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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: brain ; Germany ; MODEL ; MODELS ; PERFUSION ; imaging ; SYSTEM ; CONTRAST ; MAGNETIC-RESONANCE ; magnetic resonance imaging ; NERVOUS-SYSTEM ; CEREBRAL-BLOOD-FLOW ; CENTRAL-NERVOUS-SYSTEM ; CONTRAST-ENHANCED MRI ; functional MRI ; ENHANCEMENT ; INVERSION ; ARTERIAL ; contrast-enhanced ; functional imaging ; ARTERIAL WATER ; ASL ; BALLOON MODEL ; BOLD-fMRI ; BRAIN PERFUSION ; dynamic contrast enhanced-MRI ; dynamic susceptibility contrast-MRI ; FMRI ; HIGH-SPATIAL-RESOLUTION ; OXYGEN-CONSUMPTION ; QUIPSS II
    Abstract: This review presents the basic principles of functional imaging of the central nervous system utilizing magnetic resonance imaging. The focus is set on visualization of different functional aspects of the brain and related pathologies. Additionally, clinical cases are presented to illustrate the applications of functional imaging techniques in the clinical setting. The relevant physics and physiology of contrast-enhanced and non-contrast-enhanced methods are discussed. The two main functional MR techniques requiring contrast-enhancement are dynamic T1 - and T2(*)-MRI to image perfusion. Based on different pharmacokinetic models of contrast enhancement diagnostic applications for neurology and radio-oncology are discussed. The functional non-contrast enhanced imaging techniques are based on "blood oxygenation level dependent (BOLD)-fMRI and arterial spin labeling (ASL) technique. They have gained clinical impact particularly in the fields of psychiatry and neurosurgery
    Type of Publication: Journal article published
    PubMed ID: 15871087
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  • 3
    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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  • 4
    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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  • 5
    Keywords: AGENTS ; PHASE-I ; IMAGES ; SYSTEM ; PROTEIN ; BODY-WEIGHT ; CONTRAST AGENT ; INJECTION ; MR ; BINDING ; ACQUISITION ; arteries ; SAFETY ; MAGNETIC-RESONANCE ANGIOGRAPHY ; MR-ANGIOGRAPHY ; gadobenate dimeglumine ; GD-DTPA ; MR angiography ; BOLUS ; BREATH-HOLD ; gadobutrol ; intraindividual comparison ; RENAL- ARTERIES
    Abstract: Question. The availability of new MR contrast agents having either a protein binding effect or higher concentration leads to the question if they differ from standard compounds in their vascular contrasting properties. Methods. By intraindividual comparison five volunteers were examined (1.5 T MR system) with a multi-phasic MRA of the abdomen each receiving three different contrast agents (gadopentetate dimeglumine 0.5 M; gadobenate dimeglumine 0.5 M, and gadobutrol 1.0 M). The dose (0.15 mmol/kg body weight) and flow rate (3.0 ml/s) were kept identical. All images were quantitatively and qualitatively evaluated by blinded assessment. Results. Significantly higher maximum signal intensity was found in the arteries for the protein interacting gadobenate dimeglumine (p = 0.05). No significant difference in vascular enhancement was demonstrated in the comparison of gadobutrol to gadopentetate dimeglumine. Conclusion. Gadobenate dimeglumine was shown to be a favorable contrast agent for multi-phasic MRA. A higher concentrated Gd- chelate does not automatically lead to improved vascular contrast if standard imaging protocols are used
    Type of Publication: Journal article published
    PubMed ID: 12624674
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  • 6
    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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  • 7
    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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  • 8
    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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  • 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: 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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