Comparison of automated infarct core volume measures between non-contrast computed tomography and perfusion imaging in acute stroke code patients evaluated for potential endovascular treatment.

INTRODUCTION: Patients with small core infarction and salvageable penumbra are likely to benefit from endovascular treatment (EVT). As computed tomography perfusion imaging (CTP) is not always available 24/7 for patient selection, many patients are transferred to stroke centers for CTP. We compared automatically measured infarct core volume (NCCTcore) from the non-contrast computed tomography (NCCT) with ischemic core volume (CTPcore) from CTP and the outcome of EVT to clarify if NCCTcore measurement alone is sufficient to identify patients that benefit from transfer to stroke centers for EVT. PATIENTS AND METHODS: We included all consecutive stroke-code patients imaged with both NCCT and CTP at Helsinki University Hospital during 9/2016-01/2018. NCCTcore and CTPcore volumes were automatically calculated from the acute NCCT images. Follow-up infarct volume (FIV) was measured from 24 h follow-up NCCT to evaluate efficacy of EVT. To study whether NCCTcore could be used to identify patients eligible to EVT, we sub-grouped patients based on NCCTcore volumes (>50 mL and ≥ 70 mL). RESULTS: Out of 1743 patients, baseline NCCTcore, CTPcore and follow-up NCCT was available for 288 patients. Median time from symptom onset to baseline imaging was 74 min (IQR 52-118), and time to follow-up imaging 24.15 h (22.25-26.33). Baseline NCCTcore was 20 mL (10-42), CTPcore 4 mL (0-16), and FIV 5 mL (1-49). Out of 288 patients, 23 had NCCTcore ≥ 70 mL and 26 had CTPcore ≥ 70 mL. NCCTcore and CTPcore performed similarly well in predicting large FIV (≥70 ml). CONCLUSION: NCCTcore is a promising tool to identify patients that are not eligible to EVT due to large ischemic cores at baseline imaging.

The variability of functional MRI brain signal increases in Alzheimer's disease at cardiorespiratory frequencies.

Biomarkers sensitive to prodromal or early pathophysiological changes in Alzheimer's disease (AD) symptoms could improve disease detection and enable timely interventions. Changes in brain hemodynamics may be associated with the main clinical AD symptoms. To test this possibility, we measured the variability of blood oxygen level-dependent (BOLD) signal in individuals from three independent datasets (totaling 80 AD patients and 90 controls). We detected a replicable increase in brain BOLD signal variability in the AD populations, which constituted a robust biomarker for clearly differentiating AD cases from controls. Fast BOLD scans showed that the elevated BOLD signal variability in AD arises mainly from cardiovascular brain pulsations. Manifesting in abnormal cerebral perfusion and cerebrospinal fluid convection, present observation presents a mechanism explaining earlier observations of impaired glymphatic clearance associated with AD in humans.

Characteristics and Long-Term Outcome of 127 Children With Cerebral Arteriovenous Malformations.

BACKGROUND: Population-based long-term data on pediatric patients with cerebral arteriovenous malformations (AVMs) are limited. OBJECTIVE: To clarify the characteristics and long-term outcome of pediatric patients with AVM. METHODS: A retrospective analysis was performed on 805 consecutive brain AVM patients admitted to a single center between 1942 and 2014. The patients were defined as children if they were under 18 yr at admission. Children were compared to an adult cohort. Changing patterns of presentation were also analyzed by decades of admission. RESULTS: The patients comprised 127 children with a mean age of 12 yr. The mean follow-up time was 21 yr (range 0-62). Children presented more often with intracerebral hemorrhage (ICH) but less often with epilepsy than adults. Basal ganglia, cerebellar, and posterior paracallosal AVMs were more common in pediatric than in adult patients. Frontal and temporal AVMs, in contrast, were more common in adult than in pediatric patients. As the number of incidentally and epilepsy-diagnosed AVMs increased, ICH rates dropped in both cohorts. In total, 22 (82%) pediatric and 108 (39%) adult deaths were assessed as AVM related. After multivariate analysis, small AVM size and surgical treatment correlated with a favorable long-term outcome. CONCLUSION: Hemorrhagic presentation was more common in children than in adults. This was also reflected as lower prevalence of epileptic presentation in the pediatric cohort. Lobar and cortical AVM locations were less frequent, whereas deep and cerebellar AVMs were more common in children. Hemorrhagic presentation correlated negatively with incidentally and epilepsy-diagnosed AVMs. In children, AVM was a major cause of death, but in adults, other factors contributed more commonly to mortality.

The Application of the Novel Grading Scale (Lawton-Young Grading System) to Predict the Outcome of Brain Arteriovenous Malformation.

