Biomedical subjects

Jeroen Hendrikse

Publications and source records attributed to Jeroen Hendrikse.

At least 19 recordsLinked to original sources

PubMed2007

Increasing levels of TNFalpha are associated with increased brain perfusion.

OBJECTIVE: Recent reports of animal models have shown that growth factors have stimulating effect on brain perfusion via the development of blood vessels. However, studies on the effect of growth factors on brain perfusion in humans are lacking. The aim of our study was to prospectively investigate in humans the relation between growth factors and brain perfusion. METHODS: We analyzed circulating levels of vascular endothelial growth factor (VEGF), granulocyte-macrophage colony-stimulating growth factor (GM-CSF), tumor necrosis factor alpha (TNFalpha) and basic fibroblast growth factor (bFGF) in 121 consecutive patients (99 men and 22 women, age 58+/-10 years) who were enrolled in a prospective cohort study of patients with symptomatic atherosclerotic disease. In all patients regional cerebral blood flow (rCBF; in mL/min/100g) measurements were performed with arterial spin labeling magnetic resonance imaging. Cerebrovascular risk factors were assessed by means of a questionnaire and physical, ultrasonographic and laboratory examination. RESULTS: Increasing levels of TNFalpha were significantly associated with a higher rCBF (beta=7.0; 95% confidence interval 0.7; 13.9), independent of the presence of cerebrovascular risk factors. No significant association was found for VEGF, GM-CSF and bFGF. CONCLUSIONS: Increasing levels of TNFalpha are associated with increased rCBF, independent of the presence of cerebrovascular risk factors.

Aged↗

PubMed2007

Sensitivity comparison of multiple vs. single inversion time pulsed arterial spin labeling fMRI.

PURPOSE: To study the sensitivity for detection of activation for multiple vs. single inversion time (TI) pulsed arterial spin labeling (PASL). MATERIALS AND METHODS: The number of activated voxels and the mean t-statistic over activated voxels was measured by means of multiple and single TI PASL sequences in five volunteers during visual stimulation by means of an alternating checkerboard. Acquisition was performed by means of the transfer insensitive labeling technique (TILT) and TURBO-TILT. RESULTS: It was found that the sensitivity for the detection of activation was lower for an individual TI out of a multiple TI sequence than for the corresponding single TI acquisition of equal duration. After averaging over all TIs between and including 600 and 1400 msec, the number of activated voxels and mean t-statistic were no longer statistically lower for the multiple TI sequence than for the single TI experiment. CONCLUSION: Multiple TI PASL can be used for functional MRI (fMRI) studies, when performing the detection of activated brain regions on data that is averaged over all TIs between 600 and 1400 msec. Subsequently the multi-TI data can be used to quantify cerebral blood flow (CBF) changes upon activation. Additionally, we have shown that single TI PASL fMRI overestimates the CBF changes upon activation due to transit time changes.

Adult↗

PubMed2006

Spect measurements of regional cerebral perfusion and carbondioxide reactivity: correlation with cerebral collaterals in internal carotid artery occlusive disease.

BACKGROUND: The aim of the present study was to assess the regional variation in cerebral perfusion, vasomotor reactivity (VMR) and the role of cerebral collaterals in patients with symptomatic internal carotid artery (ICA). METHODS: Seventeen functionally independent patients (60+/-9 years, mean+/-SD) with a unilateral symptomatic internal carotid artery occlusion and a <30% contralateral ICA stenosis were investigated. (99 m) Tc-hexamethyl propyleneamine oxime (HMPAO) single photon emission computed tomography (SPECT) was performed to study cerebral blood flow in rest and during a CO(2) challenge in the cerebellum, temporal lobe, occipital lobe, basal ganglia, frontal lobe and parietal lobe. Time of flight and phase contrast MRA were used to study collateral flow via circle of Willis. RESULTS: In rest, cerebral perfusion on the side ipsilateral to the ICA occlusion was decreased compared with the contralateral side in the basal ganglia (p<0.05), frontal lobe (p<0.01) and parietal lobe (p<0.01). During a CO(2) challenge only the ipsilateral frontal lobe demonstrated a perfusion decrease compared with the contralateral frontal lobe (p<0.05). Furthermore, in patients without collateral flow via the anterior circle of Willis the perfusion of the ipsilateral frontal lobe was significantly decreased (p<0.01) during the CO(2) challenge and crossed cerebellar diaschisis with a decreased perfusion on the contralateral cerebellar hemisphere was detected (p<0.05). No cerebral blood flow (CBF) differences were found for present/absent collateral flow via the posterior communicating artery. CONCLUSION: Regional assessment of cerebral perfusion and VMR with SPECT demonstrated the heterogeneity of cerebral hemodynamics and the importance of collateral flow via the anterior circle of Willis.

