Long-term prognostic value of [15O]H2O PET imaging in patients suspected for cerebral hemodynamic insufficiency.

OBJECTIVES: Quantitative regional cerebral perfusion (rCBF) measurements using [15O]H2O PET with arterial cannulation and acetazolamide (ACZ) challenge have been reserved to identify high-risk patients that are candidates for by-pass operation. We aimed to assess the prognostic value of various parameters in quantitative [15O]H2O PET measurements in patients not subsequently undergoing surgery. METHODS: We identified 32 eligible patients who underwent [15O]H2O brain PET imaging for suspicion of hemodynamic insufficiency between 2009 and 2020. Cerebrovascular events were defined as new ischemic lesions on MRI, stroke, transient ischemic attack, vascular dementia. Follow-up period was 91 months (range: 26-146). rCBF before (rCBFbase) and after (rCBFacz) ACZ challenge and the relative increase (CVR), were examined in the anterior (ACA), middle (MCA), and posterior (PCA) cerebral artery territories of the affected hemisphere, and the most recent MRI scans were scored for infarcts and white matter lesions. RESULTS: Receiver operating characteristic (ROC) curve analysis showed higher prognostic accuracy for rCBFacz(AUC:0.82) compared to CVR (AUC:0.72) and rCBFbase (AUC:0.77). ROC AUC, optimal thresholds (and corresponding sensitivity/specificity/accuracy) for rCBFacz after ACZ in individual territories were 0.79 and 37.8 mL 100g-1 min-1 (0.81/0.63/0.72) for the ACA, 0.84 and 32 mL 100g-1 min-1 (0.81/0.75/0.78) for the MCA, and 0.70 and 43.9 ml/(mL 100g-1 min-1 (0.81/0.43/0,62) for the PCA. Kaplan Meier survival curve showed longer event-free survival in patients with rCBFacz below cut-off (p=0.007). In multivariate analysis rCBFacz remained a significant predictor when correcting for age. CONCLUSION: Quantitative rCBF measurements after ACZ challenge with [15O]H2O PET provided high prognostic value for future cerebrovascular events.

Symptoms of arteria spinalis anterior syndrome in a patient with ischaemic stroke and Takayasu arteritis.

In Denmark, around 4,500 people are diagnosed with colorectal cancer (CRC) annually. This review investigates that while the efficacy of immunotherapy in CRC is still being studied, immunotherapy is currently only indicated in the treatment of mismatch-repair deficient (dMMR) metastatic CRC, which accounts for 10-15% of patients. Recent studies indicate high rates of pathologic response in dMMR CRC treated with pre-operative immunotherapy while large-scale studies on novel immunotherapy combinations are ongoing.

Left atrial late gadolinium enhancement in patients with ischaemic stroke.

AIMS: To evaluate the extent of left atrial (LA) fibrosis in patients with a recent stroke without atrial fibrillation and controls without established cardiovascular disease. METHODS AND RESULTS: This prospectively designed study used cardiac magnetic resonance to detect LA late gadolinium enhancement as a proxy for LA fibrosis. Between 2019 and 2021, we consecutively included 100 patients free of atrial fibrillation with recent ischaemic stroke (<30 days) and 50 age- and sex-matched controls. LA fibrosis assessment was achieved in 78 patients and 45 controls. Blinded to the cardiac magnetic resonance results, strokes were adjudicated according to modified Trial of Org 10172 in Acute Stroke Treatment classification as undetermined aetiology (n = 42) or as attributable to large- or small-vessel disease (n = 36). Patients with stroke had a larger extent of LA fibrosis [6.9%, interquartile range (IQR) 3.6-15.4%] than matched controls (4.2%, IQR 2.3-7.5%; P = 0.007). No differences in LA fibrosis were observed between patients with stroke of undetermined aetiology and those with large- or small-vessel disease (6.6%, IQR 3.8-16.0% vs. 6.9%, IQR 3.4-14.6%; P = 0.73). CONCLUSION: LA fibrosis was more extensive in patients with stroke than in age- and sex-matched controls. A similar extent of LA fibrosis was observed in patients with stroke of undetermined aetiology and stroke classified as attributable to large- or small-vessel disease. Our findings suggest that LA structural abnormality is more frequent in patients with stroke than in controls independent of aetiological classification.

