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Biomedical subjects

G Witte

Publications and source records attributed to G Witte.

At least 37 records · Page 2Linked to original sources

[Digital luminescence radiography. A new method of study in thoracic diagnosis at the intensive care unit].

The digital luminescence-radiography (DLR) technique relies on a complete digitalization of the X-ray image. Luminescence crystals on the imaging plate serve as an energy reservoir following their exposure to ionized radiation from any conventional X-ray source. A Helium-Neon laser stimulates the electrons in their high energy bands and therefore will be dropped back emitting luminescence. This luminescence is digitized by the DLR-System thus delivering a complete digital image to the image processor for subsequent processing and evaluation. The processed digital image is then recorded on a conventional film or a monitor screen. More than 3000 chest examinations using DLR have been performed on intensive care unit (ICU) patients at the University Hospital Eppendorf following the first eleven months since the clinical introduction of this new technique. The positive aspects of DLR such as high-contrast resolution and optimal reproducibility were clinically evaluated under ICU conditions. It was shown that DLR greatly improves the quality of the chest X-rays of all ICU patients and offers the following advantages: reproducibility, lateral chest projection, no insufficient exposure, reduction of exposure dose, electronical post-processing and storage, quality preserving digital storage and copying.

Humans↗

[Thoracic diagnosis at the intensive care unit: digital radiography].

Only few reports have been published so far on the clinical use of digital luminescence radiography (DLR). We report on 3.000 x-ray examinations of the thorax in the intensive-care ward performed by us since a suitable system (Philips PCR) had been installed in December 1987. The following advantages must be pointed out in respect of using DLR in thoracic diagnosis in the intensive-care ward: No faulty exposures; the thorax can be x-rayed with the patient recumbent in bed, with lateral take: the image brightness in maintained at a constant level by histogram selection; electronic image processing and storage. Hence, DLR entails considerable improvement in x-ray diagnosis of intensive-care patients.

Humans↗

[NMR tomography of thoracic aortic dissection].

The results of magnetic resonance imaging in 10 patients with dissection of the thoracic aorta are presented. In 8 patients, the intimal flap was clearly contrasted from flowing blood in both lumina. In 2 patients the lack of phase shift of the intraluminal signal indicated complete thrombosis of the false lumen. Oblique sagittal sections parallel to the aortic arch and coronal sections through the ascending aorta demonstrated the extent of the dissection and provided information about the involvement of the origins of the coronary arteries and the branch vessels of the aortic arch. In 7 patients, the proximal site of communication between both lumina could be localized.

Aortic Dissection↗

[The chest picture in the intensive care station as visualized by digital luminescence radiography].

To date there have been occasional reports on the technical aspects and accounts of the clinical use of digital radiography. There has, however, been a lack of reports on the clinical use of the technique in a large number of patients. We report our experience concerning more than 1250 chest x-rays on patients in intensive care; these have been carried out since December 1987, using a digital system. The method produces improvement in the radiological diagnosis of patients in intensive care; this is due to avoidance of incorrect exposures, the ability to obtain lateral films, consistent exposures and the ability to manipulate and store images electronically.

Humans↗

[Magnetic resonance tomography of a thoracic aortic aneurysm].

The results of magnetic resonance imaging in 16 patients with non-dissecting aneurysm of the thoracic aorta are presented. Scans with ECG-gated spin-echo sequences in transversal, coronal, and left anterior oblique views demonstrated the size and extent of the aneurysms. Measurements of the maximum aneurysmal diameter differed by less than 5 mm from measurements obtained with computed tomography. In 6 of 7 patients with presence of wall adherent intraluminal signal, phase images were able to differentiate accurately between mural thrombus and slow blood flow.

Adult↗

Effectiveness of intraarterial plasminogen application in combination with percutaneous transluminal angioplasty (PTA) or catheter assisted lysis (CL) in patients with chronic peripheral occlusive disease of the lower limbs (POL).

