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  • THORACIC AORTA  (9)
  • ANGIOGRAPHY  (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: Germany ; THERAPY ; FOLLOW-UP ; SYSTEM ; SYSTEMS ; MORTALITY ; RISK ; computed tomography ; SURGERY ; PATIENT ; treatment ; DESIGN ; AGE ; REPAIR ; RATES ; tomography ; COMPUTED-TOMOGRAPHY ; COMPLICATIONS ; DISSECTION ; STROKE ; THORACIC AORTA ; THROMBOSIS ; methods ; Male ; VARIABLES ; endovascular ; GRAFTS ; ANEURYSM REPAIR ; DISSECTIONS ; PHANTOMS ; PULSATILE FLOW ; SINGLE-CENTER ; STENT-GRAFT PLACEMENT ; TRUE-LUMEN COLLAPSE
    Abstract: Objective: To outline the complications after endovascular repair in patients with acute symptomatic and chronic expanding Stanford type B aortic dissections. Methods: Between 1997 and 2004, of 125 patients with acute and chronic aortic type B dissections, 88 were treated conservatively. Thirty-seven patients ( 29 male, mean age 58 years, range 30-82 years) underwent endovascular repair (30%) using 44 stent grafts of 3 different designs: Excluder ( W. L. Gore & Associates, Inc, Flagstaff, Ariz), Talent ( Medtronic Vascular, Santa Rosa, Calif), and Endofit (Endomed, Inc, Phoenix, Ariz). Indications for treatment were acute symptomatic type B dissection in 15 patients, chronic expanding aortic dissection greater than 55 mm in 14, rupture in 3, and simultaneous type A repair in 5 patients. Twenty-two operations were performed on an emergency basis. Patient characteristics, procedural variables, outcome, and complications were prospectively recorded. All patients underwent follow-up by computed tomography before discharge, at 6 and 12 months, and annually thereafter ( mean follow-up: 24 months). Results: Correct deployment was achieved in 97% of cases. There were no instances of primary conversion, paraplegia, or stroke. Complete false lumen thrombosis was observed in 11 patients (44%). Perioperative complication rate was 22%. Thirty-day mortality rate in acute and chronic dissections was 19% and 0%, respectively. Freedom from aortic reintervention was 81%, 73%, and 68%, freedom from late rupture was 97%, 90%, and 80%, and overall success rate was 76%, 65%, and 57% at 1, 2, and 5 years, respectively. Results for patients with chronic dissections are significantly ( P =.038) better than results in those with acute dissections. Conclusions: Despite the minimally invasive approach, the complication and mortality rates for endovascular therapy of aortic dissections are still high. Frank reporting of these sequelae is if great importance to clarify the recent limitations of the method
    Type of Publication: Journal article published
    PubMed ID: 16872963
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  • 3
    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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  • 4
    Keywords: SPIRAL CT ; THORACIC AORTA ; stent-graft ; NEPHROGENIC SYSTEMIC FIBROSIS ; MULTIDETECTOR-ROW CT ; COMPUTED-TOMOGRAPHY ANGIOGRAPHY ; DOSE REDUCTION ; MOTION ARTIFACTS ; SEMIAUTOMATIC CENTERLINE ANALYSIS ; CONTRAST-MEDIUM
    Abstract: Over the last two decades, imaging of the aorta has undergone a clinically relevant change. As part of the change non-invasive imaging techniques have replaced invasive intra-arterial digital subtraction angiography as the former imaging gold standard for aortic diseases. Computed tomography (CT) and magnetic resonance imaging (MRI) constitute the backbone of pre- and postoperative aortic imaging because they allow for imaging of the entire aorta and its branches. The first part of this review article describes the imaging principles of CT and MRI with regard to aortic disease, shows how both technologies can be applied in every day clinical practice, offering exciting perspectives. Recent CT scanner generations deliver excellent image quality with a high spatial and temporal resolution. Technical developments have resulted in CT scan performed within a few seconds for the entire aorta. Therefore, CT angiography (CTA) is the imaging technology of choice for evaluating acute aortic syndromes, for diagnosis of most aortic pathologies, preoperative planning and postoperative follow-up after endovascular aortic repair. However, radiation dose and the risk of contrast induced nephropathy are major downsides of CTA. Optimisation of scan protocols and contrast media administration can help to reduce the required radiation dose and contrast media. MR angiography (MRA) is an excellent alternative to CTA for both diagnosis of aortic pathologies and postoperative follow-up. The lack of radiation is particularly beneficial for younger patients. A potential side effect of gadolinium contrast agents is nephrogenic systemic fibrosis (NSF). In patients with high risk of NSF unenhanced MRA can be performed with both ECG- and breath-gating techniques. Additionally, MRI provides the possibility to visualise and measure both dynamic and flow information.
    Type of Publication: Journal article published
    PubMed ID: 24220116
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  • 5
    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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  • 6
    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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  • 7
    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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  • 8
    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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  • 9
    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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  • 10
    Keywords: MODEL ; CT ; imaging ; SURGERY ; MRI ; RECONSTRUCTION ; FABRICATION ; THORACIC AORTA ; computer-assisted image processing ; TECHNOLOGY ; BENEFITS ; stereolithography ; Medical education ; Patient care ; Prostheses and implants ; Rapid prototyping ; RAPID PROTOTYPING TECHNIQUES
    Abstract: PURPOSE: Generation of graspable three-dimensional objects applied for surgical planning, prosthetics and related applications using 3D printing or rapid prototyping is summarized and evaluated. MATERIALS AND METHODS: Graspable 3D objects overcome the limitations of 3D visualizations which can only be displayed on flat screens. 3D objects can be produced based on CT or MRI volumetric medical images. Using dedicated post-processing algorithms, a spatial model can be extracted from image data sets and exported to machine-readable data. That spatial model data is utilized by special printers for generating the final rapid prototype model. RESULTS: Patient-clinician interaction, surgical training, medical research and education may require graspable 3D objects. The limitations of rapid prototyping include cost and complexity, as well as the need for specialized equipment and consumables such as photoresist resins. CONCLUSIONS: Medical application of rapid prototyping is feasible for specialized surgical planning and prosthetics applications and has significant potential for development of new medical applications.
    Type of Publication: Journal article published
    PubMed ID: 20467825
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