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Biomedical subjects

E W Radue

Publications and source records attributed to E W Radue.

At least 37 records · Page 2Linked to original sources
PubMed1997

Assignment of glial brain tumors in humans by in vivo 1H-magnetic resonance spectroscopy and multidimensional metabolic classification.

This study presents a simple approach for the noninvasive assignment of glial brain tumors according to malignancy by single-voxel proton magnetic resonance spectroscopy at short echo times (TE < or = 50 milliseconds). Based on peak area ratios, a five-dimensional data set was obtained for each investigated subject. This vector was then projected along metabolic coordinates in a two-dimensional metabolic space. These coordinates had been determined in a previous study (Hagberg G et al., 1995, Magn Reson Med 34: 242-252). Tumor assignment was done without any knowledge of histology by comparing the location of the new cases to the features of the previous study. All 11 investigated glioblastomas multiforme, as well as 4 of 5 astrocytomas grade II, could easily be assigned to the groups of high- and low-grade tumors, respectively. Classification was more difficult in the case of a cystic astrocytoma grade II and one astrocytoma grade III. Two spectra measured in normal-appearing matter of glioblastoma patients were not classified as healthy. Using single-voxel proton magnetic resonance spectroscopy at short echo times with the knowledge of a base study, a straightforward, fast, and noninvasive differential diagnosis of glial brain tumors is possible.

Astrocytoma↗
PubMed1997

[Results and consequences of frequent quality control of quantitative clinical 1H-MR-spectroscopy].

Different methods exist for an absolute quantification of in vivo proton MR spectra. According to the principle of reciprocity a simple method has been suggested previously, comprising the multiplication of the spectral signals with the unlocalised reference amplitude of the measurement as a correction for the different coil load. Afterwards, the result can be compared to measurements on phantoms in order to obtain in vivo metabolite concentrations. Thus, only one calibration would be sufficient in principle for all measured spectra. However, during a previous serial study on humans and phantoms we observed significant changes in transmitter amplitudes over time, although metabolite peak areas remained quite constant. Hence, the method led to incorrect metabolite concentrations. Since these effects are mostly underestimated or even neglected in clinical spectroscopy, the purpose of the present study was to investigate these instabilities over time in order to find a new correction method for quantitative MRS. According to this new method, the spectra corrected by the coil load have to be modified additionally by dividing by the reference amplitude of a phantom.

Humans↗
PubMed1997

Improving interobserver variation in reporting gadolinium-enhanced MRI lesions in multiple sclerosis.

Gadolinium-enhanced MRI is a sensitive and objective means to monitor disease activity in multiple sclerosis (MS). We evaluated the interobserver agreement and the value of observer training in reporting enhancing lesions from serial MRI. Scans of 16 MS patients were evaluated by five inexperienced and five experienced observers before and after consensus formation and training. The number of lesions at baseline, and the number of new and persistent lesions at follow-up were scored. For each condition, weighted kappa values (kappa) and the mean average difference to the median (MADM) scores were calculated. Without training, the experienced readers showed good agreement on number of lesions at baseline and new lesions at follow-up, and moderate agreement for persistent lesions. The inexperienced readers showed poor agreement for baseline and persistent lesions, and moderate agreement for new lesions. After training, both groups reported lower absolute numbers of lesions, especially the inexperienced readers. The experienced readers showed good agreement for all lesion types, the inexperienced readers showed agreement for baseline and new lesions, and agreement was moderate for persistent lesions. In both groups MADM scores were < 0.72 for baseline and new lesions, but > 1.2 for persistent lesions. Interobserver agreement is improved by training, especially in inexperienced readers. Interobserver agreement in reporting gadolinium-enhanced lesions is high, which validates the use of serial, enhanced MRI as an outcome parameter in treatment trials in MS.

Analysis of Variance↗
PubMed1997

Single-dose gadolinium with magnetization transfer versus triple-dose gadolinium in the MR detection of multiple sclerosis lesions.

PURPOSE: To compare the efficacy of single-dose gadolinium with magnetization transfer contrast (MTC) with that of triple-dose gadolinium in detecting enhancing multiple sclerosis lesions. METHODS: Twenty-one patients with multiple sclerosis were examined with MR imaging first with 0.1 mmol/kg gadolinium (single dose) and then, after 24 to 72 hours, with 0.3 mmol/kg gadolinium (triple dose). T2-weighted fast spin-echo and T1-weighted spin-echo MR images with and without MTC were obtained before contrast administration followed by either T1-weighted spin-echo images with MTC (single dose) or conventional T1-weighted spin-echo images (triple dose), starting 5, 17, and 29 minutes after contrast administration. All images were evaluated in a blinded fashion and scored in random order by two readers. Outcome parameters included number of enhancing lesions, number of active MR examinations (those containing at least one enhancing lesion), contrast ratio (signal intensity of enhancing lesion divided by signal intensity of normal-appearing white matter), and size of enhancing lesions. RESULTS: Eighty-one percent more enhancing lesions and 49% more active MR examinations were detected when a triple dose of gadolinium was used as compared with a single dose. The level of agreement between readers as to the number of enhancing lesions was significantly higher for triple-dose than for single-dose gadolinium. With triple-dose gadolinium, contrast ratios and areas of enhancement increased by 10% and 33%, respectively. Delayed imaging increased the size of the lesion by 11% on single-dose MTC images and by 18% on triple-dose images. CONCLUSION: Triple-dose gadolinium is more effective (higher sensitivity and interobserver agreement) than single-dose gadolinium in combination with MTC in detecting enhancing multiple sclerosis lesions.

