PurposeIntra-arterial Digital Subtraction Angiography (DSA) is the gold standard technique for radiosurgery target delineation in brain Arterio-Venous Malformations (AVMs). This study aims to... Show morePurposeIntra-arterial Digital Subtraction Angiography (DSA) is the gold standard technique for radiosurgery target delineation in brain Arterio-Venous Malformations (AVMs). This study aims to evaluate whether a combination of three Magnetic Resonance Angiography sequences (triple-MRA) could be used for delineation of brain AVMs for Gamma Knife Radiosurgery (GKR).MethodsFifteen patients undergoing DSA for GKR targeting of brain AVMs also underwent triple-MRA: 4D Arterial Spin Labelling based angiography (ASL-MRA), Contrast-Enhanced Time-Resolved MRA (CE-MRA) and High Definition post-contrast Time-Of-Flight angiography (HD-TOF). The arterial phase of the AVM nidus was delineated on triple-MRA by an interventional neuroradiologist and a consultant neurosurgeon (triple-MRA volume). Triple-MRA volumes were compared to AVM targets delineated by the clinical team for delivery of GKR using the current planning paradigm, i.e., stereotactic DSA and volumetric MRI (DSA volume). Difference in size, degree of inclusion (DI) and concordance index (CcI) between DSA and triple-MRA volumes are reported.ResultsAVM target volumes delineated on triple-MRA were on average 9.8% smaller than DSA volumes (95%CI:5.6-13.9%; SD:7.14%; p = .003). DI of DSA volume in triple-MRA volume was on average 73.5% (95%CI:71.2-76; range: 65-80%). The mean percentage of triple-MRA volume not included on DSA volume was 18% (95%CI:14.7-21.3; range: 7-30%).ConclusionThe technical feasibility of using triple-MRA for visualisation and delineation of brain AVMs for GKR planning has been demonstrated. Tighter and more precise delineation of AVM target volumes could be achieved by using triple-MRA for radiosurgery targeting. However, further research is required to ascertain the impact this may have in obliteration rates and side effects. Show less
Koemans, E.A.; Voigt, S.; Rasing, I.; Jolink, W.M.T.; Harten, T.W. van; Grond, J. van der; ... ; Wermer, M.J.H. 2021
Background and aimTo investigate whether a striped occipital cortex and intragyral hemorrhage, two markers recently detected on ultra-high-field 7-tesla-magnetic resonance imaging in hereditary... Show moreBackground and aimTo investigate whether a striped occipital cortex and intragyral hemorrhage, two markers recently detected on ultra-high-field 7-tesla-magnetic resonance imaging in hereditary cerebral amyloid angiopathy (CAA), also occur in sporadic CAA (sCAA) or non-sCAA intracerebral hemorrhage (ICH).MethodsWe performed 7-tesla-magnetic resonance imaging in patients with probable sCAA and patients with non-sCAA-ICH. Striped occipital cortex (linear hypointense stripes perpendicular to the cortex) and intragyral hemorrhage (hemorrhage restricted to the juxtacortical white matter of one gyrus) were scored on T-2*-weighted magnetic resonance imaging. We assessed the association between the markers, other CAA-magnetic resonance imaging markers and clinical features.ResultsWe included 33 patients with sCAA (median age 70 years) and 29 patients with non-sCAA-ICH (median age 58 years). Striped occipital cortex was detected in one (3%) patient with severe sCAA. Five intragyral hemorrhages were found in four (12%) sCAA patients. The markers were absent in the non-sCAA-ICH group. Patients with intragyral hemorrhages had more lobar ICHs (median count 6.5 vs. 1.0), lobar microbleeds (median count >50 vs. 15), and lower median cognitive scores (Mini Mental State Exam: 20 vs. 28, Montreal Cognitive Assessment: 18 vs. 24) compared with patients with sCAA without intragyral hemorrhage. In 12 (36%) patients, sCAA diagnosis was changed to mixed-type small vessel disease due to deep bleeds previously unobserved on lower field-magnetic resonance imaging.ConclusionWhereas a striped occipital cortex is rare in sCAA, 12% of patients with sCAA have intragyral hemorrhages. Intragyral hemorrhages seem to be related to advanced disease and their absence in patients with non-sCAA-ICH could suggest specificity for CAA. Show less
Background: Emerging evidence shows sex differences in manifestations of vascular brain injury in memory clinic patients. We hypothesize that this is explained by sex differences in cardiovascular... Show moreBackground: Emerging evidence shows sex differences in manifestations of vascular brain injury in memory clinic patients. We hypothesize that this is explained by sex differences in cardiovascular function.Objective: To assess the relation between sex and manifestations of vascular brain injury in patients with cognitive complaints, in interaction with cardiovascular function.Methods: 160 outpatient clinic patients (68.8 +/- 8.5 years, 38% female) with cognitive complaints and vascular brain injury from the Heart-Brain Connection study underwent a standardized work-up, including