). Transverse T1w VISTA images show a left MCA plaque (arrows in B) before contrast administration. The plaque enhances after contrast administration (arrow in C). Zoom-box shows sagittal view of the eccentric plaque (black arrow).

Relation between subcortical grey matter atrophy and conversion from mild cognitive impairment to Alzheimer's disease

Journal of neurology, neurosurgery, and psychiatry, Jan 22, 2015

To investigate whether subcortical grey matter atrophy predicts progression from mild cognitive i... more To investigate whether subcortical grey matter atrophy predicts progression from mild cognitive impairment (MCI) to Alzheimer's disease (AD), and to compare subcortical volumes between AD, MCI and controls. To assess the correlation between subcortical grey matter volumes and severity of cognitive impairment. We included 773 participants with three-dimensional T1-weighted MRI at 3 T, made up of 181 controls, who had subjective memory symptoms with normal cognition, 201 MCIs and 391 AD. During follow-up (2.0±0.9 years), 35 MCIs converted to AD (progressive MCI) and 160 MCIs remained stable (stable MCI). We segmented volumes of six subcortical structures of the amygdala, thalamus, caudate nucleus, putamen, globus pallidus and nucleus accumbens, and of the hippocampus, using FMRIBs integrated registration and segmentation tool. Analysis of variances, adjusted for sex and age, showed that all structures, except the globus pallidus, were smaller in AD than in controls. In addition, t...

Imaging intracranial vessel wall pathology with magnetic resonance imaging: current prospects and future directions

by Anja Van Der Kolk and Nikki Dieleman

Circulation, Jan 8, 2014

MORE ATROPHY OF DEEP GRAY MATTER STRUCTURES IN BEHAVIORAL VARIANT FRONTOTEMPORAL DEMENTIA COMPARED TO ALZHEIMER'S DISEASE

Alzheimer's & Dementia, 2014

DEEP GRAY MATTER ATROPHY DOES NOT PREDICT SHORT-TERM CONVERSION FROM MILD COGNITIVE IMPAIRMENT TO ALZHEIMER'S DISEASE

Alzheimer's & Dementia, 2014

and scrubbing level on connectivity was estimated with a t-test false-discovery rate (FDR) correc... more and scrubbing level on connectivity was estimated with a t-test false-discovery rate (FDR) corrected. Group differences (ECN, MCI and DAT) were investigated using t -tests for ten point-to-point connections selected based on a literature review (false-positive rate p<0.05). To test the robustness of group differences, the t -tests were replicated 1000 times for random subsamples including 70% of each group. Results: A wide range of motion level was observed in the sample. An arbitrary cut-off was used to separate the population into "moderate" and "high" motion groups". A bias in connectivity measures was observed between the "moderate" and "high" motion groups ( ). The 0.5 scrubbing significantly improve connectivity strength for both groups in the network and reduce connectivity with anticorrelated regions ( . Despite a moderate loss of subjects using the 0.5 scrubbing due to insufficient remaining data < 50 frames, the gain in data quality translated into an increased detection rate for group differences in all tested connections. Conclusions: Motion introduces a systematic bias in the measures of resting-state connectivity in elderly population. The 0.5 scrubbing procedure mitigated motion artifacts and improved the statistical power of group-level analysis.

Patterns of intracranial vessel wall changes in relation to ischemic infarcts

by Anja Van Der Kolk and Nikki Dieleman

Neurology, 2014

In this retrospective case series study, we used 7.0 tesla MRI to describe patterns of intracrani... more In this retrospective case series study, we used 7.0 tesla MRI to describe patterns of intracranial vessel wall abnormalities in relation to ischemic infarcts in 9 patients with different intracranial vessel wall pathologies. A patient-specific clinical imaging protocol was obtained after regular clinical workup, including a fluid-attenuated inversion recovery and an intracranial vessel wall sequence before and after contrast administration using 7.0 tesla MRI. An attempt was made to describe patterns by grouping the patients by intracranial vessel wall abnormalities (eccentric or concentric; enhancing or nonenhancing), then on the presence of macroinfarcts and cortical microinfarcts (CMIs), and lastly on type of macroinfarct (lacunar, small macroinfarct, or large macroinfarct). Intracranial vessel wall abnormalities were identified in all patients, totaling 45 lesions, 12 of which enhanced after contrast administration. CMIs were found in 5 patients. Two patients had eccentric, enhancing wall thickening but differed based on presence or absence of CMIs. Four patients also had eccentric but nonenhancing wall thickening, 2 of whom showed CMIs. The 2 patients lacking CMIs could be subdivided based on the type of macroinfarct. Concentric, enhanced wall thickening was observed in 2 patients with CMIs who differed regarding macroinfarct types. One patient with previous vasculitis showed concentric, nonenhancing wall thickening. Our results suggest that the combination of intracranial vessel wall abnormalities and infarct type is related to different stroke etiologies.

More atrophy of deep gray matter structures in frontotemporal dementia compared to Alzheimer's disease

Journal of Alzheimer's disease : JAD, 2015

The involvement of frontostriatal circuits in frontotemporal dementia (FTD) suggests that deep gr... more The involvement of frontostriatal circuits in frontotemporal dementia (FTD) suggests that deep gray matter structures (DGM) may be affected in this disease. We investigated whether volumes of DGM structures differed between patients with behavioral variant FTD (bvFTD), Alzheimer's disease (AD), and subjective complaints (SC) and explored relationships between DGM structures, cognition, and neuropsychiatric functioning. For this cross-sectional study, we included 24 patients with FTD and matched them based on age, gender, and education at a ratio of 1:3 to 72 AD patients and 72 patients with SC who served as controls. Volumes of hippocampus, amygdala, thalamus, caudate nucleus, putamen, globus pallidus, and nucleus accumbens were estimated by automated segmentation of 3D T1-weighted MRI. MANOVA with Bonferroni adjusted post-hoc tests was used to compare volumes between groups. Relationships between volumes, cognition, and neuropsychiatric functioning were examined using multivari...

Hyaluronan accumulation and arrested oligodendrocyte progenitor maturation in vanishing white matter disease

by Nikki Dieleman and I. Boor

Brain, 2013

High-Resolution Postcontrast Time-of-Flight MR Angiography of Intracranial Perforators at 7.0 Tesla

by Anja Van Der Kolk and Nikki Dieleman

PloS one, 2015

Different studies already demonstrated the benefits of 7T for precontrast TOF-MRA in the visualiz... more Different studies already demonstrated the benefits of 7T for precontrast TOF-MRA in the visualization of intracranial small vessels. The aim of this study was to assess the performance of high-resolution 7T TOF-MRA after the administration of a gadolinium-based contrast agent in visualizing intracranial perforating arteries. Ten consecutive patients (7 male; mean age, 50.4 ± 9.9 years) who received TOF-MRA at 7T after contrast administration were retrospectively included in this study. Intracranial perforating arteries, branching from the parent arteries of the circle of Willis, were identified on all TOF-MRA images. Provided a TOF-MRA before contrast administration was present, a direct comparison between pre- and postcontrast TOF-MRA was made. It was possible to visualize intracranial perforating arteries branching off from the entire circle of Willis, and their proximal branches. The posterior cerebral artery (P1 and proximal segment of P2) appeared to have the largest number of...

Лучший частный хостинг