New Technologies in the Assessment of Carotid Stenosis: Beyond the Color-Doppler Ultrasound-High Frame Rate Vector-Flow and 3D Arterial Analysis Ultrasound.

Atherosclerotic plaque in the carotid artery is the main cause of ischemic stroke, with a high incidence rate among people over 65 years. A timely and precise diagnosis can help to prevent the ischemic event and decide patient management, such as follow up, medical, or surgical treatment. Presently, diagnostic imaging techniques available include color-Doppler ultrasound, as a first evaluation technique, computed tomography angiography, which, however, uses ionizing radiation, magnetic resonance angiography, still not in widespread use, and cerebral angiography, which is an invasively procedure reserved for therapeutically purposes. Contrast-enhanced ultrasound is carving out an important and emerging role which can significantly improve the diagnostic accuracy of an ultrasound. Modern ultrasound technologies, still not universally utilized, are opening new horizons in the arterial pathologies research field. In this paper, the technical development of various carotid artery stenosis diagnostic imaging modalities and their impact on clinical efficacy is thoroughly reviewed.

Quantitative Assessment of Regional Pulmonary Transit Times in Pulmonary Hypertension.

BACKGROUND: Pulmonary hypertension (PH) contributes to restricted flow through the pulmonary circulation characterized by elevated mean pulmonary artery pressure acquired from invasive right heart catheterization (RHC). MRI may provide a noninvasive alternative for diagnosis and characterization of PH. PURPOSE: To characterize PH via quantification of regional pulmonary transit times (rPTT). STUDY TYPE: Retrospective. POPULATION: A total of 43 patients (58% female); 24 controls (33% female). RHC-confirmed patients classified as World Health Organization (WHO) subgroups 1-4. FIELD STRENGTH/SEQUENCE: A 1.5 T/time-resolved contrast-enhanced MR Angiography (CE-MRA). ASSESSMENT: CE-MRA data volumes were combined into a 4D matrix (3D resolution + time). Contrast agent arrival time was defined as the peak in the signal-intensity curve generated for each voxel. Average arrival times within a vessel region of interest (ROI) were normalized to the main pulmonary artery ROI (t0 ) for eight regions to define rPTT for all subjects. Subgroup analysis included grouping the four arterial and four venous regions. Intraclass correlation analysis completed for reproducibility. STATISTICAL TESTS: Analysis of covariance with age as covariate. A priori Student's t-tests or Wilcoxon rank-sum test; α = 0.05. Results compared to controls unless noted. Significant without listing P value. ICC ran as two-way absolute agreement model with two observers. RESULTS: PH patients demonstrated elevated rPTT in all vascular regions; average rPTT increase in arterial and venous branches was 0.85 ± 0.15 seconds (47.7%) and 1.0 ± 0.18 seconds (16.9%), respectively. Arterial rPTT was increased for all WHO subgroups; venous regions were elevated for subgroups 2 and 4 (group 1, P = 0.86; group 3, P = 0.32). No significant rPTT differences were found between subgroups (P = 0.094-0.94). Individual vessel ICC values ranged from 0.58 to 0.97. DATA CONCLUSION: Noninvasive assessment of PH using standard-of-care time-resolved CE-MRA can detect increased rPTT in PH patients of varying phenotypes compared to controls. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY: Stage 3.

ACR Appropriateness Criteria® Lower Extremity Arterial Claudication-Imaging Assessment for Revascularization: 2022 Update.

Arterial claudication is a common manifestation of peripheral artery disease. This document focuses on necessary imaging before revascularization for claudication. Appropriate use of ultrasound, invasive arteriography, MR angiography, and CT angiography are discussed. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Quantitative magnetic resonance angiography as an alternative imaging technique in the assessment of cerebral vasospasm after subarachnoid hemorrhage.

