The added value of longitudinal black-blood cardiovascular magnetic resonance angiography in the cross sectional identification of carotid atherosclerotic ulceration

<p>Abstract</p> <p>Background</p> <p>Carotid atherosclerotic ulceration is a significant source of stroke. This study evaluates the efficacy of adding longitudinal black-blood (BB) cardiovascular magnetic resonance (CMR) angiography to cross-sectional CMR images in the identification of carotid atherosclerotic ulceration.</p> <p>Methods</p> <p>Thirty-two subjects (30 males and two females with ages between 48 and 83 years) scheduled for carotid endarterectomy were imaged on a 1.5T GE Signa scanner using multisequence [3D time-of-flight, T1, proton density, T2, contrast enhanced T1], cross-sectional CMR images and longitudinal BB CMR angiography (0.625 × 0.625 mm/pixel). Two rounds of review (round 1: cross-sectional CMR images alone and round 2: cross-sectional CMR images plus longitudinal BB CMR angiography) were conducted for the presence and volume measurements of ulceration. Ulceration was defined as a distinct depression into the plaque containing blood flow signal on cross-sectional CMR and longitudinal BB CMR angiography.</p> <p>Results</p> <p>Of the 32 plaques examined by histology, 17 contained 21 ulcers. Using the longitudinal BB CMR angiography sequence in addition to the cross-sectional CMR images in round 2, the sensitivity improved to 80% for ulcers of at least 6 mm³in volume by histology and 52.4% for all ulcers, compared to 30% and 23.8% in round 1, respectively. There was a slight decline in specificity from 88.2% to 82.3%, though both the positive and negative predictive values increased modestly from 71.4% to 78.6% and from 48.4% to 58.3%, respectively.</p> <p>Conclusion</p> <p>The addition of longitudinal BB CMR angiography to multisequence cross-sectional CMR images increases accuracy in the identification of carotid atherosclerotic ulceration.</p

Differences in carotid arterial morphology and composition between individuals with and without obstructive coronary artery disease: A cardiovascular magnetic resonance study

Objective: We sought to determine differences with cardiovascular magnetic resonance (CMR) in the morphology and composition of the carotid arteries between individuals with angiographically-defined obstructive coronary artery disease (CAD, = 50% stenosis, cases) and those with angiographically normal coronaries (no lumen irregularities, controls). Methods and results: 191 participants (50.3% female; 50.8% CAD cases) were imaged with a multi-sequence, carotid CMR protocol at 1.5T. For each segment of the carotid, lumen area, wall area, total vessel area (lumen area + wall area), mean wall thickness and the presence or absence of calcification and lipid-rich necrotic core were recorded bilaterally. In male CAD cases compared to male controls, the distal bulb had a significantly smaller lumen area (60.0 [plus or minus] 3.1 vs. 79.7 [plus or minus] 3.2 mm[super]2, p less than 0.001) and total vessel area (99.6 [plus or minus] 4.0 vs. 119.8 [plus or minus] 4.1 mm[super]2; p less than 0.001), and larger mean wall thickness (1.25 [plus or minus] 0.03 vs. 1.11 [plus or minus] 0.03 mm; p = 0.002). Similarly, the internal carotid had a smaller lumen area (37.5 [plus or minus] 1.8 vs. 44.6 [plus or minus] 1.8 mm[super]2; p = 0.006) and smaller total vessel area (64.0 [plus or minus] 2.3 vs. 70.9 [plus or minus] 2.4 mm[super]2; p = 0.04). These metrics were not significantly different between female groups in the distal bulb and internal carotid or for either gender in the common carotid. Male CAD cases had an increased prevalence of lipid-rich necrotic core (49.0% vs. 19.6%; p = 0.003), while calcification was more prevalent in both male (46.9% vs. 17.4%; p = 0.002) and female (33.3% vs. 14.6%; p = 0.031) CAD cases compared to controls. Conclusion: Males with obstructive CAD compared to male controls had carotid bulbs and internal carotid arteries with smaller total vessel and lumen areas, and an increased prevalence of lipid-rich necrotic core. Carotid calcification was related to CAD status in both males and females. Carotid CMR identifies distinct morphological and compositional differences in the carotid arteries between individuals with and without angiographically-defined obstructive CAD.Carotid Atherosclerosis (MRI) Progression Study (CAMPS, HL076378) and Cardiovascular Research Training Program (T-32, HL07838); and the General Clinical Research Center at the Wake Forest University School of Medicine (M01 RR-07122)

