DSpace Collection:

Characterization of healing following atherosclerotic carotid plaque rupture in acutely symptomatic patients: an exploratory study using in vivo cardiovascular magnetic resonance

Wed, 26 Oct 2011 23:00:00 GMT

Title: Characterization of healing following atherosclerotic carotid plaque rupture in acutely symptomatic patients: an exploratory study using in vivo cardiovascular magnetic resonance Authors: Teng, Zhongzhao; Degnan, Andrew J; Sadat, Umar; Wang, Fang; Young, Victoria E; Graves, Martin J; Chen, Shengyong; Gillard, Jonathan H Abstract: Abstract Background Carotid plaque rupture, characterized by ruptured fibrous cap (FC), is associated with subsequent cerebrovascular events. However, ruptured FC may heal following stroke and convey decreased risk of future events. This study aims to characterize the healing process of ruptured FC by assessing the lumen conditions, quantified by the lumen curvature and roughness, using in vivo carotid cardiovascular magnetic resonance (CMR). Methods Patients suffering from transient ischemic attack underwent high resolution carotid MR imaging within 72 hours of the acute cerebrovascular ischemic event. CMR imaging was repeated at 3 and 12 months in 26 patients, in whom FC rupture/erosion was observed on baseline images and subsequent cerebrovascular events were recorded during the follow-up period. Lumen curvature and roughness were quantified from carotid CMR images and changes in these values were monitored on follow-up imaging. Results Healing of ruptured plaque was observed in patients (23 out of 26) without any ischemic symptom recurrence as shown by the lumen surface becoming smoother during the follow-up period, characterized by decreasing maximum lumen curvature (p < 0.05), increasing minimum lumen curvature (p < 0.05) and decreasing lumen roughness (p < 0.05) during the one year follow-up period. Conclusions Carotid plaque healing can be assessed by quantification of the lumen curvature and roughness and the incidence of recurrent cerebrovascular events may be high in plaques that do not heal with time. The assessment of plaque healing may facilitate risk stratification of recent stroke patients on the basis of CMR results. Description: RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.

Smoking and high-risk mammographic parenchymal patterns: a case-control study

Tue, 16 Nov 1999 00:00:00 GMT

Title: Smoking and high-risk mammographic parenchymal patterns: a case-control study Authors: Sala, Evis; Warren, Ruth M L; McCann, Jenny; Duffy, Stephen; Luben, Robert; Day, Nicholas E Abstract: Statement of findings Current smoking was strongly and inversely associated with high-risk patterns, after adjustment for concomitant risk factors. Relative to never smokers, current smokers were significantly less likely to have a high-risk pattern. Similar results were obtained when the analysis was confined to postmenopausal women. Past smoking was not related to the mammographic parenchymal patterns. The overall effect in postmenopausal women lost its significance when adjusted for other risk factors for P2/DY patterns that were found to be significant in the present study, although the results are still strongly suggestive. The present data indicate that adjustment for current smoking status is important when evaluating the relationship between mammographic parenchymal pattern and breast cancer risk. They also indicate that smoking is a prominent potential confounder when analyzing effects of other risk factors such as obesity-related variables. It appears that parenchymal patterns may act as an informative biomarker of the effect of cigarette smoking on breast cancer risk. Description: RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.

Using mammographic density to predict breast cancer risk: dense area or percent dense area

Thu, 18 Nov 2010 00:00:00 GMT

Title: Using mammographic density to predict breast cancer risk: dense area or percent dense area Authors: Stone, Jennifer; Ding, Jane; Warren, Ruth M L; Duffy, Stephen; Hopper, John L Abstract: Abstract Introduction Mammographic density (MD) is one of the strongest risk factors for breast cancer. It is not clear whether this association is best expressed in terms of absolute dense area or percentage dense area (PDA). Methods We measured MD, including nondense area (here a surrogate for weight), in the mediolateral oblique (MLO) mammogram using a computer-assisted thresholding technique for 634 cases and 1,880 age-matched controls from the Cambridge and Norwich Breast Screening programs. Conditional logistic regression was used to estimate the risk of breast cancer, and fits of the models were compared using likelihood ratio tests and the Bayesian information criteria (BIC). All P values were two-sided. Results Square-root dense area was the best single predictor (for example, χ12 = 53.2 versus 44.4 for PDA). Addition of PDA and/or square-root nondense area did not improve the fit (both P > 0.3). Addition of nondense area improved the fit of the model with PDA (χ12 = 11.6; P < 0.001). According to the BIC, the PDA and nondense area model did not provide a better fit than the dense area alone model. The fitted values of the two models were highly correlated (r = 0.97). When a measure of body size is included with PDA, the predicted risk is almost identical to that from fitting dense area alone. Conclusions As a single parameter, dense area provides more information than PDA on breast cancer risk.

