Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Proceed order?

Export
  • 1
    ISSN: 1432-1084
    Keywords: Key words: Magnetic resonance ; Brain ; Brain tumors ; Echo planar imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The aim of this study was to assess the potential of high-speed interleaved echo-planar imaging (EPI) to achieve diagnostic image quality comparable to T2-weighted imaging in patients with brain tumors. Seventeen patients with intra-axial, supratentorial tumors (10 untreated gliomas, 7 radiated gliomas) were investigated on a 1.5-T scanner. The conventional scan (SE, TR/TE = 2200/80 ms, 18 slices) was acquired in 8 min, 4 s, and EPI (TR/TE = 3000/80 ms, 18 slices) was completed in 25 s. The films were compared in a blinded trail by three radiologists. On the general impression and anatomic display, both sequences were rated to be of similar quality. Artifacts were slightly more pronounced at the skull base and around surgical clips using EPI. Tumor delineation was nearly equivalent using EPI, compared with the T2-weighted sequence. Echo-planar imaging reached diagnostic quality in all patients. Interleaved high-resolution EPI yielded sufficient quality to depict intra-axial, supratentorial brain tumors. Since EPI can be obtained in a small fraction of the time needed for conventional spin echo, in addition to other indications it could be considered to study patients unable to cooperate.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-1084
    Keywords: Key words: Heart neoplasm – Heart valves – Magnetic resonance imaging – Tomography, X-ray computed, echocardiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. We describe the findings from various cross-sectional imaging modalities in patients with cardiac valve adherent masses. The techniques are discussed, and imaging findings are compared with the results of cardiac surgery. All three patients had neurological symptoms and/or cardiac murmurs. Transthoracic and/or transesophageal echocardiography revealed the cardiac mass in all three. For differentiation of thrombus and cardiac neoplasm magnetic resonance imaging (MRI) was also performed in all three patients and electron-beam computed tomography (EBCT) in two. Fast segmented cine gradient-echo MRI techniques provided mass depiction in all patients, while T1-weighted spin-echo imaging failed in mass detection in one patient. None of the patients showed evidence of valve regurgitation or stenosis in flow sensitive cine MRI. EBCT excluded mass calcifications in both patients and reliably demonstrated the valve attached lesions. Although echocardiography is the modality of choice in evaluating cardiac masses and especially valve attached masses, MRI and EBCT provide additional information about tissue characteristics and allows an excellent overview of the cardiac and paracardiac morphology. Fast segmented cine gradient-echo MRI is especially able to depict even small tumors attached to rapidly moving cardiac valves, and valve competence can be easily assessed within the same examination.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1432-1084
    Keywords: Key words: CT ; Coronary disease ; Coronary arteriosclerosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. To identify patients with increased risk of having coronary artery disease (CAD), electron-beam computed tomography (EBCT) was used for years for quantifying calcifications of the coronary arteries. The first direct comparison between EBCT and conventional CT was performed to determine the reliability of widely available conventional CT for the assessment of the coronary calcium score. Fifty male patients with suspected CAD were investigated with both modalities, EBCT and conventional 500-ms non-spiral partial scan CT. Scoring of the coronary calcification was performed according to the Agatston method. Forty-two of these patients underwent coronary angiography for the assessment of significant luminal narrowing. The correlation coefficient of the score values of both modalities was highly significant (r = 0.982, p 〈 0.001). The variability between the two modalities was 42 %. Mean calcium score in patients with significant coronary luminal narrowing (n = 37) was 1104 ± 1089 with EBCT and 1229 ± 1327 with conventional CT. In patients without luminal narrowing (n = 5) mean calcium score was 73 ± 57 with EBCT and 26 ± 35 with conventional CT. Although images of the heart from conventional CT may suffer from cardiac motion artifacts, conventional CT has the potential to identify patients with CAD with accuracy similar to EBCT.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1432-1084
    Keywords: Key words: Tomography, X-ray computed – Coronary disease – Coronary atherosclerosis – Multirow-detector computed tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. This contribution reviews the pathology and morphology of coronary calcifications. It summarizes the indications for investigation of the coronary arteries. The standard protocols for scan acquisition using electron beam and conventional computed tomography are described as well as various methods for evaluation such as the traditional Agatston scoring method and the newer three-dimensional scoring algorithms. Guidelines for interpreting scores are also reviewed. Major limitations of the reproducibility of the calcium score measurement are summarized. Future aspects of multirow-detector spiral computed tomography with retrospective electrocardiographic triggering for quantifying coronary calcium are discussed.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1432-1084