INTRODUCTION: The major mechanism of morbidity of delayed cerebral ischemia after subarachnoid hemorrhage (SAH) is considered to be severe vasospasm. Quantitative MRA (QMRA) provides direct measurements of vessel-specific volumetric blood flow and may permit a clinically relevant assessment of the risk of ischemia secondary to cerebral vasospasm. PURPOSE: To evaluate the utility of QMRA as an alternative imaging technique for the assessment of cerebral vasospasm after SAH. METHODS: QMRA volumetric flow rates of the anterior cerebral artery (ACA), middle cerebral artery (MCA), and posterior cerebral artery (PCA) were compared with vessel diameters on catheter-based angiography. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of QMRA for detecting cerebral vasospasm was determined by receiver-operating characteristic curves. Spearman correlation coefficients were calculated for QMRA flow versus angiographic vessel diameter. RESULTS: Sixty-six vessels (10 patients) were evaluated with QMRA and catheter-based angiography. The median percent QMRA flow of all vessels with angiographic vasospasm (55.0%, IQR 34.3-71.6%) was significantly lower than the median percent QMRA flow of vessels without vasospasm (91.4%, IQR 81.4-100.4%) (p < 0.001). Angiographic vasospasm reduced QMRA-assessed flow by 23 ± 5 (p = 0.018), 95 ± 12 (p = 0.042), and 16 ± 4 mL/min (p = 0.153) in the ACA, MCA, and PCA, respectively, compared to vessels without angiographic vasospasm. The sensitivity, specificity, PPV, and NPV of QMRA for the discrimination of cerebral vasospasm was 84%, 72%, 84%, and 72%, respectively, for angiographic vasospasm >25% and 91%, 60%, 87%, and 69%, respectively, for angiographic vasospasm >50%. The Spearman correlation indicated a significant association between QMRA flows and vessel diameters (rs = 0.71, p < 0.001). CONCLUSION: Reduction in QMRA flow correlates with angiographic vessel narrowing and may be useful as a non-invasive imaging modality for the detection of cerebral vasospasm after SAH.

Occupational Exposure to Hexavalent Chromium, Nickel and PAHs: A Mixtures Risk Assessment Approach Based on Literature Exposure Data from European Countries.

Hexavalent chromium (Cr(VI)), nickel (Ni) and polycyclic aromatic hydrocarbons (PAHs) are genotoxic co-occurring lung carcinogens whose occupational health risk is still understudied. This study, conducted within the European Human Biomonitoring Initiative (HBM4EU), aimed at performing a mixtures risk assessment (MRA) based on published human biomonitoring (HBM) data from Cr(VI), Ni and/or PAHs occupational co-exposure in Europe. After data extraction, Risk Quotient (RQ) and Sum of Risk Quotients (SRQ) were calculated for binary and ternary mixtures to characterise the risk. Most selected articles measured urinary levels of Cr and Ni and a SRQ > 1 was obtained for co-exposure levels in welding activities, showing that there is concern regarding co-exposure to these substances. Similarly, co-exposure to mixtures of Cr(VI), Ni and PAHs in waste incineration settings resulted in SRQ > 1. In some studies, a low risk was estimated based on the single substances' exposure level (RQ < 1), but the mixture was considered of concern (SRQ > 1), highlighting the relevance of considering exposure to the mixture rather than to its single components. Overall, this study points out the need of using a MRA based on HBM data as a more realistic approach to assess and manage the risk at the workplace, in order to protect workers' health.

Imaging of the extracranial internal carotid artery in acute ischemic stroke: assessment of stenosis, plaques, and image quality using relaxation-enhanced angiography without contrast and triggering (REACT).

