Digitale Bilddiagnostik最新文献

Our results have shown that MR tomography - especially if gadolinium-DTPA is used as a contrast medium - is an excellent method to differentiate between the various possible causes of the post-discotomy syndrome. In particular, it is definitely possible to differentiate between a relapsed hernia of an intervertebral disc and a postoperative development of cicatricial tissue which is practically inevitable. This differentiation is of vital importance to the clinician, because a second operation should be performed only in case of a relapse, whereas cicatricial tissue is best left alone, because no matter how carefully the operation is performed with preparation of the neural structures, even more extensive cicatricial plates are bound to develop. Instability of the vertebral column in the operated disc segment, or other causes of complaints, can be identified via MR equally well if not better than by other means. Hence, the method should be the method of choice in postdiscotomy syndrome, since it facilitates the difficult choice between conservative therapy and reoperation.

A multislice gradient echo sequence was developed for screening the liver and examined in studies on probands. This sequence is characterized by pronounced T1-weighting and low susceptibility to artifacts as well as a good contrast-to-noise ratio. Examination of the probands yielded suitable parameters for the repetition time, the delay echo, the excitation pulse angle and the number of data acquisitions. The optimized sequence yields, at a repetition time of 306 msec and an echo delay of 12 msec, 18 adjacent slices. With these measurement parameters an excitation pulse angle of 90 degrees was found to be adequate. Four data acquisitions (5.4 minutes measurement time) resulted in an effective reduction of motion artifacts. Compared with the T1-weighted spin echo sequences, the entire liver can be measured in half the time when using the multislice gradient echo sequence.

Description of a method to reconstruct planar images from MRT 3D data sets. These images can be of varying orientation. Reconstruction requires a computer and the control panel of a normal magnetic resonance tomography equipment. Calculation of reconstruction is done in a few minutes. Patients can be examined parallel to this without difficulty. The method yields in a much shorter time than before images with a definitely higher resolution than by the conventional technique.

The results of CT examination of meniscopathies in 54 patients, most of them competitive athletes, are presented. CT has an overall accuracy of about 90 per cent and can hence be used for diagnosing a lesion of the meniscus with a reasonable amount of safety, while being rapid and avoiding unnecessary exposure to stress. This method, therefore, should be a focal point of the imaging methods and thus be placed between the specialist doctor's findings and possible surgery. The pros and cons of CT compared with other imaging methods are discussed.

Angiodynography is a further development of Duplex sonography and a new, non-invasive imaging method that places no stress on the patient and enables simultaneous sonomorphological diagnosis of the organs and soft parts as well as their blood supply. Experience to date has shown that the angiodynographic vascularisation pattern is a diagnostic criterion in the clarification of circumscribed thyroid changes. If thyroid findings appear to be unclear, e.g. in case of scintigraphic cold nodes, angiodynography can be used with success as a complementary method. It can also help to classify findings in focal lesions of the liver. Information on functional parameters are supplied for differentiating arterial and venous vascular processes. They are easier to apply, more rapid and more accurate than with Duplex sonography. A drawback is the limited depth of penetration (5 MHz transducer). Angiodynography can be appreciated quickly and easily. It appears to be not only a complement to conventional examination methods but may even replace established diagnostic methods in solving certain problems.

A case of scimitar syndrome is reported in which the diagnosis was first suggested on chest radiograph. The diagnosis was confirmed by computed tomography (CT) and intravenous digital subtraction angiography (DSA). CT and DSA seem to be able to evaluate the structure and distortion of the lung and the vessels.

34 patients with skeletal alterations mostly in the periphery were investigated by digital image intensifier radiography (DIIR). A high resolution image-intensifier system (1024 x 1024 matrix, 40 cm, 28 cm, 14 cm image intensifier, maximal spatial resolution: 3.6 lp/mm) was available. The image quality was diagnostic sufficient in 76% using DIIR. A good or very good image quality of fine-structures was obtained only in 41%. The quality deficits in comparison to conventional radiograms were particularly obvious in investigation of the phalangeals. Logarithmic amplification and software upgrading lead after these first clinical investigations to a better image quality.

In this study healthy subjects and schizophrenic patients of the so-called Type I and Type II subgroups were examined in each case with a morphological method to determine the size of the corpus callosum and with a method to measure a physiological functional parameter, namely, the regional cerebral blood flow (rCBF). MR and dynamic single photon emission CT were used (in our case as differential method). The study reveals for the first time classified into subgroups of the disease, scientifically measured differences both in the size of the corpus callosum and in the distribution pattern of the blood flow. Whereas the patients of type I had an enlarged corpus callosum and increased blood flow during the task with which they were confronted, these organs were mainly smaller in size with type II patients without an increase in the global blood flow during the relevant task. The statistical data--averaged over patient groups--show these differences clearly, but due to biological scatter it has so far not been possible to arrive at a diagnosis in individual cases.

The diagnostic possibilities of magnetic resonance imaging compared with computed tomography in lymphomas and pathological enlargement of the lymph nodes in the head and neck region are presented. Whereas plain MRI examinations showed the same diagnostic sensitivity as CT, application of the paramagnetic contrast medium Gd-DTPA in 50 of 87 patients clearly increased diagnostic accuracy. Signal intensities of T1- or T2-weighted images before therapy (operation, chemotherapy, radiotherapy) and after administration of Gd-DTPA were enhanced, compared with posttherapeutic and plain examinations. An increase after therapy in two patients signalled a relapse or residual tumour tissue; a decrease in three cases was evaluated as response to therapy. Other differential diagnostic processes such as lipomas, neurinomas, glomus tumours etc. were differentiated with the help of signal intensity curves after administration of contrast media and the use of a gradient echo sequence TR/TE = 30/12 msec with a flip angle of 30 degrees. Differentiation of tissue based on morphological criteria such as homogeneity of tumour tissue or the delineation against surrounding tissue structures showed in the case of Hodgkin's disease and inflammatory diseases mainly homogeneous elements without ring-shaped structure. Non-Hodgkin lymphomas had a predominantly homogeneous structure. In squamous cell carcinomas MR revealed in two cases a ring-shaped enhancement.

MR tomography yields better contrasts for soft tissues than other imaging methods. This allows a reliable measurement of the volume of brain structures, in particular for the ventricular system and e. g. structures in hydrocephalic states. Therefore a method is proposed for segmentation and volume estimation of MR tomograms that is implemented via a computer program. This method provides an accurate determination of the volume tested on multiple-slice-images of normal patients and a phantom. The substantial features and possibilities of this program usable for all kinds of structures in MR-tomograms are explained here in detail.