PubMed Health⌕ Search

Biomedical subjects

I Zuna

Publications and source records attributed to I Zuna.

At least 19 recordsLinked to original sources
PubMed1992

New method of estimating the ultrasonic beam ratio parameter for characterizing sound propagation in tissue.

The backscattered ultrasonic signal from soft tissue can be considered to consist of two parts: a spatially fluctuating component due to coherent scattering from randomly distributed scattering centers and a relatively constant component related to structural ordering. The relationship between these, which has been termed the "beam ratio parameter" influences the speckle pattern of an ultrasound image. First-order image statistics for this special speckle pattern are characterized by the Rician distribution. Changes of second-order statistics have also been derived as a function of the beam ratio parameter. A new method for the estimation of the beam ratio parameter from the intensity distribution of the ultrasonic signal is described in this paper. This method was used to measure the parameter in ultrasonic images from phantoms and liver tissue yielding values of about 0.1. The measured changes of the second-order statistics were not correlated to this parameter. The results indicate that the relatively constant intensity component related to structural ordering has only a small influence on the speckle pattern.

Biopsy↗
PubMed1992

[Recurrence paralysis: computed tomographic analysis of intrathoracic findings].

The long and singular course of the inferior (recurrent) laryngeal nerve makes it very vulnerable to infiltration by tumors of various locations. In particular, mediastinal and pulmonary lesions must be considered in the case of left vocal chord palsy. Recurrent nerve paralysis caused by a tumor indicates advanced disease. We retrospectively reviewed the computed tomography (CT) findings in 29 patients with bronchogenic carcinoma or mediastinal tumors and recurrent nerve paralysis with respect to the site, size and extent of the tumor and the lymph node status. The review revealed a marked predominance of left upper lobe tumors with extensive lymph node metastases to the anterior mediastinum and the aortopulmonary window. The extent of mediastinal involvement exceeded the average involvement in a control group of 30 randomly selected patients with bronchogenic carcinoma at the time of presentation. In all patients CT demonstrated tumor tissue which could have caused the paralysis at one or more sites along the anatomical course of the recurrent nerve. In most cases the tumor was located at the aortic arch. The left paratracheal region, right paratracheal region and right pulmonary apex were affected in one case each. We conclude that in patients with cancer, CT is a suitable method for localizing a recurrent nerve lesion.

Carcinoma, Bronchogenic↗
PubMed1991

Computerized ultrasound B-scan texture analysis of experimental diffuse parenchymal liver disease: correlation with histopathology and tissue composition.

By means of statistical pattern recognition procedures, a quantitative description of the ultrasound B-scan images of experimental diffuse liver disease has been carried out. Fatty livers, fatty fibrosis/cirrhosis, and cirrhosis without fatty infiltration of the liver were studied in female Wistar rats. Separation accuracies of more than 80% between the tissue classes "normal" vs "fatty infiltration," or "normal" vs "fatty cirrhosis," using only two statistical image parameters were found. A subclassification of the diffuse parenchymal liver disease was not possible. It is shown by multiple linear regression analysis that the image parameter "mean grey level" correlates better with total lipid content than with the amount of connective tissue. Furthermore it is demonstrated that connective tissue leads only to a weak increase in "mean grey level," whereas the addition of connective tissue to a given tissue lipid can lead to a reduction in image brightness.

Animals↗
PubMed1991

[Influence of abdominal wall composition and thickness on ultrasound B scan].

Using a tissue-mimicking phantom and a computerised sonography system an ultrasound b scan analysis was performed. The images were acquired with different fat-muscle combinations as ultrasound wave path. These are simulations of a different composition or thickness of the abdominal wall. The analysis of the ultrasound images was performed using mathematical statistical parameters for ultrasound tissue characterisation. We examined the influence of the thickness or composition of the abdominal wall on ultrasound image brightness, microtexture and macrotexture. A dependence of ultrasound image brightness and microtexture on the thickness of the fat path was observed. Muscle tissue shows only a weak influence on the microtexture of the ultrasound image. These data demonstrate that a thick fat layer leads to a darker and diffuse image. This disturbs the evaluation e.g. of the liver parenchyma by analysis of the echo structure and may lead to false diagnoses especially in adiposity.

Abdominal Muscles↗
PubMed1990

Investigations concerning the potential for using 1H NMR relaxometry or high-resolution spectroscopy of plasma as a screening test for malignant lung disease.