Corrigendum: Sex-differences in oral anticoagulant-related intracerebral hemorrhage.

[This corrects the article DOI: 10.3389/fneur.2022.832903.].

Atrial cardiomyopathy in patients with ischaemic stroke: a cross-sectional and prospective cohort study-the COAST study.

INTRODUCTION: Despite workup for the aetiology of ischaemic stroke, about 25% of cases remain unexplained. Paroxysmal atrial fibrillation is typically suspected but often not detected. Even if atrial fibrillation (AF) is detected, the quantitative threshold of clinically relevant AF remains unclear. Emerging evidence suggests that left atrial (LA) functional and structural abnormalities may convey a risk of ischaemic stroke in which AF is only one of several features. These abnormalities have been termed 'atrial cardiomyopathy'. This study uses cardiac magnetic resonance (CMR) to evaluate atrial cardiomyopathy among patients with stroke of undetermined aetiology compared with those with an attributable mechanism and controls without established cardiovascular disease. METHODS AND ANALYSIS: This cross-sectional and prospective cohort study included 100 patients with recent ischaemic stroke and 50 controls with no established cardiovascular disease. The study will assess LA structural and functional abnormalities with CMR. Inclusion began in March 2019, and follow-up is planned to be complete in January 2023. There are two scheduled follow-ups: (1) 18 months after individual inclusion, counting from the index diagnostic MRI of the brain, (2) end of study follow-up at 18 months after inclusion of the last patient, assessing the incidence of recurrent ischaemic stroke, AF and cardiovascular death. The primary endpoint is the extent of CMR-assessed atrial fibrosis in the LA at baseline. The study is powered to detect a difference of 6% fibrosis between stroke of undetermined aetiology and stroke of known mechanism with a SD of 9%, a significance level of 0.05, and power of 80%. ETHICS AND DISSEMINATION: This study has been approved by the Danish National Committee on Health Research Ethics (H-18055313). All participants in the study signed informed consent. Results from the study will be published in peer-reviewed journals regardless of the outcome. TRIAL REGISTRATION NUMBER: NCT03830983.

Sex-Differences in Oral Anticoagulant-Related Intracerebral Hemorrhage.

Introduction and Aim: Data remain limited on sex-differences in patients with oral anticoagulant (OAC)-related intracerebral hemorrhage (ICH). We aim to explore similarities and differences in risk factors, acute presentation, treatments, and outcome in men and women admitted with OAC-related ICH. Method: This study was a retrospective observational study based on 401 consecutive patients with OAC-related ICH admitted within 24 h of symptom onset. The study was registered on osf.io. We performed logarithmic regression and cox-regression adjusting for age, hematoma volume, Charlson Comorbidity Index (CCI), and pre-stroke modified Ranking Scale (mRS). Gender and age were excluded from CHA2DS2-VASc and CCI was not adjusted for age. Results: A total of 226 men and 175 women were identified. More men were pre-treated with vitamin K-antagonists (73.5% men vs. 60.6% women) and more women with non-vitamin K-antagonist oral anticoagulants (26.5% men vs. 39.4% women), p = 0.009. Women were older (mean age 81.9 vs. 76.9 years, p < 0.001). CHA2DS2-VASc and CCI were similar in men and women.Hematoma volumes (22.1 ml in men and 19.1 ml in women) and National Institute of Health Stroke Scale (NIHSS) scores (13 vs. 13) were not statistically different, while median Glasgow Coma Scale (GCS) was lower in women, (14 [8;15] vs. 14 [10;15] p = 0.003).Women's probability of receiving reversal agents was significantly lower (adjusted odds ratio [aOR] = 0.52, p = 0.007) but not for surgical clot removal (aOR = 0.56, p = 0.25). Women had higher odds of receiving do-not-resuscitate (DNR) orders within a week (aOR = 1.67, p = 0.04). There were no sex-differences in neurological deterioration (aOR = 1.48, p = 0.10), ability to walk at 3 months (aOR = 0.69, p = 0.21) or 1-year mortality (adjusted hazard ratio = 1.18, p = 0.27). Conclusion: Significant sex-differences were observed in age, risk factors, access to treatment, and DNRs while no significant differences were observed in comorbidity burden, stroke severity, or hematoma volume. Outcomes, such as adjusted mortality, ability to walk, and neurological deterioration, were comparable. This study supports the presence of sex-differences in risk factors and care but not in presentation and outcomes.

