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  • 11
    ISSN: 1432-2161
    Keywords: Key words Pisiform bone transposition ; MRI ; Lunatomalacia ; Asceptic bone necrosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Objective. Transposition of the pisiform bone is an operative treatment for lunatomalacia. The postoperative viability of the transposed pisiform bone is difficult to assess. The purpose of the study was to evaluate the utility of MRI for postoperative assessment of viability of the pisiform and lunate bones. Design and patients. Six patients who underwent transposition of the pisiform for treatment of lunatomalacia, were assessed pre- and postoperatively with conventional radiographs (including tomography), CT and MRI. Results. Conventional radiographs, conventional tomograms and CT were all useful in demonstrating the location of the transposed pisiform. CT showed the transposed pisiform without superposition. However, neither CT nor conventional techniques provided information regarding viability of the pisiform. In all patients investigated in the first year following surgery, T1-weighted MR images showed high signal intensity in the transposed bones. In all patients investigated after 1 year, the signal intensity decreased to an intermediate level on T1-weighted images. Enhancement following contrast medium administration in the transposed pisiform and the lunate was noted in all patients, indicative of viability. Conclusion. Contrast-enhanced MRI is able to provide important information regarding the viability of the transposed pisiform and the remaining parts of the lunate. Thus, contrast-enhanced MRI provides an improved means of postoperative assessment regarding short-term follow-up following pisiform transposition. In the long-term follow-up conventional radiography and CT may be equal to MRI in showing increasing sclerosis and/or fragmentation.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Der Radiologe 38 (1998), S. 185-193 
    ISSN: 1432-2102
    Keywords: Key words Interventional MRI • Biopsy needle • Rapid imaging • Artifacts ; Schlüsselwörter Interventionelle MRT • Biopsienadeln • Schnelle Bildgebung • Artefakte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Nachdem die interventionelle MRT zunächst nur bei neurochirurgischen Eingriffen Anwendung fand, umfaßt das Indikationsspektrum mittlerweile Biopsien, minimalinvasive neurochirurgische Therapieverfahren sowie Thermoablationen von Tumoren. Hierbei werden besondere Anforderungen an das Sequenzdesign gestellt: 1. verkürzte Meßzeit, 2. Visualisierung von Instrumenten, 3. klare Abgrenzbarkeit von Läsionen und 4. Thermosensitivität. Der erste Abschnitt der Arbeit beinhaltet die passive Visualisierung MR-kompatibler Nadeln und den Einfluß von Feldstärke, Sequenzdesign sowie der Ausrichtung der Nadel im Bezug auf das statische Magnetfeld des Tomographen. Sowohl für Niederfeld- als auch für Hochfeldtomographen werden diesbezüglich praktische Empfehlungen gegeben und erläutert. Der zweite Teil der Arbeit behandelt die verschiedenen in der Interventionellen MRT verwendeten Methoden der schnellen Bildgebung, die auf die „konventionelle“ Phasenkodierung verzichten („wavelets“, „locally focused imaging“, „singular value decomposition“ und „keyhole imaging“). Im letzten Abschnitt werden die verschiedenen Möglichkeiten thermosensitiver Sequenzen [Spin-Gitter-Relaxationszeit (T1), Wasserdiffusionskoeffizient (D) und chemische Verschiebung der Wasserprotonen (δ ) ] dargestellt.
    Notes: Summary While initially advocated primarily for intrasurgical visualization (e. g., craniotomy), interventional MRI rapidly evolved into roles in image-guided localization for needle-based procedures, minimally invasive neurosurgical procedures, and thermal ablation of cancer. In this contest, MRI pulse sequences and scanning methods serve one of four primary roles: (1) speed improvement, (2) device localization, (3) anatomy/lesion differentiation and (4) temperature sensitivity. The first part of this manuscript deals with passive visualization of MR-compatible needles and the effects of field strength, sequence design, and orientation of the needle relative to the static magnetic field of the scanner. Issues and recommendations are given for low-field as well as high-field scanners. The second part contains methods reported to achieve improved acquisition efficiency over conventional phase encoding (wavelets, locally focused imaging, singular value decomposition and keyhole imaging). Finally, the last part of the manuscript reports the current status of thermosensitive sequences and their dependence on spin-lattice relaxation time (T1), water diffusion coefficient (D) and proton chemical shift (δ ).
    Type of Medium: Electronic Resource
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  • 13
    ISSN: 1432-2102
    Keywords: Schlüsselwörter Spiral-CT ; Virtuelle Endoskopie ; Larynx ; Key words Helical CT ; Virtual endoscopy ; Larynx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary This pilot study investigated the feasibility and clinical value of high-resolution virtual real-time laryngoscopy based on helical CT data sets. Nine patients with laryngeal pathology (three with tumors of the vocal cords, two laryngeal carcinomas, one with invasion of the larynx by thyroid carcinoma and six subglottic stenoses) underwent examination by helical CT at a collimation of 1 mm. Following acquisition, the images were processed at a workstation with standard visualization software, such that virtual endoscopy (VE) in real time was possible. The images were then compared with the findings of conventional endoscopy. Because of swallowing artifacts, reconstruction failed in 2 of 12 patients. None of the carcinomas of the vocal cords was recognized at VE or in the cross-sectional CT images. VE provided the correct diagnosis in 8 of 12 cases (laryngeal tumors, subglottic stenoses). Virtual laryngoscopy is capable of simulating the visual findings of endoscopy in cases of laryngeal tumors and subglottic stenoses. Small tumors of the vocal cords are not adequately visualized. The major problem affecting results is motion artifacts resulting from involuntary swallowing.