heart-brain MRI. We calculated sex differences in vascular brain injury (lacunar infarcts, non-lacunar infarcts, white matter hyperintensities [WMHs], and microbleeds) and cardiovascular function (arterial stiffness, cardiac index, left ventricular [LV] mass index, LV mass-to-volume ratio and cerebral blood flow). In separate regression models, we analyzed the interaction effect between sex and cardiovascular function markers on manifestations of vascular brain injury with interaction terms (sex*cardiovascular function marker).Results: Males had more infarcts, whereas females tended to have larger WMH-volumes. Males had higher LV mass indexes and LV mass-to-volume ratios and lower CBF values compared to females. Yet, we found no interaction effect between sex and individual cardiovascular function markers in relation to the different manifestations of vascular brain injury (p-values interaction terms > 0.05).Conclusion: Manifestations of vascular brain injury in patients with cognitive complaints differed by sex. There was no interaction between sex and cardiovascular function, warranting further studies to explain the observed sex differences in injury patterns. Show less
Amier, R.P.; Marcks, N.; Hooghiemstra, A.M.; Nijveldt, R.; Buchem, M.A. van; Roos, A. de; ... ; Heart-Brain Connection Consortium 2021
OBJECTIVES This study sought to investigate the extent of hypertensive exposure as assessed by cardiovascular magnetic resonance imaging (MRI) in relation to cerebral small vessel disease (CSVD)... Show moreOBJECTIVES This study sought to investigate the extent of hypertensive exposure as assessed by cardiovascular magnetic resonance imaging (MRI) in relation to cerebral small vessel disease (CSVD) and cognitive impairment, with the aim of understanding the role of hypertension in the early stages of deteriorating brain health.BACKGROUND Preserving brain health into advanced age is one of the great challenges of modern medicine. Hypertension is thought to induce vascular brain injury through exposure of the cerebral microcirculation to increased pressure/pulsatility. Cardiovascular MRI provides markers of (subclinical) hypertensive exposure, such as aortic stiffness by puke wave velocity (PWV), left ventricular (LV) mass index (LVMi), and concentricity by mass-to-volume ratio.METHODS A total of 559 participants from the Heart-Brain Connection Study (431 patients with manifest cardiovascular disease and 128 control participants), age 67.8 +/- 8.8 years, underwent 3.0-T heart-brain MRI and extensive neuropsychological testing. Aortic PWV, LVMi, and LV mass-to-volume ratio were evaluated in relation to presence of CSVD and cognitive impairment. Effect modification by patient group was investigated by interaction terms; results are reported pooled or stratified accordingly.RESULTS Aortic PWV (odds ratio [OR]: 1.17; 95% confidence interval [CI]: 1.05 to 1.30 in patient groups only), LVMi (in carotid occlusive disease, OR: 5.69; 95% CI: 1.63 to 19.87; in other groups, OR: 1.30; 95% CI: 1.05 to 1.62]) and LV mass-to-volume ratio (OR: 1.81; 95% CI: 1.46 to 2.24) were associated with CSVD. Aortic PWV (OR: 1.07; 95% CI: 1.02 to 1.13) and LV mass-to-volume ratio (OR: 1.27; 95% CI: 1.07 to 1.51) were also associated with cognitive impairment. Relations were independent of sociodemographic and cardiac index and mostly persisted after correction for systolic blood pressure or medical history of hypertension. Causal mediation analysis showed significant mediation by presence of CSVD in the relation between hypertensive exposure markers and cognitive impairment.CONCLUSIONS The extent of hypertensive exposure is associated with CSVD and cognitive impairment beyond clinical brood pressure or medical history. The mediating role of CSVD suggests that hypertension may lead to cognitive impairment through the occurrence of CSVD. (C) 2021 Published by Elsevier on behalf of the American College of Cardiology Foundation. Show less
Franklin, S.L.; Bones, I.K.; Harteveld, A.A.; Hirschler, L.; Stralen, M. van; Qin, Q.; ... ; Schmid, S. 2020
Purpose Flow-based arterial spin labeling (ASL) techniques provide a transit-time insensitive alternative to the more conventional spatially selective ASL techniques. However, it is not clear which... Show morePurpose Flow-based arterial spin labeling (ASL) techniques provide a transit-time insensitive alternative to the more conventional spatially selective ASL techniques. However, it is not clear which flow-based ASL technique performs best and also, how these techniques perform outside the brain (taking into account eg, flow-dynamics, field-inhomogeneity, and organ motion). In the current study we aimed to compare 4 flow-based ASL techniques (ie, velocity selective ASL, acceleration selective ASL, multiple velocity selective saturation ASL, and velocity selective inversion prepared ASL [VSI-ASL]) to the current spatially selective reference techniques in brain (ie, pseudo-continuous ASL [pCASL]) and kidney (ie, pCASL and flow alternating inversion recovery [FAIR]).Methods Brain (n = 5) and kidney (n = 6) scans were performed in healthy subjects at 3T. Perfusion-weighted signal (PWS) maps were generated and ASL techniques were compared based on temporal SNR (tSNR), sensitivity to perfusion changes using a visual stimulus (brain) and robustness to respiratory motion by comparing scans acquired in paced-breathing and free-breathing (kidney).Results In brain, all flow-based ASL techniques showed similar tSNR as pCASL, but only VSI-ASL showed similar sensitivity to perfusion changes. In kidney, all flow-based ASL techniques had comparable tSNR, although all lower than FAIR. In addition, VSI-ASL showed a sensitivity to B-1-inhomogeneity. All ASL techniques were relatively robust to respiratory motion.Conclusion In both brain and kidney, flow-based ASL techniques provide a planning-free and transit-time insensitive alternative to spatially selective ASL techniques. VSI-ASL shows the most potential overall, showing similar performance as the golden standard pCASL in brain. However, in kidney, a reduction of B-1-sensitivity of VSI-ASL is necessary to match the performance of FAIR. Show less
Petitclerc, L.; Schmid, S.; Hirschler, L.; Osch, M.J.P. van 2020
Purpose Arterial spin labeling can be used to assess the transition time of water molecules across the blood-brain barrier when combined with sequence modules, which allow a separation of... Show morePurpose Arterial spin labeling can be used to assess the transition time of water molecules across the blood-brain barrier when combined with sequence modules, which allow a separation of intravascular from tissue signal. The bipolar gradient technique measures the intravascular fraction by removing flowing spins. The T-2-relaxation-under-spin-tagging (TRUST) technique modulates the TE to differentiate between intravascular and extravascular spins based on T-2. These modules were combined into a single time-encoded pseudo-continuous arterial spin labeling sequence to compare their mechanisms of action as well as their assessment of water transition across the blood-brain barrier.Methods This protocol was acquired on a scanner with 9 healthy volunteers who provided written, informed consent. The sequence consisted of a Hadamard-encoded pseudo-continuous arterial spin labeling module, followed by the TRUST module (effective TEs of 0, 40, and 80 ms) and bipolar flow-crushing gradients (2, 4, and infinity cm/s). An additional experiment was performed with TRUST and a 3D gradient and spin-echo readout.Results Gradients imperfectly canceled the intravascular signal, as evidenced by the presence of residual signal in the arteries at early postlabeling delays as well as the underestimation of the intravascular fraction as compared with the TRUST method. The TRUST module allowed us to detect the transport of water deeper into the vascular tree through changes in T-2 than the used crusher gradients could, with their limited b-value.Conclusion Of the implemented techniques, TRUST allowed us to follow intravascular signal deeper into the vascular tree than the approach with (relatively weak) crusher gradients when quantifying the transport time of water across the blood-brain barrier. Show less
Vlastra, W.; Nieuwkerk, A.C. van; Bronzwaer, A.S.G.T.; Versteeg, A.; Bron, E.E.; Niessen, W.J.; ... ; Delewi, R. 2020
BACKGROUND Transcatheter aortic valve implantation (TAVI) is a minimally invasive, life-saving treatment for patients with severe aortic valve stenosis that improves quality of life. We examined... Show moreBACKGROUND Transcatheter aortic valve implantation (TAVI) is a minimally invasive, life-saving treatment for patients with severe aortic valve stenosis that improves quality of life. We examined cardiac output and cerebral blood flow in patients undergoing TAVI to test the hypothesis that improved cardiac output after TAVI is associated with an increase in cerebral blood flow. DESIGN Prospective cohort study. SETTING European high-volume tertiary multidisciplinary cardiac care. PARTICIPANTS Thirty-one patients (78.3 +/- 4.6 years; 61% female) with severe symptomatic aortic valve stenosis. MEASUREMENTS Noninvasive prospective assessment of cardiac output (L/min) by inert gas rebreathing and cerebral blood flow of the total gray matter (mL/100 g per min) using arterial spin labeling magnetic resonance imaging in resting state less than 24 hours before TAVI and at 3-month follow-up. Cerebral blood flow change was defined as the difference relative to baseline. RESULTS On average, cardiac output in patients with severe aortic valve stenosis increased from 4.0 +/- 1.1 to 5.4 +/- 2.4 L/min after TAVI (P= .003). The increase in cerebral blood flow after TAVI strongly varied between patients (7% +/- 24%;P= .41) and related to the increase in cardiac output, with an 8.2% (standard error = 2.3%;P= .003) increase in cerebral blood flow per every additional liter of cardiac output following the TAVI procedure. CONCLUSION Following TAVI, there was an association of increase in cardiac output with increase in cerebral blood flow. These findings encourage future larger studies to determine the influence of TAVI on cerebral blood flow and cognitive function. Show less
