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Biomedical subjects

M D Seemann

Publications and source records attributed to M D Seemann.

33 records · Page 2Linked to original sources
PubMed1999

Evaluation of the carotid and vertebral arteries: comparison of 3D SCTA and IA-DSA-work in progress.

OBJECTIVE: The purpose of this study was to develop a method for three-dimensional (3D) visualization of the whole vascular system of the carotid and vertebral arteries using spiral computed tomographic angiography (SCTA), that allows accurate, qualitative and quantitative evaluation, of anatomical abnormalities, including detection of additional lesions, and estimation of degree of stenosis. MATERIALS AND METHODS: Fifteen patients with anatomical and pathological abnormalities of the arterial vascular system detected by color-coded duplex ultrasound were studied using intraarterial digital subtraction angiography (IA-DSA) with aortic arch injection, and SCTA. The carotid and vertebral arteries were segmented using an interactive threshold interval density volume-growing method and visualized with a color-coded shaded-surface display (SSD) rendering method. The adjacent bone structures were visualized using a transparent volume rendering method. RESULTS: In all cases, the entire volume of the vascular system of the carotid and vertebral arteries could be visualized on SCTA, and the anatomical and pathological abnormalities on 3D SCTA correlated well with that seen on IA-DSA. CONCLUSION: Results of 3D SCTA had a high degree of correlation with results of IA-DSA in the evaluation of the vascular system of the carotid and vertebral arteries. The 3D SCTA with a subsecond spiral CT scanner is useful for the visualization of anatomical and pathological abnormalities in the circulation in the carotid and vertebral arteries and offer a promising minimally invasive alternative compared with other diagnostic procedures.

Adult↗
PubMed1999

Usefulness of morphological characteristics for the differentiation of benign from malignant solitary pulmonary lesions using HRCT.

The aim of this study was to analyze different characteristics on high-resolution computed tomography (HRCT) that help differentiate benign solitary pulmonary lesions (BSPLs) from malignant solitary pulmonary lesions (MSPLs). High-resolution computed tomography was performed on 104 consecutive patients with SPLs. The whole lesion was examined with a slice thickness of 1 mm and a 12-cm field of view. All lesions were surgically excised within 24 h of the CT examination. Satellite nodules, cavitations, and necrosis were found only in MSPLs. Useful characteristics for the differentiation of BSPLs from MSPLs were the presence of spicules (p < 0.00005), spicules extending to the visceral pleura (p < 0.0005), the vessel sign (p < 0.0005), pleural retraction (p < 0.001), circumscribed pleural thickening (p < 0.001), the bronchus sign (p < 0.005), the presence of ground-glass attenuation adjacent to the SPL (p < 0.01), the density of the lesion (p < 0.05), and the length of spicules (p < 0.05). Using the significant characteristics p < 0.01 for the identification of MSPLs, a sensitivity of 91.4 % and a specificity of 56.5 % (accuracy of 83.7 %) was found. A precise morphological assessment of the periphery of the pulmonary lesion is necessary. The HRCT technique is useful in differentiation of BSPLs from MSPLs. However, metastases strongly resembled benign lesions in terms of size and edge type, and chronic inflammatory pseudotumors as a group mimic MSPLs.

Biopsy, Needle↗
PubMed1999

Evaluation of the middle and inner ear structures: comparison of hybrid rendering, virtual endoscopy and axial 2D source images.