Order and the Virtual: Toward a Deleuzian Cosmology

None provided, have taken the following from the "Introduction" Order is a more or less explicit topic for any thinker who undertakes to write about nature. Even those who assert that randomness or chaos is the most fundamental trait of nature are obliged to account for the apparent permanence, organisation and structure we observe around us. No less is true for Gilles Deleuze, who champions the power of chaos through his work. On one reading, Deleuze’s chief impulse is to wrench loose the lynchpins of order; to ‘affirm chaos’ and disarticulate the law of excluded middle; to refuse jurisdiction to laws of nature and render provisional its every constant; to banish identity and negation alike. If we are to be left with no fixed point, we might ask, what remains of order? This study is nevertheless an examination of that notion in Deleuze’s natural philosophy. For me the counter-reading is much more productive and insightful. Deleuze is rather a firm believer in order, even there where he affirms chaos. If we could furnish a ‘Deleuzian Question’ par excellence, it would be; ‘Given that there are no fixed points, how is order expressed in the world?’ This question is implicitly reprised across the entirety of his work and inflected at each stage by fresh vocabulary coined to treat it anew, as though for each new Deleuzian territory a new phrasebook is required

Wi-Fi based people tracking in challenging environments

People tracking is a key building block in many applications such as abnormal activity detection, gesture recognition, and elderly persons monitoring. Video-based systems have many limitations making them ineffective in many situations. Wi-Fi provides an easily accessible source of opportunity for people tracking that does not have the limitations of video-based systems. The system will detect, localise, and track people, based on the available Wi-Fi signals that are reflected from their bodies. Wi-Fi based systems still need to address some challenges in order to be able to operate in challenging environments. Some of these challenges include the detection of the weak signal, the detection of abrupt people motion, and the presence of multipath propagation. In this thesis, these three main challenges will be addressed. Firstly, a weak signal detection method that uses the changes in the signals that are reflected from static objects, to improve the detection probability of weak signals that are reflected from the person’s body. Then, a deep learning based Wi-Fi localisation technique is proposed that significantly improves the runtime and the accuracy in comparison with existing techniques. After that, a quantum mechanics inspired tracking method is proposed to address the abrupt motion problem. The proposed method uses some interesting phenomena in the quantum world, where the person is allowed to exist at multiple positions simultaneously. The results show a significant improvement in reducing the tracking error and in reducing the tracking delay

Rigorous dimension estimates for Cantor sets arising in Zaremba theory

We address the question of the accuracy of bounds used in the study of Zaremba’s conjecture. Specifically, we establish rigorous estimates on the Hausdorff dimension of certain Cantor sets which arise in the analysis of Zaremba’s conjecture in [5, 18, 19, 23]

Arterial Remodeling in the Subclinical Carotid Artery Disease

ObjectivesWe sought to identify clinical and/or plaque characteristics that affect atherosclerotic disease progression and arterial remodeling in the carotid artery with subclinical stenosis.BackgroundIncreasing severity of stenosis has been associated with a higher risk of stroke. Factors that drive subclinical lesions to become stenotic plaques remain ambiguous. Carotid magnetic resonance imaging (MRI) has been validated with histology to accurately quantify in vivo arterial morphology and plaque composition.MethodsA total of 67 asymptomatic participants with 16% to 49% carotid stenosis as demonstrated by duplex ultrasonography were imaged at 1.5-T with a carotid MRI protocol at baseline and at 18-month follow-up. Clinical and/or intra-arterial metrics with a significant association with change in plaque burden during multivariate analysis were evaluated for effects on lumen, wall, and total vessel volume.ResultsFrom multiple regression analysis, intraplaque hemorrhage (IPH) (p &#x003C; 0.001) and statin therapy (p = 0.015) were identified as key determinants of change in plaque burden. The group with IPH compared with the group without IPH demonstrated luminal narrowing, with a mean &#x00B1; SD decrease in lumen volume (&#x2212;24.9 &#x00B1; 21.1 mm3/year vs. &#x2212;0.5 &#x00B1; 26.9 mm3/year; p = 0.005), a larger increase in wall volume (44.1 &#x00B1; 36.1 mm3/year vs. 0.8 &#x00B1; 34.5 mm3/year; p &#x003C; 0.001), and no difference in total vessel volume (19.3 &#x00B1; 27.4 mm3/year vs. 0.4 &#x00B1; 42.4 mm3/year; p = 0.15). The nonstatin group compared with the statin group demonstrated outward remodeling, with an increase in wall volume (22.4 &#x00B1; 35.6 mm3/year3/year vs. 0.9 &#x00B1; 38.0 mm3/year; p = 0.026) and total vessel volume (19.2 &#x00B1; 36.9 mm3/year vs. &#x2212;4.9 &#x00B1; 40.4 mm3/year; p = 0.019) and no difference in lumen volume (&#x2212;5.8 &#x00B1; 26.6 mm3/year vs. &#x2212;3.2 &#x00B1; 29.5 mm3/year; p = 0.72).ConclusionsIPH may represent an indication of accelerated plaque growth and impending luminal compromise in the subclinical carotid artery. Statin therapy may stabilize lesions by slowing or halting lesion progression. This phase of plaque stenosis (16% to 49%) may be a critical stage for intrinsic and extrinsic factors to affect the atherosclerotic disease process