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Biomedical subjects

H U Kauczor

Publications and source records attributed to H U Kauczor.

At least 19 recordsLinked to original sources
PubMed1998

[A new method for imaging ventilation-distribution with 3Helium in magnetic resonance tomography].

BACKGROUND: Conventional 1H-MRI of the lung is restricted by susceptibility effects and low proton density: Recently, imaging of lung ventilation in MRI has become feasible using hyperpolarised inert gases with a spin of I = 1/2, such as 3He and 129Xe, as inhalative "contrast agents". New technical developments, preclinical and clinical application of this method are described. MATERIALS AND METHODS: With optical laser pumping high polarisation rates can be achieved, resulting in a high signal-to-noise ratio (S/N). A dedicated application system allows accurate administration of 3He boli at different time points during inspiration. Thus, dynamic ventilation imaging becomes possible. Prerequisites for this method include a dedicated coil as well as a spectroscopy option at the MRI system. Fast sequences and low flip angles are employed to comply with the relaxation of hyperpolarise 3He in vivo. RESULTS: Overall homogeneous signal intensity (SI) represents physiological conditions. Obstructive lung disease is associated with generalised or localised signal inhomogeneity. Different time constants of specific lung regions are probably responsible for this kind of inhomogeneous inspiratory distribution of ventilation. Tumours show a clear ventilation deficit, correlating with non-ventilated lung areas. CONCLUSION: 3He MRI is a promising new modality for the evaluation of ventilation distribution under different pathological conditions. This may include obstructive lung disease and assessment of ventilation distribution before and after thoracic surgery. Furthermore, evaluation of patients with acute lung failure and validation of ventilator settings in anaesthesia may be performed.

Contrast Media↗
PubMed1997

[CT-angiography in carotid stenosis].

PURPOSE: Prospective evaluation of the accuracy of CT angiography (CTA) with different postprocessing for extracranial carotid artery in comparison with DSA. METHOD: One hundred patients were studied with standardized CTA. For postprocessing, MPR, MIP, and 3D reconstruction based on segmentation with upper and lower threshold were used. Intravascular density profiles were considered. All CTA studies were correlated with intra-arterial angiography. The degree and classification of stenoses was determined using the guidelines established by the NASCET collaborators. RESULTS: Measurement of stenosis was possible by MPR in 82.5%, by MIP in 85%, and 3D in 100%. Correct classification was found in 65.5% for MPR, 66% for MIP and 88.5% for 3D. The sensitivity for severe stenoses was 74% for MPR, 82% for MIP, and 93% for 3D. The specificity of these methods was 98%, 96%, and 97%, respectively. All carotid occlusions were correctly identified, no carotid artery was wrongly classified as occluded. CONCLUSIONS: CT angiography allows reliable examinations in carotid artery stenoses and occlusions. 3D reconstruction based on threshold segmentation is superior to MPR and MIP. In some circumstances, e.g., carotid occlusion, further investigation by invasive procedures is not necessary.

Angiography↗
PubMed1997

Aneurysms complicating inflammatory diseases in immunocompromised hosts: value of contrast-enhanced CT.

We studied the value of contrast-enhanced CT in the detection of aneurysms in immunocompromised patients suffering from inflammatory diseases eventually complicated by hemorrhage. Contrast-enhanced spiral CT was applied in three patients with immunocompromise due to chemotherapy, alcohol abuse or HIV. They suffered from invasive aspergillosis, chronic pancreatitis with pseudocyst formation, and acute pancreatitis together with HIV-associated lymphadenopathy. Complicating hemorrhage was present in two cases. Contrast-enhanced CT showed aneurysms complicating the underlying inflammatory disease in all three cases. The feeding vessels were identified and the patients with signs of bleeding were subsequently referred for angiography and embolization. Contrast-enhanced spiral CT is suited to detect aneurysms in immunocompromised patients suffering from inflammatory disease. It is recommended in these patients prior to angiography and intervention.

Adult↗
PubMed1997

Pneumomediastinum and pneumopericardium due to malignant subcarinal lymphadenopathy: CT demonstration.

A 52-year-old man had been treated for oral cancer T3 N0 M0 by radical surgery, neck dissection on the right and cervical irradiation (60 Gy). Two months after therapy he presented with dysphagia and hemoptysis. Admission chest X-ray revealed a pneumopericardium. It was caused by a bronchomediastinal fistula due to necrotic metastatic lymph nodes as shown by CT, which also revealed a concomitant pneumomediastinum. The patient died 10 days later from pneumonia. The CT findings were confirmed at autopsy. We conclude that malignant mediastinal lymphadenopathy is a potential cause of pneumopericardium and pneumomediastinum.