    Notes: Zusammenfassung Im vorliegenden Beitrag wird eine Pilotstudie zur Überprüfung der Machbarkeit und des klinischen Nutzens einer hochauflösenden virtuellen Echtzeitlaryngoskopie aus Spiral-CT-Datensätzen vorgestellt. 12 Patienten mit Erkrankungen im Kehlkopfbereich (3 Stimmlippentumore, 2 Larynxkarzinome, ein in den Larynx eingebrochenes Schilddrüsenkarzinom und 6 subglottische Stenosen) wurden mittels hochauflösender Spiral-CT (Kollimation 1 mm) untersucht. Anschließend wurden die Bilder auf einer Workstation mit einer standardmäßigen Visualisierungssoftware so rekonstruiert, daß eine virtuelle Endoskopie (VE) in Echtzeit möglich wurde, welche der herkömmlichen Fiberendoskopie gegenübergestellt wurde. 2 der 12 Patienten waren bedingt durch Schluckartefakte nicht zu rekonstruieren. Keines der Stimmlippenkarzinome war in der VE oder den Querschnittsbildern zu erkennen. In 8 von 12 Fällen war die VE diagnostisch (Larynxtumore, subglottische Stenosen). Die virtuelle Laryngoskopie in der hier beschriebenen Technik vermag Larynxtumoren und subglottische Stenosen, nicht aber kleine Stimmbandtumoren in einer dem Kliniker vertrauten endoskopischen Sichtweise darzustellen. Hauptproblem sind Bewegungsartefakte durch unwillkürliche Schluckbewegungen.
    Type of Medium: Electronic Resource
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  • 14
    ISSN: 1432-2161
    Keywords: Key words Echinococcosis ; Bone ; Soft tissue ; Liver
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Objective. The present study demonstrates the osseous and soft tissue manifestations of alveolar echinococcosis (AE). Patients. We report on eight patients with AE with bone or soft tissue involvement confirmed at biopsy or needle cytology. Results. All eight patients showed hepatic involvement. Four exhibited infiltration of the spine as a result of direct spread of the hepatic primary lesion; distant metastases were observed in only three of these patients. Calcifications, which are typical for hepatic manifestations of the disease, were observed in soft tissue in only two of eight cases (25%); we observed no instances of endovesicular daughter cysts. Conclusion. AE manifests itself in the vertebral column as a form of spondylitis and in soft tissue presents similar to an abscess. Since in most of these cases spread of the disease per continuitatem from the liver is present, the diagnosis is easily made from the characteristic hepatic findings.
    Type of Medium: Electronic Resource
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  • 15
    ISSN: 1432-2161
    Keywords: Key words Anterior cruciate ligament reconstruction ; ACL ; Isometry ; MRI ; Radiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Objective. Correct placement of tunnels for anterior cruciate ligament (ACL) reconstruction is of prime importance for the clinical outcome of the patient. In this study, the possibility of using MRI to document tunnel placement and provide a more comprehensive report following ACL reconstruction was explored at no additional cost in patients scheduled for routine knee MRI. Design and patients. One year after ACL reconstruction, 45 patients underwent clinical examination (IKCD score), radiographic examination, and MRI using a 1.5-T unit. Results. Twenty patients with good tibial and femoral attachment results were found at clinical examination to have a stable knee joint with a full range of motion. In 25 patients with suboptimal placements, examination showed either a stable knee with a decreased range of motion or instability with a normal range of motion. Conclusion. Patients’ clinical outcome, and the radiographic and MRI findings, correlated closely with the quality of operative tunnel placement. A record of this finding is important for completeness of the radiological report. Furthermore the MRI findings can be used to improve the surgical quality of tunnel placement. Because tunnel placement can be shown adequately with radiography, however, MRI cannot be justified for this reason alone, so such assessment is advised only when MRI is needed to show all postoperative features.
    Type of Medium: Electronic Resource
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  • 16
    ISSN: 1432-0584
    Keywords: Key words Bisphosphonate ; Multiple myeloma ; Pulmonary calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  A-52-year-old patient presented with a 2-year history of multiple myeloma, recurrent episodes of hypercalcemia, and extensive bone involvement. She developed pulmonary infiltrates, initially misdiagnosed as interstitial pneumonia. High-resolution computed tomography and bone scintiscanning indicated pulmonary calcification, which was confirmed by a transbronchial biopsy. Cytostatic treatment of multiple myeloma in combination with repetitive i.v. administration of bisphosphonates over a period of 6 months led to a significant improvement of clinical symptoms. Regression of pulmonary infiltrates was demonstrated by chest radiograph and computed tomography. There are only a few reports on pulmonary calcification in patients with multiple myeloma; the condition was associated mostly with progressive disease, kidney failure, adult respiratory distress syndrome and bad prognosis. In our patient isolated calcification of the lungs without involvement of other organ systems was successfully treated. These findings suggest that interstitial pulmonary calcinosis in multiple myeloma can be reversed by normalization of serum calcium levels using bisphosphonates combined with cytostatic treatment.
    Type of Medium: Electronic Resource
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