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Radiological imaging to examine intracranial blood vessels is critical for preoperative planning and postoperative follow-up. Automated segmentation of cerebrovascular anatomy from Time-Of-Flight Magnetic Resonance Angiography (TOF-MRA) can provide radiologists with a more detailed and precise view of these vessels. This paper introduces a domain generalized artificial intelligence (AI) solution for volumetric monitoring of cerebrovascular structures from multi-center MRAs. Our approach utilizes a multi-task deep convolutional neural network (CNN) with a topology-aware loss function to learn voxel-wise segmentation of the cerebrovascular tree. We use Decorrelation Loss to achieve domain regularization for the encoder network and auxiliary tasks to provide additional regularization and enable the encoder to learn higher-level intermediate representations for improved performance. We compare our method to six state-of-the-art 3D vessel segmentation methods using retrospective TOF-MRA datasets from multiple private and public data sources scanned at six hospitals, with and without vascular pathologies. The proposed model achieved the best scores in all the qualitative performance measures. Furthermore, we have developed an AI-assisted Graphical User Interface (GUI) based on our research to assist radiologists in their daily work and establish a more efficient work process that saves time. [ABSTRACT FROM AUTHOR]

Background: Phase-contrast magnetic resonance imaging (PC-MRI) quantifies blood flow and velocity noninvasively. Challenges arise in neurovascular disorders due to small vessels. We evaluated the impact of voxel size, number of signal averages (NSA), and velocity encoding (VENC) on PC-MRI measurement accuracy and precision in a small-lumen vessel phantom. Methods: We constructed an in vitro model with a constant flow rate using a 2.2-mm inner diameter plastic tube. A reservoir with a weight scale and timer was used as standard reference. Gradient-echo T1 weighted PC-MRI sequence was performed on a 3-T scanner with varying voxel size (2.5, 5.0, 7.5 mm3), NSA (1, 2, 3), and VENC (200, 300, 400 cm/s). We repeated measurements nine times per setting, calculating mean flow rate, maximum velocity, and least detectable difference (LDD). Results: PC-MRI flow measurements were higher than standard reference values (mean ranging from 7.3 to 9.5 mL/s compared with 6.6 mL/s). Decreased voxel size improved accuracy, reducing flow rate measurements from 9.5 to 7.3 mL/s. The LDD for flow rate and velocity varied between 1 and 5%. The LDD for flow rate decreased with increased voxel size and NSA (p = 0.033 and 0.042). The LDD for velocity decreased with increased voxel size (p < 10-16). No change was observed when VENC varied. Conclusions: PC-MRI overestimated flow. However, it has high precision in a small-vessel phantom with constant flow rate. Improved accuracy was obtained with increasing spatial resolution (smaller voxels). Improved precision was obtained with increasing signal-to-noise ratio (larger voxels and/or higher NSA). Relevance statement: Phase-contrast MRI is clinically used in large vessels. To further investigate the possibility of using phase-contrast MRI for smaller intracranial vessels in neurovascular disorders, we need to understand how acquisition parameters affect phase-contrast MRI-measured flow rate and velocity in small vessels. Key points: • PC-MRI measures flow and velocity in a small lumen phantom with high precision but overestimates flow rate. • The precision of PC-MRI measurements matches the precision of standard reference for flow rate measurements. • Optimizing PC-MRI settings can enhance accuracy and precision in flow rate and velocity measurements. [ABSTRACT FROM AUTHOR]

Purpose: Very preterm birth increases risk for neonatal white matter injury, but there is limited data on to what extent this persists into adolescence and how this relates to ophthalmological outcomes. The aim of this study was to assess brain MRI findings in 12-year-old children born very preterm compared to controls and their association with concurrent ophthalmological outcomes. Methods: We included 47 children born very preterm and 22 full-term controls (gestational age <32 and >37 weeks, respectively). Brain MRI findings were studied in association with concurrent ophthalmological outcomes at 12-year follow-up. Results: Evans index (0.27 vs 0.25, p<0.001) and a proposed "posterior ventricle index" (0.47 vs 0.45, p=0.018) were increased in children born very preterm. Higher gestational age associated with larger corpus callosum area (β=10.7, 95%CI 0.59–20.8). Focal white matter lesions were observed in 15 (32%) of very preterm children and in 1 (5%) of full-term controls. Increased posterior ventricle index increased risk for visual acuity ≤1.0 (OR=1.07×1011, 95%CI=7.78–1.48×1021) and contrast sensitivity <0.5 (OR=2.6×1027, 95%CI=1.9×108–3.5×1046). Decreased peritrigonal white matter thickness associated with impaired visual acuity (β=0.04, 95%CI 0.002–0.07). Conclusion: More white matter lesions and evidence of lower white matter volume were found in children born very preterm compared with full-term controls at 12-year follow-up. The association between larger posterior ventricle index and reduced visual acuity and contrast sensitivity suggests disturbances of the posterior visual pathway due to diffuse white matter lesions. [ABSTRACT FROM AUTHOR]