    Keywords: Hemophilia ; Knee joint ; Synovial proliferation ; MR studies ; Gadolinium ; Contrast enhancement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A total of 17 patients with hemophilic arthropathy of the knee joint were studied with static and dynamic MRI before and after an IV bolus injection of Gadolinium-DTPA (Gd-DTPA; 0.1 mmol/kg body weight). The T1-weighted spin-echo (SE) and gradient-echo (fast-field echo [FFE]) sequences were applied. The FFE sequences of eight consecutive scans carried out over a time interval of 160 s were used in order to determine the time to signal intensity (SI) curves of the synovial proliferations surrounding soft tissue, bone marrow, and joint effusion. After the administration of a contrast agent, synovial proliferations exhibited an increase on FFE and SE images of 47.7 % (SD ± 14.3 %) and 37.4 % (SD ± 11.2 %), respectively, whereas muscle and fatty tissue, tendons, bone marrow, and joint effusion revealed only a minor increase in SI. The gradient of SI (ratio SI/time) of pannus was 39.6 %/min (SD ± 7.7 %/min) and differed significantly (P 〈 0.001) from that of bone marrow, fatty tissue, muscle tissue, tendons, and joint effusion (P 〈 0.05). In contrast to synovial proliferations in rheumatoid arthritis, no differentiation between various pannus vascularities based on the degree of enhancement was possible. The Gd-DTPA-enhanced MRI studies delineate and quantify the synovial proliferations in hemophilic arthropathy. Dynamic studies in hemophilic arthropathy do not provide qualitative assessment of the inflammatory process.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1432-1084
    Keywords: Key words: Actinomycosis ; Adrenal ; Misleading diagnosis ; MIBG ; MRI
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. A 34-year-old woman presented with a left-sided suprarenal space-occupying lesion on sonography. Culture of material obtained during sonographic-guided puncture of the retroperitoneal lesion yielded a mixed flora of Actinomyces and Peptostreptococcus. Initially, a misleading diagnosis of an adrenal pheochromocytoma was initiated by highly positive metaiodobenzylguanidine scintigraphy after chemical chemistry vanillylmandelic acid (VMA) test showed elevated values for adrenaline and its derivatives. Retroperitoneal actinomycosis with yet unproven spread into thoracic and cervical compartments is a particular unusual presentation of an infection with these organisms. Because it may mimic subacute infections or malignant masses in terms of clinical and laboratory findings, radiological diagnosis of this entity may be difficult. The diagnosis was based on results of culture and the response of the patient to long-term penicillin-derivate therapy after surgical drainage of the suprarenal abscess formation.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 3633-3638 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Reversible structural relaxation has been studied in (Fe1−xNix)80B10Si10 by differential scanning calorimetry and x-ray diffraction. It is found that surface crystallization plays a major role in inhibiting reversibility. In consequence, previously published data have presented a misleading picture about the composition dependence of the reversible effect in Fe-Ni-B-Si, which simply increases monotonically with Ni composition. There is no evidence that chemical short-range order plays any role in reversibility, and the data have been quantitatively modeled by simply assuming that reversible relaxation is caused by the thermal repopulation of excited structural states.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1432-2102
    Keywords: Schlüsselwörter Spiral-CT ; Elektronenstrahl-CT ; Virtuelle Realität ; Bronchialsystem ; Bronchoskopie ; Key words Spiral CT ; Electron-beam CT ; Virtual reality ; Bronchi ; Bronchoscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Purpose: To compare spiral computed tomography (CT) and electron-beam CT (EBT) for 3D and virtual CT-bronchoscopy. Materials and methods: 17 patients with various disorders of the tracheobronchial system were examined using fiberoptic bronchoscopy, spiral CT and EBT. 3D images were reconstructed from CT data sets using automated segmentation based on volume-growing methods. Surface-rendered, volume-rendered, and hybrid reconstructions were visualized in real time using a data helmet. Results: All data sets could be processed to high-quality three-dimensional (3D) and virtual reconstructions. The reduction of motion artifacts due to shorter scan times made EBT data sets better suited for automated segmentation and less susceptible to motion artifacts. 3D and virtual reconstructions did not increase the diagnostic sensitivity of CT compared to axial reconstructions alone. Conclusions: Shorter scan times of CT imaging yield higher-quality 3D and virtual reconstructions. Modern reconstruction techniques are valuable visualization tools for select indications and are the prerequisite for future developments in computer-aided medicine.