Recent developments in 3D reconstructions can enhance the quality and diagnostic value of axial 2D image data sets with direct benefits for clinical practice. To show the possible advantages of a hybrid rendering method [color-coded 3D shaded-surface display (SSD)- and volume rendering method] with the possibility of virtual endoscopy we have specifically highlighted the use in relation to the middle and inner ear structures. We examined 12 patients with both normal findings and postoperative changes, using image data sets from high-resolution spiral computed tomography (HRSCT). The middle and inner ear was segmented using an interactive threshold interval density volume-growing method and visualized with a color-coded SSD rendering method. The temporal bone was visualized using a transparent volume rendering method. The 3D- and virtual reconstructions were compared with the axial 2D source images. The evaluated middle and inner ear structures could be seen in their complete form and correct topographical relationship, and the 3D- and virtual reconstructions indicated an improved representation and spatial orientation of these structures. A hybrid and virtual endoscopic method could add information and improve the value of imaging in the diagnosis and management of patients with middle or inner ear diseases making the understanding and interpretation of axial 2D CT image data sets easier. The introduction of an improved rendering algorithm aids radiological diagnostics, medical education, surgical planning, surgical training, and postoperative assessment.

Adult↗
PubMed1999

An evaluation of the tumour markers, carcinoembryonic antigen (CEA), cytokeratin marker (CYFRA 21-1) and neuron-specific enolase (NSE) in the differentiation of malignant from benign solitary pulmonary lesions.

PURPOSE: The aim of this prospective study was to assess the diagnostic value of the tumour markers carcinoembryonic antigen (CEA), cytokeratin 19 fragment marker (CYFRA 21-1) and neuron-specific enolase (NSE) in the differentiation of malignant (MSPLs) from benign solitary pulmonary lesions (BSPLs). METHODS: Solitary pulmonary lesions (SPLs) were diagnosed using plain radiography and spiral computed tomography (SCT) and then completely removed by surgery in 104 consecutive patients (MSPLs; n = 81, BSPLs; n = 23). The serum concentrations of the tumour markers were determined 1-3 days prior to surgery by ELISA for CEA and CYFRA 21-1 and by IRMA for NSE using commercially available assay kits. The cut-off values were set at 3 ng/ml (for non-smokers) and 5 ng/ml (for smokers) for CEA, at 3.3 ng/ml for CYFRA 21-1 and at 12.5 ng/ml for NSE. RESULTS: MSPLs were identified with a sensitivity between 13.6 and 45.7%, a specificity between 87.0 and 100% and an accuracy between 32.7 and 54.8%. Using the tumour markers alone, the highest sensitivity (27.2%) and accuracy (40.4%) was found with CEA, the highest specificity (100%) with CYFRA 21-1 and with NSE. Primary lung cancers (n = 39) were identified with a sensitivity between 17.9 and 61.5%, a specificity between 87.0 and 100% and an accuracy between 48.4 and 71.0%. Using the tumour markers alone, the highest sensitivity (35.9%) and accuracy (59.7%) was found with CYFRA 21-1, the highest specificity (100%) with CYFRA 21-1 and with NSE. The combination of all three tumour markers resulted in a greater sensitivity and greater diagnostic accuracy but a loss in specificity compared with CYFRA 21-1 and NSE. CONCLUSION: The use of the tumour markers alone or in combination showed a low sensitivity and low accuracy for the diagnostic differentiation of MSPLs from BSPLs and primary lung cancers from BSPLs. However, both CYFRA 21-1 and NSE exhibited a specificity of 100% and may be useful complements to standard clinical imaging methods.

Antigens, Neoplasm↗
PubMed1998

Psybertherapy on the Internet and its implications for psychiatry, psychotherapy, and psychosomatics.

First of all, an introduction to worldwide communication networks is given. Some relevant basic features are explained. Actual and future aspects of the Internet for psychiatry, psychotherapy, and psychosomatic medicine are highlighted. There is a variety of possible advantages in World Wide Web telemedicine for patients, clients, consultants, clinicians and scientists. Useful tools and established opportunities are discussed and listed as Web-sites. The systematic review gives access to the most important fields of mental health on the Internet. Finally, some of the risks of this kind of communication for therapy and society are visible.

Databases, Factual↗
PubMed1998

Hybrid rendering and virtual endoscopy of the auditory and vestibular system.

