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Biomedical subjects

E Hofmann

Publications and source records attributed to E Hofmann.

At least 91 records · Page 5Linked to original sources
PubMed1995

[Improvement of temperature and vibration sense in chronic uremia after a single dialysis].

Pathophysiology and pathoanatomy of uremic neuropathy are not yet well understood. A single hemodialysis positively increases nerve conduction velocities of uremic patients, thus demonstrating a functional A alpha-fiber improvement by detoxification. This study tested whether non-invasive Vibrameter and Thermotest studies show a similarly positive effect for A beta-, A delta- and C-fibers and whether the psychophysical techniques might substitute for nerve conduction studies. 20 uremic patients depending on chronic intermittent hemodialysis were examined shortly before and after a hemodialysis. Using a scaled 128 Hz tuning fork, a Vibrameter and a "Marstock"-Thermotest, vibratory and warm and cold thresholds were assessed at both internal malleoli according to the method of limits. In addition, thermal thresholds were determined at the volar aspect of the non-shunted wrist. In nine patients the Vibrameter showed elevated thresholds before and after dialysis as did six patients with the tuning fork. Warm or cold thresholds were abnormal in four patients before treatment and in eight patients after dialysis. This was due to some patients reporting elevated thresholds after dialysis although they had had normal thresholds before the treatment. Still, the overall sum of abnormal thermal or vibratory thresholds at the different tested body sites had decreased after treatment. Moreover, mean values of thermal and vibratory thresholds of the 20 patients improved with dialysis (p < 0.05). Tuning fork results were too coarse and failed to show a dialysis effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Transcranial color-coded real-time sonography of intracranial veins. Normal values of blood flow velocities and findings in superior sagittal sinus thrombosis.

Sonographic findings in patients with superior sagittal sinus thrombosis were compared to those in healthy adults. Two patients with angiographically verified superior sagittal sinus thrombosis were examined by transcranial color-coded real-time sonography (TCCS) after intravenous application of a pulmonary stable ultrasound contrast agent. For comparison, 10 patients without venous pathology had contrast-enhanced TCCS; in addition, 30 healthy adults had plain TCCS to determine the identification rate for deep and superficial venous segments and to define normal values of venous blood flow velocities. The straight sinus was identified in 22 of 30 healthy subjects by plain TCCS, and in 9 of 10 patients by contrast-enhanced TCCS. The mean peak and angle-corrected blood flow velocity was 19.1 +/- 7.1 cm/sec. The superior and inferior sagittal sinuses were identified by contrast-enhanced TCCS in 2 and 1 subjects, respectively; they were never seen on plain TCCS. In the 2 patients with sagittal sinus thrombosis a distinct increase of blood flow velocity was recorded from the straight sinus (83 and 92 cm/sec), most likely reflecting collateral circulation. These preliminary data indicate that TCCS and particularly contrast-enhanced TCCS permit identification and blood flow measurements within the deep and occasionally, the superficial venous system. TCCS may contribute to an assessment of hemodynamic repercussions of venous thrombosis and may indicate the risk of venous infarction and hemorrhage.

Adult↗
PubMed1995

Intravascular MR tracking catheter: preliminary experimental evaluation.

OBJECTIVE: This article reports on the preliminary evaluation of a new technique for guiding intravascular interventional procedures with MR imaging. Active real-time position monitoring of catheters with MR imaging is made possible by incorporating a small RF coil into the tip of the catheter. The purpose of this study was to evaluate the practicability and localizing precision of this MR catheter tracking technique in vitro and in vivo in comparison with fluoroscopy. MATERIALS AND METHODS: Feed cables employing a 0.9-mm-diameter coaxial cable, a 0.5-mm-diameter partially shielded coaxial cable, and a twisted pair cable attaching RF coils at the catheter tip to a coaxial plug at the catheter base were assessed. Further, miniature copper loop RF coils of two, three, and four turns were tested. In vitro validation of MR tracking was achieved by using a phantom consisting of a water-filled harvested segment of human aorta and iliac arteries embedded in gel. Accuracy of catheter placement was compared with MR and fluoroscopy. Subsequently, the MR tracking technique was evaluated in a swine model using a prototype 5-French MR tracking catheter. RESULTS: A fully shielded coaxial cable was found to be crucial for localizing the attached RF coil by means of the tracking technique. The number of coil turns had a lesser impact. Positions of the catheter tip measured with the MR technique and with fluoroscopy correlated well (r > .98), with a 6-mm 95% confidence interval of positional differences. Active real-time tracking of the coil-tipped catheters was achieved both in vitro and in vivo. The 5-French tracking catheter was successfully placed in the splenic and renal arteries of the swine. CONCLUSION: Robust in vivo tracking and accurate placement of catheters equipped with miniature RF coils are possible with MR imaging.