Background: In stroke magnetic resonance imaging (MRI), contrast-enhanced magnetic resonance angiography (CE-MRA) is the clinical standard to depict extracranial arteries but native MRA techniques are of increased interest to facilitate clinical practice. The purpose of this study was to assess the detection of extracranial internal carotid artery (ICA) stenosis and plaques as well as the image quality of cervical carotid arteries between a novel flow-independent relaxation-enhanced angiography without contrast and triggering (REACT) sequence and CE-MRA in acute ischemic stroke (AIS). Methods: In this retrospective, single-center study, 105 consecutive patients (65.27±18.74 years, 63 males) were included, who received a standard stroke protocol at 3T in clinical routine including Compressed SENSE (CS) accelerated (factor 4) 3D isotropic REACT (fixed scan time: 02:46 min) and CS accelerated (factor 6) 3D isotropic CE-MRA. Three radiologists independently assessed scans for the presence of extracranial ICA stenosis and plaques (including hyper-/hypointense signal) with concomitant diagnostic confidence using 3-point scales (3= excellent). Vessel quality, artifacts, and image noise of extracranial carotid arteries were subjectively scored on 5-point scales (5= excellent/none). Wilcoxon tests were used for statistical comparison. Results: Considering CE-MRA as the standard of reference, REACT provided a sensitivity of 89.8% and specificity of 95.2% for any and of 93.5% and 95.8% for clinically relevant (≥50%) extracranial ICA stenosis and yielded a to CE-MRA comparable diagnostic confidence [mean ± standard deviation (SD), median (interquartile range): 2.8±0.5, 3 (3-3) vs. 2.7±0.5, 3 (2-3), P=0.03]. Using REACT, readers detected more plaques overall (n=57.3 vs. 47.7, P<0.001) and plaques of hyperintense signal (n=12.3 vs. 5.7, P=0.02) with higher diagnostic confidence [2.8±0.5, 3 (3-3) vs. 2.6±0.7, 3 (2-3), P<0.001] than CE-MRA. After analyzing a total of 1,260 segments, the vessel quality of all segments combined [4.61±0.66 vs. 4.58±0.68, 5 (4-5) vs. 5 (4-5), P=0.0299] and artifacts [4.51±0.70 vs. 4.44±0.73, 5 (4-5) vs. 5 (4-5), P>0.05] were comparable between the sequences with REACT showing a lower image noise [4.43±0.67 vs. 4.25±0.71, 5 (4-5) vs. 4 (4-5), P<0.001]. Conclusions: Without the use of gadolinium-based contrast agents or triggering, REACT provides a high sensitivity and specificity for extracranial ICA stenosis and a potential improved depiction of adjacent plaques while yielding to CE-MRA comparable vessel quality in a large patient cohort with AIS.

Cost-Effective Analysis of Different Diagnostic Strategies in Screening for Aneurysms After Spontaneous Subarachnoid Hemorrhage.

PURPOSE: With an increasing number of patients being treated by coiling for aneurysms, using computed tomographic angiography (CTA) or magnetic resonance angiography (MRA) as an initial screening test becomes less important because digital subtraction angiography (DSA) is the first step of endovascular treatment procedure. The objective of this study is to investigate whether CTA or MRA remained to be the optimal screening strategy in patients with spontaneous subarachnoid hemorrhage (SAH). METHODS: CTA, MRA, and DSA strategy were evaluated in a decision tree model created with TreeAge Pro Suite 2011. Input parameters were derived from published literature and our institutional database. Base case and sensitivity analyses were conducted to assess the cost-effectiveness of each strategy. A Monte Carlo simulation was performed with all parameters ranged among their distributions to evaluate the validation of results. RESULTS: The base case scenario showed that MRA was the most cost-effective strategy. Using a willingness-to-pay threshold of ¥70,892/quality adjusted life year, MRA remained to be most cost-effective when its sensitivity is >0.907. DSA was not cost-effective compared to CTA or MRA unless over 91.56% of patients were treated by coiling. The Monte Carlo simulation reported DSA not to be a cost-effective strategy at willingness-to-pay of ¥70,892 in 99.99% of the iterations. CONCLUSION: DSA is not cost-effective compared to CTA or MRA and should not be used as the initial diagnostic tool for spontaneous SAH.

Magnetic Resonance Angiography and Multidetector CT Angiography in the Diagnosis of Takayasu's Arteritis: Assessment of Disease Extent and Correlation with Disease Activity.

BACKGROUND: Takayasu's Arteritis (TA) is a large vessel vasculitis with diverse clinical presentations and arterial vascular bed involvement.It is characterized by chronic, nonspecific inflammation of all layers of the vessel wall which results in stenosis, occlusion, dilatation, or aneurysm formation in the involved blood vessels. METHODS: The study included 36 patients of TA. All patients fulfilled the modified Ishikawa's diagnostic criteria for TA. All patients were evaluated for clinical presentation, angiographic findings, and severity of the disease. The disease activity was assessed based on Erythrocyte Sedimentation Rate (ESR) and C-Reactive Protein (CRP) and also by CT Angiography (CTA)/Magnetic resonance angiography (MRA) imaging. The angiographic types were classified based on the International TA Conference in Tokyo 1994 angiographic classification. RESULTS: A total of 36 patients were included in the study, 86% were females and a mean age of 21.6 years. Hypertension (78%) was the most common clinical presentation. Type V was the most common angiographic type (42%) followed by type III (25%), type IV (14%), type IIb (11%), type I (5%) and type IIa (3%). Among the aortic arch branches the left subclavian artery (50%), right subclavian artery (38.8%), left vertebral artery (33.3%) and left common carotid artery (27.7%) were the most commonly involved arteries. Disease activity based on CT / MR imaging showed a significant statistical correlation with elevated ESR and positive CRP (p < 0.0001). Mediastinal lymphadenopathy was seen in 21 patients out of which 11 had active disease. However, no significant correlation was found between mediastinal lymphadenopathy and disease activity. CONCLUSION: TA presents with varied symptomatology and differing vascular involvement. CT/MR angiography is effective in diagnosis and accurately predicted the active stage of the disease.

