Ediri Sideso

Absolute arterial cerebral blood volume quantification using inflow vascular-space-occupancy with dynamic subtraction magnetic resonance imaging

In patients with steno-occlusive disease of the internal carotid artery (ICA), cerebral blood flow may be maintained by autoregulatory increases in arterial cerebral blood volume (aCBV). Therefore, characterizing aCBV may be useful for understanding hemodynamic compensation strategies. A new ‘inflow vascular-space-occupancy with dynamic subtraction (iVASO-DS)’ MRI approach is presented where aCBV (mL blood/100 mL parenchyma) is quantified without contrast agents using the difference between images with and without inflowing blood water signal. The iVASO-DS contrast mechanism is investigated (3.0 T, spatial resolution=2.4 × 2.4 × 5 mm3) in healthy volunteers (n=8; age=29±5 years), and patients with mild (n=7; age=72±8 years) and severe (n=10; age=73±8 years) ICA stenoses. aCBV was quantified in right and left hemispheres in controls, and, alongside industry standard dynamic susceptibility contrast (DSC), contralateral (cont), and ipsilateral (ips) to maximum stenosis in patients. iVASO contrast significantly correlated (R=0.67, P<0.01) with DSC-CBV after accounting for transit time discrepancies. Gray matter aCBV (mL/100 mL) was 1.60±0.10 (right) versus 1.61±0.20 (left) in controls, 1.59±0.38 (cont) and 1.65±0.37 (ips) in mild stenosis patients, and 1.72±0.18 (cont) and 1.58±0.20 (ips) in severe stenosis patients. aCBV was asymmetric (P<0.01) in 41% of patients whereas no asymmetry was found in any control. The potential of iVASO-DS for autoregulation studies is discussed in the context of existing hemodynamic literature.

Intracranial Hemodynamics Is Altered by Carotid Artery Disease and After Endarterectomy A Dynamic Magnetic Resonance Angiography Study

Background and Purpose— Carotid endarterectomy (CEA) has become a routine procedure to treat symptomatic carotid artery disease and reduce the risk of recurrent cerebral ischemic events. The purpose of this study was to use an arterial spin labeling dynamic magnetic resonance angiography technique to characterize intracranial hemodynamics before and after CEA. Methods— Thirty-seven carotid artery disease patients participated in this study, of whom 24 underwent magnetic resonance imaging before and after CEA. Seventeen control subjects spanning 5 decades underwent magnetic resonance imaging to assess age-related changes. Hemodynamic metrics (that is, relative time to peak and amplitude) were calculated with a &ggr;-variate model. Linear regression was used to relate carotid artery disease burden to downstream hemodynamics in the circle of Willis. Results— Relative time to peak increased with age in controls (P<0.020). For patients, relative time to peak was positively correlated with percent stenosis (P<0.050), independent of age. At 1 day after CEA, the middle cerebral artery ipsilateral to the CEA showed significant dynamic magnetic resonance angiography changes: relative time to peak decreased (P<0.017) and the flow amplitude increased (P<0.009). No pre- versus post-CEA changes were significant in the contralateral middle cerebral artery or posterior segments. Conclusions— This noninvasive, arterial spin labeling–based method produced time-resolved images that were used to characterize intracranial arterial flow associated with aging, extracranial carotid artery disease, and CEA. Results demonstrate that the technique has the sensitivity to detect hemodynamic changes after CEA.

Incidence, risk factors, outcome and projected future burden of acute aortic dissection.

Acute aortic dissection has a high mortality rate, despite well-established treatment guidelines (1). Data on risk factors, incidence and outcome of aortic dissection are limited, largely due to a lack of contemporary population-based studies of this condition. Existing hospital-based studies, often from specialist centers or studies of retrospective registry data such as the International Registry of Acute Aortic Dissection (IRAD), may underestimate incidence and case fatality by incomplete inclusion of deaths prior to hospital admission, which might also bias assessment of risk factors and predictors of outcome. This research highlight outlines the findings of our recent population-based research of acute aortic dissection, which is the first-ever prospective epidemiological study of this condition (2). We studied event rates, incidence, risk factors, early case fatality, and long-term outcome of all acute aortic events occurring in a population of 92,728 in Oxfordshire, UK, during 2002-2012, as part of the Oxford Vascular Study (OXVASC). Using current incidence data and Office of National Statistics (ONS) population projections (3), we went on to predict UK incidence event rates for acute aortic dissection over the next 40 years.

General or Local Anesthesia for Carotid Endarterectomy—The “Real-World” Experience:

Perioperative complications from carotid endarterectomy (CEA) are the main drawbacks of the procedure. The aim of this study was to assess the complication rates in patients undergoing CEA under general anesthesia (GA) or regional anesthesia (local anesthesia [LA]) at our institution. Patients undergoing CEA at our regional vascular unit between 2000 and 2004 were included. Data were collated retrospectively from a prospective database. Follow-up was up to 62 months. In all, 383 endarterectomies were performed, 260 of which were under LA. Outcome measures included 30-day death (2.1%), stroke (1.8%), and combined stroke and death (2.8%). A 30-day incidence of stroke, death, and combined stroke and death was lower in the LA group. Incidence of myocardial infarction and transient ischemic attacks, and annual mortality were higher in the LA group. No significant difference was found between the 2 groups. In a unit where CEA is preferentially performed under LA, anesthesia technique failed to significantly influence outcome.