Aged↗

PubMed2006

Hemodynamic effect of carotid stenting and carotid endarterectomy.

BACKGROUND: Carotid angioplasty with stent placement (CAS) may offer an alternative treatment to carotid endarterectomy (CEA). However, in contrast to CEA, which has been shown to normalize impaired cerebral hemodynamics, the effects of CAS remain unclear. To investigate alterations in cerebral hemodynamics, we prospectively studied patients undergoing CAS and compared them with a group of similar patients undergoing CEA. METHODS: Twenty-three patients undergoing CAS for recently symptomatic internal carotid artery (ICA) stenosis were prospectively studied. Volume flow in the ICAs and basilar artery (BA) were measured with magnetic resonance volume flow quantification before CAS and 1 month after. The results were compared with those in 13 similar patients undergoing CEA and 40 control subjects without ICA stenosis. RESULTS: After CAS, volume flow in the ipsilateral ICA increased from 114 +/- 17 to 231 +/- 17 mL/min (P < .001), and total volume flow (ICAs plus BA) increased from 495 +/- 24 to 552 +/- 28 mL/min (P < .05). No significant changes were seen in the contralateral ICA and BA after CAS. Total volume flow and flow in the stenosed ICA normalized after CAS compared with control subjects. Volume flow values similarly improved after CEA. CONCLUSIONS: CAS results in a normalization of impaired cerebral hemodynamics, as assessed by magnetic resonance volume flow measurements. The degree of improvement is similar to that seen after CEA.

Aged↗

PubMed2006

Magnetic resonance evaluation of the cerebral circulation in obstructive arterial disease.

BACKGROUND: The aim of the current overview is to highlight the possibilities of magnetic resonance imaging (MRI) in the assessment of patients with obstructive arterial disease. The anatomic and hemodynamic aspects of the extra- and intracranial cerebral circulation were analyzed and show the importance of combining both aspects in studying cerebral hemodynamic changes. RESULTS: Three levels of cerebral circulation are distinguished: blood flow to the brain (level 1); the distribution of blood flow in the brain (level 2), and finally perfusion of the brain (level 3). To investigate the anatomy of the arteries in the neck and the circle of Willis, contrast-enhanced, time-of-flight and phase contrast MR angiography (MRA) are available. To evaluate the hemodynamics at the 1st and 2nd level of the cerebral circulation two-dimensional phase contrast (volume flow and flow direction) MRA can be used. In addition, the distribution of blood via the circle of Willis can be visualized with dynamic MRA. At the 3rd level, measurements of regional brain perfusion can be obtained by injecting gadolinium, dynamic susceptibility contrast MRI, or noninvasively with arterial spin labeling (ASL) MRI. In addition, selective ASL MRI is able to evaluate the perfused territories of individual brain-feeding arteries. CONCLUSION: The currently available MR techniques allow evaluation of the cerebral circulation from the aortic arch upwards towards the microvasculature and brain tissue perfusion in a comprehensive 20-min protocol. The combined use of the described MR methods in patients with steno-occlusive disease will further clarify the pathophysiological relations between the vasculature, perfusion and brain function.

Arterial Occlusive Diseases↗

PubMed2005

Magnetic resonance angiography of cerebral arteries after neonatal venoarterial and venovenous extracorporeal membrane oxygenation.