Non-invasive MR imaging of inflammation in a patient with both asymptomatic carotid atheroma and an abdominal aortic aneurysm: a case report

Wed, 21 Feb 2007 00:00:00 GMT

Title: Non-invasive MR imaging of inflammation in a patient with both asymptomatic carotid atheroma and an abdominal aortic aneurysm: a case report Authors: Howarth, Simon P S; Tang, Tjun Y; Graves, Martin J; U-King-Im, Jean-Marie; Li, Zhi-Yong; Walsh, Stewart R; Gaunt, Michael E; Gillard, Jonathan H Abstract: Abstract Inflammation is a recognized risk factor for the vulnerable atherosclerotic plaque. USPIO-enhanced MRI imaging is a promising non-invasive method to identify high-risk atheromatous plaque inflammation in vivo in humans, in which areas of focal signal loss on MR images have been shown to correspond to the location of activated macrophages, typically at the shoulder regions of the plaque. This is the first report in humans describing simultaneous USPIO uptake within atheroma in two different arterial territories and again emphasises that atherosclerosis is a truly systemic disease. With further work, USPIO-enhanced MR imaging may be useful in identifying inflamed vulnerable atheromatous plaques in vivo, so refining patient selection for intervention and allowing appropriate early aggressive pharmacotherapy to prevent plaque rupture. Description: RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.

Peroneal artery pseudoaneurysm - a case report and literature review

Wed, 28 Mar 2007 23:00:00 GMT

Title: Peroneal artery pseudoaneurysm - a case report and literature review Authors: Sadat, Umar; See, Teikchoon; Cousins, Claire; Hayes, Paul; Gaunt, Michael E Abstract: Abstract Background Aneurysms of the peroneal artery are infrequent and consist mainly of pseudoaneurysms. Case presentation This report describes an unusual case of peroneal pseudoaneurysm developing after thromoboembolectomy with a Fogarty catheter. It was managed successfully using an endovascular technique consisting of selective catheterization and coil embolization. The coils were placed in the peroneal artery, both proximal and distal to the pseudoaneurysm. Conclusion Endovascular technique can be successfully used to treat pseudoaneurysms in difficult settings. Description: RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.

Does PGA external stenting reduce compliance mismatch in venous grafts?

Sun, 15 Apr 2007 23:00:00 GMT

Title: Does PGA external stenting reduce compliance mismatch in venous grafts? Authors: Teng, Zhong-zhao; Ji, Guang-yu; Chu, Hong-jun; Li, Zhi-Yong; Zou, Liang-jian; Xu, Zhi-yun; Huang, Sheng-dong Abstract: Abstract Background Autogenous vein grafting is widely used in regular bypassing procedures. Due to its mismatch with the host artery in both mechanical property and geometry, the graft often over expands under high arterial blood pressure and forms a step-depth where eddy flow develops, thus causing restenosis, fibrous graft wall, etc. External stents, such as sheaths being used to cuff the graft, have been introduced to eliminate these mismatches and increase the patency. Although histological and immunochemical studies have shown some positive effects of the external stent, the mechanical mismatch under the protection of an external stent remains poorly analyzed. Methods In this study, the jugular veins taken from hypercholesterolemic rabbits were transplanted into the carotid arteries, and non-woven polyglycolic acid (PGA) fabric was used to fabricate the external stents to study the effect of the biodegradable external stent. Eight weeks after the operation, the grafts were harvested to perform mechanical tests and histological examinations. An arc tangent function was suggested to describe the relationship between pressure and cross-sectional area to analyse the compliance of the graft. Results The results from the mechanical tests indicated that grafts either with or without external stents displayed large compliance in the low-pressure range and were almost inextensible in the high-pressure range. This was very different from the behavior of the arteries or veins in vivo. The data from histological tests showed that, with external stents, collagen fibers were more compact, whilst those in the graft without protection were looser and thicker. No elastic fiber was found in either kind of grafts. Furthermore, grafts without protection were over-expanded which resulted in much bigger cross-sectional areas. Conclusion The PGA external extent contributes little to the reduction of the mechanical mismatch between the graft and its host artery while remodeling develops. For the geometric mismatch, it reduces the cross-section area, therefore matching with the host artery much better. Although there are some positive effects, conclusively the PGA is not an ideal material for external stent. Description: RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.