Arterial spin labeling (ASL) has undergone significant development since its inception, with a focus on improving standardization and reproducibility of its acquisition and quantification. In a... Show moreArterial spin labeling (ASL) has undergone significant development since its inception, with a focus on improving standardization and reproducibility of its acquisition and quantification. In a community-wide effort towards robust and reproducible clinical ASL image processing, we developed the software package ExploreASL, allowing standardized analyses across centers and scanners.The procedures used in ExploreASL capitalize on published image processing advancements and address the challenges of multi-center datasets with scanner-specific processing and artifact reduction to limit patient exclusion. ExploreASL is self-contained, written in MATLAB and based on Statistical Parameter Mapping (SPM) and runs on multiple operating systems. To facilitate collaboration and data-exchange, the toolbox follows several standards and recommendations for data structure, provenance, and best analysis practice.ExploreASL was iteratively refined and tested in the analysis of >10,000 ASL scans using different pulse-sequences in a variety of clinical populations, resulting in four processing modules: Import, Structural, ASL, and Population that perform tasks, respectively, for data curation, structural and ASL image processing and quality control, and finally preparing the results for statistical analyses on both single-subject and group level. We illustrate ExploreASL processing results from three cohorts: perinatally HIV-infected children, healthy adults, and elderly at risk for neurodegenerative disease. We show the reproducibility for each cohort when processed at different centers with different operating systems and MATLAB versions, and its effects on the quantification of gray matter cerebral blood flow.ExploreASL facilitates the standardization of image processing and quality control, allowing the pooling of cohorts which may increase statistical power and discover between-group perfusion differences. Ultimately, this workflow may advance ASL for wider adoption in clinical studies, trials, and practice. Show less
Retinal Vasculopathy with Cerebral Leukoencephalopathy and Systemic manifestations (RVCL-S) is a small vessel disease caused byTREX1mutations. RVCL-S is characterized by retinal vasculopathy and... Show moreRetinal Vasculopathy with Cerebral Leukoencephalopathy and Systemic manifestations (RVCL-S) is a small vessel disease caused byTREX1mutations. RVCL-S is characterized by retinal vasculopathy and brain white matter lesions with and without contrast enhancement. We aimed to investigate cerebrovascular reactivity (CVR) in RVCL-S. In this cross-sectional observational study, 21 RVCL-S patients, 23 mutation-negative family members, and 31 healthy unrelated controls were included. CVR to a hypercapnic challenge was measured using dual-echo arterial spin labeling magnetic resonance imaging. Stratified analyses based on age were performed. We found that CVR was decreased in gray and white matter of RVCL-S patients compared with family members and healthy controls (ANCOVA;P < 0.05 for all comparisons). This was most noticeable in RVCL-S patients aged >= 40 years (ANCOVA,P < 0.05 for all comparisons). In RVCL-S patients aged < 40 years, only CVR in white matter was lower when compared to healthy controls (P < 0.05). Gray matter CVR was associated with white matter lesion volume in RVCL-S patients (r = -0.527,P = 0.01). In conclusion, impaired cerebrovascular reactivity may play an important role in the pathophysiology of RVCL-S and may be an useful early biomarker of cerebrovascular disease severity. Show less
Purpose To determine whether sacrificing part of the scan time of pseudo-continuous arterial spin labeling (PCASL) for measurement of the labeling efficiency and blood T1 is beneficial in terms of... Show morePurpose To determine whether sacrificing part of the scan time of pseudo-continuous arterial spin labeling (PCASL) for measurement of the labeling efficiency and blood T1 is beneficial in terms of CBF quantification reliability.Methods In a simulation framework, 5-minute scan protocols with different scan time divisions between PCASL data acquisition and supporting measurements were evaluated in terms of CBF estimation variability across both noise and ground truth parameter realizations taken from the general population distribution. The entire simulation experiment was repeated for a single-post-labeling delay (PLD), multi-PLD, and free-lunch time-encoded (te-FL) PCASL acquisition