Animals↗
PubMed1995

[Modern neuroradiologic diagnosis and interventional strategies for the ENT physician].

The value of imaging and interventional neuroradiological methods in ENT is surveyed. The role of CT and MRI is discussed in the diagnosis of various diseases. CT remains the method of choice in inflammatory paranasal sinus disease and in craniofacial trauma, whereas MRI has become the preferred imaging technique in patients with sensorineural hearing loss. CT and MRI are complementary in the assessment of skull base tumors. Preoperative embolization facilitates surgery of highly vascular tumors. Endovascular procedures play a prominent role in the control of hemorrhages of the head and neck region and are the method of choice in the treatment of arteriovenous fistulas.

Embolization, Therapeutic↗
PubMed1995

[The status of transcranial color-coded real time ultrasound in diagnosis of cerebral lesions].

Transcranial color-coded real-time sonography (TCCS) combines transcranial Doppler sonography and color-coded B-mode scanning of the brain parenchyma and cerebral vessels. This technique is not invasive and a broad spectrum of intracerebral lesions such as vascular lesions (ischemic stroke and intracerebral hemorrhage, aneurysms, arteriovenous malformations, arteriosclerotic vascular degeneration) and parenchymal lesions (brain tumors, degenerative and neuropsychiatric disorders) can be disclosed. Compared with MRI and CT, the ultrasound system is movable. Thus, it can be used easily in emergency rooms and intensive care units. In addition, TCCS can disclose new insights into the pathophysiology of disorders of the CNS, as in neuropsychiatric diseases. Ultrasound contrast agents improve the depiction of intracranial vessels. The pathology of the venous system can be identified.

Adult↗
PubMed1994

Contribution of transcranial color-coded real-time sonography to the etiopathogenetic classification of middle cerebral artery stenosis.

Transcranial color-coded real-time sonography (TCCS) and cranial computed tomography were applied to patients with middle cerebral artery (MCA) stenosis to evaluate whether these techniques may disclose additional aspects of the pathophysiology of the stenotic lesion. In 15 patients with MCA stenosis identified by transcranial Doppler sonography, the echogenicity of the stenotic segment was estimated subjectively by TCCS. The density of the stenotic segment, prior to being detected by TCCS, was quantified by computed tomography. In 5 of the 15 patients, transcranial image-directed Doppler sonography identified a hyperechogenic lesion in association with the stenotic vascular segment; computed tomography demonstrated a "dense" artery (Hounsfield units [HU] > 120) in the corresponding vascular segment. In 10 patients the echogenicity of the stenotic segment was found to be normal, with a computed tomography density of < 100 HU in the corresponding segment. Hyperechogenic and hyperdense stenotic vascular segments in TCCS and computed tomography, respectively, may indicate an arteriosclerotic vascular lesion with calcium deposits. Normal echogenicity and normal to slightly elevated computed tomography-density of a stenotic vascular segment may suggest the presence of a thrombotic/embolic lesion.

Adolescent↗
PubMed1994

Vascular interventions guided by ultrafast MR imaging: evaluation of different materials.

The ability of MRI to acquire not only anatomical but also functional information makes MRI guided vascular interventions an interesting goal. Recent developments in ultrafast MR imaging sequences such as fast gradient echo or echo planar (EPI) mean that not only real time MRI but also MRI guided vascular interventions are real possibilities for the not too distant future. However, currently available guide wires and catheters are potentially unusable in MRI because they are either ferromagnetic or MRI invisible. In order to find different materials suitable for real time MRI, various devices were examined with fast gradient echo and interleaved EPI pulse sequences. The measurements were performed using a continuously running, pseudo real time MRI system to investigate the dynamic imaging behavior under guide wire insertion. Suggestions are made as how to construct guide wires and catheters, which can be visualized with ultrafast imaging sequences, while not causing prohibitive artifacts or image distortions.

