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Biomedical subjects

M Westhoff-Bleck

Publications and source records attributed to M Westhoff-Bleck.

17 recordsLinked to original sources
PubMed2005

Dilatation of the entire thoracic aorta in patients with bicuspid aortic valve: a magnetic resonance angiography study.

BACKGROUND: The presence of a bicuspid aortic valve (BAV) might be associated with a progressive dilatation of the aortic root and ascending aorta. However, involvement of the aortic arch and descending aorta has not yet been elucidated. PATIENTS AND METHODS: Magnetic resonance angiography (MRA) was used to assess the diameter of the ascending aorta, aortic arch, and descending aorta in 28 patients with bicuspid aortic valves (mean age 30 +/- 9 years). RESULTS: Patients with BAV, but without significant aortic stenosis or regurgitation (n = 10, mean age 27 +/- 8 years, n.s. versus control) were compared with controls (n = 13, mean age 33 +/- 10 years). In the BAV-patients, aortic root diameter was 35.1 +/- 4.9 mm versus 28.9 +/- 4.8 mm in the control group (p < 0.01). The diameter of the ascending aorta was also significantly increased at the level of the pulmonary artery (35.5 +/-5.6 mm versus 27.0 +/- 4.8 mm, p < 0.001). BAV-patients with moderate or severe aortic regurgitation (n = 18, mean age 32 +/- 9 years, n.s. versus control) had a significant dilatation of the aortic root, ascending aorta at the level of the pulmonary artery (41.7 +/- 4.8 mm versus 27.0 +/- 4.8 mm in control patients, p < 0.001) and, furthermore, significantly increased diameters of the aortic arch (27.1 +/- 5.6 mm versus 21.5 +/- 1.8 mm, p < 0.01) and descending aorta (21.8 +/- 5.6 mm versus 17.0 +/- 5.6 mm, p < 0.01). CONCLUSIONS: The whole thoracic aorta is abnormally dilated in patients with BAV, particularly in patients with moderate/severe aortic regurgitation. The maximum dilatation occurs in the ascending aorta at the level of the pulmonary artery. Thus, we suggest evaluation of the entire thoracic aorta in patients with BAV.

Adult↗
PubMed1998

Sonography under Daylight Conditions.

PURPOSE: Gray scale image assessment in clinical ultrasound requires working in dim light or a dark room. Daylight conditions offer the advantage of shorter visual reaction time and enhanced visual perception. Look-up table manipulations could improve image brightness. MATERIALS AND METHODS: We investigated the possibility of brightness and contrast enhancement of coloured adaptive linear look-up tables (CALUT's) and their artifact resistance. Therefore under real-time conditions red/brown, green and blue CALUT's were calculated using the gray scale distribution (mean and standard deviation) of the actual image. The changes in contrast of several structural features (echo-poor and echogenic lesions, artifacts) were assessed by clinical investigators (n = 7). RESULTS: The CALUT's produced, independent of the original, images with constant brightness and contrast. Even under daylight conditions no artifacts appeared. Under scotopic conditions the red/brown CALUT's showed the best results compared to the unchanged image and the gray, green, and blue CALUT's. Hyper and hypoechoic differences with small contrast to the surrounding tissue are enhanced and can be detected more easily. CONCLUSION: Daylight sonography allows examination even in non-darkened rooms without loss of information. Eye adaptation to changing light conditions is no longer necessary; the offered image information is more suitable for the eye.

Algorithms↗
PubMed1998

Percutaneous sonographic gastrostomy: method, indications, and problems.