Adult↗
PubMed1996

Langerhans cell histiocytosis in monocygote twins: case reports.

Langerhans cell histiocytosis includes three clinical forms of histiocytosis X. We describe a disseminated form of Langerhans cell histiocytosis (Letterer-Siwe disease) in monozygotic twins. The twins showed simultaneous onset of disease, almost identical clinical follow-up and findings on cranial CT. The cause of this phenomenon remains unknown.

Brain↗
PubMed1996

Proton chemical shift imaging, metabolic maps, and single voxel spectroscopy of glial brain tumors.

Seventeen patients with presumed glial brain tumors were examined with proton chemical shift imaging and single voxel spectroscopy that used different echo times. Metabolite resonances were evaluated by metabolic ratios and absolutely by correcting for coil load and comparison to phantom measurements. Metabolic images were created to visualize the metabolic changes. All patients showed spectra that were different from those measured in healthy control subjects. Spectral changes were also present in normal-appearing matter (NAM) that was distant from lesions. The resonance at 3.55 ppm which is usually assigned to both myo-inositol and glycine, was the only one to allow a discrimination between healthy volunteers, astrocytoma grade II, and glioblastoma multiforme (GBM) (p < 0.02). From the different echo times used we conclude that an increase in this resonance has to be assigned to glycine rather than myo-inositol. This resonance might be used to grade human gliomas more reliably. Total creatine (Cr) decreased more drastically with malignancy than N-acetylated metabolites (NA). This led to a higher NA/Cr ratio in GBM compared to astrocytoma grade II. NA/Cr was thus pseudonormal in GBM due to a change in both nominator and denominator. This study reveals the importance of comparing magnetic resonance spectroscopy data of lesions to spectra measured in identical localizations in healthy control subjects instead of NAM and the importance of quantifying single metabolic peaks instead of creating metabolic ratios in clinical magnetic resonance spectroscopy.

Adult↗
PubMed1996

Anatomic evaluation of the circle of Willis: MR angiography versus intraarterial digital subtraction angiography.

PURPOSE: To evaluate the reliability of source images and maximum intensity projection images of MR angiography in showing the arterial segments of the circle of Willis. METHODS: In 62 patients, 526 arterial segments of the circle of Willis were determined to be present, partially present, or absent by blinded observers evaluating MR angiographic source images and maximum intensity projection images. Vessel diameter was measured on source images. These results were then compared with the results from intraarterial digital subtraction angiography. RESULTS: MR angiographic maximum intensity projection images had a sensitivity of 87% and a specificity of 88% and MR angiographic source images had a sensitivity of 89% and a specificity of 63% in depicting the presence of a vessel segment. The positive predictive value of an arterial segment with a diameter of at least 1 mm was 99%. CONCLUSION: MR angiography is a sensitive technique for detecting the anatomy of the circle of Willis. Maximum intensity projection images are more specific than source images. An arterial segment with a diameter of at least 1 mm on the source image is almost always present and patent.

Adolescent↗
PubMed1995

Proton MRS of gadolinium-enhancing MS plaques and metabolic changes in normal-appearing white matter.

Localized short echo time (TE = 20 ms), stimulated echo acquisition mode, and double spin echo (TE = 135 ms) proton spectroscopy were performed in clearly defined, acute Gadolinium (Gd)-enhancing multiple sclerosis (MS) plaques of 22 patients with clinically definite MS. The resonances of N-acetylated metabolites (NA), creatine/phosphocreatine (Cr), choline-containing compounds (Cho), glycine/myo-inositol (Ino), and lactate were evaluated. The ratios of NA/Cr and NA/Cho were significantly decreased, Cho/Cr increased, and Ino/Cr remained unchanged. No marker peaks or elevated lactate levels were found. The measured metabolic changes were practically independent of the relative plaque size within the volume of interest (8 ml). Thus, the spectral changes measured with 1H MRS in acute Gd-enhancing MS plaques originate not only from the lesion as depicted by MRI, but also from the surrounding normal-appearing white matter.

Adult↗
PubMed1995

In vivo proton MR spectroscopy of human gliomas: definition of metabolic coordinates for multi-dimensional classification.