Bronchial Fistula↗
PubMed1997

[Spiral CT and 3-D reconstruction of the tracheobronchial tree for the selection of the proper double-lumen tubes before individual lung ventilation].

PURPOSE: To assess the potential of 3-D spiral CT in the selection of adequate double-lumen tubes (DLT) for one-lung-ventilation. MATERIALS AND METHODS: 3-D spiral CT of eight different DLTs was performed with standardized acquisition parameters: section thickness 4 mm, table speed 6 mm/s, increment 3 mm and standardised thresholds, window settings and magnification zoom. The accuracy was confirmed by measuring 3-D objects on screen and original DLTs by vernier caliper. 3-D spiral CT was performed in 20 patients preoperatively with slice thickness 4-8 mm, pitch 1-1.5, increment 4-8 mm. To select the adequate DLT size the 3-D reconstructions of the patient's tracheobronchial tree and of the DLT were superimposed by templates or computer animation. The accuracy was controlled by endoscopic and clinical measurements. RESULTS: The accuracy of the 3 D spiral CT was nearly 0.1 mm. The superimposition with templates was easy and reliable. The 3-D spiral CT determined DLTs were shown to fit perfectly by clinical and endoscopic measurements in all cases. CONCLUSION: 3-D reconstructions of the tracheobronchial tree obtained from routine preoperative spiral CT scans allow for an easy and accurate individual selection of double-lumen tubes.

Adult↗
PubMed1997

[The helium-3 MRT of pulmonary ventilation: the initial clinical applications].

PURPOSE: of the study is the visualisation of normal pulmonary ventilation in healthy volunteers and the evaluation of abnormalities in patients with different lung diseases using 3He magnetic resonance imaging (3He-MRI). MATERIAL AND METHODS: Hyperpolarized 3He gas (V = 300 ml, p = 3 x 10(5) Pa, polarised to 35-45% by optical pumping, provided in special glass cells) was inhaled by eight healthy volunteers and ten patients with different lung diseases. A 3D FLASH sequence (TR = 11.8 ms; TE = 5 ms; matrix 144 x 256, FOV 350 mm, section thickness 7-10 mm, coronal orientation) was performed in a single breath-hold (22-42 s). Clinical and radiological examinations were available for correlation. RESULTS: The studies were successfully carried out in 8/8 volunteers and in 8/10 patients. The central airways were constantly visualised with intermediate to high signal intensity. The lung parenchyma of volunteers with normal ventilatory function showed rather homogeneous intermediate to high signal, whereas patients with chronic obstructive lung disease and/or pneumonia presented severe signal inhomogeneities. Space-occupying lesions and pleural effusion caused large areas with little or no signal. The represented the lesion and adjacent ventilatory disturbances whose extent had not been presumed from chest x-ray or CT. The spatial resolution was higher than in ventilation scintigraphy. CONCLUSION: 3He MRI is a promising new modality for the assessment of pulmonary ventilation and its anomalies.

Administration, Inhalation↗
PubMed1997

[The algorithm of imaging diagnostics of pulmonary embolism: is it time for a new definition?].

Acute pulmonary embolism (PE) is an increasing and underdiagnosed cause of mortality and morbidity in hospitalised patients: pulmonary hypertension based on chronic pulmonary embolism is an uncommon, but severe and surgically curable complication. Since clinical signs might be silent or unspecific, both acute and chronic PE require imaging methods for diagnosis and treatment planning. Chest radiographic findings are usually non-specific. Scintigraphy provides a high sensitivity for PE, but lacks anatomic resolution and sufficient specificity. Pulmonary angiography, albeit accurate, is an invasive procedure associated with low but still not negligible morbidity and mortality. Hence, non-invasive methods offer advantages. Spiral CT, for example, is most reliable in the diagnosis of acute and chronic PE: Such fast CT techniques provide a non-invasive means to detect and differentiate acute emboli and organised thrombi, as well as perfusion abnormalities and other concomitant findings. MRI offers both morphological and functional information on lung perfusion and right heart function, but its image quality still needs improvement to be comparable with CT. Thus, while MRI must still be tested in clinical studies. CT is recommended as a screening method in acute and chronic pulmonary embolism.