    Notes: Zusammenfassung Spiral-CT und Elektronenstrahlcomputertomographie (EBT) sollten hinsichtlich ihrer Eignung für die 3D und virtuelle CT-Bronchoskopie verglichen werden. 17 Patienten mit pathologischen Veränderungen des Bronchialsystems wurden mit fiberoptischer Bronchoskopie sowie Spiral-CT oder EBT untersucht. Die CT-Datensätze wurden mit automatisierten Segmentationsverfahren zu 3D Oberflächenrekonstruktionen bzw. zu Volumenrekonstruktionen und zu hybriden Darstellungsformen weiterverarbeitet. Die virtuelle Visualisierung erfolgte über einen Datenhelm in Echtzeit. Alle Datensätze konnten zu räumlichen Rekonstruktionen guter Qualität weiterverarbeitet werden. Aufgrund der kürzeren Scanzeiten waren die EBT-Datensätze besser für die automatisierte Segmentation und für eine artefaktarme Rekonstruktion geeignet. Die diagnostische Aussagekraft wurde durch die räumlichen Darstellungsformen gegenüber den axialen Schichten nicht erhöht. Kürzere Scanzeiten wirken sich günstig auf die Qualität von 3D- und virtuellen Rekonstruktionen aus. Räumliche Darstellungsformen stellen teilweise wertvolle Ergänzungen zur invasiven Bronchoskopie sowie zur Schichtbilddiagnostik dar. Die moderne Bildverarbeitung bildet eine wichtige Grundlage für computergestützte Techniken in der Medizin.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 1432-2102
    Keywords: Schlüsselwörter Elektronenstrahl Computertomographie ; Physikalische Grundlagen ; Strahlenbelastung ; Key words Electron beam tomography ; Physical priciples ; X-ray radiation exposure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Purpose: In this review the technical principle and scanner characteristics of electron beam computer tomography (EBCT) are discussed. Methods: In contrast to conventional CT, image acquisition in EBCT is achieved without mechanically moving parts. This construction allows for short acquisition times in investigating given anatomical regions (100 ms per slice) or up to 8 levels without table movement and short interscan delays (50 ms per slice). Results: Depending on the nature of the investigation, the scanner can be used in the single slice, continuous volume scanning and multi slice mode. The single slice mode is used for detection and quantification of coronary calcifications and for CT angiography of the coronary vessels. Equivalent to the spiral mode in conventional CT, continous volume scanning may be used for routine investigation of the chest and abdomen. Functional investigations of the heart and perfusion measurement of different organs can be performed in multi slice mode. Because of the geometry of the electron beam scanner, radiation exposure for certain investigations is above the exposure with conventional CT. Conclusion: Future developements will focus on dose efficient radiation collimation, high resolution detector systems and artefact reducing reconstruction kernels.
    Notes: Zusammenfassung Fragestellung: In dieser Übersichtsarbeit soll das Konstruktionsprinzip und die Aufnahmebedingungen der Elektronenstrahl-Computertomographie (EBCT) dargestellt werden. Methodik: Im Gegensatz zum konventionellen CT werden beim EBCT die Schichtaufnahmen ohne mechanische Bauteile akquiriert. Dieses Konstruktionsprinzip erlaubt es, kurze Aufnahmezeiten zur Untersuchung eines anatomischen Bereichs (100 ms pro Schicht) oder bis zu 8 Schichthöhen ohne Tischbewegung kurz nacheinander abzutasten (50 ms pro Schicht). Ergebnisse: Der Scanner kann je nach Einsatzgebiet im Einzelschicht-, kontinuierlichen Scan- und Multischicht-Modus betrieben werden. Der Einzelschicht-Modus wird zum Nachweis und zur Quantifizierung von Koronarkalzifikationen und für die CT Angiographie der Koronargefäße eingesetzt. Der kontinuierliche Scan-Modus entspricht dem Spiral-Modus bei dem konventionellen CT und kann bei Routinefragestellungen des Thorax und Abdomen eingesetzt werden. Der Multischichtbetrieb ist für Funktionsuntersuchungen des Herzens ebenso wie für Perfusionsuntersuchungen verschiedener Organe geeignet. Aufgrund der besonderen Scannergeometrie liegt die Strahlenbelastung bei einigen Betriebsarten jedoch deutlich über der eines konventionellen Spiral-CT-Scanners. Schlußfolgerung: Künftige Entwicklungen zielen auf dosiseffiziente Kollimation, hochauflösende Detektortechnologien und artefaktreduzierende Rekonstruktionsalgorithmen ab.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...