Denitrification in sediments is a key microbial process that removes excess fixed nitrogen, while dissimilatory nitrate reduction to ammonium (DNRA) converts nitrate to ammonium. Although microorganisms are responsible for essential nitrogen (N) cycling, it is not yet fully understood how these microbially mediated processes respond to toxic hydrophobic organic compounds (HOCs) and metals. In this study, we sampled long-term polluted sediment from the outer harbor of Oskarshamn (Baltic Sea), measured denitrification and DNRA rates, and analyzed taxonomic structure and N-cycling genes of microbial communities using metagenomics. Results showed that denitrification and DNRA rates were within the range of a national reference site and other unpolluted sites in the Baltic Sea, indicating that long-term pollution did not significantly affect these processes. Furthermore, our results indicate an adaptation to metal pollution by the N-cycling microbial community. These findings suggest that denitrification and DNRA rates are affected more by eutrophication and organic enrichment than by historic pollution of metals and organic contaminants. [ABSTRACT FROM AUTHOR]

Purpose: Moyamoya (MM) disease is characterized by progressive intracranial arterial stenosis. Patients commonly need revascularization surgery to optimize cerebral blood flow (CBF). Estimation of CBF and cerebrovascular reserve (CVR) is therefore necessary before and after surgery. However, assessment of CBF before and after indirect revascularization surgery with the multiple burr hole (MBH) technique in MM has not been studied extensively. In this study, we describe our initial experience using arterial spin labeling magnetic resonance perfusion imaging (ASL-MRI) for CBF and CVR assessment before and after indirect MBH revascularization surgery in MM patients. Methods: Eleven MM patients (initial age 6–50 years, 1 male/10 female) with 19 affected hemispheres were included. A total of 35 ASL-MRI examinations were performed using a 3D-pCASL acquisition before and after i.v. acetazolamide challenge (1000 mg in adults and 10 mg/kg in children). Twelve MBH procedures were performed in seven patients. The first follow-up ASL-MRI was performed 7–21 (mean 12) months after surgery. Results: Before surgery, CBF was 46 ± 16 (mean ± SD) ml/100 g/min and CVR after acetazolamide challenge was 38.5 ± 9.9 (mean ± SD)% in the most affected territory (middle cerebral artery). In cases in which surgery was not performed, CVR was 56 ± 12 (mean ± SD)% in affected hemispheres. After MBH surgery, there was a relative change in CVR compared to baseline (preop) of + 23.5 ± 23.3% (mean ± SD). There were no new ischemic events. Conclusion: Using ASL-MRI we followed changes in CBF and CVR in patients with MM. The technique was encouraging for assessments before and after revascularization surgery. [ABSTRACT FROM AUTHOR]

Background: Trigeminal neuralgia (TN), a severe type of facial pain, is mainly caused by a neurovascular conflict (NVC). The severity of the NVC seems associated with the outcome following microvascular decompression (MVD) surgery. This study aimed to investigate the outcome after MVD and whether it is affected by NVC severity and sex. Methods: TN patients (n = 109) were followed for 5 to 10 years after MVD. Barrow Neurology Index (BNI), Patients Global Impression of Change (PGIC), complications, and time to relapse were evaluated. The NVC severity was retrospectively reviewed from presurgical MRI. Demographic and clinical factors and NVC severity were analyzed for potential association with outcome after MVD. Results: The success rate (BNI ≤ 2) was 80% after 5 to 10 years follow-up for TN patients with severe NVC (grade 2–3) and 56% for TN patients with mild NVC (grade 0–1, P = 0.003). No sex difference was observed in outcome for patients with both mild (P = 0.924) and severe NVC (P = 0.883) respectively. Three patients (2.8%) during the hospital stay, and two patients (1.8%) at 6 weeks, experienced a complication requiring invasive treatment. At long-term 52/109 patients (47.7%) reported some type of persistent adverse event, of which the majority were mild and required no treatment. Conclusions: MVD offers an 80% probability of long-term pain relief in TN patients with severe NVC, with low frequency of serious complications. NVC severity significantly affects outcome after MVD, while no sex differences in outcome were found. In consistency with previous work, the results stress the importance of adequate neuroradiological assessment of the NVC for preoperative patient selection. [ABSTRACT FROM AUTHOR]