Several multi-dimensional statistical evaluation methods were applied to single-voxel proton MR spectra of glial brain tumors and of healthy volunteers. Metabolic coordinates with histological relevance for future diagnosis were found by which spectra from controls, low-grade tumors, and high-grade tumors were completely separated. Significant differences between low-grade and high-grade glioma patients and controls were found for several metabolic ratios by variance analysis. Cluster analysis both with and without principal component analysis was applied. The outcome of these two approaches depended mainly on the lipid-to-creatine ratio. Two other approaches, discriminant factor analysis and the orthonormal discriminant vector method were then used to find discriminatory metabolic coordinates. It turned out that a linear combination of all evaluable metabolic ratios made it possible to separate the three groups completely. On the basis of these results, a classification method that uses the entire proton MRS spectrum is proposed.

Adult↗
PubMed1995

Intracranial arteries: prospective blinded comparative study of MR angiography and DSA in 50 patients.

PURPOSE: To compare the reliability of magnetic resonance (MR) angiography performed with magnetization transfer suppression and variable flip angle excitation with that of intraarterial digital subtraction angiography (DSA) in imaging of the cerebral arteries. MATERIAL AND METHODS: Fifty nonconsecutive patients referred for intraarterial DSA gave informed consent to also undergo MR angiography of the intracranial arteries. RESULTS: MR angiography had a sensitivity of 100% and a specificity of 95% for detection of vessel occlusion (10 abnormalities). For detection of substantial vessel stenosis (seven abnormalities), sensitivity and specificity were both 86%; for detection of aneurysm (six abnormalities), sensitivity was 83% and specificity was 98%. Sensitivity and specificity were 100% for detection of arteriovenous malformation (three abnormalities), vessel displacement (three abnormalities), and extracranial-intracranial bypass (two abnormalities). MR angiography did not reliably demonstrate small feeding vessels of a tumor or faint residual perfusion of a thrombosed aneurysm. CONCLUSION: MR angiographic diagnosis of disease of the intracranial vasculature has high sensitivity and specificity but still is limited in comparison with intraarterial DSA.

Angiography, Digital Subtraction↗
PubMed1990

Cerebral blood flow and common carotid flow in neurologically asymptomatic carotid endarterectomy patients.

To define subgroups in 50 neurologically asymptomatic patients with carotid stenosis (mean diam. of stenosis 81.1 +/- 12.5%) regional cerebral blood flow (rCBF) and common carotid artery flow were measured by means of the intravenous Xenon-133 technique and a Doppler flowmeter, respectively. The rCBF studies were performed both at rest and after administration of acetazolamide (Diamox). In this asymptomatic cohort of 50 patients we found subgroups with significant hemispheric baseline asymmetry (BA) (five patients; BA = 7.2 +/- 1.8%) and/or pathological Diamox asymmetry enhancement (DAE) (five patients; DAE = 8.8 +/- 1.3%). Carotid endarterectomy in these cases resulted in a significant reduction of hemispheric differences of rCBF (postoperative BA = 0.4 +/- 3.4, postoperative DAE = 1.7 +/- 3.8). Measurements of common carotid flow revealed significantly higher flow rates in the postoperative period and compensation of intercarotid flow asymmetry. In pathophysiologically defined preclinical subgroups of cerebrovascular disease with hemispheric rCBF differences and/or impairment of the cerebral vascular reserve capacity surgical procedures might be useful.

Adult↗
PubMed1990

Aneurysm, arteriovenous malformation and arteriovenous fistula in posterior fossa compression syndrome.

To discuss the problem of neuroradiological preoperative procedures in patients with therapy-resistant facial pain, we present 3 case examples of vascular processes in the cerebellopontine angle (aneurysm, arteriovenous malformation, arteriovenous fistula). The microsurgical treatment in combination with artificial embolization is described. The vascular causes of microvascular compression at the root entry zone of the trigeminal nerve and malformations involving the nucleus caudalis are reviewed.

Aged↗
PubMed1980

Evaluation of computed tomography in vascular lesions of the vertebrobasilar territory.

Forty-nine patients with clinical features of vascular disease in the vertebrobasilar territory were examined to evaluate the diagnostic performance of computed tomography. It provided useful information in the diagnosis of acute vascular lesions in patients in whom a definite episode had occurred not longer than 2 weeks before computed tomography was undertaken. It was of value in both haemorrhagic and thromboembolic groups but in many patients angiography was required to make a substantive diagnosis. It was of less value in patients with vague and ill defined symptoms and of no value in transient ischaemia.

Basilar Artery↗
PubMed1978

Iodide and xenon enhancement of computed tomography (CT) in multiple sclerosis (MS).

The characteristic findings on computed tomography (CT) in multiple sclerosis (MS) are discussed. In a series of 49 cases plain CT was normal in 21 (43%), cerebral atrophy alone was present in 17 (35%) and plaques were visible in 11 (23%). These were most often adjacent to the lateral ventricles (14 plaques) and in the parietal white matter (10 plaques). CT was performed after the intravenous administration of iodide in 16 of these cases. Three of the low attenuation and three additional isodense lesions enhanced. Two patients with low attenuation plaques were scanned with xenon enhancement; the plaques absorbed less xenon than the corresponding contralateral brain substance and additional, previously isodense plaques were revealed. In one case the white matter absorbed much less xenon than normal and its uptake relative to grey matter was reduced.

Adult↗