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G Wittenberg

Publications and source records attributed to G Wittenberg.

At least 37 records · Page 2Linked to original sources
PubMed1998

[In vitro studies to determine the degree of stenosis using spiral CT angiography].

UNLABELLED: Aim of the study was to evaluate the influence of different spiral-CT parameters for the visualisation of vascular stenoses, especially of the renal arteries. MATERIAL AND METHODS: Models with a density equivalent to that of fat, filled with diluted contrast agent, and an inner lumen of 4, 6, 8 mm were scanned in x-, y- and z-direction. Data were acquired in up to 24 second long spiral-CT scans using different spiral-CT parameters (collimation, table speed, reconstruction algorithm, tube current). Detection of the degree of stenosis was achieved by assessment of the axial images and 3D reconstructions. RESULTS: The best correlation between real and measured degree of stenosis was seen by using a small collimation, a low table increment and assessment of the axial images reconstructed in standard algorithm. The stenosis degrees of models directed in x- and y-direction were overestimated and those in z-direction were underestimated depending on the spiral-CT parameters. CONCLUSION: For optimal imaging of renal artery stenoses, collimation of 2 mm (pitch = 1-2 and a reconstruction interval of 1 mm is recommended.

Algorithms↗
PubMed1998

[The stepchild of intestinal diagnosis. Evaluation of radiologic methods in the diagnosis of leiomyoma of the small intestine].

PURPOSE: Various radiological methods to diagnose small bowel neoplasms and problems of differential diagnosis specially considering leiomyomas are discussed. PATIENTS AND METHODS: Two patients with leiomyoma of the ileum underwent enteroclysis, computed tomography of the abdomen, intra-arterial DSA and colour Doppler sonography. Another patient with leiomyosarcoma just underwent CT of the abdomen with CT-guided biopsy. RESULTS: Due to the homogenous density and the smooth surface of the tumors in computed tomography and respectively enteroclysis and the presentation of the tumor vascularisation in the angiography and Colour Doppler sonography in both patients a leiomyoma of the small bowel was diagnosed. Postoperatively this diagnosis was histologically confirmed. The CT-findings of the patient with leiomyosarcoma were not suspicious of a malignant tumor. CONCLUSION: Radiologically it is not possible to determine the dignity of smooth muscle cell tumors safely. That is the reason why the diagnosis has to be achieved operatively. But the histopathological diagnosis based on the mitotic rate may be difficult. Therefore the after care has to be carried out thoroughly.

Aged↗
PubMed1997

[Implantation of a transvenous defibrillation system in isolated persistent left superior vena cava].

HISTORY AND CLINICAL FINDINGS: A 49-year-old man, an alcoholic for the past 7 years, complained of dizziness, palpitations and exertional dyspnoea (NYHA stage III). Physical examination revealed peripheral cyanosis, slightly raised jugular venous pressure, râles in the lung bases, a loud systolic murmur, maximal over the apex, and an enlarged palpable liver. INVESTIGATIONS: Results of biochemical tests were unremarkable. The ECG showed sinus rhythm, 1 degree AV block and signs of left ventricular hypertrophy. Chest radiogram demonstrated cardiac dilatation and probably absent right superior vena cava (SVC). Long-term ECG monitoring during episodes of dizziness and one syncope revealed self-limited periods of unifocal ventricular tachycardia. Echocardiography and angiography showed bilateral ventricular dilatation with an ejection fraction reduced to 20%, as well as mild mitral and moderate tricuspid regurgitation but normal cardiac valves, suggesting a dilated cardiomyopathy. Coronary angiography was normal. No myocarditis was revealed on myocardial biopsy. The patient declined electrophysiological investigation. TREATMENT AND COURSE: Amiodarone caused higher degree AV block. A temporary pacemaker lead was inserted via the persistent left SVC, amiodarone discontinued and later a pacemaker-defibrillator system (ICD) implanted, previous digital subtraction angiography having demonstrated a left SVC and absent right SVC. The transvenous electrode had been placed via the left subclavian vein, left SVC (anode), coronary sinus, right atrium into the right ventricle (cathode), and the pacemaker-defibrillator implanted subpectorally. Stable electrode position and correct ICD function has been documented over 2 years. 4 months after implantation bursts of ventricular tachycardia recurred every few minutes that responded to renewed amiodarone administration. CONCLUSION: Good long-term results can be obtained with ICD electrodes implanted via a persistent LSVC.