Evaluating quantitative approaches to dynamic susceptibility contrast MRI among carotid endarterectomy patients.

To evaluate two dynamic susceptibility contrast (DSC) quantification methods in symptomatic carotid artery disease patients undergoing carotid endarterectomy (CEA) surgery by comparing methods directly and assessing the reliability of each method in the hemisphere contralateral to surgery.

Assessing the quality and reproducibility of a proteomic platform for clinical stroke biomarker discovery.

The aim of this study was to investigate the quality and reproducibility of mass spectra derived from a matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS) platform in a patient population undergoing carotid endarterectomy. Plasma samples were either digested with trypsin or left undigested, fractionated with either C18 or weak cation exchange (WCX) columns and analysed by MALDI-TOF MS. Quality of mass spectra for each method was assessed by baseline correction (lower area under the curve ratio indicating higher quality) and signal-to-noise ratio. Mean coefficient of variation (CV%) assessed reproducibility between repeated experiments and methods. Identified mass peak intensity differences were assessed for consistency across repeated experiments. Plasma from six patients was analysed. The quality of mass spectra was significantly better when derived from digested plasma fractionated by either WCX or C18 methods compared to undigested plasma fractionated by WCX (analysis of variance, p < 0.05). Mean CV% for repeated experiments was 18% and 28% for WCX and C18 fractionated digested plasma, respectively. A small number of differences in mass peak intensities were consistently observed in repeated experiments. Repeated experiments are required to confidently identify non-random mass peak intensity differences as putative plasma biomarkers that merit further investigation.

Flow Mediated Dilatation and Progression of Abdominal Aortic Aneurysms.

Objective/Background Biomarker(s) for prediction of the future progression rate of abdominal aortic aneurysms (AAA) may be useful to stratify the management of individual patients. AAAs are associated with features of systemic inflammation and endothelial dysfunction. Flow mediated dilatation (FMD) of the brachial artery is a recognised non-invasive measurement for endothelial function. We hypothesised that FMD is a potential biomarker of AAA progression and reflects the temporal changes of endothelial function during AAA progression. Methods In a prospectively recruited cohort of patients with AAAs (Oxford Abdominal Aortic Aneurysm Study), AAA size was recorded by antero-posterior diameter (APD) (outer to outer) on ultrasound. Annual AAA progression was calculated by (ΔAPD/APD at baseline)/(number of days lapsed/365 days). FMD was assessed at the same time as AAA size measurement. Analyses of data were performed in the overall cohort, and further in subgroups of AAA by size (small: 30–39 mm; moderate: 40–55 mm; large: > 55 mm). Results FMD is inversely correlated with the diameter of AAAs in all patients (n = 162, Spearman’s r = −.28, p < .001). FMD is inversely correlated with AAA diameter progression in the future 12 months (Spearman’s r = −.35, p = .001), particularly in the moderate size group. Furthermore, FMD deteriorates during the course of AAA surveillance (from a median of 2.0% at baseline to 1.2% at follow-up; p = .004), while surgical repair of AAAs (n = 50 [open repair n = 22, endovascular repair n = 28)] leads to an improvement in FMD (from 1.1% pre-operatively to 3.8% post-operatively; p < .001), irrespective of the type of surgery. Conclusion FMD is inversely correlated with future AAA progression in humans. FMD deteriorates during the natural history of AAA, and is improved by surgery. The utility of FMD as a potential biomarker in the context of AAA warrants further investigation.

Delays in the presentation to stroke services of patients with transient ischaemic attack and minor stroke

The UK National Institute for Health and Care Excellence (NICE) guidelines state that carotid endarterectomy should be scheduled within 2 weeks of symptoms. The recent National Stroke Strategy has reduced the time interval to 48 h. This study aimed to review the possible delays.

Applied Machine Learning for the Prediction of Growth of Abdominal Aortic Aneurysm in Humans

Objective Accurate prediction of abdominal aortic aneurysm (AAA) growth in an individual can allow personalised stratification of surveillance intervals and better inform the timing for surgery. The authors recently described the novel significant association between flow mediated dilatation (FMD) and future AAA growth. The feasibility of predicting future AAA growth was explored in individual patients using a set of benchmark machine learning techniques. Methods The Oxford Abdominal Aortic Aneurysm Study (OxAAA) prospectively recruited AAA patients undergoing the routine NHS management pathway. In addition to the AAA diameter, FMD was systemically measured in these patients. A benchmark machine learning technique (non-linear Kernel support vector regression) was applied to predict future AAA growth in individual patients, using their baseline FMD and AAA diameter as input variables. Results Prospective growth data were recorded at 12 months (360 ± 49 days) in 94 patients. Of these, growth data were further recorded at 24 months (718 ± 81 days) in 79 patients. The average growth in AAA diameter was 3.4% at 12 months, and 2.8% per year at 24 months. The algorithm predicted the individuals AAA diameter to within 2 mm error in 85% and 71% of patients at 12 and 24 months. Conclusions The data highlight the utility of FMD as a biomarker for AAA and the value of machine learning techniques for AAA research in the new era of precision medicine.

Abdominal aortic aneurysm and lumbar plexus palsy

An 82-year-old man was found to have a 6 cm infra-renal abdominal aortic aneurysm (AAA) ( Panel A , white arrow). Elective AAA surgery was postponed due to incidental finding of a hepatocellular carcinoma ( Panel A inset, red arrow), for which he underwent successive catheter-directed embolization to good result ( Panel B inset, red …