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Biomedical subjects

S Lieberenz

Publications and source records attributed to S Lieberenz.

17 recordsLinked to original sources
PubMed2001

Gross-total surgery of supratentorial low-grade gliomas under intraoperative MR guidance.

BACKGROUND AND PURPOSE: Length of survival of patients with low-grade glioma correlates with the extent of tumor resection. These tumors, however, are difficult to distinguish intraoperatively from normal brain tissue, often leading to incomplete resection. Our goal was to evaluate the effectiveness of intraoperative MR guidance in achieving gross-total resection. METHODS: We studied 12 patients with low-grade glioma who underwent surgery within a vertically open 0.5-T MR system. During surgery, localization of residual tumor tissue was guided by interactive, near real-time imaging. The amount of residual tumor tissue on MR images was evaluated at the point of the operation at which the neurosurgeon would have terminated the procedure under conventional conditions (first control) and again before closing the craniotomy. RESULTS: Significant residual tumor (more than 10% of original tumor volume) was shown in eight patients at the first control condition. The percentage of resection varied from 26% to 100% (mean, 68%) at this time. Twelve tissue samples from seven patients were obtained in areas identified as residual tumor on MR images. In 10 cases, the neuropathologic investigation confirmed the presence of residual low-grade glioma; in two cases, the borderzone of tumor was identified. In evaluating the final sets of images, we found total resection in six cases, over 90% resection in five cases, and 85% resection in one case (mean, 96%). CONCLUSION: Surgical treatment of low-grade gliomas under intraoperative MR guidance provides improved resection results with maximal patient safety.

Adult↗
PubMed1999

Preliminary experience with interactive guided brain biopsies using a vertically opened 0.5-T MR system.

The purpose of our study was to evaluate the feasibility and accuracy of brain biopsies performed within a vertically opened MR system. We worked with the interventional 0.5-T MR "SIGNA SP" (General Electric Medical Systems, Milwaukee, Wis.) with an integrated tracking device "Flashpoint Position Encoder" (Image Guided Technologies, USA). As a holding device for this instrument we constructed a special frame. The whole system allows an exact adjustment of an optimum biopsy direction and guidance of the biopsy in a non-stereotactic, interactive mode in near real-time. As biopsy tools we used MR-compatible aspiration and specially made side-cut needles (Daum, Germany; E-Z-EM, USA). We performed a prospective diagnostic brain biopsy study in 18 patients. Guidance of the needle was carried out using gradient-echo single-slice technique. The sample was taken after controlling the exact position of the needle tip on spin-echo images. In 12 cases an exact neuropathological diagnosis was possible. In 6 cases of negative biopsy (4 aspiration biopsies) the samples were not representative. Our results demonstrate the feasibility of interactive MR-guided minimally invasive brain biopsies in an open MR system. The best results were achieved using cut needles for biopsies of contrast-enhancing lesions visible on T1-weighted gradient-echo guidance sequence.

Adult↗
PubMed1998

[Operation of multidisciplinary, interventional 0.5 Tesla magnetic resonance tomograph. Technical and logistic problems and initial clinical results].

Multidisciplinary usage of a MRI system with a superconducting 0.5-T magnet (Signa SP, General Electric) with a vertical gap suited for diagnostic and therapeutic interventions raises complex problems. The MR equipment, including a special localizing system and the instruments for diagnostic and therapeutic interventions, is described. Before putting the system into operation tests were necessary to check MR compatibility of various materials and instruments and to build some auxiliary equipment. We report on the coordinating activities of the radiologist in the context of MR use by different medical specialities. Within the course of 12 months, 428 examinations/interventions of different kinds were carried out, among them 75 functional examinations of the spine or of joints, 31 diagnostic biopsies, 23 cerebral biopsies, and 23 operations. The special design of the Signa SP allows the whole scale of functional examinations, up to complete neurosurgical interventions, in the sitting position and under nearly real-time imaging control.

Equipment Design↗
PubMed1998

[In vitro investigations for detection of vascular stenosis using spiral CT angiography].

PURPOSE: This experimental study investigates the suitability of spiral CT angiography for detection of stenoses. MATERIAL AND METHODS: Three vessel phantoms of 4, 7, and 10 mm diameter were scanned with spiral CT several times using different scanning parameters each time. Axial scans were viewed in different ways. Stenoses were adjusted axial, oblique, and parallel to the scan plane, and in between. 7 radiologists had to make a total of 630 decisions about the detectability of stenoses. RESULTS: Adequate scan and reconstructional parameters improve detection of stenoses significantly. 100% recognition can be reached with 5 mm layer thickness and table feed and 2 mm reconstructional interval provided axial scans are viewed in cine mode on a monitor. Vessels running parallel to the layer plane show better results than vessels axial to the plane, which in turn show better results than those running oblique. Vessels of 4 to 10 mm diameter are almost equally suitable. CONCLUSIONS: Viewing axial scans, the detectability is rather influenced by different locations of stenoses than by varying vessel diameters.

Arterial Occlusive Diseases↗
PubMed1998

[New method of MR-guided mammary biopsy].