Introduction: Roux-en-Y gastric bypass (RYGB) leads to beneficial effects on glucose homeostasis, and attenuated hormonal counterregulatory responses to hypoglycemia are likely to contribute. RYGB also induces alterations in neural activity of cortical and subcortical brain regions. We aimed to characterize RYGB-induced changes in resting-state connectivity of specific brain regions of interest for energy homeostasis and behavioral control during hypoglycemia. Method: Ten patients with BMI > 35 kg/m2 were investigated with brain PET/MR imaging during a hyperinsulinemic normo- and hypoglycemic clamp, before and 4 months after RYGB. Hormonal levels were assessed throughout the clamp. Resting-state (RS) fMRI scans were acquired in the glucose-lowering phase of the clamp, and they were analyzed with a seed-to-voxel approach. Results: RS connectivity during initiation of hypoglycemia was significantly altered after RYGB between nucleus accumbens, thalamus, caudate, hypothalamus and their crosstalk with cortical and subcortical regions. Connectivity between the nucleus accumbens and the frontal pole was increased after RYGB, and this was associated with a reduction of ACTH (r = −0.639, p = 0.047) and cortisol (r = −0.635, p = 0.048) responses. Instead, connectivity between the caudate and the frontal pole after RYGB was reduced and this was associated with less attenuation of glucagon response during the hypoglycemic clamp (r = −0.728, p = 0.017), smaller reduction in fasting glucose (r = −0.798, p = 0.007) and less excess weight loss (r = 0.753, p = 0.012). No other significant associations were found between post-RYGB changes in ROI-to-voxel regional connectivity hormonal responses and metabolic or anthropometric outcomes. Conclusion: RYGB alters brain connectivity during hypoglycemia of several neural pathways involved in reward, inhibitory control, and energy homeostasis. These changes are associated with altered hormonal responses to hypoglycemia and may be involved in the glucometabolic outcome of RYGB. [ABSTRACT FROM AUTHOR]

Ovarian hormones fluctuations across the menstrual cycle are experienced by about 58% of women in their fertile age. Maladaptive brain sensitivity to these changes likely leads to the severe psychological, cognitive, and physical symptoms repeatedly experienced by women with Premenstrual Dysphoric Disorder (PMDD) during the late luteal phase of the menstrual cycle. However, the neuroanatomical correlates of these symptoms are unknown. The relationship between grey matter structure and PMDD symptom severity was delineated using structural magnetic resonance imaging during the late luteal phase of fifty-one women diagnosed with PMDD, combined with Voxel- and Surface-Based Morphometry, as well as subcortical volumetric analyses. A negative correlation was found between depression-related symptoms and grey matter volume of the bilateral amygdala. Moreover, the severity of affective and somatic PMDD symptoms correlated with cortical thickness, gyrification, sulcal depth, and complexity metrics, particularly in the prefrontal, cingulate, and parahippocampal gyri. The present findings provide the first evidence of grey matter morphological characteristics associated with PMDD symptomatology in brain regions expressing ovarian hormone receptors and of relevance to cognitive-affective functions, thus potentially having important implications for understanding how structural brain characteristics relate to PMDD symptomatology. [ABSTRACT FROM AUTHOR]

Craniopharyngiomas are histologically benign but locally aggressive tumors in the sellar region that may cause devastating neurological and endocrine deficits. They tend to recur following surgery with high morbidity; hence, postoperative radiotherapy is recommended following sub-total resection. BRAFV600E mutation is the principal oncogenic driver in the papillary variant of craniopharyngiomas. Recently, a dramatic tumor reduction has been reported in a patient with BRAFV600E mutated, multiply recurrent papillary craniopharyngioma using a combination therapy of BRAF inhibitor dabrafenib and MEK inhibitor trametinib. Here, we report on near-radical reduction of a growing residual BRAFV600E craniopharyngioma using the same neoadjuvant therapy. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the technique of whole-body magnetic resonance angiography (MRA) of patients with a standard clinical scanner. Thirty-three patients referred for stenoses, occlusions, aneurysms, assessment of patency of vascular grafts, vasculitis and vascular aplasia were examined in a 1.5-T scanner using its standard body coil. Three-dimensional sequences were acquired in four stations after administration of one intravenous injection of 40 ml conventional gadolinium contrast agent. Different vessel segments were evaluated as either diagnostic or nondiagnostic and regarding the presence of stenoses with more than 50% diameter reduction, occlusions or aneurysms. Of 923 vessel segments, 67 were not evaluable because of poor contrast filling (n=31), motion artefacts (n=20), venous overlap (n=12) and other reasons (n=4). Stenoses of more than 50%, occlusions or aneurysms were observed in 26 patients (129 segments). In nine patients additional unsuspected pathology was found. In 10 out of 14 patients (71/79 segments) there was conformity between MRA and digital subtraction angiography regarding the grade of stenosis. This study shows that whole-body MRA with a standard clinical scanner is feasible. Motion artefacts and the timing of the contrast agent through the different segments are still problems to be solved. [ABSTRACT FROM AUTHOR]

