Digitale Bilddiagnostik最新文献

Arthrography was performed during the last 12 months in 14 patients who had 2 months to 10 years after implantation of a silicone-elastomer- or fascia-lata-prosthesis recurrent complaints in their operated wrists. Following an extensive radiological native examination either midcarpal or radiocarpal arthrography was performed in dependence of the site of carpal-bone-substitute. Inflammatory changes of the prosthetic bed, missing penetration of contrast medium into the periprosthetic space and other less common additional findings showed the advantages of the relatively handsome procedure.

The characteristics of the DS-1000, a new digital imaging equipment, using an image-intensifier-video-system are described. The digital images are displayed on a monitor with 1024 x 1024 matrix, are stored on a hard disc and can be postprocessed with regard to gray-scale-level and recognition of details. The spatial resolution ist 1,1 Lp/mm, using the 47-cm-image-intensifier. The DS 1000 was employed for chest-examinations. The diagnostic accuracy of 70 selected cases with a great variety of pathologic conditions was verified in comparison to conventional chest films. There was no significant difference in the recognition of normal anatomic structures between the two imaging systems. Pathologic states with low contrast to the surrounding structures (mediastinal and hilar masses, airspace disease, pulmonary nodules) were displayed at least equivalent with the digital technique. The accuracy in recognizing pathologic states with the digital equipment as compared to the conventional technique was inferior for conditions requiring high spatial resolution (subtle interstitial infiltrations, septal lines, scars, subtle calcifications).

By means of registration of somatosensory (SSEP) and visual (VEP) evoked potentials under the influence of different magnetic and electromagnetic fields of Magnetic Resonance we investigated the influence of Magnetic Resonance Imaging (MRI) on human nervous system (all measurements with an 1.0 T MR imager are performed outside and inside the static magnetic field, before and after MR imaging). In vivo experiments on 20 healthy volunteers show in SSEP registrations as well as in VEP-registrations no measurable influence on nerve conduction. The measured latencies before and after MR imaging are found inside the standard values which are valid for healthy volunteers. In vivo experiments at field-strengthens up to 1.0 Tesla show no significant changes of the central and peripheral conduction velocity with human beings.

Quantitative computed tomography for measuring vertebral bone mineral content offers high sensitivity and reproducibility. However, several systematic errors of the method have to be considered, such as the influence of fat present in the spongiosa in varying concentrations as well as beam hardening effects and different calibration methods. The unknown fat content of the spongiosa of the vertebral bodies can be responsible for errors up to 30%. Beam hardening effects result in comparatively minor errors which can moreover be easily corrected via reference phantoms. The calibration method, on the other hand, results in potentially major systematic deviations due to the necessarily arbitrary determination of the reference points. These deviations must be taken into account especially in cross-comparisons of measured data. Dual energy methods enable a highly selective determination of the density of calcified tissue and soft tissue and decisively reduces the systematic errors mentioned above. The order of magnitude of the individual errors for different CT techniques was assessed by means of phantom studies and clinical studies.

Computed tomography findings were studied after successful lumbar disk surgery. All patients were asymptomatic after the operation thus presenting morphological changes that probably correspond to regular postoperative conditions. Small seromas in the area of surgery are well-known "normal" findings and have no pathological significance. Dorsal bulging at the level of the intervertebral disc operated upon has not yet been studied systematically. This protrusion that can even exceed the preoperative amount of bulging is due to swelling and folding of the posterior longitudinal ligament. In our patients it disappeared spontaneously within a few months and it should not be confused with real recurrent or residual disc herniation.

The results of computed tomography of 48 patients after operation on rectal carcinoma who underwent close-meshed computer tomographic examinations are given in a prospective study. (First examination 6 weeks after operation, further examinations at intervals of 3 months, mean observation time: 12 months). The results of follow-up by means of computer tomographic examination are compared with clinical examinations and control of CEA levels. The use of computer tomographic examination resulted in 43 confirmed negative, 3 confirmed positive and 2 false negative findings (including cases with CT-aided fine needle biopsy). These results give an accuracy of 96% and thus exceed clinical examination and controls of CEA-level. How far early diagnosis of local recurrence of rectal cancer influences survival time, can be answered after completion of this study in the next few years.

Dimethylsiloxane polymers are tested to serve as a reference medium in quantitative MR imaging. Simultaneously measured during the patient's examination, the reference data are used to normalize the intrinsic MR tissue parameters. This method helps to achieve interindividual comparability of tissue vectors which are defined by proton density, spin-spin and spin-lattice relaxation times, thus leading to a remarkable improvement in tissue classification.

Contrast enhancement around the nipple has been evaluated retrospectively in 51 of 70 patients in respect of the underlying breast disease. 2 of the patients had to be considered separately because of malignant disease of the nipple or areola itself. The remaining 49 patients showed no close relation between the underlying breast disease and the amount of contrast enhancement in the nipple. This phenomenon of a non-pathological significant contrast enhancement of the nipple appears important to avoid false positive diagnoses in MRI of the breast with Gd-DTPA.

The authors report on a patient of 5 months of age in whom the computer tomogram revealed a space-occupying growth without any sign of a compressive intracranial process. Histological diagnosis yielded the rare occurrence of a fibrillary astrocytoma of grade 2.

The importance of follow-up monitoring of the course of irradiated intracranial tumours was underlined by a study of 98 cerebral dynamic computer tomograms made on 38 irradiated intracranial tumour patients. It is demonstrated that dynamic cerebral CT is a sensitive method for assessing tumour vascularisation and for assessing a disturbance of the blood-brain barrier. An adequately adjusted and standardised examination programme is demonstrated and recommended for determining the blood-brain barrier disturbance. The assessment criteria of the density-time curves for evaluating the radiotherapeutic effectively are presented; in this connection, the change in tumour vascularisation. In conclusion, the article explains the most important indications for cerebral dynamic CT in intracranial tumours.