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  • 1
    ISSN: 1432-1173
    Keywords: Schlüsselwörter Magnetresonanztomographie ; MRT ; Haut ; In-vivo-Histometrie ; Tumore ; Keywords MRT ; Skin ; Thickness ; Dermatology ; Tumors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Purpose: To characterize human skin qualitatively and quantitatively using high-resolution magnetic resonance tomography (MRT) and to compare skin thickness measurements from MRT and histological specimens. Material and Methods: The skin of 84 persons was examined by use of a 2.5 cm coil in a whole-body tomography (gradient field strength 1.5 T) at a linear resolution of 100 μm. To evaluate the ability to identify various skin structures, following an initial visual description, the signal-noise and contrast-noise ratios were analyzed and the MRT-image compared to the corresponding histological specimen. Results: Using the high-resolution coil, epidermis, dermis and subcutis were discernible. Problem areas included the cheek, distal leg and foot. Reproducible measuring of skin thickness with MRT is possible, but it does not correlate well with conventional histologic measurements.
    Notes: Zusammenfassung Ziel: Anhand von In-vivo-Untersuchungen war die Schnittbildanatomie der Haut hinsichtlich ihrer bislang unbekannten Erscheinung im hochauflösenden Magnetresonanztomogramm (MRT) zunächst qualitativ und quantitativ zu charakterisieren. Anschließend sollte der Wert der MRT hinsichtlich der Hautdickenmessung anhand eines Vergleiches mit histologischen Schnitten analysiert werden. Methodik: In einer prospektiven Studie wurde die Haut von 84 Personen mit Hilfe eines 2,5 cm großen Spulenkopfes in einem Ganzkörpertomographen (Gradientenfeldstärke: 1,5 T) bei einer linearen Auflösung von 100 μm untersucht. Zur Bewertung der Abgrenzbarkeit verschiedener Hautstrukturen wurden nach visueller Charakterisierung deren Signal-Rausch- und deren Kontrast-Rausch-Verhältnisse objektiviert und ein Vergleich mit histologischen Präparaten vorgenommen. Ergebnisse: Mit der Hochauflösungsspule lassen sich Epidermis, Dermis und Subkutis differenzieren (p〈0,05). Problematisch ist dies nur an Wange, distalem Unterschenkel und Fuß. Hautdickenmessungen mit der MRT sind zuverlässig möglich. Die Ergebnisse korrelieren aber nicht mit jenen der Histologie.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cardiac surgery 12 (1997), S. 0 
    ISSN: 1540-8191
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract An analysis of three-dimensional movement of the mitral valve annulus (MVA) may address the question of geometrical change after mitral valve repair to preserve mitral annular function. Conventionally, annular contraction has been studied for this purpose. We investigated this geometrical change occurring in the anterior half of the MVA and discuss its clinical significance. Three-dimensional images of the MVA during systole were reconstructed from magnetic resonance images of eight normal subjects. The posterior half of the MVA exhibited translational motion. We assume that this portion, exhibiting translational motion as well as contraction, purely follows the motion of the left ventricular contraction. Compensating for the discrepancy between the motion of the aortic root and that of the posterior half of the MVA, the anterior half exhibited a flexible change in shape during systole, thus maintaining a sufficient left ventricular outflow tract (LVOT). The increase in the extent of displacement of the anterior MVA from the posterior half of the MVA during systole, which was 3.6 ± 1.0 mm (mean ± SD), indicates the annular flexibility. The preservation of annular flexibility may prevent LVOT obstruction. Further geometrical analysis of patients after mitral repair will clarify annular function as presented in this article.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1084