Methodological Development of a Multi-Readout Assay for the Assessment of Antiviral Drugs against SARS-CoV-2.

Currently, human infections with the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) are accelerating the ongoing spread of the pandemic. Several innovative types of vaccines have already been developed, whereas effective options of antiviral treatments still await a scientific implementation. The development of novel anti-SARS-CoV-2 drug candidates demands skillful strategies and analysis systems. Promising results have been achieved with first generation direct-acting antivirals targeting the viral polymerase RdRp or the protease 3CLpro. Such recently approved or investigational drugs like remdesivir and GC376 represent a basis for further development and optimization. Here, we establish a multi-readout assay (MRA) system that enables the antiviral assessment and mechanistic characterization of novel test compounds, drug repurposing and combination treatments. Our SARS-CoV-2-specific MRA combines the quantitative measurement of several parameters of virus infection, such as the intracellular production of proteins and genomes, enzymatic activities and virion release, as well as the use of reporter systems. In this regard, the antiviral efficacy of remdesivir and GC376 has been investigated in human Caco-2 cells. The readouts included the use of spike- and double-strand RNA-specific monoclonal antibodies for in-cell fluorescence imaging, a newly generated recombinant SARS-CoV-2 reporter virus d6YFP, the novel 3CLpro-based FRET CFP::YFP and the previously reported FlipGFP reporter assays, as well as viral genome-specific RT-qPCR. The data produced by our MRA confirm the high antiviral potency of these two drugs in vitro. Combined, this MRA approach may be applied for broader analyses of SARS-CoV-2-specific antivirals, including compound screenings and the characterization of selected drug candidates.

Microbial-Maximum Likelihood Estimation Tool for Microbial Quantification in Food From Left-Censored Data Using Maximum Likelihood Estimation for Microbial Risk Assessment.

In food microbial measurements, when most or very often bacterial counts are below to the limit of quantification (LOQ) or the limit of detection (LOD) in collected food samples, they are either ignored or a specified value is substituted. The consequence of this approach is that it may lead to the over or underestimation of quantitative results. A maximum likelihood estimation (MLE) or Bayesian models can be applied to deal with this kind of censored data. Recently, in food microbiology, an MLE that deals with censored results by fitting a parametric distribution has been introduced. However, the MLE approach has limited practical application in food microbiology as practical tools for implementing MLE statistical methods are limited. We therefore developed a user-friendly MLE tool (called "Microbial-MLE Tool"), which can be easily used without requiring complex mathematical knowledge of MLE but the tool is designated to adjust log-normal distributions to observed counts, and illustrated how this method may be implemented for food microbial censored data using an Excel spreadsheet. In addition, we used two case studies based on food microbial laboratory measurements to illustrate the use of the tool. We believe that the Microbial-MLE tool provides an accessible and comprehensible means for performing MLE in food microbiology and it will also be of help to improve the outcome of quantitative microbial risk assessment (MRA).

Assessment of Intracranial Atherosclerotic Plaques Using 3D Black-Blood MRI: Comparison With 3D Time-of-Flight MRA and DSA.