Alloys↗
PubMed1994

Reliability of transcranial colour-coded real-time sonography in assessment of brain tumours: correlation of ultrasound, computed tomography and biopsy findings.

Transcranial colour-coded real-time sonography (TCCS) was carried out in 25 patients with brain tumours to determine whether this noninvasive method provides additional information about the extent of solid tumour, its differentiation from oedema, and its tissue components. All 25 patients had serial computed tomography (CT)-guided stereotactic biopsies. Comparison of ultrasound, CT and histological findings revealed that the vast majority of contrast enhancing areas on CT were hyperechogenic (32/33; 97%) and contained tumour tissue (29/32; 91%). Hyperechogenic areas always represented solid tumour (23/23 patients), even when CT showed low density non-enhancing lesions. In lesions hypoechogenic on TCCS and low density on CT, histology consistently revealed necrotic tumour (7/7). Biopsies obtained from parenchyma with normal echogenicity revealed tumour in only 3 of 16 specimens. Despite the high specificity of TCCS in the differentiation of tumour components, its sensitivity to tumour was inferior to that of CT (24/25; 96%). TCCS thus allows noninvasive preoperative identification of tumour tissue and its extent setting.

Biopsy↗
PubMed1994

Identification of ventricular enlargement and estimation of intracranial pressure by transcranial color-coded real-time sonography.

Transcranial color-coded real-time sonography (TCCS) was applied to 26 patients with ventricular enlargement to quantify the ventricular size and to estimate intracranial pressure. Intracranial pressures, as determined by lumbar, epidural, or ventricular tonometry, ranged from 6.5 to 55 cm H2O (8 patients had pressures > 18 cm H2O). The widths of the third ventricle and the frontal horns of both lateral ventricles depicted by TCCS were compared to corresponding computed tomography data: TCCS and computed tomography findings correlated well for the third ventricle (r = 0.96) and for the right (r = 0.86) and left (r = 0.92) frontal horns. The capability of the septum pellucidum to undulate relative to the ventricular wall during short (20-degree) rotatory movements of the head was related to intracranial pressure. In all patients with intracranial pressure below 17 cm H2O, rotatory head movements induced septum pellucidum undulation; no lateral deflection of the septum pellucidum was found in patients with an intracranial pressure above 21 cm H2O. Therefore, TCCS may be employed to quantify and follow-up ventricular enlargement. Dynamic neurosonographic tests may allow a gross estimation of intracranial pressure.

Adult↗
PubMed1994

Vascularization of primary central nervous system tumors: detection with contrast-enhanced transcranial color-coded real-time sonography.

PURPOSE: To study the potential of contrast material-enhanced transcranial color-coded real-time sonography (TCCS) in detection of primary intracranial tumor vascularization. MATERIALS AND METHODS: Primary central nervous system (CNS) tumors in 28 patients were examined with TCCS before and during administration of a transpulmonary, stable, galactose, microparticle-based ultrasound (US) contrast agent. All patients underwent cranial computed tomography and magnetic resonance imaging; nine patients also underwent intraarterial digital subtraction angiography. RESULTS: All lesions were hyperechoic on B-mode US scans except one grade 2 astrocytoma. The location and extent of hyperechoic lesions correlated well with findings on CT scans and MR images. After injection of contrast material, color Doppler flow signals were seen in nine of 14 low-grade lesions and 14 of 14 high-grade lesions. High-grade malignant tumors always had atypical arterial and venous Doppler spectra with irregular distribution of Doppler shift and signal intensities; these atypical flow patterns were also detected in some low-grade tumors. CONCLUSION: In addition to depiction of primary CNS tumors in B-mode, contrast-enhanced TCCS enables evaluation of vascularization associated with tumor parenchyma.

Adult↗
PubMed1994

[Hyperintensive intramedullary lesions in psychiatric patients. Spatial distribution and psychopathologic symptoms].