Trends in incidence of oral anticoagulant-related intracerebral hemorrhage and sales of oral anticoagulants in Capital Region of Denmark 2010-2017.

INTRODUCTION: Non-vitamin K-antagonist oral anticoagulants (NOAC) have become first choice oral anticoagulant (OAC) with decreasing use of vitamin K antagonists (VKA), partly due to lower risk of intracerebral hemorrhage (ICH). Aim: to identify trends in sale of OACs and relate them to trends in OAC-related ICH (OAC-ICH). PATIENTS AND METHODS: Study was based on the population in the Capital Region of Denmark (1.8 million inhabitants). We identified all patients admitted with a non-traumatic OAC-ICH in 2010-2017 and ascertained diagnosis and drug use through medical charts. We used information available in the public domain on sale of defined daily doses (DDD) of OAC in the Capital Region of Denmark. RESULTS: 453 patients with OAC-ICH out of a total of 2877 ICH-events were identified. From 2010 to 2017 sale of NOAC rose from 0.1 to 11.8 DDD/1000 inhabitants/day (p < 0.001); while VKA sale decreased from 7.6 to 5.2 DDD/1000 inhabitants/day (p < 0.001). The total number of ICH events was stable between 2010 and 2017, but the proportion of OAC-ICH events increased from 13% in 2010 to 22% in 2017 (p < 0.001). The proportion of ICH events related to NOAC had a significant increasing trend (p < 0.001), whereas a decreasing trend was observed for VKA (p = 0.04). DISCUSSION: In Denmark, the population on OACs has increased; resulting from increased use of NOACs. Parallel to this development, the proportion of OAC-ICH overall has increased based on an increasing trend in NOAC-related ICH. CONCLUSION: Our findings document a need for further research on prevention and treatment of this complication.

[Todd's paralysis].

Todd's paralysis is a clinical entity consisting of acute focal neurological deficits following an epileptic seizure. It occurs after 6-13% of seizures, and the symptoms may last from minutes to 36 hours. Stroke with seizure at symptom onset is difficult to differentiate clinically from Todd's paralysis. The use of advanced imaging such as cerebral CT and MRI with angiography is recommended. This is a review of the current knowledge on pathogenesis, clinical presentation and differential diagnoses, and we propose an investigation plan for patients presenting with symptoms of Todd's paralysis.

Dural tear from diagnostic lumbar puncture followed by long-term morbidity: a case report.

BACKGROUND: Lumbar punctures are performed in different medical settings and are a key procedure in the diagnosis of several neurological conditions. Complications are rare and generally self-limiting. There are no reports of symptomatic accumulation of fluid in the epidural space after lumbar puncture in adults and there are no studies on long-term outcome after post dural puncture headache (PDPH). CASE: A lumbar puncture was performed in a 29 y.o. slender woman with unspecific symptoms to rule out neuro-infection. Next day MRI showed substantial accumulation of CSF in the epidural space from C2 to the sacrum dislocating the spinal chord in the spinal canal. The condition was ameliorated by epidural blood-patching. At 5 months she was still impaired by severe orthostatic headache. CONCLUSIONS: The only plausible explanation for the massive CSF leak was a dural tear occurring during multiple attempts of lumbar puncture. Anterior dislocation of the spinal chord due to CSF leak is not a recognised complication to lumbar puncture. This complication was followed by long-term disability in our case. The diagnosis can be made by MRI. A difficult procedure with several attempts and use of traumatic technique may increase risk of this complication.

Computer-Based Cognitive Rehabilitation in Patients with Visuospatial Neglect or Homonymous Hemianopia after Stroke.