BACKGROUND: A supplementary grading scale (Supplemented Spetzler-Martin grade, Supp-SM) was introduced in 2010 as a refinement of the SM system to improve preoperative risk prediction of brain arteriovenous malformations (AVMs). OBJECTIVE: To determine the ability to predict surgical outcomes using the Supp-SM grading scale. METHODS: This retrospective study was conducted on 200 patients admitted to the Helsinki University Hospital between 2000 and 2014. The validity of the Supp-SM and SM grading systems was compared using the area under the receiver operating characteristic (AUROC) curves, with respect to the change between preoperative and early (3-4 mo) as well as final postoperative modified Rankin Scale (mRS) scores. RESULTS: The performance of the Supp-SM was superior to that of the SM grading scale in the early follow-up (3-4 mo): AUROC = 0.57 (95% confidence interval [CI]: 0.49-0.65) for SM and AUROC = 0.67 (95% CI: 0.60-0.75) for Supp-SM. The Supp-SM performance continued improving over SM at the late follow-up: AUROC = 0.63 (95% CI: 0.55-0.71) for SM and AUROC = 0.70 (95% CI: 0.62-0.77) for Supp-SM. The perforating artery supply, which is not part of either grading system, plays an important role in the early follow-up outcome (P = .008; odds ratio: 2.95; 95% CI: 1.32-6.55) and in the late follow-up outcome (P < .001; odds ratio: 5.89; 95% CI: 2.49-13.91). CONCLUSION: The Supp-SM grading system improves the outcome prediction accuracy and is a feasible alternative to the SMS, even for series with higher proportion of high-grade AVMs. However, perforators play important role on the outcome.

Fibre optic sensor for non-invasive monitoring of blood pressure during MRI scanning.

This report focuses on designing and implementing a non-invasive blood pressure (NIBP) measuring device capable of being used during magnetic resonance imaging (MRI). Based on measuring pulse wave velocity in arterial blood, the device uses the obtained result to estimate diastolic blood pressure. Pulse transit times are measured by two fibre optical accelerometers placed over the chest and carotid artery. The fabricated accelerometer contains two static fibres and a cantilever beam, whose free end is angled at 90 degrees to act as a reflecting surface. Optical fibres are used for both illuminating the surface and receiving the reflected light. When acceleration is applied to the sensor, it causes a deflection in the beam, thereby changing the amount of reflected light. The sensor's output voltage is proportional to the intensity of the reflected light. Tests conducted on the electronics and sensors inside an MRI room during scanning proved that the device is MR- compatible. No artifacts or distortions were detected.

A sliding time-window ICA reveals spatial variability of the default mode network in time.

Recent evidence on resting-state networks in functional (connectivity) magnetic resonance imaging (fcMRI) suggests that there may be significant spatial variability of activity foci over time. This study used a sliding time window approach with the spatial domain-independent component analysis (SliTICA) to detect spatial maps of resting-state networks over time. The study hypothesis was that the spatial distribution of a functionally connected network would present marked variability over time. The spatial stability of successive sliding-window maps of the default mode network (DMN) from fcMRI data of 12 participants imaged in the resting state was analyzed. Control measures support previous findings on the stability of independent component analysis in measuring sliding-window sources accurately. The spatial similarity of successive DMN maps varied over time at low frequencies and presented a 1/f power spectral pattern. SliTICA maps show marked temporal variation within the DMN; a single voxel was detected inside a group DMN map in maximally 82% of time windows. Mapping of incidental connectivity reveals centrifugally increasing connectivity to the brain cortex outside the DMN core areas. In conclusion, SliTICA shows marked spatial variance of DMN activity in time, which may offer a more comprehensive measurement of the overall functional activity of a network.

Age-Related Differences in Functional Nodes of the Brain Cortex - A High Model Order Group ICA Study.

Functional MRI measured with blood oxygen dependent (BOLD) contrast in the absence of intermittent tasks reflects spontaneous activity of so-called resting state networks (RSN) of the brain. Group level independent component analysis (ICA) of BOLD data can separate the human brain cortex into 42 independent RSNs. In this study we evaluated age-related effects from primary motor and sensory, and, higher level control RSNs. One hundred sixty-eight healthy subjects were scanned and divided into three groups: 55 adolescents (ADO, 13.2 ± 2.4 years), 59 young adults (YA, 22.2 ± 0.6 years), and 54 older adults (OA, 42.7 ± 0.5 years), all with normal IQ. High model order group probabilistic ICA components (70) were calculated and dual-regression analysis was used to compare 21 RSN's spatial differences between groups. The power spectra were derived from individual ICA mixing matrix time series of the group analyses for frequency domain analysis. We show that primary sensory and motor networks tend to alter more in younger age groups, whereas associative and higher level cognitive networks consolidate and re-arrange until older adulthood. The change has a common trend: both spatial extent and the low frequency power of the RSN's reduce with increasing age. We interpret these result as a sign of normal pruning via focusing of activity to less distributed local hubs.