strategy. Furthermore, a real data study was designed for preliminary validation.Results For the considered population statistics, measuring the labeling efficiency and the blood T1 proved beneficial in terms of CBF estimation variability for any distribution of the 5-minute scan time compared to only acquiring ASL data. Compared to single-PLD PCASL without support measurements as recommended in the consensus statement, a 26%, 33%, and 42% reduction in relative CBF estimation variability was found for optimal combinations of supporting measurements with single-PLD, free-lunch, and multi-PLD PCASL data acquisition, respectively. The benefit of taking the individual variation of blood T1 into account was also demonstrated in the real data experiment.Conclusions Spending time to measure the labeling efficiency and the blood T1 instead of acquiring more averages of the PCASL data proves to be advisable for robust CBF quantification in the general population. Show less
Disruption of the blood-brain barrier (BBB) might play a role in the pathophysiology of cerebral small vessel disease-related ICH. The aim of this study was to assess presence and extent of... Show moreDisruption of the blood-brain barrier (BBB) might play a role in the pathophysiology of cerebral small vessel disease-related ICH. The aim of this study was to assess presence and extent of contrast agent leakage distant from the hematoma as a marker of BBB disruption in patients with spontaneous ICH. We prospectively performed 7 tesla MRI in adult patients with spontaneous ICH and assessed contrast leakage distant from the hematoma on 3D FLAIR images. Thirty-one patients were included (mean age 60 years, 29% women). Median time between ICH and MRI was 20 days (IQR 9-67 days). Seventeen patients (54%; seven lobar, nine deep, one infratentorial ICH) had contrast leakage, located cortical in 16 and cortical and deep in one patient. Patients with contrast leakage more often had lobar cerebral microbleeds (CMBs; 77%) than those without (36%; RR 2.5, 95% CI 1.1-5.7) and a higher number of lobar CMBs (patients with contrast leakage: median 2, IQR 1-8 versus those without: median 0, IQR 0-2; p = 0.02). This study shows that contrast leakage distant from the hematoma is common in days to weeks after spontaneous ICH. It is located predominantly cortical and related to lobar CMBs and therefore possibly to cerebral amyloid angiopathy. Show less
Background The prevalence of impaired cognitive functioning in older patients with end stage kidney disease (ESKD) is high. We aim to describe patterns of memory, executive function or psychomotor... Show moreBackground The prevalence of impaired cognitive functioning in older patients with end stage kidney disease (ESKD) is high. We aim to describe patterns of memory, executive function or psychomotor speed and to identify nephrologic, geriatric and neuroradiologic characteristics associated with cognitive impairment in older patients approaching ESKD who have not yet started with renal replacement therapy (RRT). Methods The COPE-study (Cognitive Decline in Older Patients with ESRD) is a prospective cohort study including 157 participants aged 65 years and older approaching ESKD (eGFR <= 20 ml/min/1.73 m(2)) prior to starting with RRT. In addition to routinely collected clinical parameters related to ESKD, such as vascular disease burden and parameters of metabolic disturbance, patients received a full geriatric assessment, including extensive neuropsychological testing. In a subgroup of patients (n = 93) a brain MRI was performed. Results The median age was 75.3 years. Compared to the normative data of neuropsychological testing participants memory performance was in the 24th percentile, executive function in the 18th percentile and psychomotor speed in the 20th percentile. Independent associated characteristics of impairment in memory, executive and psychomotor speed were high age, low educational level and low functional status (all p-values < 0.003). A history of vascular disease (p = 0.007) and more white matter hyperintensities on brain MRI (p = 0.013) were associated with a lower psychomotor speed. Conclusion Older patients approaching ESKD have a high prevalence of impaired memory, executive function and psychomotor speed. The patterns of cognitive impairment and brain changes on MRI are suggestive of vascular cognitive impairment. These findings could be of potentially added value in the decision-making process concerning patients with ESKD. Show less
Bel, R. van der; Verbree, J.; Gurney-Champion, O.J.; Osch, M.J.P. van; Stroes, E.S.G.; Nederveen, A.J.; Krediet, C.T.P. 2020