OBJECTIVES: The purpose of this pilot study was to investigate the feasibility and effects of computer-based cognitive rehabilitation (CBCR) in patients with symptoms of visuospatial neglect or homonymous hemianopia in the subacute phase following stroke. METHOD: A randomized, controlled, unblinded cross-over design was completed with early versus late CBCR including 7 patients in the early intervention group (EI) and 7 patients in the late intervention group (LI). EI received CBCR training immediately after inclusion (m = 19 days after stroke onset) for 3 weeks and LI waited for 3 weeks after inclusion before receiving CBCR training for 3 weeks (m = 44 days after stroke onset). RESULTS: CBCR improved visuospatial symptoms after stroke significantly when administered early in the subacute phase after stroke. The same significant effect was not found when CBCR was administered later in the rehabilitation. The difference in the development of the EI and LI groups during the first 3 weeks was not significant, which could be due to a lack of statistical power. CBCR did not impact mental well-being negatively in any of the groups. In the LI group, the anticipation of CBCR seemed to have a positive impact of mental well-being. CONCLUSION: CBCR is feasible and has a positive effect on symptoms in patients with visuospatial symptoms in the subacute phase after stroke. The study was small and confirmation in larger samples with blinded outcome assessors is needed.

Brain resting-state connectivity in the development of secondary hyperalgesia in healthy men.

Central sensitization is a condition in which there is an abnormal responsiveness to nociceptive stimuli. As such, the process may contribute to the development and maintenance of pain. Factors influencing the propensity for development of central sensitization have been a subject of intense debate and remain elusive. Injury-induced secondary hyperalgesia can be elicited by experimental pain models in humans, and is believed to be a result of central sensitization. Secondary hyperalgesia may thus reflect the individual level of central sensitization. The objective of this study was to investigate possible associations between increasing size of secondary hyperalgesia area and brain connectivity in known resting-state networks. We recruited 121 healthy participants (male, age 22, SD 3.35) who underwent resting-state functional magnetic resonance imaging. Prior to the scan session, areas of secondary hyperalgesia following brief thermal sensitization (3 min. 45 °C heat stimulation) were evaluated in all participants. 115 participants were included in the final analysis. We found a positive correlation (increasing connectivity) with increasing area of secondary hyperalgesia in the sensorimotor- and default mode networks. We also observed a negative correlation (decreasing connectivity) with increasing secondary hyperalgesia area in the sensorimotor-, fronto-parietal-, and default mode networks. Our findings indicate that increasing area of secondary hyperalgesia is associated with increasing and decreasing connectivity in multiple networks, suggesting that differences in the propensity for central sensitization, assessed as secondary hyperalgesia areas, may be expressed as differences in the resting-state central neuronal activity.

Significance of arterial spin labeling perfusion and susceptibility weighted imaging changes in patients with transient ischemic attack: a prospective cohort study.

BACKGROUND: In a prospective cohort of patients with transient ischemic attack (TIA), we investigated usefulness and feasibility of arterial spin labeling (ASL) perfusion and susceptibility weighted imaging (SWI) alone and in combination with standard diffusion weighted (DWI) imaging in subacute diagnostic work-up. We investigated rates of ASL and SWI changes and their potential correlation to lasting infarction 8 weeks after ictus. METHODS: Patients with TIA underwent 3T-MRI including DWI, ASL and SWI within 72 h of symptom onset. We defined lasting infarction as presence of 8-week MRI T2-fluid attenuated inversion recovery (FLAIR) hyperintensity or atrophy in the area of initial DWI-lesion. RESULTS: We included 116 patients. Diffusion and perfusion together identified more patients with ischemia than either alone (59% vs. 40%, p < 0.0001). The presence of both diffusion and perfusion lesions had the highest rate of 8-week gliosis scars, 65% (p < 0.0001). In white matter, DWI-restriction was the determinant factor for scar development. However, in cortical gray matter half of lesions with perfusion deficit left a scar, while lesions without perfusion change rarely resulted in scars (56% versus 21%, p = 0.03). SWI lesions were rare (6%) and a subset of perfusion lesions. SWI-lesions with DWI-lesions were all located in cortical gray matter and showed high scar rate. CONCLUSIONS: ASL perfusion increased ischemia detection in patients with TIA, and was most useful in conjunction with DWI. ASL was fast, robust and useful in a subacute clinical diagnostic setting. SWI had few positive findings and did not add information. TRIAL REGISTRATION: http://www.clinicaltrials.gov . Unique Identifier NCT01531946 , prospectively registered February 9, 2012.