In 158 plasma samples, obtained from patients with lung carcinoma, lung metastases, and infectious or inflammatory lung diseases and from healthy controls, the NMR relaxation times T1 and T2 of water protons were measured at a resonance frequency of 20 MHz by pulsed NMR techniques and adjusted to a standardized total plasma protein concentration. For one-third of these samples water-suppressed 500-MHz 1H NMR spectroscopy at 37 degrees C was used (a) to determine the widths of the composite lipid methyl and methylene signals, and (b) to quantitate individual lipid methylene signal components that could be detected in resolution-enhanced spectra. In addition, hematological parameters and the plasma levels of several acute phase proteins and apolipoprotein-A were monitored. No diagnostically significant differences between lung carcinoma patients and patients with nonmalignant lung disease could be found for any of the plasma NMR parameters, nor could T1 or lipid linewidth data distinguish between any patient group and healthy controls. However, the mean T2 was significantly shortened by about 15% for any kind of lung disease compared to healthy controls. Similar but less significant results were found for apolipoprotein-A levels. A linear discriminant function, calculated from the apolipoprotein-A and T2 data, did not improve the differentiation between malignant and nonmalignant lung disease but did improve the discrimination between tumor patients and healthy controls up to a sensitivity and specificity of 80 and 96.5%, respectively. T2 correlates inversely with plasma fibrinogen levels and the blood sedimentation rate and, therefore, appears to monitor a general inflammatory status of a tumor patient rather than the presence or absence of cancer. For all groups except healthy pregnant women, the lipid methylene composite signal linewidth correlates inversely with the fraction of mobile triglyceride present (mainly as VLDL), as estimated from resolution-enhanced spectra.

Blood Proteins↗
PubMed1990

Evaluation of recurrent bronchogenic carcinoma by computed tomography.

Thirty-five patients with strongly suspected recurrent tumor of the lung and definitely positive computed tomography (CT) scan were reviewed. The patients had undergone surgery (group A, n = 17) or radiation therapy (group B, n = 18). TNM-staging of lung cancer in both groups revealed similar results. Small cell carcinoma (P less than 0.05), central tumors (P less than 0.003), and elderly patients (P less than 0.05) were more often found in group B. Disease-free interval was longer in patients with tumor resection (45.5 v 11.7 months, P less than 0.007) and depended on T-stage in irradiated cases (P less than 0.05). Local recurrence with or without mediastinal lymph node involvement occurred in all irradiated patients; 3 of 16 surgical patients showed isolated mediastinal lymph node enlargement without tumor relapse (not seen by plain chest roentgenographs). Plain films failed to detect nearly 20% of the space-occupying lesions, which could easily be identified by CT. In one patient the suspected tumor recurrence turned out to be a tuberculous infiltration. A second lung cancer (no tumor recurrence) was pathohistologically assumed in three of the resected cases with an interval from 10-181 mo after surgery. On the basis of these findings, CT-monitoring can be recommended when the patient is resected for cure. Some patients will benefit by an early diagnosis of a local-regional tumor recurrence when the time until the necessary secondary treatment may be shortened. Long-term survival may be achieved in a small group of these patients.

Carcinoma, Bronchogenic↗
PubMed1990

Echographic tissue characterization in diffuse parenchymal liver disease: correlation of image structure with histology.

Seventy livers were examined in vitro using a computerized ultrasound B-mode data acquisition and analysis system. For tissue characterization, statistical parameters from pattern recognition algorithms describing image brightness and image structure were used. Reference classification based on histopathology as well as on chemical/morphometrical analysis led to the diagnostic classes of normal, fatty liver, fibrosis/cirrhosis and fatty fibrosis/cirrhosis. Comparing the two reference methods for ultrasound tissue characterization, reclassification based on chemical/morphometrical analysis resulted in a significant increase in diagnostic accuracy. The strong correlations between statistical ultrasound image parameters and morphometrical features reflect the relevance of our statistical approach to ultrasound tissue characterization.

Fatty Liver↗
PubMed1990

Computerized ultrasound B-scan texture analysis of experimental fatty liver disease: influence of total lipid content and fat deposit distribution.