    Keywords: Magnetic resonance imaging ; Nuclear magnetic resonance ; Central nervous system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This study was set up to see whether lowering the flip angle in proton density- and T2-weighted double-spin echo sequences allows for shortening of repetition time (TR) and imaging time without significant change of image quality. Ten patients with celebral white matter lesions were investigated with an 1.5 T MR scanner using a conventional long- TR double-spin echo sequence (TR = 2500 ms, TE = 15 and 70 ms) and reduced-TR double-spin echo sequences (TR = 1900 ms, TE = 15 and 70 ms) at flip angles of 90°, 80°, 70°, 60°, and 50°. Lowering the flip angle resulted in less T1-contrast and a relative increase of T2-contrast. At a flip angle of 70°, contrast-to noise ratios (NNRs) between lesions and brain, as well as image artifacts of the reduced-TR sequence (CNR: 22.4) were similar to the conventional long-TR sequence (CNR:21.1), while imaging time was shortened by about 25%.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-7241
    Keywords: magnetic resonance imaging ; acute myocardial infarction ; gadolinium ; coronary heart disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Twenty-six patients admitted to the Free University of Berlin University Hospital catheterization laboratory with acute myocardial infarction were studied. The diagnosis was confirmed by angiography, but acute revascularization was unsuccessful in every case. MR imaging was performed within 7 days of the acute event in 11 patients with uncomplicated clinical courses after acute infarction. Imaging was performed within 3 weeks in three additional cases, while the remaining 12 patients underwent studies more than 3 weeks after infarction. We determined signal intensity at three points within the area of infarction and at three other points in adjacent myocardial tissue. Decreased signal intensity within the area of infarction was found in native scans in 60% of all cases. Administration of gadolinium-DTPA 0.1 mmol/kg body weight was followed by a mean 70% increase in signal intensity within the zones of acute infarction, as compared to a 20% increase in surrounding myocardial tissue. In cases of subacute and chronic infarction, there was no significant signal enhancement after administration of gadolinium-DTPA. Uptake of the substance in the area of acute infarction may be a positive marker of acute myocardial necrosis and as such may prove useful in the clinical setting.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1619-7089
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Radioimmunoscintigraphy (RIS) with 131I labeled OC-125 F(ab')2 monoclonal antibody fragments was prospectively studied in 43 women for primary diagnosis and follow up of ovarian cancer. Total body planar photoscans with a scintillation camera were performed one to seven days after antibody application and results were compared with operation and or CT examination. By the region of interest technique the tumor to non tumor tissue ratio (T/N) was calculated in vivo. Sensitivity in primary diagnosis was 100% (10/10), specificity 33% (1/3). For local recurrency, sensitivity was 86% (19/22), for metastatic loci 80% (17/21). Specificity was 75% and 50%. T/N ratio was in the rage from 1.3 to 2.8. Sensitivity for ovarian cancer is high in primary diagnosis and follow up. By the region of interest technique it is possible to detect small recurrencies and to presume peritoneal carcinosis. Antibody accumulations in diseases different from ovarian cancer however diminish specificity.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1619-7089
    Keywords: Technetium-99m sestamibi ; Tracer washout ; Tracer redistribution ; Exercise studies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this study was to assess whether a clinically relevant change in myocardial sestamibi activity could be documented within the first 120 min following injection (p.i.). In 17 patients planar anterior imaging of the heart was performed 5 min and 120 min p.i. During this time interval, mean decay-corrected myocardial activity declined to 77.9%±9.7% after stress and to 85.7%±7.9% after injection at rest (P〈0.05). In 19 patients with angiographically documented coronary artery disease, single-photon emission tomography was performed 5 min and 120 min after injection at maximum stress. For analysis, sestamibi activity was scored semiquantitatively in six left ventricular segments. Furthermore, sestamibi