Role of carotid duplex imaging in carotid screening programmes- an overview

Thu, 03 Jul 2008 23:00:00 GMT

Title: Role of carotid duplex imaging in carotid screening programmes- an overview Authors: Saleem, Muhammad A; Sadat, Umar; Walsh, Stewart R; Young, Victoria E; Gillard, Jonathan H; Cooper, David G; Gaunt, Michael E Abstract: Abstract Background Stroke is the third most common cause of death in the UK and the largest single cause of severe disability. Each year more than 110,000 people in England suffer from a stroke which costs the National Health Service (NHS) over GBP2.8 billion. Thus, it is imperative that patients at risk be screened for underlying carotid artery atherosclerosis. Aim To assess the role of carotid ultrasound in different carotid screening programmes. Methods A literature overview was carried out by using PubMed search engine, to identify different carotid screening programmes that had used ultrasound scan as a screening tool. Results It appears that the carotid ultrasound is an effective method for screening carotid artery disease in community as it effectively predicts the presence of stenosis with high accuracy. There is a need for primary care to recommend high risk patients for regular screening, to reduce stroke and transient ischemic attack (TIA) related morbidity and mortality. Conclusion Screening programmes using carotid ultrasonography contribute to public health awareness and promotion which in long term could potentially benefit in disease prevention and essentially promote better standards of healthcare. Description: RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.

Emergency endovascular management of peripheral artery aneurysms and pseudoaneurysms- A review

Sun, 20 Jul 2008 23:00:00 GMT

Title: Emergency endovascular management of peripheral artery aneurysms and pseudoaneurysms- A review Authors: Sadat, Umar; Kullar, P J; Noorani, A; Gillard, Jonathan H; Cooper, David G; Boyle, Jonathan R Abstract: Abstract Endovascular stenting has been successfully employed in the management of aortic aneurysms; however, its use in managing peripheral arterial conditions remains questionable. We review the utility of endovascular technique in the management of peripheral arterial conditions like aneurysms, pseudoaneurysms and arterio-venous fistulas in the emergency setting. Though long term data about graft patency rates is not yet available, the endovascular approach appears to be a useful minimally invasive technique in situations where open repair is either difficult or not feasible. Description: RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.

Torsion of parietal-peritoneal fat mimicking acute appendicitis: a case report

Sun, 26 Apr 2009 23:00:00 GMT

Title: Torsion of parietal-peritoneal fat mimicking acute appendicitis: a case report Abstract: Abstract Introduction Infarctions of the greater omentum and appendices epiploicae are uncommon, but well documented causes of acute abdominal pain. We present a rare case of torted fat on the parietal peritoneum over the anterior abdominal wall, mimicking clinical signs of acute appendicitis, which was diagnosed at laparoscopy. We are aware of only two other similar reported cases, both of which were diagnosed at the time of laparotomy. Case presentation A 41-year-old Caucasian woman presented with clinical signs of acute appendicitis. On diagnostic laparoscopy, a non-inflamed appendix was found. Further exploration revealed a necrotic torted appendage of fat overlying the parietal peritoneum of the right iliac fossa of the anterior abdominal wall. Conclusion Torted fatty appendages can be a diagnostic dilemma often mimicking more common causes of an acute abdomen. Laparoscopy is an excellent tool making the correct diagnosis in such cases. Description: RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.

Intraplaque hemorrhage is associated with higher structural stresses in human atherosclerotic plaques: an in vivo MRI-based 3d fluid-structure interaction study

Fri, 31 Dec 2010 00:00:00 GMT

Title: Intraplaque hemorrhage is associated with higher structural stresses in human atherosclerotic plaques: an in vivo MRI-based 3d fluid-structure interaction study Authors: Huang, Xueying; Teng, Zhong-zhao; Canton, Gador; Ferguson, Marina; Yuan, Chun; Tang, Dalin Abstract: Abstract Background Studies using medical images have shown that intraplaque hemorrhage may accelerate plaque progression and may produce a stimulus for atherosclerosis development by increasing lipid core and plaque volume and creating new destabilizing factors. Image-based 3D computational models with fluid-structure interactions (FSI) will be used to perform plaque mechanical analysis and investigate possible associations between intraplaque hemorrhage and both plaque wall stress (PWS) and flow shear stress (FSS). Methods In vivo MRI data of carotid plaques from 5 patients with intraplaque hemorrhage confirmed by histology were acquired. 3D multi-component FSI models were constructed for each plaque to obtain mechanical stresses. Plaque Wall Stress (PWS) and Flow Shear Stress (FSS) were extracted from all nodal points on the lumen surface of each plaque for analysis. Results The mean PWS value from all hemorrhage nodes of the 5 plaques combined was higher than that from non-hemorrhage nodes (75.6 versus 68.1 kPa, P = 0.0003). The mean PWS values from hemorrhage nodes for each of the 5 plaques were all significantly higher (5 out of 5) than those from non-hemorrhage nodes (P < 0.05). The mean FSS value from all hemorrhage nodes of the 5 plaques combined was 30.4% higher than that from all non-hemorrhage nodes (15.0 versus 11.5 dyn/cm2, P = 0.0002). However, the mean flow shear stress values from individual cases showed mixed results: only one out of five plaques showed mean FSS value from hemorrhage nodes was higher than that from non-hemorrhage nodes; three out of five plaques showed that their mean FSS values from hemorrhage nodes were lower than those from non-hemorrhage nodes; and one plaque showed that the difference had no statistical significance. Conclusion The results of this study suggested that intraplaque hemorrhage nodes were associated with higher plaque wall stresses. Compared to flow shear stress, plaque wall stress has a better correlation with plaque component feature (hemorrhage) linked to plaque progression and vulnerability. With further validation, plaque stress analysis may provide additional stress indicators for image-based vulnerability assessment. Description: RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.