In a sample of 130 patients who had undergone MRI (transverse T2-weighted SE sequence) patchy white matter lesions (WML) were documented according to number and spatial distribution in the brain. Ventricle-to-Brain Ratio (VBR) was determined. Configural frequency analysis led to delineation of four patient groups on the basis of WML location: 1. no WML (n = 35), 2. right frontal-temporal WML (n = 23), 3. bifrontal WML (n = 12), 4. WML in all/all but one brain region (n = 16). Psychopathological symptoms reported in the course of a maximum of 3 years were documented by chart review. In the 'pervasive WML' group psychopathological items characteristic of organic brain syndromes prevailed, mean VBR exceeded values in all other groups (ANOVA, p < 0.001). WML spatial distribution accounted for 10.2% of total psychopathological variance. Patient age, but not VBR, had a significant impact on symptom profile (MANCO-VA). When the 'pervasive WML' group was excluded, the finding of a significant effect of WML location on psychopathological symptom profiles was robust. Bifrontal WML were associated with thought incoherence, right frontal-temporal WML with affective symptoms. Findings support an impact of spatial distribution of unspecific WML on psychopathological symptoms in psychiatric patients.

Adult↗
PubMed1993

Focal myositis of the temporal muscle.

Focal myositis is a rare inflammatory disease of the skeletal muscle that may involve any part of the body. We present a 19-year-old man with a short history of a painful pseudotumor in the right temporal region. MRI pictures showed a swollen right temporal muscle and muscle biopsy revealed the characteristic histological and immunocytochemical findings of polymyositis.

Adult↗
PubMed1993

Differentiation between ischemic and hemorrhagic stroke by transcranial color-coded real-time sonography.

Transcranial color-coded real-time sonography was applied to 20 patients with ischemic stroke and 28 patients with spontaneous intracerebral hemorrhage. In all patients the sonographic diagnosis corresponded closely to cranial computed tomography findings. Recent hemorrhages were visualized as a hyperechodense mass. The high contrast to minor echodense adjacent parenchyma led to a clear sonographic distinction. Older clots were characterized by a continuous decrease of echodensity and subsequently were interspersed by hypoechodense zones. In the acute stage of ischemic infarction, the vessel occlusion (17/20) and collateral vascular supply (10/20) could be depicted in the color-B-mode in two perpendicular planes and further verified by the Doppler mode. Brain edema was not visualized. Although in the acute stage no change of echo texture was observed within the infarction, hyperechodense regions (7/11) could be observed in some patients during the time course. Complications of intracerebral hemorrhage and ischemic stroke, such as disturbance of cerebrospinal fluid circulation, midline shift, and compression of adjacent territories, were depicted by transcranial color-coded sonography. These preliminary results illustrate that transcranial color-coded real-time sonography may be helpful in the early noninvasive differential diagnosis as well as long-term follow-up in patients with cerebrovascular disorders.

Brain Ischemia↗
PubMed1993

Effect of embolisation of meningioma on Ki-67 proliferation index.

The proliferation indices (PIs) were determined in 33 meningiomas using two monoclonal antibodies to the Ki-67 antigen (Ki-67 and MIB1). PIs obtained using Ki-67 on frozen material were intermediate between the lowest and highest MIB1 PIs determined in paraffin wax sections. Preoperative embolisation did not influence Ki67 PI, but four of the 15 embolised tumours showed substantially increased MIB1 PIs around embolisation necroses. Proliferation can be reliably assessed in routinely processed meningioma tissues using MIB1; and increased perinecrotic PIs may occur in embolised meningiomas without being an indication of malignancy.

Antibodies, Monoclonal↗
PubMed1993

On the evaluation of cranio-cervical decompression: normalisation of the cerebral spinal fluid circulation in MRI?

1) By means of "cine-MRI" a semi-quantitative analysis of CSF pulsations in the aqueduct of Sylvius can be carried out. 2) This investigation enables a qualitative evaluation of the cranio-spinal CSF flow phenomena. On the one hand this information is a valuable aid for neurosurgeons for diagnosis and on the other, cine-MRI progress controls allow an evaluation of the success of an operation in the sense of a quality control.

Aged↗