uptake was assessed quantitatively using a circumferential profile method. In 35 of 114 segments the score improved within 120 min p.i. (early fillin); in these segments relative sestamibi activity rose from 69.9%±22.5% to 74.5%±20.8% (P〈0.01). In five patients this early fill-in was the only sign of exercise-induced hypoperfusion. In 7 of 114 segments the score deteriorated 120 min p.i. (early tracer washout); in these segments relative sestamibi activity declined from 85.6%±9.9% to 80.1%±10.7% (P〈0.02). In three of four patients with early tracer washout the corresponding coronary artery was significantly narrowed. In conclusion, a global myocardial sestamibi washout was registered within the first 120 min after injection. A fill-in of initial defects as well as an early tracer loss could be detected in a relevant number of patients with chronic coronary artery disease during the first 2 h p.i. In these patients the extent of detected reversible perfusion abnormality depends on the chosen time interval between injection and imaging. The results of this study suggest that exercise imaging should be started immediately after injection.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nuclear medicine 9 (1984), S. 62-67 
    ISSN: 1619-7089
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract By means of continuous lung imaging, regional mucociliary removal rates of inhaled 99mTc-labeled human serum albumin minimicrospheres were determined over upper, middle, lower, central, and peripheral anterior lung areas. Additionally, an index was employed for analysis of initial pulmonary radioaerosol distribution in order to quantify the site of particle deposition in various degrees of airways obstruction. The study involved 15 volunteer healthy subjects, 20 asymptomatic smokers with early small airways obstruction, and 30 patients with advanced chronic obstruction of large airways. The healthy group showed evenly distributed lung activity and (normal) clearance rates consistent with data from earlier work. While most uneven lung aerosol distribution was seen in the patients with large airways obstruction, slowest mucociliary clearance velocity was encountered in the smokers with small airways dysfunction. The aerosol technique, if carefully controlled, can be a useful supplement to pulmonary ventilatory function testing, showing reduction of bronchial mucous velocity to be one of the earliest signs of functional impairment in asymptomatic cigarette smokers.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1433-0423
    Keywords: Key words Magnetic resonance imaging • Lacrimal drainage system • Stenosis ; Schlüsselwörter Magnetresonanztomographie • Tränenwege • Stenose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Hintergrund: Dakryozystographie und Dakryoszintigraphie sind etablierte bildgebende Verfahren in der Diagnostik von Tränenwegstenosen. Beide erlauben nur indirekte Aussagen zur Morphologie des tränenableitenden Systems. Es wird untersucht, inwiefern mit Hilfe der Magnetresonanztomographie (MRT) neben der direkten detaillierten Darstellung der Tränenwege auch funktionelle Aussagen getroffen werden können, um die Rolle der Methode im Spektrum der bildgebenden Verfahren bei Tränenwegerkrankungen zu definieren. Patienten und Methoden: Es wurden 27 Tränenwegsysteme von 23 Patienten mit Epiphora in einem Ganzkörpermagnetresonanztomographen mit einer Oberflächenspule vor und nach konjunktivaler und intravenöser Gabe von Gd-DTPA untersucht. Ergebnisse: Passagestörungen wurden in 23 von 27 Tränenwegsystemen gefunden, konnten den Canaliculi lacrimales (n = 3), dem Saccus lacrimalis (n = 8) und Ductus nasolacrimalis (n = 12) zugeordnet, in Stenosen und Verschlüsse unterteilt werden und teilweise ätiologisch charakterisiert werden. Schlußfolgerungen: Die hochauflösende MRT mit konjunktivaler Kontrastmittelapplikation erlaubt neben der direkten und detaillierten Darstellung der ableitenden Tränenwege und periduktaler Strukturen zugleich eine funktionelle Beurteilung des Tränenwegsystems. Limitierungen einer verbreiteten Anwendung resultieren u. a. aus Anforderungen an gerätetechnische und patientengebundene Voraussetzungen sowie aus Kostengründen.