The association between areas of secondary hyperalgesia and volumes of the caudate nuclei and other pain relevant brain structures-A 3-tesla MRI study of healthy men.

INTRODUCTION: Central sensitization plays a pivotal role in maintenance of pain and is believed to be intricately involved in several chronic pain conditions. One clinical manifestation of central sensitization is secondary hyperalgesia. The degree of secondary hyperalgesia presumably reflects individual levels of central sensitization. The objective of this study was to investigate the association between areas of secondary hyperalgesia and volumes of the caudate nuclei and other brain structures involved in pain processing. MATERIALS AND METHODS: We recruited 121 healthy male participants; 118 were included in the final analysis. All participants underwent whole brain magnetic resonance imaging (MRI). Prior to MRI, all participants underwent pain testing. Secondary hyperalgesia was induced by brief thermal sensitization. Additionally, we recorded heat pain detection thresholds (HPDT), pain during one minute thermal stimulation (p-TS) and results of the Pain Catastrophizing Scale (PCS) and Hospital Anxiety and Depression score (HADS). RESULTS: We found no significant associations between the size of the area of secondary hyperalgesia and the volume of the caudate nuclei or of the following structures: primary somatosensory cortex, anterior and mid cingulate cortex, putamen, nucleus accumbens, globus pallidus, insula and the cerebellum. Likewise, we found no significant associations between the volume of the caudate nuclei and HPDTs, p-TS, PCS and HADS. CONCLUSIONS: Our findings indicate that the size of the secondary hyperalgesia area is not associated with the volume of brain structures relevant for pain processing, suggesting that the propensity to develop central sensitization, assessed as secondary hyperalgesia, is not correlated to brain structure volume.

Prevalence of early neurological deterioration after I.V - thrombolysis in acute ischaemic stroke patients - A hospital-based cohort study.

OBJECTIVES: Early Neurological Deterioration (END) occur in up to 25% of patients with ischaemic stroke receiving stroke-unit-care and in 11-13.8% of patients treated with iv-tissue-Plasmniogen-Activator (iv-tPA). The aim of the study was to establish and compare the prevalence of END and symptomatic Intracranial Hemorrhage (sICH) in a prospectively designed registry of consecutive patients treated with iv-tPA to a historic cohort of iv-tPA eligible patients whom were hospitalized prior to implementation of iv-tPA-treatment but receiving otherwise comparable acute stroke care. PATIENTS AND METHODS: Single center registry from a public Danish stroke-unit. Three-hundred-sixty-one unselected consecutive iv-tPA-treated patients admitted within 4.5 h from symptom-onset with symptoms of acute stroke and >17 years of age. The iv-tPA-treated cohort was compared to a pre-tPA cohort of 246 iv-tPA-eligible patients who were admitted to the same stroke center from 1998 to 2001. Acute stroke care apart from iv-tPA was comparable. Outcome measures was assessed on admission and at 24 h; END as any increase in National Institute of Health Stroke Scale (NIHSS) and symptomatic Intracranial Hemorrhage (sICH) with use of CT-head-scan. RESULTS: END was observed in 27 (7.5%) of the 361 patients in the tPA-cohort and 43 (17.5%) of 246 in the pre-tPA-cohort, p < 0.0001. Any ICH was detected in 23 (6.4%) and sICH in 3 (0.8%) of the iv-tPA-treated patients. CONCLUSION: END is significantly less frequent in acute stroke patients treated with iv-tPA. Deterioration due to ICH was rare and of limited severity in this population. END though remains a significant complication after stroke why more detailed knowledge on the various causes of END is needed to further improve patient outcome.

Arterial spin labeling: a technical overview.