Statistical pattern recognition procedures allow a quantitative description of ultrasound-B-scan image texture. According to well-established animal models, different types of fatty liver disease were induced in female Wistar rats. For the correlation of the computerized ultrasound image with its underlying histology a variable tissue model based on histomorphological data, texture analysis of the histological image and biochemical measurements of total lipid, water and hydroxyproline content was created. Whereas a regional arrangement of large fat deposits leads to a significant increase in the "mean grey level" (measure of image brightness) of the ultrasound-B-scan image, there is no difference in image brightness between normal liver tissue and liver steatosis for the tissue model with diffuse homogeneous fatty infiltration. It is demonstrated by multiple linear regression analysis that the "mean grey level" of the ultrasound-B-scan image depends not only on total lipid content but even more on the histomorphological fat deposit distribution.

Animals↗
PubMed1990

[The place of computed tomography in the diagnosis of recurrences in patients with bronchogenic carcinoma].

Thirty-five patients with strongly suspected recurrent tumor of the lung and a definitely positive CT scan were reviewed. The patients had undergone surgery (group A, n = 17) or radiation therapy (group B, n = 18). TNM staging of lung cancer in both groups revealed similar results. Small-cell carcinoma (p less than 0.05), central tumors (p less than 0.003) and elder patients (p less than 0.05) were more often found in group B. The disease-free interval was longer in patients with tumor resection (45.5 vs 11.7 months, p less than 0.007) and depended on the T-stage in irradiated cases (p less than 0.05). Local recurrence with or without mediastinal lymph node involvement occurred in all irradiated patients: 3 out of 17 surgical patients showed isolated mediastinal lymph node enlargement without tumor relapse (not seen by plain chest roentgenographs). Plain films failed to detect nearly 20% of space-occupying lesions, which could easily be identified by CT. In one patient the suspected tumor recurrence turned out to be a tuberculous infiltration. A second lung cancer--no tumor recurrence--was pathohistologically assumed in 3 of the resected cases with an interval of from 10 to 181 months after surgery. On the basis of these findings, CT monitoring can be recommended when the patient is resected for cure. Some patients will benefit by an early diagnosis of local regional tumor recurrence when the time until the necessary secondary treatment can be shortened. Long-term-survival may be achieved in a small part of these patients.

Adenocarcinoma↗
PubMed1990

[Preoperative assessment of perirectal lymph nodes by ultrasound].

Endorectal ultrasound is a new technique which is having an increasing impact on the surgical community. Beyond the assessment of tumor penetration depth two kinds of lymph nodes are to be differentiated by ultrasound in the perirectal fat. 1) Inflammatory enlarged lymph nodes which appear hyperechoic, unsharply limited to the surrounding tissue and 2) lymph node metastases which are hypoechoic having the same density as the tumor. Sensitivity and specificity of endorectal ultrasound in the detection of lymph node metastases in 97 patients was 80%, the positive predictive value was 78%, the negative 82%. In an in vitro study we examined 27 lymph nodes of patients with either inflammatory or cancerous colon diseases by computerized B-scan texture analysis. An HP-77020 A realtime electronic sector-scanner was connected with HP-1000 microcomputer which permitted the selection and texture-analysis of a region of interest (ROI). Afterwards the lymph nodes were examined histologically. Independent of size and surrounding fat tissue there was a highly significant difference between inflammatory and cancerous enlarged lymph nodes concerning mean grey level and mean gradient. Tumor infiltrated lymph nodes are hypoechoic with poor contrast within the node whereas inflammatory enlarged nodes are more hyperechoic and show more contrast. Thus, we can state that it is possible by consideration of echogenity and contrast to distinguish sonographically between tumor infiltrated and inflammatory enlarged lymph nodes.

Diagnosis, Differential↗
PubMed1989

[The liquefactive behavior of bronchial carcinomas and their metastases from the radiological viewpoint].

Necrosis in bronchial carcinomas and in their soft tissue metastases was studied in 368 patients by means of CT and ultrasound. In primary bronchial carcinomas (59 cases) there was clear correlation between tumour necrosis and the histology. There was a significant preponderance amongst squamous carcinomas, whereas small cell carcinomas rarely show radiologically visible necrosis (p less than 0.01). Amongst metastases in the liver (128 cases), central nervous system (164 cases) and suprarenals (23 cases) there was no correlation between histology and the recurrence of necrosis. Necrosis in deposits in suprarenals and in the brain depends on the size of the lesion and could be demonstrated in more than 50% of cases. Liver metastases show necrosis in less than 5% of the cases by the imaging methods used.