BACKGROUND: Noninvasive assessment of intracranial stenosis is important to manage ischemic stroke patients. However, few previous studies have compared 3D black-blood MRI with 3D time-of-flight (TOF), magnetic resonance angiography (MRA), and digital subtraction angiography (DSA) for intracranial artery plaque assessment. PURPOSE: To compare 3D black-blood MRI and 3D TOF-MRA, using DSA as the reference standard for intracranial stenosis and atherosclerotic plaque assessment in patients with posterior circulation stroke or transient ischemic attacks (TIAs). STUDY TYPE: Prospective, cohort study. POPULATION: One hundred and one patients with posterior circulation stroke and/or TIA (age 63 ± 10 years, 84 male) who underwent DSA and MRI within 4 weeks of each other. FIELD STRENGTH/SEQUENCE: 3D fast-spin-echo MRI for intracranial vessel wall imaging (IVWI) and 3D TOF at 3T. ASSESSMENT: Two radiologists independently measured the degree of stenosis on 3D IVWI and TOF, using DSA as a reference. Plaque enhancement was recorded when the plaque was stenosis-free on DSA. STATISTICAL TESTS: Shapiro-Wilk's test, Student's t-test, Mann-Whitney U-test, Spearman correlation, Bland-Altman analysis, and interclass correlation coefficient (ICC). RESULTS: A total of 238 intracranial plaques (203 posterior, 35 anterior) were included. 3D IVWI showed better agreement with DSA in measuring stenosis than TOF (ICC = 0.89 vs. 0.64). 3D IVWI had higher sensitivity and specificity for detecting stenosis >50% and stenosis >75% than TOF, using DSA as the standard. TOF significantly overestimated the degree of stenosis compared to DSA (65 ± 19% vs. 51 ± 15%, P < 0.001). DSA did not observe 62 nonstenotic plaques (26.1%) that were shown only on 3D IVWI, in which 36 plaques (58.1%) showed contrast enhancement. The interreader agreement for measuring stenosis were excellent, with ICCs >0.90 for all three modalities. DATA CONCLUSION: 3D black-blood MRI is accurate and reproducible for quantifying intracranial artery stenosis compared with DSA, and performs better than 3D TOF. As compared to DSA, it detects more nonstenotic plaques. Level of Evidence 1 Technical Efficacy Stage 2 J. MAGN. RESON. IMAGING 2021;53:469-478.

Comparison of Magnetic Resonance Angiography and Digital Subtraction Angiography for the Assessment of Infrapopliteal Arterial Occlusive Lesions, Based on the TASC II Classification Criteria.

This paper aimed to study the agreement and repeatability, both intra- and interobserver, of infrapopliteal lesion assessment with magnetic resonance angiography (MRA), using the TransAtlantic Inter-Society Consensus (TASC) II criteria, with perioperative digital subtraction angiography (DSA) as a reference. Sixty-eight patients with an MRA preceding an endovascular infrapopliteal revascularization were included. Preoperative MRAs and perioperative DSAs were evaluated in random order by three independent observers using the TASC II classification. The results were analyzed using visual grading characteristics (VGC) analysis and Krippendorff's α. No systematic difference was found between modalities: area under the VGC curve (AUCVGC) = 0.48 (p = 0.58) or intraobserver; AUCVGC for Observer 1 and 2 respectively, 0.49 (p = 0.85) and 0.53 (p = 0.52) for MRA compared with 0.54 (p = 0.30) and 0.49 (p = 0.81) for DSA. Interobserver differences were seen: AUCVGC of 0.63 (p < 0.01) for DSA and 0.80 (p < 0.01) for MRA. These results were confirmed using Krippendorff's α for the three observers showing 0.13 (95% confidence interval (CI) -0.07-0.31) for MRA and 0.39 (95% CI 0.23-0.53) for DSA. Poor interobserver agreement was also found in the choice of a target vessel on preoperative MRA: Krippendorff's α = 0.19 (95% CI 0.01‒0.36). In conclusion, infrapopliteal lesions can be reliably determined on preoperative MRA, but interobserver variability regarding the choice of a target vessel is a major concern that appears to affect the overall TASC II grade.

Pharmaceutical Manufacturing in the EU and the EU-US Mutual Recognition Agreement.

