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 = 2.4¾2.4¾5 mm 3 ) 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.

ObjectivesThe aim of this study was to: 1) provide tissue validation of quantitative T2 mapping to measure plaque lipid content; and 2) investigate whether this technique could discern differences in plaque characteristics between symptom-related and non–symptom-related carotid plaques.BackgroundNoninvasive plaque lipid quantification is appealing both for stratification in treatment selection and as a possible predictor of future plaque rupture. However, current cardiovascular magnetic resonance (CMR) methods are insensitive, require a coalesced mass of lipid core, and rely on multicontrast acquisition with contrast media and extensive post-processing.MethodsPatients scheduled for carotid endarterectomy were recruited for 3-T carotid CMR before surgery. Lipid area was derived from segmented T2 maps and compared directly to plaque lipid defined by histology.ResultsLipid area (%) on T2 mapping and histology showed excellent correlation, both by individual slices (R = 0.85, p < 0.001) and plaque average (R = 0.83, p < 0.001). Lipid area (%) on T2 maps was significantly higher in symptomatic compared with asymptomatic plaques (31.5 ± 3.7% vs. 15.8 ± 3.1%; p = 0.005) despite similar degrees of carotid stenosis and only modest difference in plaque volume (128.0 ± 6.0 mm3 symptomatic vs. 105.6 ± 9.4 mm3 asymptomatic; p = 0.04). Receiver-operating characteristic analysis showed that T2 mapping has a good ability to discriminate between symptomatic and asymptomatic plaques with 67% sensitivity and 91% specificity (area under the curve: 0.79; p = 0.012).ConclusionsCMR T2 mapping distinguishes different plaque components and accurately quantifies plaque lipid content noninvasively. Compared with asymptomatic plaques, greater lipid content was found in symptomatic plaques despite similar degree of luminal stenosis and only modest difference in plaque volumes. This new technique may find a role in determining optimum treatment (e.g., providing an indication for intensive lipid lowering or by informing decisions of stents vs. surgery).

ObjectiveAccurate 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.MethodsThe 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.ResultsProspective 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 individual's AAA diameter to within 2 mm error in 85% and 71% of patients at 12 and 24 months.ConclusionsThe 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.

Background and purposeTechniques to stratify subgroups of patients with asymptomatic carotid artery disease are urgently needed to guide decisions on optimal treatment. Reliance on estimates of % luminal stenosis has not been effective, perhaps because that approach entirely disregards potentially important information on the pathological process in the wall of the artery.MethodsSince plaque lipid is a key determinant of plaque behaviour we used a newly validated, high-sensitivity T2-mapping MR technique for a systematic survey of the quantity and distribution of plaque lipid in patients undergoing endarterectomy. Lipid percentage was quantified in 50 carotid endarterectomy patients. Lipid distribution was tested, using two imaging indices (contribution of the largest lipid deposit towards total lipid (LLD %) and a newly-developed LAI ‘lipid aggregation index’).ResultsThe bifurcation contained maximal lipid volume. Lipid percentage was higher in symptomatic vs. asymptomatic patients with degree of stenosis (DS ≥ 50%) and in the total cohort (P = 0.013 and P = 0.005, respectively). Both LLD % and LAI was higher in symptomatic patients (P = 0.028 and P = 0.018, respectively), suggesting that for a given plaque lipid volume, coalesced deposits were more likely to be associated with symptomatic events. There was no correlation between plaque volume or lipid content and degree of luminal stenosis measured on ultrasound duplex (r = -0.09, P = 0.53 and r = -0.05, P = 0.75), respectively. However, there was a strong correlation in lipid between left and right carotid arteries (r = 0.5, P <0.0001, respectively).ConclusionsPlaque lipid content and distribution is associated with symptomatic status of the carotid plaque. Importantly, plaque lipid content was not related to the degree of luminal stenosis assessed by ultrasound. Determination of plaque lipid content may prove useful for stratification of asymptomatic patients, including selection of optimal invasive treatments.

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.

LAN is associated with delayed Type IA endoleak occurrence and lower overall survival.

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 ␥-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 (PϽ0.020). For patients, relative time to peak was positively correlated with percent stenosis (PϽ0.050), 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 (PϽ0.017) and the flow amplitude increased (PϽ0.009). 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. (Stroke. 2011;42:979-984.)Key Words: endarterectomy Ⅲ carotid stenosis Ⅲ arterial spin labeling Ⅲ angiography Ⅲ dynamic Ⅲ blood flow Ⅲ aging A therosclerosis is a major risk factor for ischemic cerebrovascular events. Extracranial steno-occlusive disease influences hemodynamics and physiology in the brain. 1 Therefore, carotid endarterectomy (CEA) is a standard treatment for patients with symptomatic stenosis Ͼ70% because surgical therapy is associated with higher event-free survival compared with medical therapy. 2 However, CEA is not without risk; 1 study reported a 4.3% increase in the risk of stroke or death within 30 days of CEA. 2 Other studies report silent infarcts, evident postoperatively on diffusion-weighted images in 17% to 33% of CEA patients. 3,4 Therefore, there is merit in developing imaging techniques that can be used to assess the downstream impact of extracranial steno-occlusive disease. phase encoding, nor does it require that slices be perpendicular to the vessels of interest. The purpose of this study was to determine whether ASL-based DynAngio could be used to characterize circle of Willis hemodynamics, as it provides the primary means of collateral blood supply in the brain. We collected data from control subjects and patients with carotid artery disease to test the hypotheses that DynAngio hemodynamic measures are capab...

When obtaining informed consent, simply describing patency and limb salvage rates does not provide an accurate picture of the outcome of femorofemoral grafting.