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G J Rosenbusch

Publications and source records attributed to G J Rosenbusch.

9 recordsLinked to original sources
PubMed1998

Quantitative ultrasonic analysis of liver metastases.

The performance of five features of ultrasonic tissue characterization (UTC) of metastases in vivo in liver was investigated. We acquired serial radiofrequency data sets of 12 patients with metastases in the liver from adenocarcinoma of the colon. Parenchyma and metastases UTC features were estimated in semiautomatically segmented regions. Over 200 metastases were measured in patients and 43 dummy metastases in healthy volunteers. Two attenuation features could be estimated in only 15% of the metastases, and these were not different from those in parenchyma. The texture features signal-to-noise ratio (SNR) could not discriminate real from dummy metastases. Average backscatter intensity, b0, is an established discriminative echographic image feature. However, the metastases that were hypoechoic relative to surrounding parenchyma appeared to be isoechoic relative to normal liver parenchyma. They were visible because of an increased b0 in the surrounding liver parenchyma. Finally, we found an increased backscatter coefficient slope vs. frequency in hypoechoic metastases that may predict a deterioration of lesion contrast at higher transducer frequencies. We conclude that the backscatter coefficient slope can improve detection of metastases, and that b0 measured relative to normal liver parenchyma should be used to correctly correlate metastasis echography with histology.

Acoustics↗
PubMed1993

Correlations between acoustic and texture parameters from RF and B-mode liver echograms.

Radio frequency (RF) echograms were acquired from human subjects without liver pathology (n = 126), who were in the range of 20 to 84 years of age. After appropriate correction for the equipment settings and performance characteristics, acoustospectrographic parameters were estimated. The data were corrected for the frequency-dependent attenuation and then software demodulated. Image texture parameters were calculated based on the assumption of a particular tissue model, and purely statistical parameters were also estimated. The data thus obtained from each subject were corrected for the age trend that was assessed in an earlier publication by the authors. A total of 18 parameters was considered and the correlations were analyzed. It is concluded that nine parameters could be identified which did not strongly correlate with each other. This conclusion is supported by analysis of correlation data from patients. In a companion paper, a discriminant analysis is reported, based on the selected parameters (nine) and applied to the differentiation between normals and various classes of diffuse liver disease.

Adolescent↗
PubMed1993

Detection of diffuse liver disease by quantitative echography: dependence on a Priori choice of parameters.

Quantitative acoustic parameters and image texture parameters were used in a linear discriminant analysis. This analysis was applied to detect retrospectively the classes of diffuse liver disease against a population of normal livers. Three different sets of parameters were employed. The first set was selected by the authors, and the other two were taken from the literature. The area under the Receiver Operating Characteristic (ROC) (or percentage correct classification) obtained with the first set ranged from 88% to 97%, depending on the disease class. It is concluded that the first-order statistical parameters of the image texture (diffuse scattering model) together with the slope of the attenuation coefficient are the most important parameters. As an alternative to the texture parameters, the backscattering parameters (second set of parameters) also yielded a comparably high score. The texture analysis involving structural scattering (third set of parameters) produced a lower percentage of correct classification. The overall conclusion is that the methods devised might be used for prospective diagnosis.

Adolescent↗
PubMed1993

Detection and differentiation of diffuse liver disease by quantitative echography. A retrospective assessment.

RATIONALE AND OBJECTIVES: The detectability of diffuse liver diseases by quantitative echography was retrospectively investigated using scans of patients with known pathologic findings (n = 103) and of normal subjects (n = 129). The authors determined the best set of quantitative parameters for this task. METHODS: Quantitative echography was comprised of acoustospectrographic parameters (frequency dependence of attenuation and backscattering) and image texture parameters. The disease processes studied included: acute hepatitis, hepatitis/cirrhosis, alcoholic hepatitis/cirrhosis, primary biliary cirrhosis, and steatosis. RESULTS: Correct differentiation of these diseases ranged from 88% to 97%. Correlations between histologic grading and echographic parameters were poor. With only one exception, the differentiation between any two of the diseases could be made in 60% to 99% of cases. Different parameters better differentiated abnormal from normal scans than among diseases. CONCLUSIONS: The detection of diffuse liver diseases can be based on echographic parameters, related to a diffuse scattering model, whereas the differentiation among diseases needs additional parameters derived from a structural scattering model. Further studies are indicated to assess the prospective potential of the devised methods.

