Biomedical subjects
Publications and source records attributed to G Reuther.
The radiological appearance of 6 posterior epidiaphragmatic fatty tissue masses in MRI and CT is reported. The differential diagnostic considerations of lipoma, herniation or dystopia and the value of imaging techniques are discussed.
Accuracy in the assessment of lesion extension, specificity for histologic type and tumour status were reviewed in MRI and CT scans of 27 chondrosarcomas, 18 osteochondromas and 10 enchondromas and compared with the results obtained by plain radiography. No significant differences in the description of the lesion were found in chondrosarcomas and enchondromas between MRI and CT. In osteochondromas cartilage caps smaller than 5 mm and isodense to muscle were missed or not adequately delineated in CT. The specificity for the primary benign and malignant forms was equally high for CT and plain films, while MRI implies a much lower specificity due to the low sensitivity for matrix mineralisations. The criteria for malignant transformation of osteochondromas are visualised to better advantage by MRI. Solid ossified and small unmineralised recurrences of chondrosarcomas are detected by MRI with a higher sensitivity and specificity than by CT.
Renal allograft recipients were routinely monitored by means of duplex Doppler ultrasound. In a 20-month survey period, four instances of acute renal vein thrombosis were detected among 75 patients. All episodes occurred within the first 3 postoperative days. The examinations disclosed peaked, abruptly dropping systolic frequency shifts and retrograde plateaulike frequency shifts during diastole at the level of the main renal artery and its proximal branches. A venous Doppler signal could not be recorded. The findings are interpreted as indicating renal impedance exceeding diastolic pressure with nonpropulsive blood flow within the arterial vasculature.
Intraosseous lipomas exhibit a very characteristic radiological appearance. Diagnosis can be derived exclusively from x-ray examinations if a sharply defined cystic lesion with dense central sclerosis and fat-equivalent CT values is detected. When the latter criterion is not markedly pronounced the occurrence of a lipoma-derived, e.g. myxomatous, process can be discussed.
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This is a review of CT criteria in the evaluation of potential instability, giving a simple guideline to fracture classification according to biomechanics and a survey of imaging pitfalls, as well as a diagnostic regimen of radiological imaging for acute trauma and posttraumatic states.
In a prospective study we compared the results of MRI and ultrasound in assessing renal dysfunctions in 22 patients with renal allografts. The current diagnostic criteria are presented and the range of indications is evaluated in relation to perfusion scans.
A case report points to a venous obstruction expressed by high signal intensities in the MR tomogram that had not been noted so far when using this method.
MRI of the orbit is strongly improved by the use of surface coils due to a higher signal-to-noise ratio. Oblique views without moving the patient present the optic nerve in full length on one slice. First experience with a small number of cases demonstrates normal anatomy and lesions in detail only at T1-weighted pulse sequences. Losses in contrast variation and detail accuracy are caused by movements of the eyeballs. Edge artifacts due to chemical shifting impair the image quality. So far there are no pointers towards tissue-specific signal intensity behaviour. Procedure and most favourable parameters at 1 tesla are given.
The use of surface coils in magnetic resonance imaging of the orbit leads to an increase in spatial resolution. With the first 14 patients in whom we used the method we obtained detailed images of the orbital topography, especially in cases with tumors and foreign bodies, but the method proved to be little use in finding minimal tissue changes of the muscles or of the optic nerve. The use of oblique views without moving the patients, enables the optic nerve to be imaged in one slice. Edge artefacts caused by "chemical shift" and motion artefacts caused by motion of the bulbs still diminish detail accuracy and contrast differentiation range. Since no side effects have been described so far, magnetic resonance imaging with a surface coil is a highly suitable complementary procedure in the diagnosis of orbital disease.
A device is presented to increase placement accuracy and to reduce localization scans during CT-guided biopsies. The device provides an accurate anticipation of the needle path by external radiopaque landmarks.