1,721,165 research outputs found
Cardio-respiratory motion-corrected 3D cardiac water-fat MRI using model-based image reconstruction
Full text linkMyocardial fat infiltrations are associated with a range of cardiomyopathies. The purpose of this study was to perform cardio-respiratory motion-correction for model-based water-fat separation to image fatty infiltrations of the heart in a free-breathing, non-cardiac-triggered high-resolution 3D MRI acquisition
Myocarditis and pericarditis in focus: a brief report comparing the 2025 ESC guidelines and latest ACC position papers
No full textMyocarditi
Diagnosis of Myocardial Diseases Applying Cardiac Magnetic Resonence
No full textHabilitationsschriftIn der Kardiologie stellt die nichtinvasive Differenzierung von Myokardschäden
noch immer eine diagnostische Herausforderung dar. In dieser Arbeit wurde die
kardiale Magnetresonanztomographie genutzt, um Myokardschäden zu
differenzieren und Zusammenhänge zu funktionellen Veränderungen, insbesondere
bei primären und sekundären Kardiomyopathien zu untersuchen. Es ist gelungen,
Einsatzmöglichkeiten der Methode aufzuzeigen, die bereits auch Verbreitung in
der klinischen Routine gefunden haben. Bei der Hypertrophischen
Kardiomyopathie führten wir die Planimetrie der Fläche des linksventrikulären
Ausflusstraktes zur Quantifizierung der Obstruktion ein und konnten nicht nur
Patienten nach Septumablation kontrollieren, sondern erstellten auch Normwerte
zur Differenzierung der Obstruktion. Nach der Intervention wurden im
zeitlichen Verlauf die Evolution des peri-infarziellen Ödemes und der
Infarktnarbe, einschließlich des Zusammenhanges zur funktionellen und
klinischen Verbesserung untersucht. Durch die Anwendung einer Kombination von
T2-gewichteten und kontrastverstärkten T1-gewichteten Sequenzen im zeitlichen
Verlauf konnten sowohl die sehr frühen als auch die späten
Myokardveränderungen dargestellt werden. Da die therapeutisch indizierte
Intervention ohne Induktion einer alkoholbedingten Kolliquationsnekrose mit
Schaumstoffpartikeln durchführt wurde, ist das Ergebnis mit einer nicht
iatrogenen akuten Koronararterienokklusion vergleichbar. Dies erlaubt
Rückschlüsse auf die Darstellung eines akuten Infarkt mittels
Magnetresonanztomographie. Der echokardiographische Nachweis von
Wandbewegungsstörungen ist eine grundlegende diagnostische Information,
allerdings ist die Unterscheidung zwischen einer entzündlichen oder
ischämischen Genese nicht möglich. Diese Lücke kann nunmehr durch die kardiale
Magnetresonanztomographie geschlossen werden. Das von uns eingeführte
multisequentielle Protokoll führte zum Beispiel bei der Myokarditis zu einer
Verbesserung der diagnostischen Genauigkeit der magnetresonanztomographischen
Untersuchungen. Ebenso konnte eine myokardiale Mitbeteiligung bei Sarkoidose
bereits bei normaler linksventrikulärer Funktion gezeigt werden. Für die
Darstellung der Koronararterien wurde eine 3D-Steady-State-Free-Precession-
Sequenz bei gesunden Probanden und in klinischer Umgebung geprüft, sie erwies
sich als verlässlich, muss aber noch weiter evaluiert werden. Die kardiale MRT
hat in einigen kardiologischen Bereichen bereits Eingang in die Routine
gefunden. Die Methode hat das Potenzial, prospektiv reversible und
irreversible myokardiale Veränderungen zu unterscheiden und sie darüber hinaus
im Verlauf zu untersuchen. Es ist zu erwarten, dass auf dem Gebiet der
myokardialen Erkrankungen nichtinvasive bildgebende Differenzierungen zur
Charakterisierung des klinischen Status und Therapieerfolges beitragen werden.