Discriminant Analysis↗
PubMed1991

Variability of quantitative echographic parameters of the liver: intra- and interindividual spread, temporal- and age-related effects.

The values of acoustic and image texture parameters were estimated from liver scans of healthy subjects. The values were obtained after appropriate preprocessing of the radio frequency echograms by an on-line computerized system. The preprocessing comprised a correction for the Time Gain Compensation (TGC), the beam diffraction and the frequency dependent attenuation in the Region of Interest (ROI). The intra- and interindividual variability of the parameter values appeared to be of the same order of magnitude, but significantly larger than the variability assessed by measurements of a homogeneously scattering tissue mimicking phantom. Significant temporal effects were found for all the parameters, which consistently occurred during the morning. These results are discussed in relation to the circadian rhythm of the glycogen content and of the hepatic circulation. All the parameters appeared to be significantly correlated to age. The slope of the regression ranged from 3.6% per decade (attenuation coefficient) to 7.6% per decade (mean echo-level). A tentative explanation to these results is presented: the increased stiffness of hepatic vasculature with age.

Adult↗
PubMed1991

Ultrasound attenuation and texture analysis of diffuse liver disease: methods and preliminary results.

A study was performed to find and test quantitative methods of analysing echographic signals for the differentiation of diffuse liver diseases. An on-line data acquisition system was used to acquire radiofrequency (RF) echo signals from volunteers and patients. Several methods to estimate the frequency-dependent attenuation coefficient were evaluated, in which a correction for the frequency and depth-dependent diffraction and focusing effects caused by the sound beam was applied. Using the estimated value of the attenuation coefficient the RF signals themselves were corrected to remove the depth dependencies caused by the sound beam and by the frequency-dependent attenuation. After this preprocessing the envelope of the corrected RF signals was calculated and B-mode images were reconstructed. The texture was analysed in the axial direction by first- and second-order statistical methods. The accuracy and precision of the attenuation methods were assessed by using computer simulated RF signals and RF data obtained from a tissue-mimicking phantom. The phantom measurements were also used to test the performance of the methods to correct for the depth dependencies. The echograms of 163 persons, both volunteers and patients suffering from a diffuse liver disease (cirrhosis, hepatitis, haemochromatosis), were recorded. The mutual correlations between the estimated parameters were used to preselect parameters contributing independent information, and which can subsequently be used in a discriminant analysis to differentiate between the various diseased conditions.

Adult↗
PubMed1987

Percutaneous transluminal renal angioplasty in children and adolescents.

Percutaneous transluminal renal angioplasty (PTRA) was performed in 12 children and adolescents with renal artery stenosis. Patients were divided into three groups: those with a short stenosis in the middle or distal part of the renal artery (n = 5), those with a short stenosis at or near the origin of the renal artery (n = 3), and those with a long stenosis at or near the origin (n = 4). The patients in the first group responded to PTRA. Those in the second group had a poor clinical response, and dilation was unsuccessful in the patients in the third group, who remained hypertensive. The location and length of the renal artery stenosis and its underlying cause appear to be important in determining the results of PTRA.

Adolescent↗
PubMed1986

[Reliability of sonography in diagnosing liver metastases in breast and bronchial cancer. A retrospective comparison of physical examination, laboratory tests and liver scintigraphy].

To determine the accuracy of liver sonography in the diagnosis of liver metastases, the results of 99 patients with breast or lung cancer were compared with liver scintigraphy, physical examination, laboratory tests, histological examination and clinical follow-up. Liver sonography proved to be an accurate method to demonstrate or exclude liver metastases, with a sensitivity of 78.6% and a specificity of 90.0%. The highest accuracy was achieved if the sonographic examination of the liver was performed while there was a clinical suspicion of liver metastases and if compoundscan sonography was supplemented by real-time sonography.

Breast Neoplasms↗