Algorithms↗
PubMed1997

[Clinical relevance of CT of paranasal sinuses prior to bone marrow transplantation].

PURPOSE: To investigate the clinical necessity of CT of the paranasal sinuses before bone marrow or peripheral blood stem cell transplantation. PATIENTS AND METHODS: 80 patients with malignant disease underwent coronal CT of the paranasal sinuses prior to transplantation to exclude sinusitis. RESULTS: CT revealed sinusitis requesting therapy in 17/80 patients (21%). Patients with leukaemia and non-Hodgkin lymphoma were significantly more affected. Chronic sinusitis was found in two patients, mucosal swelling not requesting therapy in 22, and normal findings in 39. CONCLUSION: CT of the paranasal sinuses is advised in patients suffering haemoblastoses with an increased risk of infectious complications during the transplantation phase, because pathological findings can be expected in 21% of the patients. Diagnosis and therapy of an infectious focus within the paranasal sinuses is especially important prior to allogenous bone marrow transplantation.

Adolescent↗
PubMed1997

[Spiral CT for the detection of coronary artery calcifications and the prognosis of coronary heart disease--a comparison with fluoroscopy and coronary angiography].

PURPOSE: Evaluation of clinical relevance of coronary calcifications detected by helical CT. Evaluation of congruence with fluoroscopy (FS) and coronary angiography. Comparison with studies reporting on application of ultrafast computed tomography. MATERIALS AND METHODS: 40 patients underwent helical CT (2 mm slice thickness, table-feed 3 mm/s). Coronary angiography and FS were performed in usual technique. Stenosis and calcifications were evaluated semiquantitatively. RESULTS: 28 of 28 stenoses > or = 75% were detected via helical CT by evaluation of calcification (FS: 19). One non-detected solitary stenosis was calculated as 40%. FS did not detect 4 cases with 2-vessel and 3-vessel disease each one case with 1-vessel disease, and one case with a main stem stenosis. Sensitivity of helical CT was 97% (FS: 66%). For the evaluation of stenosis III degree (> or = 75%), sensitivity was 100% (FS: 58%), specificity was 77% (FS: 48%). CONCLUSION: Helical CT is more sensitive for haemodynamically relevant stenoses than FS. Helical CT is suitable as a substantial non-invasive diagnostic procedure in coronary heart disease. In certain cases, e.g. if the patient suffers from additional risks, helical CT should be done prior to coronary angiography. Coronary calcifications found incidentally in symptomatic patients at chest CT warrant further cardiological investigation.

Adult↗
PubMed1997

Spiral CT of pulmonary hypertension and chronic thromboembolism.

Pulmonary hypertension caused by chronic pulmonary embolism (PE) represents an uncommon, but severe and surgically curable complication of recurrent acute embolism. Because clinical signs might be silent or nonspecific, chronic PE requires imaging methods for diagnosis and treatment planning. Chest radiographic findings are usually nonspecific. Scintigraphy provides a high sensitivity for PE, but lacks anatomic resolution and sufficient specificity. Pulmonary angiography, albeit accurate, is an invasive procedure associated with low but still considerable morbidity and mortality. Thus, noninvasive methods are required. Most reliably in the diagnosis of acute and chronic PE, fast computed tomography (CT) techniques like spiral CT provide noninvasive means to detect and differentiate organized mural thrombi, as well as perfusion abnormalities and concomitant findings. Magnetic resonance imaging offers morphologic as well as functional information on lung perfusion and right heart function, but image quality needs improvement to be comparable with spiral CT. Thus, although spiral CT is recommended as the screening method for acute and chronic PE, magnetic resonance imaging might be the method of the future.

Chronic Disease↗
PubMed1997

Early detection of pneumonia in febrile neutropenic patients: use of thin-section CT.