Amiodarone↗
PubMed1997

Inappropriate discharge of an implantable cardioverter defibrillator during atrial flutter and intermittent ventricular antibradycardia pacing.

INTRODUCTION: Inappropriate discharges of an implantable cardioverter defibrillator (ICD) are troublesome to the patient and sometimes a difficult task for the physician trying to identify and treat the cause. METHODS AND RESULTS: For the first time, we report a mechanism of inappropriate ICD discharges during episodes of atrial flutter with a slow ventricular response and intermittent antibradycardia pacing. The episodes occurred in two patients and were triggered by the unique sensing algorithm of the Ventritex Cadence V-100 in combination with the tripolar CPI Endotak 072 transvenous defibrillation lead, which provides integrated bipolar sensing. CONCLUSION: Besides treatment of the underlying arrhythmia, reprogramming of the device, an electrode position far away from the atria, and true bipolar sensing will enhance the performance of ICD systems with respect to the episodes described here. In addition, more flexible sensing algorithms may, in the future, prevent this overall rare complication.

Aged↗
PubMed1997

[Massive hemorrhage from jejunal varices].

A 21-year-old male presented with melaena and signs of hemorrhagic shock. In the following days several episodes of hematochezia occurred requiring the transfusion of nine units of blood. Findings at gastroscopy were normal, at colonoscopy fresh blood was noted from the ileocecal valve. Angiography performed in a bleeding-free interval showed no abnormalities. At repeat angiography, bleeding (from a left lateral branch of the superior mesenteric artery) was provoked by instillation of plasminogen activator. Subsequently, hemostasis was achieved by superselective embolization using coils. At operation one week later, a polypoid tumor of 1 cm diameter was resected along with a 4 cm segment of adjacent jejunum (40 cm distal to the ligament of Treitz). Histologically, a jejunal varix with superficial ulceration was diagnosed.

Adult↗
PubMed1996

[Computerized tomography volumetry of the cerebrospinal fluid by semiautomatic contour recognition and gray value histogram analysis].

PURPOSE: A program (VAC, Siemens) using self-made, anthropomorphous phantoms to measure semiautomatically the volume of the cerebral liquor in CT scans of the whole skull was tested. MATERIAL AND METHODS: Cerebral tissue was simulated by ellipsoid bodies made from Agar and NaI which were placed in a human skull. Volumes of the ventricular and subarachnoidal liquor could be defined arbitrarily. RESULTS: A correlation coefficient of r > = 0.9 using a slice thickness of 1-5 mm was found (thickness 8 mm: r = 0.75). The volume of the cerebral liquor was underestimated by 25-68%. Separate measurements of the ventricular and subarachnoidal liquor spaces showed a high accuracy of the measurements done in the ventricles (r = 0.997, y = 0.996 x -1). The volume of the subarachnoidal liquor was not detected completely due to partial volume effects which were seen especially in the basal and apical scans. CONCLUSION: The program VAC is useful for the semiautomatic measurement of the volume of the ventricles. The assessment of the subarachnoidal liquor is limited to semiquantitative results which may, however, be useful for follow-up studies.

Brain↗
PubMed1996

[Initial experiences with dilatation of dialysis shunts with color-coded duplex ultrasonography monitoring].

PURPOSE: Aim of the study was to evaluate the technical aspects of colour coded duplex sonography guided interventions of peripheral vessels. METHODS: During 15 months 39 stenoses of shunt veins in 24 patients were dilated guided by colour coded duplex sonography. RESULTS: 38 stenoses were dilated without complications. The blood flow volume was increased from 361.9 +/- 83.5 to 718.9 +/- 189.2 ml/min. In one case it was not possible to dilate the stenosis because of a vasospasm. CONCLUSION: PTA guided by colour coded duplex sonography is an alternative to DSA guided interventions of superficial vessels without x-ray exposure or contrast agent application.

Adult↗
PubMed1995

Stereolithography in oral and maxillofacial operation planning.

Stereolithography (STL) is a method of organ-model-production based on computed tomography scans which enables the representation of complex 3-dimensional anatomical structures. Surfaces and internal structures of organs can be produced by polymerization of UV-sensitive liquid resin using a laserbeam. In oral and maxillofacial surgery this technique is advantageous for reconstruction of severe skull defects because a more accurate preoperative planning is possible. Using recently developed software we are able to reconstruct unilateral bony defects by virtual mirror imaging of the contralateral side and production of a STL mirror model as well as the reconstruction of non-mirrorable defects by superposition. Advantages of STL are the representation of complex anatomical structures, high precision and accuracy, and the option to sterilize the models for intraoperative use. More accurate planning using this method improves postoperative results, decreases risks and shortens treatment time.