Weitere Studien werden gestatten, die prognostische Relevanz frühzeitig
erfasster Veränderungen zur bewerten.Non-invasive differentiation of myocardial injury is an ongoing diagnostic
challenge in cardiology. We used cardiac magnetic resonance to characterize
myocardial injuries and to investigate their relations to functional changes,
especially in primary and secondary cardiomyopathies. We were able to describe
novel applications of CMR, which are currently used in routine settings. The
planimetry of the left ventricular outflow tract area to quantify obstruction
was developed to characterize hypertrophic cardiomyopathies (HCM). We applied
the method in patients after septal artery embolization to monitor the success
of the intervention. We then extended our observations to establish cut-off
values to differentiate between the obstructive and non-obstructive forms of
HCM and to provide the first reference standard for planimetric values in
healthy volunteers. After intervention infarct related edema and fibrosis was
detected during follow-up and correlated to functional and clinical
improvement of the patients. Combining of T2-weighted and contrast-enhanced
T1-weighted images allowed the detection of very early and late myocardial
changes during follow-up. As the intervention was performed using foam gel
instead of alcohol, the therapeutically induced infarction was similar to an
abrupt coronary occlusion in the clinical setting in contrast to the non-
physiological alcohol-like colliquation-necrosis. As such, we were able not
only to monitor the intervention-related tissue injuries but also to gain
novel insights into the very early myocardial tissue injuries in acute
myocardial infarction Assessment of wall motion abnormalities applying
echocardiography is a basic diagnostic information, but it is not possible to
differentiate between e.g. inflammatory or ischemic aetiologies. Applying
cardiac magnetic resonance (CMR), this information can be provided. Exploiting
the unique tissue characterization capabilities of CMR, we introduced a multi-
sequential approach, which was shown to increase the diagnostic accuracy of
magnetic resonance imaging to detect myocarditis. Applying a similar approach
we were able to detect myocardial involvement in sarcoidosis even when left
ventricular function was still preserved. A 3D-steady-state-free-precession
pulse sequence was applied in volunteers and patients and could be shown to be
applicable, but has to be improved. Cardiac magnetic resonance is routinely
applied in many areas of cardiology. The method has the potential to
differentiate prospectively between reversible and irreversible myocardial
injuries. The changes can be detected during follow-up. One could expect, that
in the field of myocardial diseases the differentiation by non-invasive
imaging modalities will improve clinical characterization and monitor the
success of therapy or (therapeutic success). Further studies will allow
identifying the prognostic values of the early-detected injuries
Rapid parametric mapping of the longitudinal relaxation time T1 using two-dimensional variable flip angle magnetic resonance imaging at 1.5 Tesla, 3 Tesla, and 7 Tesla.
Full text linkINTRODUCTION: Visual but subjective reading of longitudinal relaxation time (T1) weighted magnetic resonance images is commonly used for the detection of brain pathologies. For this non-quantitative measure, diagnostic quality depends on hardware configuration, imaging parameters, radio frequency transmission field (B1+) uniformity, as well as observer experience. Parametric quantification of the tissue T1 relaxation parameter offsets the propensity for these effects, but is typically time consuming. For this reason, this study examines the feasibility of rapid 2D T1 quantification using a variable flip angles (VFA) approach at magnetic field strengths of 1.5 Tesla, 3 Tesla, and 7 Tesla. These efforts include validation in phantom experiments and application for brain T1 mapping. METHODS: T1 quantification included simulations of the Bloch equations to correct for slice profile imperfections, and a correction for B1+. Fast gradient echo acquisitions were conducted using three adjusted flip angles for the proposed T1 quantification approach that was benchmarked against slice profile uncorrected 2D VFA and an inversion-recovery spin-echo based reference method. Brain T1 mapping was performed in six healthy subjects, one multiple sclerosis patient, and one stroke patient. RESULTS: Phantom experiments showed a mean T1 estimation error of (-63±1.5)% for slice profile uncorrected 2D VFA and (0.2±1.4)% for the proposed approach compared to the reference method. Scan time for single slice T1 mapping including B1+ mapping could be reduced to 5 seconds using an in-plane resolution of (2×2) mm2, which equals a scan time reduction of more than 99% compared to the reference method. CONCLUSION: Our results demonstrate that rapid 2D T1 quantification using a variable flip angle approach is feasible at 1.5T/3T/7T. It represents a valuable alternative for rapid T1 mapping due to the gain in speed versus conventional approaches. This progress may serve to enhance the capabilities of parametric MR based lesion detection and brain tissue characterization
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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