A hybrid rendering method (color-coded 3D shaded-surface and volume display) with the possibility of virtual endoscopy using image data sets from HR-SCT was developed. To show the possible advantages and benefits of the improved rendering algorithm we have specifically highlighted the use in relation to the auditory and vestibular system. Postprocessing image visualization offers improved morphological analysis, and will benefit radiological diagnostics, medical education, surgical planning, surgical training and postoperative assessment.

Adult↗
PubMed1998

Gene therapy and medical genetics on Internet.

In this report we consider the development of the Internet, from its origins as a military invention in the times of the cold war to its present day role, together with the World Wide Web, as a means of global communication which plays a key role in medical research and particularly in medical genetics. A few of the major genetics related research projects and gene research centers are introduced and their aims are briefly discussed. Detailed information about chromosome and gene mapping, together with sequence and structure databases, can be easily and rapidly accessed through the Internet. A variety of web-sites are briefly described and then listed at the end of the report, which will serve as a useful starting point from which the interested reader can access an almost endless source of genetics related information on the Internet. Finally, some of the ethical, legal and social implications of the links between gene therapy and the Intemet are considered.

Databases, Factual↗
PubMed1998

[Comparison of a high-end ultrasound system with a spiral CT scanner in screening for liver metastases].

AIM: To assess prospectively the sensitivity of a high-end ultrasound system in comparison to a spiral computed tomographic scanner in screening for liver metastases. METHOD: 88 consecutive patients with malignant diseases were examined using gray-scale sonography and contrast enhanced two-phase spiral computed tomography during arterial dominant and portal venous phase. For both methods all focal lesions of the liver were reported. RESULTS: 99 focal lesions of the liver were detected by gray-scale sonography and/or two-phase spiral computed tomography. The sensitivity for gray-scale sonography was 93.9% (93 of 99 lesions) and for two-phase spiral computed tomography (71.7% (71 of 99 lesions), respectively. CONCLUSION: Screening for liver metastases should be performed by using a diagnostic method with a high sensitivity. Gray-scale sonography with a high-end ultrasound system fulfill' these requirements.

Adult↗
PubMed1997

Hybrid rendering of multidimensional image data.

The most important rendering methods applied in medical imaging are surface and volume rendering techniques. Each approach has its own advantages and limitations: Fast surface-oriented methods are able to support real-time interaction and manipulation. The underlying representation, however, is dependent on intensive image processing to extract the object surfaces. In contrast, volume visualization is not necessarily based on extensive image processing and interpretation. No data reduction to geometric primitives, such as polygons, is required. Therefore, the process of volume rendering is currently not operating in real time. In order to provide the radiological diagnosis with additional information as well as to enable simulation and preoperative treatment planning we developed a new hybrid rendering method which combines the advantages of surface and volume presentation, and minimizes the limitations of these approaches. We developed a common data representation method for both techniques. A preprocessing module enables the construction of a data volume by interpolation as well as the calculation of object surfaces by semiautomatic image interpretation and surface construction. The hybrid rendering system is based on transparency and texture mapping features. It is embedded in a user-friendly open system which enables the support of new application fields such as virtual reality and stereolithography. The efficiency of our new method is described for 3-D subtraction angiography and the visualization of morpho-functional relationships.

Computer Graphics↗
PubMed1996

Demonstration of spiral CT scans and reconstructions of a right atrial myxoma with bilateral pulmonary tumor emboli and a coincidental benign mediastinal thymoma.

A very rare case of a right atrial myxoma with bilateral pulmonary tumor emboli and a coincidental benign mediastinal thymoma is reported. A 52-year-old male patient was admitted with complaints of a single episode of haemoptysis. Spiral CT scans has been performed, the data has been subjected to multiplanar reconstructions and 3-D imaging. They revealed the presence of right mediastinal, right atrial and bilateral intrapulmonary masses. The tumors were removed during cardiopulmonary bypass surgery without any complications. All masses appeared to be benign under histopathological and immunohistochemical examinations. This case has been reported since the simultaneous appearance of such masses is unusual and in order to demonstrate that multi-planar and 3-D reconstructions of spiral CT data can help to clarify the anatomical relationships of tumorous masses and there-by a benign etiology of the intracardiac mass has been inferred.