OBJECTIVES: This study evaluated the application of ultrasound (US) guidance in the percutaneous placement of gastric feeding tubes in patients in whom endoscopic placement of a nutrition tube is not possible. METHODS: Thirty-eight patients with upper gastrointestinal obstruction were entered in a prospective study with US-guided nutrition tube application. Feasibility of placement, side effects, and nutritional states were monitored for a mean follow-up of 4 months. RESULTS: Ultrasound allowed rapid puncture after filling of the stomach with water through a nasal tube in 34/38 cases. In four cases a total upper gastrointestinal obstruction required an initial stomach insufflation through a direct puncture. Puncture-related major complications were not observed. Minor complications during the observation time were one late dislocation, five cases with broken material after about 6 months (four could be changed by using the Seldinger technique), and two minor local infections. The nutrition through feeding tubes stabilized body weight and body composition parameters. CONCLUSION: The percutaneous sonographic gastrostomy (PSG) is a safe and minimally invasive procedure for enteral nutrition in all cases with upper gastrointestinal obstruction when endoscopic placement of a feeding tube is not possible. Percutaneous sonographic gastrostomy may help to stabilize the nutritional parameters and general condition in patients with malignant diseases.

Adult↗
PubMed1997

[Approaches to objective assessment of differences in tissue textures by ultrasound equipment as a contribution to quality assurance].

PURPOSE: For clinical investigators the increasing number of ultrasonic machines with different technological equipment makes it difficult to reliably assess their ability to differentiate between the textures of various tissues. We investigated a procedure for a standardised method to measure the tissue texture when using different ultrasonic machines. METHODS: The texture parameters concern brightness, standard deviation, coefficient of variation and spatial coefficient of variation. These were calculated for three tissue phantoms with changing levels of gain and distance. These parameters, well established in literature for speckle detection, texture differentiation and contrast monitoring were useful for rapid comparison of the texture differentiation achieved by several ultrasonic machines. RESULTS: A linear relationship between standard deviation and mean image brightness seems to be an important factor for the detection of small changes in ultrasonic textures. We noticed great differences between the various ultrasonic machines tested by us. The best parameter in our set was the spatial coefficient of variation. CONCLUSION: The method allows rapid orientation regarding the ability of a machine to distinguish between several textures depending on the brightness, and offers an opportunity of determining the best working point for a given machine.

Equipment Design↗
PubMed1996

Diltiazem increases blood concentrations of cyclized cyclosporine metabolites resulting in different cyclosporine metabolite patterns in stable male and female renal allograft recipients.

1. Six male and six female stable renal allograft recipients under cyclosporine immunosuppression and without concomitant therapy with drugs known either to induce or inhibit CYP3A enzymes were included in the study and received 180 mg day-1 diltiazem for 1 week in a two-period cross-over fashion. Cyclosporine (352 +/- 56 mg day-1) was given in two daily oral doses. The daily doses were not changed during the study. Blood samples were collected for 12 h after receiving cyclosporine alone and after receiving diltiazem in addition for 1 week. Cyclosporine and nine of its metabolites were quantified using h.p.l.c. 2. Co-administration of diltiazem caused a 1.6 fold increase of the AUC (0, 12 h) of cyclosporine and a 1.7 fold increase of the AUC(0, 12 h) of its metabolites. Analysis of the metabolite patterns showed an over-proportional increase of the AUC(0, 12 h) of the cyclized metabolites AM1c (2.6 fold) and AM1c9 (2.2 fold). The AUC(0, 12 h) values of cyclosporine and the hydroxylated metabolites increased less than two fold. 3. Differences of the AUC(0, 12 h) values of cyclosporine with and without diltiazem were significantly higher in female than in male patients (P < 0.02). The differences in the AUC(0, 12 h) values of the metabolites, especially AM1c, tended to be higher in female patients as well. 4. It is concluded that coadministration of diltiazem not only increases the blood concentration of cyclosporine but also those of its metabolites, leads to a shift of the metabolite pattern towards cyclized metabolites, and that the pharmacokinetic changes under diltiazem administration are more prominent in female than in male patients.

Adult↗
PubMed1994

Tissue characterization using intelligent adaptive filter in the diagnosis of diffuse and focal liver disease.