The pharmaceutical industry is one of the most competitive sectors in Europe and has a strong presence in many European Union (EU) countries. The mutual recognition agreement (MRA) for inspections of medicines manufacturers between the United States (US) Food and Drug Administration (FDA) and the EU started by the end of 2017 and gradually extended to all EU member states (MSs) in July 2019. We quantified the number of FDA and EU good manufacturing practice (GMP) inspections carried out in each other's territory between 2009 and 2018. The five EU MSs with the largest number of FDA inspections were Germany, followed by Italy, France, the United Kingdom (UK), and Spain. All of them, with the exception of Germany, were included in the group of the first eight EU MSs recognized by the FDA in the context of the MRA. In 2018, these five EU MSs were within the top 10 EU exporters of pharmaceutical products to the US. Four of these five EU MSs (Italy, Germany, France, and the UK) accounted for 53.4% of the total pharmaceutical production in the EU in 2018. We also studied the type of manufacturing operations covered by the manufacturer's authorizations issued by each EU MS for the manufacturers within its territory. We verified a high prevalence of conventional technology versus complex technology manufacturing for many EU countries. Going forward, this unbalance should be addressed at a national and EU level. Supporting for instance (bio)pharmaceutical manufacturing through pharma policy initiatives, especially for EU countries with a lower level of innovation and technological development, would promote the pharmaceutical manufacturing sustainability and competitiveness of these countries. The full implementation of the MRA between the US FDA and the EU can make it faster and less costly for both sides to bring medicines to the market, improving future competitiveness of the EU and the US pharmaceutical industry.

Preoperative Assessment of Upper Extremity Secondary Lymphedema.

Introduction: The purpose of this study was to evaluate the most commonly used preoperative assessment tools for patients undergoing surgical treatment for secondary upper extremity lymphedema. Methods: This was a prospective cohort study performed at a tertiary cancer center specializing in the treatment of secondary lymphedema. Lymphedema evaluation included limb volume measurements, bio-impedance, indocyanine green lymphography, lymphoscintigraphy, magnetic resonance angiography, lymphedema life impact scale (LLIS) and upper limb lymphedema 27 (ULL-27) questionnaires. Results: 118 patients were evaluated. Limb circumference underestimated lymphedema compared to limb volume. Bioimpedance (L-Dex) scores highly correlated with limb volume excess (r2 = 0.714, p < 0.001). L-Dex scores were highly sensitive and had a high positive predictive value for diagnosing lymphedema in patients with a volume excess of 10% or more. ICG was highly sensitive in identifying lymphedema. Lymphoscintigraphy had an overall low sensitivity and specificity for the diagnosis of lymphedema. MRA was highly sensitive in diagnosing lymphedema and adipose hypertrophy as well as useful in identifying axillary vein obstruction and occult metastasis. Patients with minimal limb volume difference still demonstrated significantly impaired quality of life. Conclusion: Preoperative assessment of lymphedema is complex and requires multimodal assessment. MRA, L-Dex, ICG, and PROMs are all valuable components of preoperative assessment.

The role of financial development on carbon emissions: a meta regression analysis.

The study analyzes the role of financial development on CO2 emissions based on the primary studies in the existing literature. However, the heterogeneity in reported effect size estimates of the primary studies complicates to test the competing hypotheses for the role of financial development on CO2 emissions. The paper tries to determine and quantify the representative empirical genuine effect of financial development on CO2 emissions, if any. To address the issue, a meta-regression analysis has been carried out for 275 estimation results from 72 primary studies. We have found a substantial publication selection bias in the literature due to the design characteristics of the primary studies. The results suggest the presence of an authentic positive empirical effect of financial development on CO2 emissions beyond publication selection bias. Hence, financial development leads to environmental degradation. The effect of financial development on carbon emissions changes both in magnitude and direction depending on which financial development indicator is used, which estimation technique is employed, which countries or region are included and which time period is analyzed.

Differential Subsampling with Cartesian Ordering for Ultrafast High-Resolution MRA in the Assessment of Intracranial Aneurysms.