OBJECTIVE: The purpose of this study was to evaluate the usefulness of thin-section CT for early detection of pneumonia in neutropenic patients with an unknown site of infection and normal or nonspecific findings on chest radiographs. SUBJECTS AND METHODS: Eighty-seven patients with febrile neutropenia that persisted for more than 2 days despite empiric antibiotic treatment underwent 146 prospective examinations. If findings on chest radiographs were normal (n = 126) or nonspecific (n = 20), thin-section CT (1-mm collimation, 10-mm increment) was done. If thin-section CT scans showed opacities, bronchoalveolar lavage was recommended. RESULTS: Findings on chest radiographs were nonspecific for pneumonia in 20 (14%) of 146 cases, and CT findings in those cases were suggestive of pneumonia. Microorganisms were detected in 11 of those 20 cases. Seven of the 11 cases were not optimally treated before CT diagnosis, the other four were sufficiently treated. Findings on chest radiographs and thin-section CT scans were normal in 56 (38%) of 146 cases. In 70 (48%) of 146 cases, findings on chest radiographs were normal, whereas findings on thin-section CT scans were suggestive of pneumonia. Microorganisms were detected in 30 of the 70 cases. Nineteen of 30 cases were not optimally treated before CT, whereas the other 11 cases were sufficiently treated before CT. In 22 (31%) of these 70 cases, an opacity was observed on the chest radiograph during the 7 days after the CT study. Only three (5%) of 56 pneumonias occurred during the first 7 days after thin-section CT studies with normal findings (p < .005). Additional risk factors for pneumonia occurring later that were detectable on chest radiographs were poorly defined nodules (p < .05), consolidation (p < .05), and younger age (p < .05). CONCLUSION: Thin-section CT scans show findings suggestive of pneumonia about 5 days earlier than chest radiographs show suggestive findings. When thin-section CT scans show findings suggestive of pneumonia, the probability of pneumonia being detected on chest radiographs during the 7-day follow-up is 31%, whereas the probability is only 5% when the findings on the prior thin-section CT scan were normal (p < .005). All neutropenic patients with fever of unknown origin and normal findings on chest radiographs should be examined with thin-section CT.

Antineoplastic Agents↗
PubMed1996

Pulmonary hypertension in patients with chronic pulmonary thromboembolism: chest radiograph and CT evaluation before and after surgery.

The purpose of this study was to assess the value of morphometric data on conventional radiography and CT predicting the presence and degree of pulmonary hypertension and to assess the reversibility after surgery. On preoperative X-ray films and CT scans of 50 patients with pulmonary hypertension secondary to chronic thromboembolism, we measured the cardiothoracic ratio, basal diameter, length of cardiac contact to sternum, pulmonary trunk, right and left descending pulmonary artery, and the septum angle. These data were correlated with pulmonary arterial pressure. In 14 X-ray patients and 18 CT patients, with follow-up after surgical thromboendarterectomy the reversibility of these changes was assessed. A dilated pulmonary trunk was the most common abnormality (96% each on X-ray and CT). Pulmonary arteries were dilated on X-ray in 40% (right) and 14% (left), and on CT in 92% (right) and 96% (left). The best correlation with mean arterial pressure was found measuring the pulmonary trunk on CT (r = 0.43, p < 0.01). After surgery, reversibility was most significant for the pulmonary trunk on CT (p < 0.0001). In patients with chronic pulmonary embolism, pulmonary hypertension can best be predicted by assessing the diameter of the pulmonary trunk both on X-ray and CT. No close correlation is present between the extent of any parameter and the level of pulmonary pressure.

Adult↗
PubMed1996

[High resolution computed tomography of the lung in neutropenic patients with fever].

PURPOSE: To determine the sensitivity and clinical impact of high-resolution CT (HRCT) of the lung in febrile neutropenic patients under antibiotic therapy. MATERIAL AND METHODS: Chest X-ray and HRCT were prospectively performed to exclude pneumonia in 34 patients (53 examinations) suffering from febrile neutropenia following antitumor therapy. Diagnosis was confirmed by bronchoalveolar lavage or sputum cultures. RESULTS: Chest X-ray showed pneumonia in 13/53 examinations, in 12/13 a micro-organism was found. HRCT demonstrated pneumonia in 39/53, in 31/39 a micro-organism was found. All cases with positive cultures showed suspicious HRCT findings. Changes in antibiotic treatment resulted in findings suspicious for pneumonia and evidence of a new or a just treated micro-organism (chest X-ray 8/53, HRCT 31/53); the search for the source of fever was escalated in cases without evidence of micro-organisms and without suspicion of pneumonia findings 14/53. CONCLUSION: HRCT of the lung exhibits a higher sensitivity than conventional radiographs. Findings resulted in relevant therapeutic consequences. Hence, HRCT is indicated in neutropenic patients with fever and inconspicuous chest X-ray.

Adolescent↗
PubMed1996

[Functional CT imaging of the lung in axial and coronal plane after single lung transplantation].