In ultrasonic imaging an adaptive two-dimensional filter (ATDF) can suppress randomly generated speckle using the ratio of the local variance to the local mean as the speckle recognition feature (R). The degree of smoothing depends on the difference between the recognition feature in the region to be filtered and the selected reference tissue. We have investigated the clinical application of ATDF for ultrasound B-mode images of liver abnormalities. Using the R values of normal liver as reference values, the ATDF images were displayed. Normal livers (n = 17, R = 2.19 +/- 0.14 M +/- SEM), fatty livers (N = 16, R = 1.89 +/- 0.15) and those with acute hepatitis (N = 10, R = 2.25 +/- 0.18) appeared smooth after application of the adaptive filter, but those diseases with higher R values, such as chronic hepatitis (N = 10, R = 3.04 +/- 0.30), cirrhosis (n = 16, R = 4.44 +/- 0.30), metastases (N = 16, R = 6.43 +/- 0.53) and hepatocellular carcinomas (N = 8, R = 7.92 +/- 0.85), were largely unsmoothed. In conclusion, ATDF allows differentiation of some forms of liver disease and may be helpful in the detection of microfocal echogenic textural lesions.

Adult↗
PubMed1991

Increased thrombin levels during thrombolytic therapy in acute myocardial infarction. Relevance for the success of therapy.

BACKGROUND: It has been suggested that thrombolysis in a feedback reaction may generate pro-coagulant activities. METHODS AND RESULTS: Fifty-five patients were treated with urokinase-preactivated prourokinase (n = 35) or tissue-type plasminogen activator (n = 20) for acute myocardial infarction and underwent coronary angiography at 90 minutes and at 24-36 hours into thrombolysis, and fibrinogen (Ratnoff-Menzie), D-dimer (ELISA) and thrombin-antithrombin III complex levels (ELISA) were measured. Primary patency was achieved in 39 patients (70.9%), 13 of whom (33.3%) suffered early reocclusion. Nonsignificant decreases in fibrinogen levels were observed while D-dimer levels increased +3,008 +/- 4,047 micrograms/l (p less than 0.01), differences not being significant in respect to the thrombolytic agents or to the clinical course. In contrast, while thrombin-antithrombin III complex levels decreased -4.4 +/- 13.0 micrograms/l in patients with persistent patency, they increased +7.5 +/- 13.6 micrograms/l in case of nonsuccessful thrombolysis (p less than 0.02) and +11.9 +/- 23.8 micrograms/l in case of early reocclusion (p less than 0.001). For patients with thrombin-antithrombin III complex levels greater than 6 ng/l 120 minutes into thrombolysis, the unfavorable clinical course was predicted with 96.2% sensitivity and 93.1% specificity. CONCLUSION: Generation of thrombin, occurring during thrombolysis, is a major determinant for the success of therapy and thrombin-antithrombin III levels may serve as predictors for the short-term prognosis.

Antithrombin III↗
PubMed1990

[Incidence of residual thrombi following successful thrombolytic therapy in acute myocardial infarct and their significance for the rate of early re-occlusion. A report of a multicenter dose-finding study for thrombolytic therapy with urokinase preactivated natural prourokinase (TCL 598)].

Thrombolysis with urokinase preactivated prourokinase was performed in 74 patients. At control angiography, 90 min into thrombolysis, in 39 (52.7%) patients the infarct-related coronary artery was found patent. However, 26 out of the 39 patients (66.7%) with a patent infarct artery demonstrated angiographic signs of residual coronary thrombi. With an estimated average of 75 +/- 25% in both, patients with and without residual thrombus, the severity of the residual stenosis after thrombolysis was found to be independent from the presence of angiographic signs of residual coronary artery thrombosis. In patients with residual coronary thrombi, however, a trend towards poorer coronary perfusion was observed (50% vs 77% of the patients with prompt antegrade [TIMI grade III] perfusion [p less than 0.2]. Control angiography performed 24 to 36h after thrombolysis revealed reocclusion of the infarct artery in 26.3% of the patients with residual coronary thrombi, while none of the infarct vessels without angiographic signs of residual thrombosis had reoccluded (p less than 0.05). At follow-up angiography 17 to 23 days after thrombolysis this difference in the incidence of reocclusions had further increased to 43.8% of patients with vs 12.5% of patients without residual coronary thrombus (p less than 0.01). Thus, after thrombolysis, residual thrombotic material remaining in the infarct related vessel seems to be a major risk factor, indicating early reocclusion of the infarct artery.