Purpose There is ample evidence that systemic sympathetic neural activity contributes to the progression of chronic kidney disease, possibly by limiting renal blood flow and thereby inducing renal... Show morePurpose There is ample evidence that systemic sympathetic neural activity contributes to the progression of chronic kidney disease, possibly by limiting renal blood flow and thereby inducing renal hypoxia. Up to now there have been no direct observations of this mechanism in humans. We studied the effects of systemic sympathetic activation elicited by a lower body negative pressure (LBNP) on renal blood flow (RBF) and renal oxygenation in healthy humans. Methods Eight healthy volunteers (age 19-31 years) were subjected to progressive LBNP at - 15 and - 30 mmHg, 15 min per level. Brachial artery blood pressure was monitored intermittently. RBF was measured by phase-contrast MRI in the proximal renal artery. Renal vascular resistance was calculated as the MAP divided by the RBF. Renal oxygenation (R2*) was measured for the cortex and medulla by blood oxygen level dependent (BOLD) MRI, using a monoexponential fit. Results With a LBNP of - 30 mmHg, pulse pressure decreased from 50 +/- 10 to 43 +/- 7 mmHg; MAP did not change. RBF decreased from 1152 +/- 80 to 1038 +/- 83 mL/min to 950 +/- 67 mL/min at - 30 mmHg LBNP (p = 0.013). Heart rate and renal vascular resistance increased by 38 +/- 15% and 23 +/- 8% (p = 0.04) at - 30 mmHg LBNP, respectively. There was no change in cortical or medullary R2* (20.3 +/- 1.2 s(-1) vs 19.8 +/- 0.43 s(-1); 28.6 +/- 1.1 s(-1) vs 28.0 +/- 1.3 s(-1)). Conclusion The results suggest that an increase in sympathetic vasoconstrictor drive decreases kidney perfusion without a parallel reduction in oxygenation in healthy humans. This in turn indicates that sympathetic activation suppresses renal oxygen demand and supply equally, thus allowing adequate tissue oxygenation to be maintained. Show less
Purpose Arterial transit time uncertainties and challenges during planning are potential issues for renal perfusion measurement using spatially selective arterial spin labeling techniques. To... Show morePurpose Arterial transit time uncertainties and challenges during planning are potential issues for renal perfusion measurement using spatially selective arterial spin labeling techniques. To mitigate these potential issues, a spatially non-selective technique, such as velocity-selective arterial spin labeling (VSASL), could be an alternative. This article explores the influence of VSASL sequence parameters and respiratory induced motion on VS-label generation. Methods VSASL data were acquired in human subjects (n= 15), with both single and dual labeling, during paced-breathing, while essential sequence parameters were systematically varied; (1) cutoff velocity, (2) labeling gradient orientation and (3) post-labeling delay (PLD). Pseudo-continuous ASL was acquired as a spatially selective reference. In an additional free-breathing single VSASL experiment (n= 9) we investigated respiratory motion influence on VS-labeling. Absolute renal blood flow (RBF), perfusion weighted signal (PWS), and temporal signal-to-noise ratio (tSNR) were determined. Results (1) With decreasing cutoff velocity, tSNR and PWS increased. However, undesired tissue labeling occurred at low cutoff velocities (<= 5.4 cm/s). (2) Labeling gradient orientation had little effect on tSNR and PWS. (3) For single VSASL high signal appeared in the kidney pedicle at PLD < 800 ms, and tSNR and PWS decreased with increasing PLD. For dual VSASL, maximum tSNR occurred at PLD = 1200 ms. Average cortical RBF measured with dual VSASL (264 +/- 34 mL/min/100 g) at a cutoff velocity of 5.4 cm/s, and feet-head labeling was slightly lower than with pseudo-continuous ASL (283 +/- 55 mL/min/100 g). Conclusion With well-chosen sequence parameters, tissue labeling induced by respiratory motion can be minimized, allowing to obtain good quality RBF maps using planning-free labeling with dual VSASL. Show less
Harteveld, A.A.; Hutter, J.; Franklin, S.L.; Jackson, L.H.; Rutherford, M.; Hajnal, J.V.; ... ; Vita, E. de 2020
Purpose: Placental function is key for successful human pregnancies. Perfusion may be a sensitive marker for the in vivo assessment of placental function. Arterial spin labeling (ASL) MRI enables... Show morePurpose: Placental function is key for successful human pregnancies. Perfusion may be a sensitive marker for the in vivo assessment of placental function. Arterial spin labeling (ASL) MRI enables noninvasive measurement of tissue perfusion and it was recently suggested that ASL with velocity-selective (VS) labeling could be advantageous in the placenta. We systematically evaluated essential VS-ASL sequence parameters to determine optimal settings for efficient placental perfusion measurements.Methods: Eleven pregnant women were scanned at 3T using VS-ASL with 2D multislice echo planar imaging (EPI)-readout. One reference VS-ASL scan was acquired in all subjects; within subgroups the following parameters were systematically varied: cutoff velocity, velocity encoding direction, and inflow time. Visual evaluation and region of interest analyses were performed to compare perfusion signal differences between acquisitions.Results: In all subjects, a perfusion