Cardiopulmonary Bypass↗
PubMed1996

Identification of characteristics for malignancy of solitary pulmonary nodules using high-resolution computed tomography.

The aim of this prospective study was to apply the described single pathological appearance and possibilities of differentiating signs from other studies and summarize them concerning their differential diagnostic importance to improve differential diagnostic strategies concerning the dignity of solitary pulmonary nodules. 55 consecutive patients with solitary pulmonary nodules were examinated using high-resolution computed tomography (HRCT) before surgery. Thereafter HRCT-diagnosis was proven by histological assessment. Only lesions which were removed by surgery were used. No lesion was excluded by size. Necrotic areas, cavitation, satellite lesions and circumscribed pleural thickening were only found in the malignant nodules. Discrimination between benign and malignant lesions was possible by: mean diameter (P<.01), mean density (P<.01) and air inclusion (P<.05), by air bronchogram/bronchiologram (P<.05), indistinct/fogged (P<.05) and dystelectatic (P<.01) margin, the presence (P<.01) and length (P<.01) of spiculae, spiculae extended into the pleura visceralis (P<.05) and pleural distension (P<.01). A single sign can be seen in either benign or malignant nodules, but if considered together with other signs it may have a different meaning. HRCT can enable a differentiation of BSPN from MSPN in the majority of cases. As imaging methods could not get a nearly complete certainty about the dignity the chance of survival of patients could be preserved exclusively by an early surgery.

Carcinoma↗
PubMed1996

[Differentiation of solitary pulmonary coin lesions by high-resolution computerized tomography].

PURPOSE: The aim of this prospective study was not to describe individual morphological findings in benign and malignant solitary intrapulmonary nodules; it was instead to examine in a critical manner the indications for differentiation found in the literature in order to facilitate safe differential diagnosis of benign and malignant nodules. PATIENTS AND METHODS: A total of 64 solitary pulmonary nodules were examined with high-resolution computed tomography and correlated with histological findings. Only lesions that had been removed by surgery were used. No lesion was excluded on the grounds of size. RESULTS: Useful characteristics for the differentiation of benign from malignant pulmonary nodules were: diameter and density of the lesion, air inclusion, unsharp and dystelectatic margin, the presence of spicules, length of spicules, spicules extending to the visceral pleura, pleural tail sign and cirumscribed pleural thickening. CONCLUSION: For the differentiation of benign and malignant solitary pulmonary nodules meticulous assessment of the margin of the nodule is necessary. Using the criteria mentioned, a sensitivity of 85% and a specifity of 78% can be achieved for the identification of malignant pulmonary nodules. Since it was not possible to differentiate between benign and malignant nodules with certainty using imaging methods, the chance of patient survival could only be promoted by early surgery.

Adult↗
PubMed1994

Interference fixation versus postfixation of bone-patellar tendon-bone grafts for anterior cruciate ligament reconstruction. A biomechanical comparative study in porcine knees.

This study compares biomechanical characteristics of interference screw fixation to "postfixation" (sutures tied over cancellous screw and washer) of bone-patellar tendon-bone grafts in porcine anatomic specimen knees. Maximum pull-out strength (ultimate failure load), displacement of the bone graft at 110 N of force, and mode of failure were compared in a progressive load to failure test. Interference screw fixation demonstrated statistically significantly (p = 0.04) higher mean ultimate failure loads (535 N) compared to postfixation (309.1 N). Interference fixation also demonstrated statistically significantly (p = 0.0003) less displacement of the bone graft at 110 N of force (0.32 mm vs. 2.21 mm). All failures occurred at the fixation site. The authors conclude that interference fixation is stronger than postfixation and, in the immediate postoperative period, should better protect the graft from loosening after anterior cruciate ligament reconstruction, improving stability and allowing more aggressive rehabilitation.

Animals↗