Angioplasty, Balloon, Coronary↗
PubMed1989

Subcutaneous amyloid-tumor of beta-2-microglobulin origin in a long-term hemodialysis patient.

beta 2-Microglobulin (beta 2M)-derived amyloidosis has become a major concern in long-term hemodialysis patients. Clinical symptomatology is largely restricted to the articular and periarticular sites and in rare cases systemic manifestations have been described. We present a long-term hemodialysis patient, who after 16 years of hemodialysis with regenerated cellulosic membranes not only had a bilateral carpal tunnel syndrome, cystic bone translucencies and humeroscapular periarthritis but also developed two subcutaneous tumors in both gluteal regions, causing discomfort when sitting. Histology, immunohistology and electron microscopy of the tumor from the right side showed that it consisted of beta 2M-derived amyloid with concurrent scattered amyloid infiltration of the overlying skin. This report therefore adds a new clinical manifestation to the symptomatology of this type of amyloid.

Amyloidosis↗
PubMed1988

[Opportunistic pulmonary infections: immunologic principles].

In patients suffering from an immunosuppressive state pneumonia is a common manifestation of infection. In these patients the radiological appearance of pneumonia is influenced by the still existing immunocompetent reaction and not by the germ itself. Basic defense mechanisms in known underlying disease, clinical condition and the influence of epidemiology on the occurrence of pneumonia are discussed briefly.

Acquired Immunodeficiency Syndrome↗
PubMed1988

[Radiologic diagnosis of opportunistic pulmonary infections].

Advances in the area of tumour therapy and transplantation medicine as well as increasing numbers of immunodeficiency syndromes have resulted into growing importance of opportunistic infections. The radiological diagnosis and differential diagnosis become more difficult due to the broad spectrum of possible pathogenic organisms, pulmonary complications as part of the underlying disease and finally through possible side effects of therapy. An assignment of these changes to certain radiographic patterns seems useful. However, very few infections present with a characteristic pattern. In the majority of cases the radiography by itself cannot lead to the correct diagnosis. Here, more than in other areas, additional information and wide experience are of great importance to the radiologist.

Acquired Immunodeficiency Syndrome↗
PubMed1987

[Viral pneumonias: typical and atypical findings].

The clinical and radiological features of viral pneumonias are summarized and discussed. Although viral infections of the lung belong to atypical pneumonias they do not demonstrate always the radiographic pattern of an interstitial pneumonia. Characteristic radiographic findings are quite rare. In most cases the microbial etiology cannot be predicted from chest radiographs. The appearance varies depending on the virulence of the organism and the resistance of the host. In this regard knowledge of epidemiological data as well as patient condition and underlying disease is of utmost importance. Differentiation between community- and hospital-acquired infections may be very helpful.

Diagnosis, Differential↗
PubMedDate not supplied

The adverse effects of angiographic radiocontrast media.

Radiographic procedures which require the intravascular administration of water-soluble radiocontrast media are performed with increasing frequency. Each examination carries risks that are related either to the technique itself or to the opaque medium chosen. The pathogenesis of radiocontrast media-related adverse effects cannot be explained by a unique theory. The major factors implicated are direct chemotoxic effects and the physicochemical properties of contrast media, the latter being the basis for development of new contrast agents. With nonionic opaque media cardiovascular adverse effects, heat sensation and local pain are observed less frequently. However, it remains unclear whether the incidence of organ dysfunction or anaphylactic reactions with nonionic contrast media currently used can be reduced. This review compares ionic and nonionic contrast media, and current thoughts on the pathophysiology and treatment of adverse reactions are presented.

Angiography↗