BACKGROUND AND PURPOSE: In newborns with severe respiratory failure, extracorporeal membrane oxygenation (ECMO) has been proven to improve survival. With venoarterial ECMO, the right common carotid artery is ligated, whereas with venovenous ECMO, this carotid artery remains intact. The authors present the magnetic resonance angiography (MRA) evaluation of cerebral hemodynamics in a case of venoarterial and a case of venovenous ECMO. METHODS: With 2D phase-contrast MRA flow volume (mL/min), measurements are obtained of the brain feeding arteries and draining veins. Time-of-flight and flow-directional MRA are used to demonstrate the anatomy and flow patterns at the level of the circle of Willis. RESULTS: A total volume flow of 63 mL/min at the skull base and collateral flow via the anterior circle of Willis were measured in the infant after venoarterial ECMO, and a total volume flow of 86 mL/min and a fetal type configuration of the circle of Willis were observed in the infant after venovenous ECMO. CONCLUSION: MRA is a useful technique to quantify cerebral blood flow in neonates after venoarterial or venovenous ECMO and could be used to select neonates with insufficient collateral compensation after venoarterial ECMO, requiring revascularization surgery.

Carotid Arteries↗

PubMed2005

In vivo flow territory mapping of major brain feeding arteries.

The ability to visualize the perfusion territories of major feeding arteries to the brain is important for many clinical applications. Since the work of Duret in 1874 on vascularization of the brain, many textbooks and atlases have shown schematic drawings of the supply areas of the major cerebral arteries. Recent postmortem studies demonstrated that the variability of the cerebral vascular territories is significantly greater than previously assumed. The aim of the present study was to investigate in vivo, the variability of flow territories of major brain feeding arteries. Flow territory mapping of the anterior (internal carotid arteries) and posterior (basilar artery) circulation was performed in 115 (58 +/- 9 years of age) subjects with selective arterial spin labeling MRI. Flow territory maps for the entire population indicated significant variation in flow territories. However, when the subjects are further categorized into groups with a complete circle of Willis, with a missing A1 segment and with a unilateral or bilateral fetal-type posterior cerebral artery, the results showed considerably lower variation within groups. It is therefore concluded that, the variation observed from the entire population is mainly caused by anatomical variants of the circle of Willis. To relate focal brain lesions to underlying flow territories in individual cases, knowledge of the anatomy of the circle of Willis is essential.

Aged↗

PubMed2005

Non-invasive visualization of collateral blood flow patterns of the circle of Willis by dynamic MR angiography.

The circle of Willis plays an important role in the distribution of blood flow in the brain. To obtain dynamic information of the blood flow through the circle of Willis, a dynamic MRA technique based on arterial spin labeling (ASL) is introduced as a non-invasive technique. When the ASL labeling slab is restricted to a single artery, it is possible to visualize selectively the flow distribution of that specific artery. However, because of the decay of the label and the presence of noise it is difficult to extract functional information from these images. In the present study we propose three visualization and post-processing methods for the interpretation of these images. Firstly, the passage of labeled blood was corrected for decay of the label and hereafter shown as a movie. Secondly, by calculating the time of arrival at every location in the arteries of the circle of Willis, a 2D image was reconstructed summarizing the information of the movie. Finally, quantitative flow values were obtained by relating the arterial input function to the passage of labeled blood through a region of interest encompassing the vessel under investigation. Experiments in a circle of Willis phantom showed a high linear relation between measured flow and true flow, although the measured values were 10-15% lower than the true flow values. Measurements in healthy volunteers showed the potential to quantify the flow in all major arteries of the circle of Willis.

Circle of Willis↗

PubMed2005

Distribution of cerebral blood flow in the circle of Willis.

PURPOSE: To prospectively determine the effect of anatomic variations in the circle of Willis on volume flow in the internal carotid arteries (ICAs) and basilar artery (BA). MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained. Phase-contrast magnetic resonance (MR) angiography was used to measure the volume flow in the BA and ICAs in 208 patients (182 men, 26 women; mean age, 60 years) with symptomatic atherosclerosis or risk factors for atherosclerosis. Patients with steno-occlusive disease were excluded, and flow values were normalized for age. Three-dimensional time-of-flight MR angiograms were used to assess the anatomy of the circle of Willis. Differences in volume flow between a complete circle of Willis, a circle with a missing A1 segment, and a circle with a fetal-type posterior cerebral artery were analyzed (analysis of variance and Scheffe post hoc tests). RESULTS: The ICA volume flow in subjects with a complete configuration of the circle of Willis was 245 mL/min +/- 65 (standard deviation). Flow in the contralateral ICA was significantly increased (P < .01) in subjects with a missing A1 segment (303 mL/min +/- 56) compared with control subjects and compared with flow on the ipsilateral side (214 mL/min +/- 94; P < .01). In subjects with a unilateral or bilateral fetal-type posterior cerebral artery, the ICA volume flow was increased (P < .01) and the BA volume flow was decreased (P < .01) in comparison with the flow in subjects with no fetal-type circle of Willis. CONCLUSION: Large asymmetries in volume flow between the right and left ICAs or decreased volume flow in the BA is not necessarily caused by vascular disease but may be caused by variations in the anatomy of the circle of Willis.

