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G Layer

Publications and source records attributed to G Layer.

At least 73 records · Page 4Linked to original sources
PubMed1992

[Magnetic resonance tomography of the bone marrow for the detection of metastases of solid tumors].

The bone marrow is a common site of metastases in patients with solid tumors. Metastatic bone marrow involvement is found much more frequently at autopsy than in routine staging procedures. The purpose of this study was to evaluate the diagnostic efficacy of bone marrow MRI in such patients, and especially in those with small cell lung cancer and female breast carcinoma. MRI is a fast and reliable method for the early detection of bone marrow metastases in patients with carcinoma. In many studies and according to our own experience, it is much more sensitive than radionuclide bone scan, iliac crest biopsy and plain film radiography. However, a clear clinical benefit of its use in the initial staging has so far been proven only for patients with small cell lung cancer. As a consequence, MRI should be applied for the staging of solid tumors only when clinical examination does not yield unambiguous results. Owing to its superiority to biopsy and bone scan, bone marrow MRI should become an integral part of the initial staging procedure in small cell lung cancer and wherever it is sufficiently available it can replace the conventional diagnostic procedures.

Bone Marrow↗
PubMed1992

["Metastasizing" Echinococcus alveolar of the liver].

We report a case of metastatic alveolar echinococcosis of the liver. There were calcifications of the liver parenchyma, and a large tumour adjacent to the porta hepatis infiltrated neighbouring structures. In addition, haematogenous metastases to the spine and foot were found. This extensive haematogenous "metastasis" is rare and may complicate diagnosis, but the typical findings in the liver should permit the correct conclusion.

Echinococcosis, Hepatic↗
PubMed1992

[Mesothelioma of the pleura--diagnosis with imaging procedures].

Typical radiological findings in patients with diffuse malignant pleural mesothelioma are nodular opacities of the pleura including the fissures, pleural effusion, shrinking of the ipsilateral hemithorax, and mediastinal shift. The radiological differentiation between pleural mesothelioma and benign pleural tumors is possible; however, a secondary metastatic pleural involvement imitates pleural mesothelioma. Magnetic resonance imaging is superior to computed tomography in the preoperative assessment of tumor extension, because it demonstrates exactly the tumor extension in the coronal or sagittal plane. The noninvasive ultrasound examination is helpful in the evaluation of the diaphragmatic pleura and the costodiaphragmatic spaces.

Diagnosis, Differential↗
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

Three-dimensional time-of-flight MR-angiography and the surgical indication of brainstem cavernomas.

This study was designed to assess the diagnostic value of 3D time-of-flight MR-angiography in cerebral cavernomas. In seven patients, nine out of ten cavernomas were removed by microsurgery. While MR-angiography demonstrated well branches of brain arteries adjacent to the lesions, no flow signal in the vascular malformations was observed. On the other hand, there was a high intensity signal induced by methaemoglobin in those three patients with brainstem cavernomas who had experienced a significant bleeding attack seven months prior to admission. It had a spotted appearance in MR-angiography with volumes of the largest spots around 1.8 cm3. It is suggested that this spot signal could be used as a path marker for the surgical approach in brainstem cavernomas.

Adult↗
PubMed1991

[MR tomography and MR angiography in cerebral arteriovenous malformations].

Av malformations are cerebral abnormalities with a high risk of bleeding. The role of MRI and MR angiography (MRA) for demonstrating these congenital vascular malformations has been studied. It has been shown that MRI/MRA can provide a rapid and certain diagnosis. MRA can demonstrate arteries to the second set of branches beyond the main cerebral vessels. It has the advantage of being able to produce rapidly and noninvasively 3-D images and, unlike conventional angiography, it can be repeated at will. The disadvantage is the limited special resolution and the difficulty in distinguishing between arteries and veins.

Adolescent↗
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

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

[Staging of non-small cell bronchial carcinoma using CT and MRT].

The TNM Classification was rewritten by UICC in 1987. For non-small-cell bronchogenic carcinoma, stages T4 and N3 were redefined. Controversy exists in the literature regarding the clinical merits of CT and MRI examinations for staging. For the evaluation of very small tumors and lung parenchyma CT is superior to MRI. MRI, however, permits direct imaging of sagittal and coronal projections. This is favorable in the diagnosis of "superior sulcus tumors" and tumors with chest wall invasion. For the evaluation of T4 tumors and mediastinal lymph-node involvement, no additional contrast medium is necessary if MRI is used. Up to now, the main limitations for the application of MRI in thoracic imaging have been and still are the availability of the equipment, the costs, the necessary technical support, and the extensive study time.

Carcinoma, Bronchogenic↗
PubMed1990

[A supratentorial hemangioblastoma].

A case of supratentorial hemangioblastoma combined with two hemangiomas of the liver without manifestation of von Hippel-Lindau disease is presented. The cerebral cystic hemangioblastoma was localized in the right parietal lobe and contained a calcified area but no visible mural solid nodules. The CT and MRT differential diagnosis (arachnoidal cyst, glioma, Echinococcosis, hamartoma and metastasis) is discussed, and the literature on the subject is reviewed.

Brain Neoplasms↗
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↗
PubMed1990

[Congenital lung hypoplasia in adulthood].

This is a report on a largely asymptomatic patient with a unilaterally non-functional lung. The differential diagnosis between an acquired, "destroyed" lung and congenital hypoplasia of the lung with secondary inflammatory changes proves difficult. The various imaging procedures that are available, used in conjunction with the histological findings, permit a classification.

Diagnosis, Differential↗
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↗