Introduction: The purpose of the present study was to investigate normal ranges and test-retest reproducibility of phase-contrast MRI (PC-MRI)-measured flow and velocity parameters in intracranial arteries. Methods: Highest flow (HF), lowest flow (LF), peak systolic velocity (PSV), and end diastolic velocity (EDV) were measured at two dates in the anterior (ACA), middle (MCA), and posterior (PCA) cerebral arteries of 30 healthy volunteers using two-dimensional PC-MRI at 3 T. Least detectable difference (LDD) was calculated. Results: In the left ACA, HF was (mean (range, LDD)) 126 ml/min (36-312, 59 %), LF 61 ml/min (0-156, 101 %), PSV 64 cm/s (32-141, 67 %), and EDV 35 cm/s (18-55, 42 %); in the right ACA, HF was 154 ml/min (42-246, 49 %), LF 77 ml/min (0-156, 131 %), PSV 75 cm/s (26-161, 82 %), and EDV 39 cm/s (7-59, 67 %). In the left MCA, HF was 235 ml/min (126-372, 35 %), LF 116 ml/min (42-186, 48 %), PSV 90 cm/s (55-183, 39 %), and EDV 46 cm/s (20-66, 28 %); in the right MCA, HF was 238 ml/min (162-342, 44 %), LF 120 ml/min (72-216, 48 %), PSV 88 cm/s (55-141, 35 %), and EDV 45 cm/s (26-67, 23 %). In the left PCA, HF was 108 ml/min (42-168, 54 %), LF 53 ml/min (18-108, 64 %), PSV 50 cm/s (24-77, 63 %), and EDV 28 cm/s (14-40, 45 %); in the right PCA, HF was 98 ml/min (30-162, 49 %), LF 49 ml/min (12-84, 55 %), PSV 47 cm/s (27-88, 59 %), and EDV 27 cm/s (16-41, 45 %). Conclusion: PC-MRI-measured flow and velocity parameters in the main intracranial arteries have large normal ranges. Reproducibility is highest in MCA. [ABSTRACT FROM AUTHOR]

Improving train traffic control can be a cost-efficient way to improve train traffic punctuality and increase utilization of existing and future railway infrastructure. However, performance in train traffic control tasks currently involves working on a technical level in order to regulate the traffic flow. Working in a preventive manner is poorly supported and train traffic controllers are usually restricted to just solving problems as they occur. This often results in unnecessarily long delays and decreased timeliness of train traffic. The main objective of this paper is to describe a proposed control strategy and a case study, which evaluates the control strategy and the prototype tool derived from the research. By shifting the control paradigm to a high-level control strategy, many of today’s problems may be avoided, with benefits of the reduction in delays, improved timeliness and better utilization of the infrastructure. Twenty-one train traffic controllers participated in a case study, with a simulated prototype environment. The majority of the participating train traffic controllers were positive to the new concepts and ideas. Many of the important aspects of the proposed control strategy can be investigated with the simulation, but due to the complexity of train traffic some issues must be evaluated in an operative environment. [ABSTRACT FROM AUTHOR]

Purpose of Review: To provide insight into the mechanisms underlying cerebral pathophysiology and to highlight possible methods for evaluation, screening, and surveillance of cerebral complications in preeclampsia. Recent Findings: The pathophysiology of eclampsia remains enigmatic. Animal studies show that the cerebral circulation in pregnancy and preeclampsia might be affected with increased permeability over the blood-brain barrier and altered cerebral blood flow due to impaired cerebral autoregulation. The increased blood pressure cannot be the only underlying cause of eclampsia and cerebral edema, since some cases of eclampsia arise without simultaneous hypertension. Findings from animal studies need to be confirmed in human tissues. Evaluation of brain alterations in preeclampsia and eclampsia is challenging and demands a multidisciplinary collaboration, since no single method can accurately and fully describe how preeclampsia affects the brain. Summary: Cerebral complications of preeclampsia are significant factors in maternal morbidity and mortality worldwide. No single method can accurately describe the full picture of how preeclampsia affects the brain vasculature and parenchyma. We recommend an international and multidisciplinary effort not only to overcome the issue of limited sample availability but also to optimize the quality of research. [ABSTRACT FROM AUTHOR]

The response by Maria Correia de Verdier and Johan Wikström to a letter to editor about their article "Normal ranges and test-retest reproducibility of flow and velocity parameters in intracranial arteries measured with phase-contrast magnetic resonance imaging," published in a previous issue is presented.