pattern with clear hyperintense focal regions was observed. Perfusion signal decreased with inflow time and cutoff velocity. Subject-specific dependence on velocity encoding direction was observed. High temporal signal-to-noise ratios with high contrast on the perfusion images between the hyperintense regions and placental tissue were seen at similar to 1.6 cm/s cutoff velocity and similar to 1000 ms inflow time. Evaluation of measurements at multiple inflow times revealed differences in blood flow dynamics between placental regions.Conclusion: Placental perfusion measurements are feasible at 3T using VS-ASL with 2D multislice EPI-readout. A clear dependence of perfusion signal on VS labeling parameters and inflow time was demonstrated. Whereas multiple parameter combinations may advance the interpretation of placental circulation dynamics, this study provides a basis to select an effective set of parameters for the observation of placenta perfusion natural history and its potential pathological changes. Show less
Franklin, S.L.; Schmid, S.; Bos, C.; Osch, M.J.P. van 2020
Purpose: In this study, the influence of the cardiac cycle on the amount of label produced by a velocity-selective (VSASL) and acceleration-selective arterial spin labeling (AccASL) module was... Show morePurpose: In this study, the influence of the cardiac cycle on the amount of label produced by a velocity-selective (VSASL) and acceleration-selective arterial spin labeling (AccASL) module was investigated.Methods: A short-PLD sequence was developed where a single VSASL- or AccASL-module was preceded by pCASL labeling to isolate the arterial blood pool. ASL subtraction was performed with label/control images with similar cardiac phase and time-of-measurement, followed by retrospective binning in 10 cardiac phase bins. ASL signal variation over the heart cycle was evaluated and tested for significance using a permutation test.Results: VSASL and AccASL showed significant arterial signal fluctuations over the cardiac cycle of up to similar to 36% and similar to 64%, respectively, mainly in areas containing large arteries. pCASL also showed significant signal fluctuations, of up to similar to 25% in arteries. Raw label/control images confirmed that the observed signal fluctuations were caused by the amount of label produced during the cardiac cycle, rather than inflow-effects, because the raw images did not all show equal cardiac phase dependence. No significant effects of the cardiac cycle were found on the gray matter ASL-signal.Conclusion: Significant influence of the cardiac cycle on the generated label was found for spatially nonselective ASL-sequences. Hence, to become independent of the cardiac cycle, sufficient averages need to be taken. Alternatively, these findings could be highly interesting for the purpose of quantifying pulsatility more distally in the vascular tree. Show less
The Dutch prospective multicenter cohort study COPE (Cognitive decline in Older Patients with End stage renal disease) aimed to investigate the association of cardiovascular structure and function... Show moreThe Dutch prospective multicenter cohort study COPE (Cognitive decline in Older Patients with End stage renal disease) aimed to investigate the association of cardiovascular structure and function with cerebrovascular changes and cognitive function in 85 older patients with chronic kidney disease stage 4 and 5, awaiting either dialysis or conservative care. MRI was performed measuring aortic stiffness (pulse wave velocity [PWV]) and cardiac systolic function (ejection fraction and cardiac index). Outcomes were MRI-derived cerebrovascular changes (microbleeds, lacunes and white matter hyperintensities) and cognitive function (memory, executive function and psychomotor speed). Mean age was 76 years and 66% were male. No statistically significant associations were observed between cardiovascular parameters and cerebrovascular changes. Cognitive function was worse in patients with high compared to low PWV in all three cognitive domains. Although there were clinically relevant associations of high PWV with poor cognition in all domains, after adjustment for age, sex and education only the Trail Making Test A remained statistically significant (p=0.030). In conclusion, this study suggests that a higher PWV might be associated with lower cognitive function, suggesting that arterial stiffness may be an underlying mechanism of development of cognitive impairment in older patients with ESRD. Larger studies should replicate and extend these findings. Show less
Pezzotti, N.; Yousefi, S.; Elmahdy, M.S.; Gemert, J.H.F. van; Schuelke, C.; Doneva, M.; ... ; Staring, M. 2020