Adult↗

PubMed2005

Altered flow territories after extracranial-intracranial bypass surgery.

OBJECTIVE: To prevent stroke after carotid sacrifice and to augment cerebral perfusion in patients with internal carotid artery (ICA) occlusion, high-flow extracranial-intracranial (EC-IC) bypass operations are performed. Although the function and efficacy of the bypass is monitored during surgery, the postoperative flow through the bypass is significantly lower than the flow in the contralateral ICA. Thus far, it is unknown whether decreased bypass flow is caused by a low tissue perfusion or by a relatively small flow territory. METHODS: Seven patients, four with an atherosclerotic ICA occlusion and three with a giant aneurysm of the ICA, were investigated; each underwent a high-flow EC-IC bypass and permanent occlusion of the ICA. Cerebral blood flow was measured with arterial spin labeling perfusion magnetic resonance imaging. Separate flow territory mapping of the EC-IC bypass, contralateral ICA, and posterior circulation was performed with selective arterial spin labeling magnetic resonance imaging. RESULTS: No significant difference was found in cerebral blood flow between the hemisphere ipsilateral to the EC-IC bypass (70.9 +/- 11.3 ml/min/100 g tissue), contralateral to the EC-IC bypass (71.9 +/- 14.3 ml/min/100 g tissue), and comparable findings in 50 healthy control participants (69.1 +/- 17.5 ml/min/100 g tissue). Paired analysis of the individual flow territories demonstrated a 15% volume reduction (P = 0.018) in flow territory of the EC-IC bypass compared with the contralateral side. CONCLUSION: In the present study, we demonstrate the feasibility of selective arterial spin labeling magnetic resonance imaging for clinical follow-up of patients after high-flow EC/IC bypass surgery, providing both information on flow territories and the level of regional cerebral blood flow.

Adult↗

PubMed2004

Internal carotid artery occlusion assessed at pulsed arterial spin-labeling perfusion MR imaging at multiple delay times.

Magnetic resonance (MR) imaging with pulsed arterial spin labeling (ASL) was performed at six different inversion times in nine patients with internal carotid artery (ICA) occlusion and in 11 control subjects. The hospital's commission on scientific research on human subjects approved the study protocol, and all study subjects gave informed consent. Cerebral blood flow (CBF) in the middle cerebral artery territories was calculated from the combined signal intensities measured with ASL at the multiple inversion times. In the patients with ICA occlusion, mean CBF values were decreased in the gray matter of the hemisphere ipsilateral to the occlusion, as compared with values in the gray matter of the contralateral hemisphere (P < .05) and with values in the gray matter of the control subjects (P < .05). Quantification of CBF with ASL at multiple inversion times can compensate for the blood transit delays in patients with ICA occlusion.

Adult↗

PubMed2004

Phase-contrast magnetic resonance imaging measurements of cerebral autoregulation with a breath-hold challenge: a feasibility study.

BACKGROUND AND PURPOSE: Vasomotor reactivity (VMR) testing can identify patients with hemodynamically critical cerebrovascular disease. The use of VMR has been limited by the invasiveness of most of the available methods and of acetazolamide as VMR stimulus. In the present study, we evaluated a completely noninvasive VMR approach by combining quantitative phase-contrast magnetic resonance imaging (MRI) with a breath-hold challenge. METHODS: Volume flow rates in the right and left internal carotid artery (ICA), basilar artery (BA), superior sagittal sinus, and sinus rectus were measured on 2-dimensional phase-contrast MR angiograms (MRAs) with a temporal resolution of 4.3 seconds. In 20 healthy control subjects, the VMR was assessed during 2 consecutive 30-second periods of breath-holding. RESULTS: A flow increase on breath-holding of 66% was found for the left ICA (240+/-54 mL/min to 398+/-120 mL/min; P<0.01), 59% for the right ICA (253+/-98 mL/min to 402+/-159 mL/min; P<0.01), 71% for the BA (107+/-48 mL/min to 184+/-79 mL/min; P<0.01), 62% for the superior sagittal sinus (232+/-75 mL/min to 375+/-130 mL/min; P<0.01), and 65% for the sinus rectus (77+/-30 mL/min to 127+/-38 mL/min; P<0.01). The coefficient of variation for the total volume flow increase in the brain feeding arteries (ICAs and BA) between the first and the second breath-holds was 18%. CONCLUSIONS: The combination of MRA phase-contrast volume flow measurements and a breath-holding challenge allows for a fast, completely noninvasive, and reproducible assessment of VMR.

