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  • ANGIOGRAPHY  (7)
  • BLOOD-FLOW  (7)
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  • 1
    Keywords: Diagnostic Imaging ; radiology ; MULTISLICE CT ; imaging ; CT ; CT ANGIOGRAPHY ; ANGIOGRAPHY ; arteries
    Type of Publication: Book chapter
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  • 2
    Keywords: computed tomography ; ANGIOGRAPHY ; ABDOMINAL-AORTA ; Aorta ; Aortic pathologies ; COMPUTED-TOMOGRAPHY AN
    Abstract: Current imaging of the aorta saw an improvement in terms of diversity and quality in recent years. In addition to verifying and documenting a clinical suspicion, it provides the basis for establishing an indication, choosing a therapy (conservative, surgical, interventional), as well as therapy planning and follow-up. Besides B-mode and duplex sonography, as well as transesophageal echocardiography (TEE), contrast-enhanced cross-sectional imaging, computer tomography (CT), with the option for CT angiography (CTA), and magnetic resonance tomography (MRT), with the option for MR angiography (MRA), play a significant role. The present article describes the possibilities offered by CTA and MRA for the diagnosis of aortic pathologies from the point of view of the radiologist in a maximum care hospital
    Type of Publication: Journal article published
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  • 3
    Keywords: Germany ; chest ; CT ; SYSTEM ; TOOL ; DEATH ; DISEASE ; MORTALITY ; RISK ; SURGERY ; PATIENT ; INJURIES ; MECHANISM ; IMPACT ; CONTRAST ; mechanisms ; treatment ; EXPERIENCE ; DISRUPTION ; REPAIR ; REGION ; ANGIOGRAPHY ; MANAGEMENT ; THORACIC AORTA ; HEIGHT ; wound ; STABILIZATION ; endovascular ; Cause of Death ; BLUNT ; DELAYED TREATMENT ; intracranial ; RUPTURE
    Abstract: Acute traumatic aortic tear (ATAT) is the second most common cause of deaths in trauma patients (about 8,000 deaths/year in the USA). Due to circumferential aortic disruption, up to 90% die at the scene. Responsible trauma mechanisms are: penetrating (gunshot/stab wounds), iatrogenic (interventional catheterization) and, most frequently, blunt chest trauma (high-speed motor vehicles, falls from heights, crushes, explosions) resulting in injury at the aortic isthmus region (loco typico, about 90%). Severe multiple system injuries (polytrauma), especially to intracranial and intraabdominal organs, are characteristic and prognostically predicitive. Immediate transthoracic open repair of ATAT has a mortality risk of 8% to 33% and paraplegia risk of 2% to 26%. Contrast enhanced CT scan has replaced the classical angiography as the diagnostic tool of choice. Patients with life-threatening multisystem injuries are scheduled for delayed repair after initial stabilization. Currently, the use of endovascular stent-grafts (EVAR) is being investigated. Our personal series confirms that EVAR for ATAT is a viable alternative to open repair while minimizing the morbidity and mortality of the open procedure and having a limited impact on trauma destabilization. The assessment of long-term durability of EVAR is one of the key issues to consider EVAR as the first choice of treatment
    Type of Publication: Journal article published
    PubMed ID: 16533692
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  • 4
    Keywords: MODEL ; VISUALIZATION ; DISEASE ; BLOOD-FLOW ; MAGNETIC-RESONANCE ; magnetic resonance imaging ; SURVEILLANCE ; ANGIOGRAPHY ; endovascular repair ; endovascular ; ANEURYSM REPAIR ; Aorta ; stent graft ; phase-contrast flow ; blood flow velocity
    Abstract: PURPOSE: To validate flow measurements within an aortic nickel-titanium (nitinol) stent graft using velocity-encoded cine magnetic resonance imaging (VEC MRI) and to assess intraobserver agreement of repeated flow measurements. MATERIALS AND METHODS: An elastic tube phantom mimicking the descending aorta was developed with the possibility to insert an aortic nitinol stent graft. Different flow patterns (constant, sinusoidal and pulsatile aortic flow) were applied by a gear pump. A two-dimensional phase-contrast sequence was used to acquire VEC perpendicular cross-sections at six equidistant levels along the phantom. Each acquisition was performed twice with and without stent graft, and each dataset was analysed twice by the same reader. The percental difference of the measured flow volume to the gold standard (pump setting) was defined as the parameter for accuracy. Furthermore, the intraobserver agreement was assessed. RESULTS: Mean accuracy of flow volume measurements was -0.45+/- 1.63% without stent graft and -0.18+/- 1.45% with stent graft. Slightly lower accuracy was obtained for aortic flow both without (-2.31%) and with (-1.29%) stent graft. Accuracy was neither influenced by the measurement position nor by repeated acquisitions. There was significant intraobserver agreement with an intraclass correlation coefficient of 0.87 (without stent graft, p〈0.001) and 0.80 (with stent graft, p〈0.001). The coefficient of variance was 0.25% without stent graft and 0.28% with stent graft. CONCLUSION: This study demonstrated high accuracy and excellent intraobserver agreement of flow measurements within an aortic nitinol stent graft using VEC MRI. VEC MRI may give new insights into the haemodynamic consequences of endovascular aortic repair.