Arterial spin labeling (ASL) is a non-invasive magnetic resonance imaging perfusion method based on changes in net-magnetization of blood water. The absence of contrast use and ionizing radiation, renders ASL valuable in hyper-acute settings as a monitoring tool for repeated dynamical measurements during and after intervention, and for patients with known co-morbidities. This text provides a short methodological introduction to ASL and contrasts it with traditional contrast-enhanced perfusion imaging. The review focused on sequence usefulness in the clinical setting of acute cerebral ischemia investigation.

Small cortical grey matter lesions show no persistent infarction in transient ischaemic attack? A prospective cohort study.

OBJECTIVES: To find determining factors for persistent infarction signs in patients with transient ischaemic attack (TIA), herein initial diffusion lesion size, visibility on apparent diffusion coefficient (ADC) or fluid-attenuated inversion recovery (FLAIR) and location. DESIGN: Prospective cohort study of patients with clinical TIA receiving 3T-MRI within 72 hours of symptom onset and at 8-week follow-up. SETTING: Clinical workflow in a single tertiary stroke centre between February 2012 and June 2014. PARTICIPANTS: 199 candidate patients were recruited, 64 patients were excluded due to non-TIA discharge diagnosis or no 8-week MRI. 122 patients completed the study. PRIMARY OUTCOME MEASURES: The primary outcome was visible persistent infarction defined as 8-week FLAIR hyperintensity or atrophy corresponding to the initial diffusion-weighted imaging (DWI) lesion. RESULTS: 50 patients showed 84 initial DWI lesions. 29 (35%) DWI lesions did not result in infarction signs on 8-week FLAIR. 26 (90%, P<0.0001) reversing lesions were located in the cortical grey matter (cGM). cGM location (vs any other location) strongly predicted no 8-week infarction sign development (OR 0.02, 95% CI 0.001 to 0.17) or partial lesion area decrease (>30% of initial DWI-area, OR 14.10, 95% CI 3.61 to 54.72), adjusted for FLAIR-visibility, DWI-area, ADC-confirmation and time to scan (TTS) from symptom onset to baseline MRI. Acute FLAIR-visibility was a strong associated factor for persistent infarction signs (OR 33.06, 95% CI 2.94 to 1432.34). For cGM lesions area size was sole associated factor for persistent infarction signs with a 0.31 cm2 (area under the curve (AUC), 0.97) threshold. In eight (16%) DWI-positive patients, all lesions reversed fully. CONCLUSIONS: 16% of DWI-positive patients and one-third of acute DWI lesions caused no persistent infarction signs, especially small cGM lesions were not followed by development of persistent infarction signs. Late MRI after TIA is likely to be less useful in the clinical setting, and it is dubious if the absence of old vascular lesions can be taken as evidence of no prior ischaemic attacks. TRIAL REGISTRATION NUMBER: NCT01531946; Results.

Does the Primary Imaging Modality-Computed Tomography or Magnetic Resonance Imaging-Influence Stroke Physicians' Certainty on Whether or Not to Give Thrombolysis to Randomized Acute Stroke Patients?

BACKGROUND: Door-to-needle time of 20 minutes to stroke patients with intravenous tissue plasminogen activator (iv-tPA) is feasible when computed tomography (CT) is used as first-line of brain imaging. Magnetic resonance imaging (MRI)-based assessment is more time-consuming but superior in detecting acute ischemia. The certainty with which stroke physicians prescribe or refrain from giving iv-tPA treatment to CT- versus MRI-examined patients has not previously been studied. The aim of the present study was to determine the effect of a primary imaging strategy of CT or MRI on clinicians' certainty to prescribe or refrain from giving iv-tPA to patients with suspected acute stroke. METHOD: Consecutive patients with suspected stroke were quasi-randomized to either CT- or MRI-based assessment before potential iv-tPA treatment. The influence of (1) the clinical findings and (2) the image findings, and (3) the certainty with which the stroke physician prescribed or refrained from giving iv-tPA treatment were assessed with visual analog scales (VAS). Predictors of treatment certainty were identified with a random-effect model. RESULTS: Four-hundred forty-four consecutive patients were quasi-randomized. MRI influenced the final treatment decision more than CT (P = .002). Compared with CT-examined patients (mean VAS score 8.6, SD ±1.6) stroke physicians were significantly more certain when prescribing or refraining from giving iv-tPA to MRI-examined patients (mean VAS score 9.0, SD ±1.2) (P = .014). No differences in modified Rankin scale or mortality were detected at 3 months in CT- versus MRI-examined iv-tPA-treated patients. CONCLUSIONS: Stroke physicians were significantly more certain when prescribing iv-tPA to MRI-examined stroke patients, and MRI influences the final treatment decision significantly more compared with CT, although no difference in mortality and functional outcome at 3 months was detected between CT- and MRI-examined patients treated with iv-tPA.