    Notes: Summary Both dacryocystography and dacryoscintigraphy are well established in the evaluation of stenoses of the lacrimal drainage system. They provide limited information about the ductal anatomy itself and about periductal structures. MR imaging was evaluated for its capability to directly visualize the lacrimal drainage system in detail and simultaneously provide functional characterization of dacryostenosis. Subjects and methods: Twenty-seven lacrimal drainage systems of 23 patients suffering from epiphora were examined in an MR unit before and after conjunctival and intravenous application of Gd-DTPA using a surface coil. Results: Dacryostenosis was found in 23 of 27 lacrimal systems. Stenoses were localized to the canalicular (n = 3), saccular (n = 8), and ductal (n = 12) level, and were classified as stenosis or occlusion. Conclusion: MR imaging with conjunctival contrast application allows within one examination both detailed morphological and functional assessment of the lacrimal drainage system with depiction of surrounding structures. Limitations arise mainly from demands on technical and patient-related preconditions.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1433-0423
    Keywords: Key words Dacryocystorhinostomy • Polyurethane stent • Stenosis of the nasolacrimal duct ; Schlüsselwörter Dakryozystorhinostomie • Polyurethan-Stent • Tränenwegsstenose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Hintergrund: Die Dakryozystorhinostomie stellt noch immer das Standardverfahren bei absoluter Tränenwegsstenose dar. In letzter Zeit wurden Methoden entwickelt, die es ermöglichen, unter Beibehaltung der natürlichen Abflußwege eine Durchgängigkeit zu erzielen. Die auf der Seldingertechnik beruhende Methode der retrograden Implantation eines durchgängigen Polyurethan-Röhrchens in den Ductus nasolacrimalis ist eine vielversprechende Alternative. Patienten und Methoden: Es wurden 30 Patienten mit einer radiologisch gesicherten Tränenwegsstenose therapiert, darunter 15 Patienten mit absoluter und 2 mit relativer postsakkaler Tränenwegsstenose. Das Alter betrug 22–87 Jahre (Mittelwert 58,9 ± 16 Jahre). Der Polyurethan-Stent wurde unter Durchleuchtungskontrolle implantiert. Seine Durchgängigkeit wurde direkt postoperativ, nach 4 Wochen und nach 8 Monaten mittels Dakryozystographie kontrolliert. Ergebnisse: Insgesamt wurden 25 kurze (35 mm) und 5 lange (45 mm) Stents implantiert. Letztere reichten bis in den Canaliculus superior. Bei 24 von 30 Patienten konnte auch nach 4 Wochen und bei 9 von 10 Patienten nach 8 Monaten Durchgängigkeit des Stents klinisch nachgewiesen werden. Bei einer Patientin mußte der Stent unter Durchleuchtungskontrolle wieder rekanalisiert werden. Bei einem weiteren Patienten kam es zu einer Verlagerung eines kurzen Stents in den oberen Kanalikulus, so daß er nach 2 Monaten gezogen werden mußte. Postoperative Dakryozystitiden traten bei keinem der Patienten auf. Schlußfolgerung: Erfolgs- und Komplikationsraten lassen den Polyurethan-Stent als eine echte Alternative zur Toti-Operation erscheinen, wenngleich die Nachkontrollzeiten noch zu kurz für eine abschließende Beurteilung sind. Die Vorteile liegen im geringeren Zeitaufwand, der fehlenden Hautinzision und der problemloseren Anästhesie, die Nachteile in der bisherigen Notwendigkeit einer Durchleuchtungseinheit.
    Notes: Summary Dacryocystorhinostomy is still the standard procedure complete stenosis of the nasolacrimal duct. New methods try to preserve the natural lacrimal pathway. Song implanted in 1995 a nasolacrimal polyurethane stent through the nasolacrimal duct. The results and complications of this new method are described in this prospective study. Methods: Thirty consecutive patients with complete obstruction of the nasolacrimal duct or lacrimal sac were included in the study. The stenosis was localized by dacryocystography. The ages ranged from 22 to 87 years (mean, 58.9 ± 16 years). Dacryocystography was performed immediately, 4 weeks and 8 months after the procedure to verify the position and patency of the stent. Results: Twenty-five short (35 mm) and 5 long (45 mm) stents were implanted. Twenty-four of 30 patients after 4 weeks and 9 of 10 patients after 8 months had reduced or no complaints. In 1 patient the stent was obstructed. Forceful irrigation with saline solution permitted recanalization. In 1 patient the stent had moved into the upper canaliculus. Because of irritation of the canaliculus it had to be pulled out after 2 months. Conclusion: The follow-up is still too short to recommend stent implantation as a real alternative to dacryocystorhinostomy. The main advantages are that the procedure is faster, no incision is necessary, and the local anesthesia is easier. The disadvantage is the need for X-ray examination.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-1998
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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