    Type of Publication: Journal article published
    PubMed ID: 20888719
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  • 5
    Keywords: POPULATION ; magnetic resonance imaging ; AGE ; NECK ; COMPUTED-TOMOGRAPHY ; ANGIOGRAPHY ; physiology ; CONFORMATIONAL-CHANGES ; THORACIC AORTA ; endovascular repair ; endovascular ; ANEURYSMS ; stent graft ; ARTERIAL STIFFNESS ; WAVE REFLECTION
    Abstract: PURPOSE: To test our hypothesis that distension and displacement in various segments of the healthy thoracic aorta are significant and can be predicted based on clinical characteristics. MATERIALS AND METHODS: Sixty-one Caucasian volunteers without cardiovascular disease (49 +/- 16 years, range 19-82; 28 men, 33 women) divided into two age groups (A: 〈50, B: 〉/= 50 years) underwent 1.5-T MRI. ECG-gated dynamic data sets were acquired at five locations perpendicular to the thoracic aorta. Aortic distension and Centre of Mass (CoM) displacement were determined as percentages of diastolic aortic diameter. A multiple linear regression model including age group, gender, location, mean arterial blood pressure, heart rate and body mass index was tested. RESULTS: Mean aortic distension averaged over all locations was 11.2 +/- 4.1% (age group A) and 6.7 +/- 3.3% (age group B), mean displacement 15.1 +/- 8.3% (A) and 11.0 +/- 6.2% (B). Systolic and diastolic aortic diameter and CoM position significantly differed at all locations (p〈0.001). Distension and displacement could be predicted based on the regression model (p〈0.001). Age group A and women exhibited significantly greater distension and displacement compared to age group B (p〈0.001) and men (p〈0.01), respectively. Distension increased, displacement decreased from proximal to distal. CONCLUSION: Distension and translational displacement are significant at all levels of the thoracic aorta and can be predicted based on clinical characteristics.
    Type of Publication: Journal article published
    PubMed ID: 20850234
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  • 6
    Keywords: ACCURACY ; BLOOD-FLOW ; PATTERNS ; HEALTHY-VOLUNTEERS ; phase-contrast MRI ; CARDIOVASCULAR MAGNETIC-RESONANCE ; TO-NOISE RATIOS ; WHOLE HEART ; 4D FLOW ; COARCTATION
    Abstract: Three-dimensional velocity-encoded cine magnetic resonance imaging (3D VEC MRI) allows for calculation of secondary flow parameters that may be used to estimate prognosis of individual cardiovascular diseases. However, its accuracy has not been fully investigated yet. The purpose of this study was to validate aortic flow quantification by 3D VEC MRI in vitro and in vivo using stacked two-dimensional acquisitions. Time-resolved stacks of two-dimensional planes with three-directional velocity-encoding (stacked-2D-3dir-MRI) were acquired in an elastic tube phantom with pulsatile flow simulating aortic flow as well as in 11 healthy volunteers (23 +/- 2 years). Previously validated two-dimensional through-plane VEC MRI at six equidistant levels in vitro and three locations in vivo (ascending aorta/aortic arch/descending aorta) was used as reference standard. The percentage difference of the stacked-2D-3dir-MRI measurement to the reference standard was defined as the parameter for accuracy. For in vitro aortic flow, stacked-2D-3dir-MRI underestimated average velocity by -6.8% (p 〈 0.001), overestimated average area by 13.6% (p 〈 0.001), and underestimated average flow by -7.4% (p 〈 0.001). Accuracy was significantly higher in the field of view centre compared to off-centre (p = 0.001). In vivo, stacked-2D-3dir-MRI underestimated average velocity (all three locations p 〈 0.001) and overestimated average area at all three locations (p = n.s./〈0.001/〈0.001). Average flow was significantly underestimated in the ascending aorta (p = 0.035), but tended to be overestimated in the aortic arch and descending aorta. In conclusion, stacked-2D-3dir-MRI tends to overestimate average aortic area and to underestimate average aortic velocity, resulting in significant underestimation of average flow in the ascending aorta.