Abdomen↗
PubMed1989

[Quantitative studies on the influence of connective tissue and fatty structures on the ultrasonic image of the liver].

Using a computerized ultrasound system, 63 autopsied livers were examined. A quantitative description of the ultrasound image was made by using statistical parameters from pattern recognition algorithms. As a reference a chemical/morphometrical classification into normal, diffuse and regional fatty infiltration and fibrosis/cirrhosis was performed. Diagnostic accuracy varied from 77% to 92%. Ultrasound tissue characterisation showed an influence of fatty and connective tissue structures on image parameters. This supplies evidence for the fact that computerised ultrasound examination yields more information from the ultrasound image than the normal observer. This may be the cause of an increased diagnostic accuracy when using computerized ultrasound systems, especially in the case of fibrosis/cirrhosis.

Diagnosis, Computer-Assisted↗
PubMed1989

[Computer-assisted ultrasonic B-scan texture analysis of experimental liver tumors].

Primary liver cancer has been induced experimentally in female Wistar rats by diaminoazobenzene intoxication or subcapsular liver implantation of Novikoff cell suspensions. The ultrasonic B-scan image of these malignant tumours are described via statistical texture parameters in respect of image brightness, microtexture and macrotexture. A discrimination of the tumour texture profiles is possible with an accuracy of about 80%. There are correlations between ultrasonic image parameters and histomorphological tissue components but there is no specific link between the histological tumour-type and these B-scan data.

Animals↗
PubMed1989

[Aortic calcification in CT. Correlation with risk factors and cardiovascular diseases].

Computed tomography is a much more sensitive method of identifying aortic calcification than conventional radiographic methods. The present study was undertaken to explore the importance of various cardiovascular risk factors with regard to their calcifying effect on the aorta. A total of 2,130 individuals, aged 8-88 years, were included. In all cases continuous 8-mm-thick CT slices were obtained from the thoracic inlet caudally to the adrenal glands. There was a significant relationship between aortic calcification and age, smoking habits, hypertension, diabetes, relative body weight, hyperlipidemia and alcohol consumption. Aortic calcification was demonstrated to be strongly associated with vascular disease.

Adolescent↗
PubMed1989

[Echographic localization diagnosis of enlarged parathyroid glands].

The authors report on their own experience with the localization of enlarged parathyroid glands by sonography. In a study of 248 patients with hyperparathyroidism, they obtained a sensitivity of 57% and a specificity of 81%, with an overall accuracy of 74%. These results are discussed in detail.

Humans↗
PubMed1989

[The value of computer-assisted sonographic tissue characterization in focal lesions of the thyroid].

Thyroid lesions are a common observation in ultrasound examination. In most cases the differentiation of malignant and benign tissue is difficult. In this study 133 thyroid lesions were examined by an ultrasonographic tissue characterization system prior to surgery. The pathologic findings (29 cancers, 31 adenomas, 46 nodular goiters, 27 cysts) were examined with reference to the quantitative evaluation of the ultrasonic images (ROI method). The selected regions of interest (ROI) were analyzed with regard to the three most discriminating parameters. The overall accuracy of differentiation between malignant and benign thyroid nodules was 83.9%.

Adenocarcinoma↗
PubMed1989

Quantification and classification of echographic findings in the thyroid gland by computerized B-mode texture analysis.

Computerized B-mode image analysis was investigated in a pilot study to establish quantitative criteria for thyroid echography and to demonstrate the diagnostic accuracy of the procedure in thyroid disease. The ten per cent percentile of grey level distribution and entropy proved to be the most efficient statistical parameters. Computerized ultrasound detected all nodular lesions with an overall accuracy of about 85%. Standard diagnostic evaluation in nodular thyroid disease includes conventional ultrasound followed by needle biopsy to confirm the final diagnosis. However, in many cases, single needle biopsy is not sufficient to exclude malignant disease. Computer-aided ultrasound proved to be helpful for the identification of typical echographic characteristics in thyroid lesions with a high risk of malignancy. We suggest that needle biopsies be repeated in cases in which computerized analysis is positive, even when initial needle biopsy is negative.

Diagnosis, Computer-Assisted↗