Adult↗

PubMed2004

Flow territory mapping of the cerebral arteries with regional perfusion MRI.

BACKGROUND AND PURPOSE: Conventional contrast-enhanced angiography is the gold standard for visualization of the vascular tree supplied by the major cerebral arteries and assessment of collateral flow. Thus far, however, no methods are available to assess the actual flow territories of the individual cerebral arteries. In the present study, we evaluate a noninvasive arterial spin labeling MRI method for selective mapping of the flow territories of the left and right internal carotid arteries and posterior circulation (basilar artery and vertebral arteries). METHODS: A spatially selective labeling approach, regional perfusion imaging, was developed on the basis of selective slab inversion of the arterial water with a pulsed arterial spin labeling sequence. The selectivity of this method was demonstrated. RESULTS: Regional perfusion imaging enables assessment of the perfusion territories of the major cerebral arteries. With selective labeling of an internal carotid artery, signal is present in both the ipsilateral anterior cerebral artery and ipsilateral middle cerebral artery flow territory. With labeling of the basilar artery, perfusion-weighted signal is symmetrically present in both posterior cerebral artery flow territories. Cerebral blood flow values measured with regional perfusion imaging in the complete hemisphere (40.1 mL x min(-1) x 100 g(-1) tissue), white matter (22.1 mL x min(-1) x 100 g(-1) tissue), and gray matter (65.8 mL x min(-1) x 100 g(-1) tissue) are in agreement with data in the literature. CONCLUSIONS: We present the first imaging method capable of evaluating both quantitatively and qualitatively the flow territories of the individual brain-feeding arteries in vivo.

Adult↗

PubMed2004

Multiple acquisitions with global inversion cycling (MAGIC): a multislice technique for vascular-space-occupancy dependent fMRI.

Recently, a new fMRI technique, termed vascular-space-occupancy (VASO), was introduced that uses T1-based blood nulling to detect cerebral blood volume (CBV) changes during brain activity. However, similar to other T1-preparation methods, this technique is hampered by the fact that there is only one zero-crossing on the relaxation curve, presently limiting its application to single-slice studies. A multislice VASO-fMRI method is presented that employs a series of nonselective 180 degrees pulses to periodically invert the magnetization and maintain it around zero, while acquiring slices in between. The effects of magnetization transfer and signal contamination by stimulated echoes are discussed. Solutions to reduce the effect of T1-signal decay as a function of slice number are provided. Phantom data show excellent agreement between experiments and numerical simulations. Multislice VASO-fMRI images of visual stimulation show effective blood nulling in all slices and appropriate functional activations in all volunteers (n=4).

Blood Volume↗

PubMed2004

Perfusion imaging using arterial spin labeling.

Arterial spin labeling is a magnetic resonance method for the measurement of cerebral blood flow. In its simplest form, the perfusion contrast in the images gathered by this technique comes from the subtraction of two successively acquired images: one with, and one without, proximal labeling of arterial water spins after a small delay time. Over the last decade, the method has moved from the experimental laboratory to the clinical environment. Furthermore, numerous improvements, ranging from new pulse sequence implementations to extensive theoretical studies, have broadened its reach and extended its potential applications. In this review, the multiple facets of this powerful yet difficult technique are discussed. Different implementations are compared, the theoretical background is summarized, and potential applications of various implementations in research as well as in the daily clinical routine are proposed. Finally, a summary of the new developments and emerging techniques in this field is provided.