Are Movement Artifacts in Magnetic Resonance Imaging a Real Problem?-A Narrative Review.

Movement artifacts compromise image quality and may interfere with interpretation, especially in magnetic resonance imaging (MRI) applications with low signal-to-noise ratio such as functional MRI or diffusion tensor imaging, and when imaging small lesions. High image resolution has high sensitivity to motion artifacts and often prolongs scan time that again aggravates movement artifacts. During the scan fast imaging techniques and sequences, optimal receiver coils, careful patient positioning, and instruction may minimize movement artifacts. Physiological noise sources are motion from respiration, flow and pulse coupled to cardiac cycles, from the swallowing reflex and small spontaneous head movements. Par example, in resting-state functional MRI spontaneous neuronal activity adds 1-2% of signal change, even under optimal conditions signal contributions from physiological noise remain a considerable fraction hereof. Movement tracking during imaging may allow for prospective correction or postprocessing steps separating signal and noise.

CT and MRI-based door-needle-times for acute stroke patients a quasi-randomized clinical trial.

OBJECTIVES: Door-Needle-times (DNT) of 20min are feasible when Computer Tomography (CT) is used for first-line brain-imaging to assess stroke-patients' eligibility for intravenous-tissue-Plasminogen-Activator (iv-tPA), but the more time-consuming Magnetic Resonance Imaging (MRI)-based-evaluation is superior in detecting acute ischaemia.

Comparison of 3- and 20-Gradient Direction Diffusion-Weighted Imaging in a Clinical Subacute Cohort of Patients with Transient Ischemic Attack: Application of Standard Vendor Protocols for Lesion Detection and Final Infarct Size Projection.

OBJECTIVE: Diffusion tensor imaging may aid brain ischemia assessment but is more time consuming than conventional diffusion-weighted imaging (DWI). We compared 3-gradient direction DWI (3DWI) and 20-gradient direction DWI (20DWI) standard vendor protocols in a hospital-based prospective cohort of patients with transient ischemic attack (TIA) for lesion detection, lesion brightness, predictability of persisting infarction, and final infarct size. METHODS: We performed 3T-magnetic resonance imaging including diffusion and T2-fluid attenuated inversion recovery (FLAIR) within 72 h and 8 weeks after ictus. Qualitative lesion brightness was assessed by visual inspection. We measured lesion area and brightness with manual regions of interest and compared with homologous normal tissue. RESULTS: 117 patients with clinical TIA showed 78 DWI lesions. 2 lesions showed only on 3DWI. No lesions were uniquely 20DWI positive. 3DWI was visually brightest for 34 lesions. 12 lesions were brightest on 20DWI. The median 3DWI lesion area was larger for lesions equally bright, or brightest on 20DWI [median (IQR) 39 (18-95) versus 18 (10-34) mm2, P = 0.007]. 3DWI showed highest measured relative lesion signal intensity [median (IQR) 0.77 (0.48-1.17) versus 0.58 (0.34-0.81), P = 0.0006]. 3DWI relative lesion signal intensity was not correlated to absolute signal intensity, but 20DWI performed less well for low-contrast lesions. 3DWI lesion size was an independent predictor of persistent infarction. 3-gradient direction apparent diffusion coefficient areas were closest to 8-week FLAIR infarct size. CONCLUSION: 3DWI detected more lesions and had higher relative lesion SI than 20DWI. 20DWI appeared blurred and did not add information. CLINICAL TRIAL REGISTRATION: http://www.clinicaltrials.gov. Unique Identifier NCT01531946.