Adaptive intelligence aims at empowering machine learning techniques with the additional use of domain knowledge. In this work, we present the application of adaptive intelligence to accelerate MR... Show moreAdaptive intelligence aims at empowering machine learning techniques with the additional use of domain knowledge. In this work, we present the application of adaptive intelligence to accelerate MR acquisition. Starting from undersampled k-space data, an iterative learning-based reconstruction scheme inspired by compressed sensing theory is used to reconstruct the images. We developed a novel deep neural network to refine and correct prior reconstruction assumptions given the training data. The network was trained and tested on a knee MRI dataset from the 2019 fastMRI challenge organized by Facebook AI Research and NYU Langone Health. All submissions to the challenge were initially ranked based on similarity with a known groundtruth, after which the top 4 submissions were evaluated radiologically. Our method was evaluated by the fastMRI organizers on an independent challenge dataset. It ranked #1, shared #1, and #3 on respectively the 8x accelerated multi-coil, the 4x multi-coil, and the 4x single-coil tracks. This demonstrates the superior performance and wide applicability of the method. Show less
In the 1980's some of the earliest studies of arterial spin labeling (ASL) MRI have demonstrated its ability to generate MR angiography (MRA) images. Thanks to many technical improvements, ASL has... Show moreIn the 1980's some of the earliest studies of arterial spin labeling (ASL) MRI have demonstrated its ability to generate MR angiography (MRA) images. Thanks to many technical improvements, ASL has been success-fully moving its position from the realm of research into the clinical area, albeit more known as perfusion imaging than as MRA. For MRA imaging, other techniques such as time-of-flight, phase contrast MRA and contrast-enhanced (CE) MRA are more popular choices for clinical applications. In the last decade, however, ASL-MRA has been experiencing a remarkable revival, especially because of its non-invasive nature, i.e. the fact that it does not rely on the use of contrast agent. Very importantly, there are additional benefits of using ASL for MRA. For example, its higher flexibility to achieve both high spatial and temporal resolution than CE dynamic MRA, and the capability of vessel specific visualization, in which the vascular tree arising from a selected artery can be exclusively visualized. In this article, the implementation and recent developments of ASI,-based MRA are discussed; not only focusing on the basic sequences based upon pulsed ASL or pseudo-continuous ASL, but also including more recent labeling approaches, such as vessel-selective labeling, velocity-selective ASL, vessel-encoded ASL and time-encoded ASL. Although these ASL techniques have been already utilized in perfusion imaging and their usefulness has been suggested by many studies, some additional considerations should be made when employing them for MRA, since there is something more than the difference of the spatial resolution of the readout sequence. Moreover, extensive discussion is included on what readout sequence to use, especially by highlighting how to achieve high spatial resolution while keeping scan-time reasonable such that the ASL-MRA sequence can easily be included into a clinical examination. Show less
Cerebral vein thrombosis (CVT) is a rare presentation of venous thromboembolism. Prompt and accurate diagnosis is essential as delayed recognition and treatment may lead to permanent disability or... Show moreCerebral vein thrombosis (CVT) is a rare presentation of venous thromboembolism. Prompt and accurate diagnosis is essential as delayed recognition and treatment may lead to permanent disability or even death. Since no validated diagnostic algorithms exist, the diagnosis of CVT mainly relies on neuroimaging. Digital subtraction angiography (DSA) is the historical diagnostic standard for CVT, but is rarely used nowadays and replaced by computed tomography (CT) and magnetic resonance imaging (MRI). High quality studies to evaluate the diagnostic test characteristics of state of the art imaging modalities are however unavailable to date. This review provides an overview of the best available evidence regarding the diagnostic performance of CT and MRI for the diagnosis of CVT. Notably, available studies are observational, mostly small, outdated, and with a high risk of bias. Therefore, direct comparison between studies is difficult due to large diversity in study design, imaging method, reference standard, patient selection and sample size. In general, contrast-enhanced techniques are more accurate for the diagnosis of CVT then non-contrast-enhanced techniques. CT venography and MRI have been both reported to be adequate for establishing a final diagnosis of CVT, but choice of modality as used in clinical practice depends on availability, local preference and experience, as well as patient characteristics. Our review underlines the need for high-quality diagnostic studies comparing CT venography and MRI in specific settings, to improve clinical care and standardize clinical trials. Show less