BACKGROUND AND PURPOSE: We aimed to evaluate the feasibility of an ultrafast whole head contrast-enhanced MRA (CE-MRA) in morphometric assessment of intracranial aneurysms in comparison to routinely used time-of-flight (TOF)-MRA. METHODS: In this prospective single institutional study, patients with known untreated intracranial aneurysm underwent MRA. Routine multislab TOF-MRA was obtained with a 3D voxel sizes of .6 × .6 × 1 (6-minute acquisition time). CE-MRA of whole head was obtained using Differential Subsampling with Cartesian Ordering (DISCO) and 2D Auto-calibrating Reconstruction for Cartesian imaging with a 3D voxel-sizes of .75 × .75 × 1 mm3 during a 6-second temporal resolution. Morphometric features of intracranial aneurysms, including size, aneurysm sac morphology, and the presence of intraluminal thrombosis, were assessed on both techniques. Statistical analysis was performed using a combination of Kappa test, Bland-Altman, and correlation coefficient analysis. RESULTS: A total of 34 aneurysms in 28 patients were included. Aneurysm size measurements (mean ± SD) were similar between DISCO-MRA (4.1 ± 2.3 mm) and TOF-MRA (4.3 ± 2.8 mm) (P = .27). Bland-Altman analysis showed a mean difference of .4 mm and there was excellent correlation r = .91 (95% CI: .87-.96). In six aneurysms (17.6%), TOF-MRA was nonconfidant to exclude intraluminal thrombosis. In seven aneurysms (20%), TOF-MRA was unable or nonconfidant in depicting aneurysm sac morphology. CONCLUSIONS: Described ultrafast high spatial-resolution MRA is superior to routinely used TOF-MRA in assessment of morphometric features of intracranial aneurysms, such as intraluminal thrombosis and aneurysm morphology, and is obtained in a fraction of the time (6 seconds).

The assessment of lenticulostriate arteries originating from middle cerebral artery using ultra high-field magnetic resonance time-of-flight angiography.

Time-of-flight angiography (ToF) was presented for the first time by Suryan and used by Hinshaw et al. This protocol allows to visualize blood flow within the vessels in vivo without the contrast administration, which is possible due to the large magnitude of magnetization, received from the moving spins and small magnitude of magnetization received from the stationary spins. Fourteen participants (male:female = 7:7) were analyzed, who have never been diagnosed with any central nervous system disease as well as any cardiovascular, metabolic disease and have never had any trauma. Although, the gold standard of cerebral vessel analysis is still DSA, ultra high-field 3D ToF-MRA shows clearer picture of all LSAs and the branches of LSAs in comparison to poor in contrast DSA imaging. Ultra high-field time-of-flight MRA is a valuable method in visualizing small perforating arteries, which can be used in the future as a diagnostic tool for clinical practice. The diversity of LSAs morphometry is vast and may alter during aging, thus the clinical anatomy of those vessels should be further investigated in vivo.

Preoperative assessment of the risk of cavernous ICA injury in endoscopic transsphenoidal surgery.

In endoscopic endonasal transsphenoidal procedures, ICA injury occurs in up to 3.8% [1]. The highest hazard of injury is in case of contact between the ICA and pituitary gland, during opening of the dura. Preoperative imaging, i.e. CTA, MRA, supports objectively intraoperative techniques of imaging. CTA as well as MRA are essential to access anatomic details in variability of cavernous segments of the ICA (C4 ICA). The aim of the study was to measure the space between Internal Carotid Arteries and distances between the pituitary gland and ICA on both sides. Anatomic relations between left and right ICAs were accessed on CTA (coronal scans) at levels: A - The most concave point of the C4-C5 bend; B - The most convex point of the C4 bend; C - The C4 posterior ascending portion. Distances between pituitary gland and ICAs were measured on both sides on MRA (axial scans): A' - The most concave point of C4-C5 bend; B' - The most convex point of the C4 bend. The Statistica 13 (StatSoft) software was used for the statistical analysis. The Mann-Whitney U test was applied to determine differences between the groups. To analyze the strength of correlations between the quantitative variables, Spearman's rank correlation coefficients were calculated. The results were considered statistically significant at the level of P < 0.05. Distance reduction was shown between pituitary glands and cavernous segment (C4) of ICAs on both sides, which is related to age. This has impact on surgical planning and highlights the risk of intraoperative injury of ICAs.

Advanced Neuroimaging of Acute Ischemic Stroke: Penumbra and Collateral Assessment.

Acute ischemic stroke (AIS) occurs when there is a sudden loss in cerebral blood flow due to embolic or thromboembolic occlusion of a cerebral or cervical artery. Patients with AIS require emergent neuroimaging to guide treatment, which includes intravenous thrombolysis and endovascular mechanical thrombectomy (EMT). Recent advances in AIS treatment by EMT has been driven in part by advances in computed tomography (CT) and MR imaging neuroimaging evaluation of ischemic penumbra and pial collateral vessels. The authors review advanced noninvasive brain imaging by CT and MR imaging for the evaluation of AIS focusing on penumbral and collateral imaging.