The accepted correct procedure for treating occlusive arterial diseases includes surgical disobstruction, CL as well as PTA. Combined non-surgical strategies are effective in about 60% of these patients. However, a high risk of rethrombosis despite from the prophylaxis with anticoagulants like heparin or antiplatelet drugs like ASA is proven, especially in patients with multi-segmental stenosis as well as in patients with extensive narrowing of the arteries. In these cases primary lesions (endangitis obliterans) or secondary lesions of the endothelium cause local depletion of plasminogen in the endothelium. Independent of the method used for reopening the vessel in these patients, a significant progression of the vessel disease and a high rethrombosis rate during longterm follow-up is observed. These results lead us to apply plasminogen locally to decrease the rate of rethrombosis. In patients suffering from stage III-IV (La Fontaine) including patients with multi-segmental stenosis as well as extended narrowing of the artery, PTA in combination with CL was performed. The catheter was placed as near as possible to the thrombus. In some cases the 'fibrinolyticum' could be injected directly into the thrombus. In these cases a bolus of 4,000 U/ml was locally infused, otherwise 1.0-1.5 million U urokinase per 24 hrs. were locally infused with heparin. In 28% (22 patients) no sufficient clinical response occurred using this combined therapy and plasminogen was applied locally. The following criteria supported our decision to include the patients in this study: 1. Insufficient response occurring after 12-24 hrs. of local infusion. 2. Following 6 bolus injections no reopening of the vessel occured within 60 minutes or the clinical response was insufficient due to rethrombosis. 3. Insufficient effects of lysis therapy after 2 hours and contraindication for a systemic fibrinolytic therapy (e.g. hypertension, age, etc.). 1,000 U plasminogen per ml were infused locally or 2,000 U up to 5,000 U plasminogen (in 5 to 10 ml 0.9% saline) were infused slowly (2-4 minutes infusion time) into the catheter in these patients 10 minutes after unsuccessful treatment with local urokinase therapy. Five minutes after administering plasminogen local intraarterial fibrinolytic therapy with urokinase was continued. No severe side effects due to this therapy were observed, although some patients suffered from acute pains in the peripheral segments of the arteries occurring immediately after infusion of plasminogen. In 16 of 22 patients a complete recanalization occurred and in 3 patients a satisfying clinical improvement was observed.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

The use of the Fourier transform in cardiac digital angiography.

Digital angiography has achieved broad clinical application as a morphological imaging modality through the technique of temporal subtraction known as digital subtraction angiography (DSA). After applying the Fourier transform to the intensity time curves (ITC) of an angiographic sequence, we are able to produce both morphological and functional images. The resulting pictures show an improved signal-to-noise ratio, reduction of motion artifacts, easy application of phase-synchronous subtraction, and integration and quantitative visualization of blood flow. The methods are demonstrated with nonselective angiograms and intravenous levocardiograms. Furthermore, when applied to angiographic sequences, the Fourier transform leads to a significant reduction in data without loss of important information.

Angiography↗

[Functional imaging of blood flow velocity amd myocardial perfusion using the Fourier transform parameter].

In the past, the radiology of the cardiovascular system has consisted of angiographic investigations which only demonstrate morphology. The introduction of digital techniques into radiology has made possible the demonstration of pure morphology and beyond that, calculations which provide functional information. We demonstrate functional images which, by using Fourier transformations, provide information on blood flow and organ perfusion. In this way, it is possible to obtain important additional diagnostic information concerning the cardiovascular system, without imposing any further stress on the patient.

Blood Flow Velocity↗

[Imaging of ventricular wall motion using venous DSA. A new method in radiologic cardiac diagnosis].

Until now, angiographical and nuclear medicine examination techniques for imaging left ventricular wall motion have been presenting with difficulties endemic to the methods themselves. For the first time in cardiological diagnostics, digital subtraction angiography (DSA) makes it possible to perform a fairly non-invasive examination with good spatial and temporal resolution. Functional analytic evaluation, however, still demands time-consuming, complicated post-processing. In this article we introduce a method that uses an additive window technique for the immediate generation of wall motion images.

Angiography↗

[3-dimensional display of computed tomographic studies of craniofacial anomalies].