After single-lung transplantation in a patient suffering from obstructive emphysema lung function parameters worsened during follow-up. To complement the routine high-resolution CT (HRCT) scans acquired in inspiration, additional scans were obtained to evaluate regional lung function. The comparison of HRCT scans acquired in inspiration and in expiration revealed different ventilation conditions of both lungs, continuous acquisition in a single slice (dynamic multiscan acquisition) in the axial and coronal plane demonstrated mediastinal shifting and the movement of the diaphragm during the whole breathing cycle. Both modalities can provide important information concerning regional differences of ventilation after single-lung transplantation. Expiratory HRCT should be applied on a regular basis in the follow-up of patients after single-lung transplantation. The application of axial and coronal dynamic multiscan acquisitions will be helpful in particular clinical conditions, like increasing hyperinflation, mediastinal shifting or bronchial collapse within the region of the anastomosis.

Follow-Up Studies↗
PubMed1996

[Triphasic spiral CT in the diagnosis of liver diseases: comparison with CT arteriography and CT arterio-portography].

PURPOSE: Assessment of the diagnostic efficacy of triphasic spiral-CT scanning (TPS-CT) for liver disease evaluation. CT arteriography (CTA) and CT arterio-portography (CTAP) were used as reference, methods which together have the highest sensitivity for detecting tumours and the perfusion conditions of the liver. MATERIAL AND METHODS: 50 TPS-CT and CTA/CTPA were performed in 49 patients. After an initial examination without enhancement the first scan was initiated 15-25s after the peripheral bolus injection of contrast medium, the second after an interscan delay of 20-25s. By this means the liver was imaged in different phases of perfusion. In the course of the CTA/CTPA-exam the imaging was carried out after selective, intraarterial application of contrast agent. RESULTS: The differentiation of the perfusion phases succeeded in 90% of the patients. When compared with standard CT, which images only the portal venous phase, the new technique, which additionally shows the arterial perfusion, accomplished an increase in sensitivity for hypervascular lesions (51% vs. 60%). Yet in comparison with CTA/CTPA fewer lesions could be detected (87 vs. 138). Furthermore, by documenting the contrast agent kinetics, characterisation of the lesion was also facilitated. CONCLUSION: DPS-CT is a valuable additional tool for imaging the liver, even if the information yield is less when compared to CTA/CTPA.

Adult↗
PubMed1996

[Radiologically assisted percutaneous gastro-/enterostomy--a retrospective analysis of 90 procedures].

PURPOSE: To analyse retrospectively the indications, technique and results of radiologically induced gastrostomies or enterostomies. PATIENTS AND METHOD: Radiologically assisted gastrostomies or enterostomies were induced in 90 patients, mostly with high grade obstructions due to head and neck tumours or oesophageal tumours. 19/90 patients had had previous resection of the oesophagus or gastric operations. RESULTS: A catheter was successfully introduced in all patients. In 11/90 patients this was followed by a two-stage procedure. In 16/90 patients puncture was performed under CT control because of some anatomical peculiarity. Serious complication occurred in 9/90 patients but in only one was surgery necessary. There were no deaths resulting from the procedure but mortality after 30 days was 6.7%. CONCLUSION: Radiologically assisted gastrostomies or enterostomies are a reliable and effective form of treatment even amongst difficult patients. The results and complications are comparable to those from endoscopic procedures.

Adult↗
PubMed1996

[What is it called? A formulation and glossary for the finding and understanding of results in HRCT of the lung].

In HRCT reports multiple different, often synonymous, German and English terms are used. The variety of terms impede understanding and acceptance of HRCT. Purpose of this paper is to present a scheme, which is based on the anatomic landmarks (secondary lobule), and the density of pathologic changes, as well as a glossary from the German HRCT-literature, including suitable terms, definitions, synonyms and English terms. Low attenuation changes include emphysemas, air-filled cavities (bullae, cysts, cavitations, honeycombing) and bronchial dilatation, changes with increased density consist of diffuse (ground glass opacity, consolidation) and focal processes (reticular and nodular densities). Reticular densities are categorised in thickened interlobular septae and translobular lines with differentiation of a reticular pattern and curvilinear lines. Nodular processes are categorised according to size, density, morphology, localisation and distribution. Parenchymal distortion and destruction indicate the severity of these processes. Certain patterns are indicative for possible differential diagnoses, and a recommendation for further procedures is given.

Dictionaries, Medical as Topic↗