    Type of Publication: Journal article published
    PubMed ID: 22362096
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  • 7
    Keywords: MODELS ; BLOOD-FLOW ; PATTERNS ; WALL ; VELOCITY ; THORACIC AORTA ; STENT-GRAFT PLACEMENT ; DIAMETER ; NUMERICAL-SIMULATION ; FLUID-DYNAMICS
    Abstract: Conservative medical treatment is commonly first recommended for patients with uncomplicated Type-B aortic dissection (AD). However, if dissection-related complications occur, endovascular repair or open surgery is performed. Here we establish computational models of AD based on radiological three-dimensional images of a patient at initial presentation and after 4-years of best medical treatment (BMT). Computational fluid dynamics analyses are performed to quantitatively investigate the hemodynamic features of AD. Entry and re-entries (functioning as entries and outlets) are identified in the initial and follow-up models, and obvious variations of the inter-luminal flow exchange are revealed. Computational studies indicate that the reduction of blood pressure in BMT patients lowers pressure and wall shear stress in the thoracic aorta in general, and flattens the pressure distribution on the outer wall of the dissection, potentially reducing the progressive enlargement of the false lumen. Finally, scenario studies of endovascular aortic repair are conducted. The results indicate that, for patients with multiple tears, stent-grafts occluding all re-entries would be required to effectively reduce inter-luminal blood communication and thus induce thrombosis in the false lumen. This implicates that computational flow analyses may identify entries and relevant re-entries between true and false lumen and potentially assist in stent-graft planning.
    Type of Publication: Journal article published
    PubMed ID: 23523079
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  • 8
    Keywords: Germany ; COMMON ; CT ; DIAGNOSIS ; FOLLOW-UP ; imaging ; DISEASE ; MORTALITY ; NEW-YORK ; ACCURACY ; computed tomography ; NUCLEAR-MEDICINE ; PATIENT ; REPAIR ; EFFICIENT ; tomography ; COMPUTED-TOMOGRAPHY ; sensitivity ; specificity ; CT ANGIOGRAPHY ; ANGIOGRAPHY ; ARTERY ; nuclear medicine ; DISSECTION ; radiology ; HIGH-RESOLUTION ; THORACIC AORTA ; MORBIDITY ; PRINCIPLES ; NUCLEAR ; USA ; aneurysm ; Aorta ; MEDICINE ; NOV ; medical imaging ; ANEURYSMS ; German ; aortic dissection ; aortic disease ; INTRAMURAL HEMATOMA ; MULTIDETECTOR-ROW CT ; multisclice computed tomography (MSCT)
    Abstract: Aortic disease is associated with high morbidity and mortality and thus require an efficient and accurate diagnostic approach, especially in the acute setting. Multislice computed tomography (MSCT) with the option of high-resolution CT angiography (CTA) has emerged as the standard of reference in diagnosis and follow-up of patients with acquired aortic disease. Aortic dissection is the most common aortic emergency, but it remains undiscovered in up to 38% of cases. Sensitivity and specificity of MSCT in the assessment of aortic dissection are greater than 99%. The sensitivity of CT in the detection of inflammatory changes is 83%; its specificity is almost 100%; and its diagnostic accuracy is ca. 94%. This article outlines state-of-the-art principles in diagnostic CT imaging of acquired aortic disease
    Type of Publication: Journal article published
    PubMed ID: 17938873
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  • 9
    Keywords: ANGIOGRAPHY ; ORIGIN ; RENAL-ARTERIES ; DISSECTIONS ; REPLACEMENT ; ATRIAL-FIBRILLATION ; BRANCHED STENT-GRAFT ; ANEURYSMS ; CTA