Aged↗
PubMed1995

[Quantitative computed tomographic determination of spleen size to assess the course of malignant lymphomas].

The purpose of this study was to correlate CT-assessed spleen indices (length x width x depth) and their changes under therapy or in the follow-up, with the clinical course and morphological changes. In 66 patients with 200 CT's of the abdomen the spleen index was calculated and 134 spleen index differences (delta SI) were correlated with the clinical outcome. The normal group showed a mean of delta SI of -8 = 112, equivalent boundaries of -120 and 104. delta SI of progressive lymphomas (n = 32) was 313 (p < 0.01). In 10/14 patients of this group, morphological signs of infiltration were found. In regressive lymphomas (n = 63) we found delta SI = -211 (p < 0.001). 23/29 with delta SI < -120 showed signs of spleen involvement in the preliminary examination. Since there are only slight intraindividual changes of CT-assessed spleen indices and a good correlation of spleen index differences with the clinical outcome. the spleen index is a useful instrument in the follow-up of malignant lymphomas.

Disease Progression↗
PubMed1995

[Quantification of lymph node perfusion using color duplex ultrasonography].

PURPOSE: 20 parameters were defined to differentiate benign from malignant lymphadenopathy using computer assisted analysis of the lymph node perfusion demonstrated by colour Doppler flow imaging. MATERIAL AND METHODS: In 112 lymph nodes a computer assisted analysis of 10 consecutive colour Doppler flow sonograms was performed after digital data transfer to a work station. Planimetric results, the colour coded Doppler shift frequency, changes of the perfusion during the heart cycle and the perfusion in the adjacent tissue were analysed using 20 parameters. RESULTS: Discriminant analysis resulted in 7 parameters which reclassified correctly 82% of the lymph nodes (sensitivity 84%, specificity 80%). 72% of the lymph nodes could be classified in the three groups reactive lymphadenopathy, lymph node metastasis and malignant lymphoma. CONCLUSIONS: Clinically known subjective signs of malignancy (increased size, low echogenicity, alterations of the perfusion) can be analysed quantitatively to differentiate benign from malignant lymphadenopathy.

Diagnosis, Differential↗
PubMed1995

[Nonobstructive mesenteric ischemia--a diagnostic problem in internal intensive care].

Four cases of acute gut ischemia in elderly patients due to non-occlusive disease (NOD) are presented. Bowel necrosis occurred after episodes of hypotension in the course of myocardial infarction, arrhythmias and sepsis. Symptoms and clinical findings were blurred by the underlying extraintestinal disease. Angiography showed coexistent atherosclerosis but no occlusion of the major celiac and mesenteric vessels. At laparotomy (three cases) or autopsy (one case) extensive small and large bowel necroses were detected. Early laparotomy (possibly preceded by laparoscopy) is recommended for patients with suspected acute gut ischemia even if angiography fails to reveal occlusion of the large splanchnic arteries.

Aged↗
PubMed1993

[Pulmonary nocardiosis].

The radiological appearances and pulmonary changes during the acute stage and after recovery from pulmonary nocardiosis are described on the basis of 10 confirmed cases. Amongst the 10 patients there were 3 with malignant disease, 1 patient with AIDS, 3 patients following organ transplantation and 3 patients on steroids. In one patient cerebral involvement was demonstrated by MRI.

AIDS-Related Opportunistic Infections↗
PubMed1993

[The computed tomographic differentiation of endobronchial tumors and tumor-caused bronchial compression].

The efficiency of computed tomography in differentiating between a bronchial compression due to tumour formation and an endobronchial tumour was tested in comparison to bronchoscopy results. 624 bronchial segments were evaluated in 65 patients with masses in the pulmonary hilus area. Computed tomographical identification of pathological lesions (n = 71) was achieved with a sensitivity of 83% and a specificity of 96%. Out of 52 bronchial segments with endobronchial tumour, 90% showed pathological lesions and 85% were classified correctly. When the morphology of the bronchial lesions (endoluminal mass, smooth or irregularly demarcated bronchostenosis or bronchial displacement) was assessed with CT, only the CT identification of an endoluminal mass could distinguish endobronchial tumour growth with a probability of 91% from bronchial narrowing due to external causes and normal bronchi.

Adult↗