PURPOSE: With a recently installed new open MR tomograph (Signa SP, General Electric MS) it is possible for the first time to examine patients with obscure lesions of the mamma by MR imaging in a sitting position, similar to mammography. METHOD: The newly developed positioning device with integrated surface coil permits in combination with the vertical gap in the new magnet and imaging of the mamma with a "real time" sequence a biopsy procedure within a short time and in a manner that is acceptable for the patient. By means of an integrated interactive scan plane guiding system ("flash point tracking system") and special MR-compatible needles and wires tissue samples can be taken, or marking by a wire can be carried out within a short time. RESULTS: Phantom experiments and first in vivo experience (10 patients) show that by means of the new mamma fixation and biopsy device a MRI of one breast in a sitting position for detecting an enhancing lesion and a MR-guided biopsy of this lesion is possible. The whole procedure takes about 25-35 minutes, comparable to the conventional stereotactic method. CONCLUSION: Direct patient access and the interactive guided biopsy allow in future both new diagnostic information (histological results after biopsy or after wire-guided open biopsy of a lesion only visible in MR) and the development of minimal invasive therapeutic procedures, e.g. MR-guided and -controlled interstitial thermotherapy.

Biopsy↗
PubMed1995

[First experiences with electron beam computed tomography of the heart:comparison with heart catheterization and echocardiographic findings].

AIM: To evaluate the diagnostic value of ultrafast CT in comparison to established methods in cardiology. MATERIAL AND METHODS: Cine and flow studies were performed in 30 patients with cardiac diseases on evolution CT. Cardiac structure and function were analysed visually and quantitatively (left ventricular ejection fraction, left ventricular myocardial mass, patency of coronary arteries, perfusion of left ventricular myocardium). The CT findings were compared with echocardiographic and angiographic findings. RESULTS: Cardiac structure, functional parameters and disorders of myocardial contraction were clearly detectable by ultrafast CT, which proved inferior in assessing cardiac valves. The patency of the first and second third of normal main coronary arteries could be estimated correctly. The estimation of the distal third, of obstructed coronary arteries and of the role of collaterals was impossible. Ten of 16 areas of myocardial infarction showed low or no enhancement. CONCLUSIONS: Ultrafast CT excellently reflects cardiac structure and function. It is an alternative to echocardiography. In view of the results of coronary artery patency one can hope that part of cardiac catheterisation would be avoidable in future.

Adult↗
PubMed1995

An examination of the dental state of an Egyptian mummy by means of computer tomography: a contribution to 'dentistry in Ancient Egypt'.

In 1991 mummies from Leipzig collections were investigated by means of conventional X-ray techniques and by computer tomography. The dental state of one of these mummies prompted a re-examination of the question of whether a dental profession actually existed in Ancient Egypt or not. To answer this question, different types of source material are discussed.

Egypt, Ancient↗
PubMed1994

[Detection of coronary calcification by ultrafast CT compared with coronary angiography].

The angiographical findings of 24 patients with coronary artery disease were compared with qualitative and quantitative detection of coronary calcification by ultrafast CT. Doubts concerning the capabilities of the ultrafast CT for a screening of coronary artery disease arise when the results of one third false positive and false negative findings are considered. Variations in the quantification of coronary calcification were too great to allow a realistic assessment of the degree of stenosis of the coronary arteries.

Adult↗
PubMed1989

[The diagnostic value of CT in siderophilia (primary idiopathic hemochromatosis)].

CT, due to its high resolution of density, is suitable, within certain limits, to quantify iron contents in the liver. - Diagnostic value and limits of dual-energy-computed tomography after 38 examinations, 31 of them in patients with verified haemochromatosis, are described: In a progressive state of iron overload a high correlation exists between results of computed tomography and usual reference methods of iron metabolism (iron determination by absorption spectrometry and histologic examination, serum-iron-level, serum-ferritin-level, relative transferrin saturation, desferal test). - With a specificity of nearly 100% CT shows a minor or medium iron overload only with low sensitivity. - Because of its noninvasive nature CT is an alternative method of biopsy in progressive liver disease with suspected hepatic siderosis.

Fatty Liver↗
PubMed1989

[Quality control in computed tomography].

In comparison to the constancy checks in conventional roentgenography, quality control in computed tomography (CT) should be limited to a few simple but essential checks for image quality and radiation burden. These requirements, however, can only be fulfilled in part, because of the complexity of CT systems. Possible parameters are: water and air values, pixel noise/contrast resolution, spatial resolution, artifacts, homogeneity, contrast scale/tube voltage, slice thickness, positioning accuracy, image quality of the topogram, radiation dose and film imaging. With a simple test program, comprising 4 CT-scans and a camera test image that is presently being tested, most of the mentioned quantities can be checked.

Quality Control↗
PubMed1984

[Computer tomographic evaluation of left ventricular kinetics].

The judgment of the function of the left ventricle is computer-tomographically possible using the ECG-regulated cardio-computer-tomography in a temporary resolution of about 0.1 sec. The qualitative and quantitative evaluation of the systolic and diastolic changes of the ventricle in patients with normal CT-findings, with idiopathic hypertrophic subaortic stenosis and with disturbances of motility in chronic ischaemic heart disease confirms the possible functional evidence known from literature. The quantitative parameters, in particular the systolic abbreviation of the axis, allow an estimation of the motility. The measurement of the thickness at the interventricular septum and at the lateral wall of the myocardium as well as the systolic abbreviation of the axis and the left-ventricular ejection fraction are essentially higher in the idiopathic hypertrophic subaortic stenosis than in the normal group. The values of the patients with disturbances of motility in the ischaemic heart disease were clearly below. The diagnosis of the idiopathic hypertrophic subaortic stenosis with response of the size of obstruction by the telesystolic and telediastolic pictures is possible in a high percentage. Sequelae of the chronic ischaemic heart disease, e.g. scars, become visible by a narrowing or an absence of the normal edge of the myocardium. Global and localized disturbances of motility are diagnosable by phase-referred systolic and diastolic ECG-regulated pictures.

Cardiac Output↗