Transomental defects as a cause of chronic abdominal pain, the role of diagnostic laparoscopy: a case series

Sun, 05 Jul 2009 23:00:00 GMT

Title: Transomental defects as a cause of chronic abdominal pain, the role of diagnostic laparoscopy: a case series Abstract: Abstract Introduction Transomental herniation is a rare but recognised clinical condition, which usually presents as an emergency with bowel obstruction. It accounts for 1-4% of intra-abdominal herniations. We reviewed 3 patients found to have a transomental defect during elective diagnostic laparoscopy performed for chronic abdominal pain. To our knowledge, there is no case series reported in the literature on transomental defect in the non-emergency situation. Case presentation A retrospective case note analysis of 3 patients, found to have transomental defect during elective diagnostic laparoscopy, was undertaken. Data were gathered with respect to clinical presentation, investigations performed, transomental defect size and outcome of surgery. All patients were followed up for 6 months post-operatively. Three females (age range 18-35 years) were referred with a 3-10 year history of chronic intermittent abdominal pain, often postprandial. Blood tests, radiological investigations (ultrasound, magnetic resonance imaging/computed tomography, small bowel studies) and endoscopy were all normal. In each case, diagnostic laparoscopy revealed the presence of a peripheral defect in the greater omentum, but no actual small bowel herniation. No other pathology was found. These defects were resected, which subsequently led to complete resolution of the patients' symptoms. Conclusion Chronic abdominal pain of unknown aetiology with normal radiological findings may be caused by intermittent obstruction due to small bowel herniation through a transomental defect. This should be considered during elective diagnostic laparoscopy, in the absence of any other obvious pathology. The omentum should be thoroughly inspected as a discrete entity and any such defects should be closed or resected. Description: RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.

Sequence optimization to reduce velocity offsets in cardiovascular magnetic resonance volume flow quantification - A multi-vendor study

Wed, 09 Mar 2011 00:00:00 GMT

Title: Sequence optimization to reduce velocity offsets in cardiovascular magnetic resonance volume flow quantification - A multi-vendor study Authors: Rolf, Marijn P; Hofman, Mark B M; Gatehouse, Peter D; Markenroth Bloch, Karin; Heymans, Martijn W; Ebbers, Tino; Graves, Martin J; Totman, John J; Werner, Beat; Rossum, Albert C van; Kilner, Philip J; Heethaar, Rob M Abstract: Abstract Purpose Eddy current induced velocity offsets are of concern for accuracy in cardiovascular magnetic resonance (CMR) volume flow quantification. However, currently known theoretical aspects of eddy current behavior have not led to effective guidelines for the optimization of flow quantification sequences. This study is aimed at identifying correlations between protocol parameters and the resulting velocity error in clinical CMR flow measurements in a multi-vendor study. Methods Nine 1.5T scanners of three different types/vendors were studied. Measurements were performed on a large stationary phantom. Starting from a clinical breath-hold flow protocol, several protocol parameters were varied. Acquisitions were made in three clinically relevant orientations. Additionally, a time delay between the bipolar gradient and read-out, asymmetric versus symmetric velocity encoding, and gradient amplitude and slew rate were studied in adapted sequences as exploratory measurements beyond the protocol. Image analysis determined the worst-case offset for a typical great-vessel flow measurement. Results The results showed a great variation in offset behavior among scanners (standard deviation among samples of 0.3, 0.4, and 0.9 cm/s for the three different scanner types), even for small changes in the protocol. Considering the absolute values, none of the tested protocol settings consistently reduced the velocity offsets below the critical level of 0.6 cm/s neither for all three orientations nor for all three scanner types. Using multilevel linear model analysis, oblique aortic and pulmonary slices showed systematic higher offsets than the transverse aortic slices (oblique aortic 0.6 cm/s, and pulmonary 1.8 cm/s higher than transverse aortic). The exploratory measurements beyond the protocol yielded some new leads for further sequence development towards reduction of velocity offsets; however those protocols were not always compatible with the time-constraints of breath-hold imaging and flow-related artefacts. Conclusions This study showed that with current systems there was no generic protocol which resulted into acceptable flow offset values. Protocol optimization would have to be performed on a per scanner and per protocol basis. Proper optimization might make accurate (transverse) aortic flow quantification possible for most scanners. Pulmonary flow quantification would still need further (offline) correction. Description: RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.