    Abstract: PURPOSE: To evaluate whether quantitative characterization of aortic arch geometry including its branches is feasible based on in vivo computed tomography (CT) angiography and magnetic resonance (MR) angiography data in healthy and diseased aortic arches. MATERIALS AND METHODS: Ten healthy volunteers, 10 patients with abdominal aortic disease, and 10 patients with aortic arch disease underwent MR angiography (10 volunteers) or CT angiography (20 patients). Commercial software was used for individual segmentation of supraaortic arteries. In-house software was developed for segmentation of aortic arch landmarks based on standardized multiplanar reformations (MPRs) and for subsequent aortic arch mapping. RESULTS: Supraaortic arteries and aortic arch landmarks were successfully segmented in all 30 subjects for CT angiography and MR angiography data. Significant tapering within the first centimeter was observed in all supraaortic arteries (P 〈 .001). The three supraaortic arteries showed significantly different vessel diameters and areas (P 〈 .001). The software developed in-house allowed detailed aortic arch mapping with quantitative definitions of the positional relationships between each supraaortic artery and the aorta. Distances between supraaortic arteries were less than 5 mm in 77.6% (mean 4.1 mm +/- 3.8). The brachiocephalic trunk tended to be positioned on the right side of the aortic arch, and the left subclavian and left common carotid arteries tended to be positioned on the left side of the aortic arch. CONCLUSIONS: The feasibility and application of a postprocessing method allowing quantification of geometry of supraaortic arteries and aortic arch mapping were successfully demonstrated. Validation and evaluation of clinical implications are warranted
    Type of Publication: Journal article published
    PubMed ID: 21459612
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  • 10
    Keywords: MODEL ; VISUALIZATION ; HEART ; BLOOD-FLOW ; blood flow ; magnetic resonance imaging ; PATTERNS ; 2D ; three-dimensional imaging ; 3D ; endovascular repair ; ANEURYSM REPAIR ; phase-contrast MRI ; Aorta ; stent graft
    Abstract: RATIONALE AND OBJECTIVES: Three-dimensional (3D) velocity-encoded cine (VEC) magnetic resonance imaging (MRI) has the potential to quantify 3D hemodynamic aspects known from computational fluid dynamics and to be used to identify hemodynamic risk factors for complications of endovascular aortic repair. The purpose of this study was to investigate the impact of an aortic nickel-titanium (nitinol) stent graft on the accuracy of flow measurements by 3D VEC MRI. MATERIALS AND METHODS: A pump generated pulsatile aortic flow in an elastic tube phantom mimicking the aorta. Stacked two-dimensional three-directional VEC MRI (stacked-2D-3dir-MRI), 3D three-directional VEC MRI (3D-3dir-MRI), and gold-standard 2D through-plane VEC MRI were applied before and after the insertion of an aortic nitinol stent graft. Six equidistant levels were analyzed twice by the same reader. The percentage difference of the measured flow rate from the gold standard was defined as the parameter of accuracy. RESULTS: The overall accuracy of in-stent flow measurements related to the gold standard was -5.4% for stacked-2D-3dir-MRI and -4.1% for 3D-3dir-MRI, demonstrating significant overall underestimation compared to the gold standard (P = .016 and P = .013). However, flow measurements with the stent graft were significantly overestimated by 4.1% using stacked-2D-3dir-MRI (P 〈 .001) and by 5.4% using 3D-3dir-MRI (P = .003) compared to identical measurements without the stent graft. In stacked-2D-3dir-MRI, this positive bias was significantly greater at the proximal and distal ends of the stent graft (P = .025). In 3D-3dir-MRI, measurements along the whole length of the stent graft were affected (P = .006). Intraobserver agreement was excellent, with intraclass correlation coefficients of 0.94 for stacked-2D-3dir-MRI (P 〈 .001) and 0.90 for 3D-3dir-MRI (P 〈 .001). CONCLUSIONS: Flow measurements within an aortic nitinol stent graft by 3D VEC MRI are feasible, but stent grafts may cause a significant positive bias.
    Type of Publication: Journal article published
    PubMed ID: 22177284
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