Craniofacial anomalies are conventionally investigated by cephalometry using ordinary radiographs and by computed tomography. Both methods have the major disadvantage of trying to demonstrate a complex three-dimensional structure, such as the skull, in two dimensions and they therefore cannot display a true spatial image. We present the principle underlying a three-dimensional display derived from computer tomographic studies and discuss the clinical application in the diagnosis of craniofacial anomalies.

Adolescent↗

[Rotator cuff ruptures of the shoulder joint. Sonography--arthrography].

47 patients suspected of rupture of the rotator cuff were sonographed and arthrographed. Rupture of the rotator cuff was diagnosed in 12 cases, both diagnostic methods yielding the same result. In 29 patients sonography and arthrography did not reveal any abnormal findings. Six ruptures evident in sonography were not confirmed by arthrography and were considered false positive. Direct pointers towards rupture of the cuff would be: echoless defects, cuff cannot be visualised fully or in part, irregularities of movement during dynamic examination. Echoless "cystic" areas in the periarticular soft parts must be considered an indirect pointer. Echorich focal findings in the echopoor cuff represent a differential diagnostic problem and we cannot give a final assessment as yet. Shoulder sonography is justified as a screening method in suspicion of rotator cuff rupture before initiating arthrography. If sonography reveals no abnormal findings, shoulder arthrography need not be performed.

Arthrography↗

[Applicability of digital methods in x-ray diagnosis].

The significance of digital examination methods continues to grow. Since the introduction of computer tomography, two additional digital imaging modalities-digital subtraction angiography (DSA) and magnetic resonance imaging (MRI)--have been developed. In this paper we present basic techniques of computerized image processing and outline foreseeable future developments. Furthermore, we discuss the possibilities and problems presented by digital picture archiving and communication systems (PACS).

Analog-Digital Conversion↗

[Angiography of the upper abdomen using DSA. An alternative to conventional arteriography?].

DSA is not suitable for the investigation of hepatic and splanchnic vessels by intravenous or non-selective arterial injections. On the other hand, its use in selective arterial injection offers many advantages compared with conventional arteriography. It can be particularly recommended for routine use in the pre-operative diagnosis of abdominal masses. In some cases additional conventional angiography may also be required and it is therefore desirable to perform both examinations at one unit in order to profit from the advantages of each technique.

Angiography↗

[Arterial digital subtraction angiography for demonstrating aortocoronary venous bypasses].

We examined the patency of aortocoronary venous bypasses in 51 patients during the early postoperative phase by using non-selective contrast injection into the aorta with digital subtraction angiography. In all patients it was possible to evaluate the degree of patency by this method. The accuracy and value of this examination, as compared with other invasive and non-invasive methods, is discussed.

Adult↗

[Functional images of the left ventricle using digital venous angiography].

Imaging and functional evaluation of the left ventricle are of great interest in cardiological diagnosis. So far, the left ventricle has been imaged by laevocardiography or by a nuclear medicine method (gated blood pool, first pass). The limited spatial and temporal resolution of nuclear methods and the invasiveness of selective laevocardiography are well known disadvantages of these techniques. With special software and hardware, it is possible to obtain functional images of the left ventricle by means of intravenous contrast injection; these provide definitive information concerning local myocardial contraction patterns.

Angiography↗

[Roentgenologic observation of the course following sternotomy].

The course of healing after medial sternotomy can be controlled by means of tomography of the sternum. If healing progresses in a normal way, restitution can be seen in the region of the corpus sterni after about 20 days, whereas restitution in the area of the manubrium sterni is evident after 8 weeks only. Osseous absorption is a leading x-ray sign of disturbed restitution, the other leading sign being persistence of dehiscence of the sternum following sternotomy.

Humans↗

[Computer tomogram of changes in pancreatic calcification during pancreatitis].

In 3 patients an increase of pancreatic calcification was observed in the course of 2 months. The increase of the calcification was combined with an improvement of the patient and a decrease of pseudocysts. Therefore the increase of pancreatic calcification was considered as a good sign. After surgical drainage of a pseudocyst one patient showed a decrease of pancreatic calcification in the course of 1 year. In this patient the clinical picture indicated a favourable development. This observation demonstrates that a recovering pancreas may show diminishing calcifications.

Calcinosis↗