Animals↗

PubMed2003

Effect of carotid endarterectomy on primary collateral blood flow in patients with severe carotid artery lesions.

BACKGROUND AND PURPOSE: In patients with severe obstruction of the internal carotid artery (ICA), it is recognized that the preoperative failure to visualize collaterals of the circle of Willis increases the risk of hemispheric ischemia before, during, and after carotid endarterectomy (CEA). The purpose of the present study was to assess the effect of CEA on the anatomy and function of the circle of Willis. METHODS: Time-of-flight and phase-contrast MR angiography were used to study changes in vessel diameter and collateral flow of the circle of Willis in 48 patients with 70% to 99% ICA stenosis before and after CEA. RESULTS: In patients with unilateral ICA stenosis, all preoperative vessel diameters on both sides of the circle of Willis were larger than in control subjects. All demonstrated a significant diameter decrease to reach normal values after CEA. Furthermore, preoperative collateral flow patterns normalized after CEA (P=0.03). In patients with stenosis and contralateral ICA occlusion, CEA resulted in a significant increase in the prevalence of collateral flow via the anterior communicating artery (33% to 83%, P<0.01) and a significant increase in diameter of both A1 segments (P<0.05) in patients in whom collateral flow developed after CEA. CONCLUSIONS: CEA reduces the caliber of compensatory collateral channels to normal levels by MR angiography measurements in the presence of severe unilateral stenosis; when the opposite side is occluded and the stenosis is removed ipsilaterally, a greater amount of compensatory collateral circulation can be measured on both the occluded side and the fully opened side.

Aged↗

PubMed2003

Measurements of cerebral perfusion and arterial hemodynamics during visual stimulation using TURBO-TILT.

Estimation of cerebral blood flow (CBF) in functional perfusion imaging could benefit from a method capable of separating effects of arterial arrival time and trailing edge. To accomplish this, the transfer insensitive labeling technique (TILT) was combined with a train of 13 consecutive acquisitions, called TURBO-TILT. Visual activation maps obtained at 13 postlabeling delay times (TI) showed a spatial shift from regions surrounding the arterial vasculature at short TI to brain parenchyma at longer delay times. High baseline CBF and short arrival times were found for the voxels with maximum activation at short TI (<1200 ms), while CBF values (43 ml / 100 g tissue/min) and its increase upon activation (55%) at longer TI were in agreement with literature data on regional cerebral perfusion.

Adult↗

PubMed2003

Hemodynamic compensation via an excimer laser-assisted, high-flow bypass before and after therapeutic occlusion of the internal carotid artery.

OBJECTIVE: High-flow, extracranial-intracranial (EC-IC) bypass operations are performed to prevent strokes among patients with giant aneurysms who cannot tolerate internal carotid artery (ICA) occlusion. However, the volume flow through the bypass, compared with preoperative ICA flow, has not been evaluated for any type of bypass. We describe a prospective case study that tested the ability of the high-flow EC-IC bypass to replace the volume flow of the ipsilateral ICA after deliberate ICA occlusion. METHODS: Seven consecutive patients with giant aneurysms of the ICA who experienced test occlusion failure underwent nonocclusive, excimer laser-assisted, EC-IC bypass surgery before permanent ICA occlusion. Volume flow values in the ICAs, the basilar artery, the EC-IC bypass, and the middle cerebral arteries were measured with magnetic resonance angiography. RESULTS: No significant changes in volume flow to the ipsilateral and contralateral hemispheres were observed after bypass surgery and therapeutic ICA occlusion. Before bypass surgery, the volume flow through the ipsilateral ICA was 243 +/- 74 ml/min, that through the contralateral ICA was 264 +/- 32 ml/min, and that through the basilar artery was 141 +/- 43 ml/min. After bypass surgery and therapeutic occlusion of the ipsilateral ICA, the volume flow through the bypass was 199 +/- 72 ml/min, that through the contralateral ICA was 303 +/- 82 ml/min, and that through the basilar artery was 153 +/- 72 ml/min. No significant preoperative versus postoperative changes in middle cerebral artery flow were observed on either side. CONCLUSION: The flow through the high-flow EC-IC bypass was able to replace the volume flow of the ipsilateral ICA after deliberate ICA occlusion for the treatment of giant aneurysms.

Adult↗