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Biomedical subjects

B Widder

Publications and source records attributed to B Widder.

At least 37 records · Page 2Linked to original sources
PubMed1991

[Terminology of ultrasound vascular diagnosis].

There is at present no accepted nomenclature regarding diagnostic vascular ultrasound. At two scientific meetings, the Study Group for Vascular Diagnosis of the German Society of Ultrasound in Medicine (DEGUM) developed a terminology for Doppler and duplex sonography of the arteries and veins supplying the brain and of peripheral vessels. The most important of these sonographic terms and their synonyms are presented. Recommendations as to which of the presently employed terms should be avoided, are given.

Blood Flow Velocity↗
PubMed1990

Morphological characterization of carotid artery stenoses by ultrasound duplex scanning.

Ulcerations and intraplaque hemorrhages are thought to play an important role in the development of neurological deficits in carotid artery stenoses. To assess the ability of duplex scanning to predict plaque morphology we compared different sonographic criteria (plaque border, plaque density, plaque structure) with the morphological findings in 169 consecutive carotid endarterectomies (144 cases with diameter reduction greater than 50%). Two percent of the sonograms were inadequate, and 20% showed poor image quality. Regular plaque borders revealed a smooth or at most minimally ulcerated surface in 92%. Grossly ulcerated stenoses, however, were only found in 27% of the irregular plaques. Moreover, the plaque border was nonvisible in 35% of all cases. Simple, fibro-atheromatous plaques were found to be echogenic in 72% and echolucency was present in 80% of the stenoses with relevant intraplaque hemorrhage. In conclusion, duplex scanning proved to be capable of detecting smooth, fibro-atheromatous stenoses with high accuracy. Ulcerations, however, cannot be predicted reliably, and intraplaque hemorrhage cannot be differentiated from atheromatous debris.

Carotid Arteries↗
PubMed1990

[Reproducibility of ultrasound criteria for characterizing carotid artery stenoses].

Comparisons with intraoperative findings suggest that Duplex scanning may be of value in predicting the morphology of carotid artery stenoses. Such studies, however, are based on the results obtained by experienced investigators. To clarify whether sonographic criteria can be standardized, 6 investigators from different hospitals each documented 30 carotid artery stenoses of greater than or equal to 40% diameter reduction which could be imaged in at least 2 planes. Three sonographic criteria (plaque surface, echo density, echo structure), each with 8 categories, were assessed from the image documentations by the 6 as well as by 2 independent further investigators. Depending on the experience and on the device used 29-81% of all stenoses greater than or equal to 40% examined in the different laboratories could be included in the study. The +/- 1 category concordance between the different investigators averaged 50-60% for all sonographic criteria independent from the degree of stenosis and from the image quality. Because of lack of sufficient reproducibility the subjective assessment of sonographic criteria is found to be not suitable for use in multicentre studies.

Brain Ischemia↗
PubMed1990

[Terminology of ultrasonic vascular diagnosis].

There is at present no accepted nomenclature regarding diagnostic vascular ultrasound. At two scientific meetings, the Study Group for Vascular Diagnosis of the German Society of Ultrasound in Medicine (DEGUM) developed a terminology for Doppler and duplex sonography of the arteries and veins supplying the brain and of peripheral vessels. The most important of these sonographic terms and their synonyms are presented. Recommendations as to which of the presently employed terms should be avoided, are given.

Brain↗
PubMed1989

Favourable effect of flunarizine on the recovery from hemiparesis in rats with intracerebral hematomas.

In 25 rats, an intracerebral hematoma was created in the foreleg area of the motor cortex by injection of 50 microliters blood. After the lesion, 13 were treated with flunarizine and 12 with the solvent. Neurological testing was performed by measuring the running time on a rotating platform. In animals with hemiparesis, the flunarizine group (n = 7) showed a significantly (P less than 0.05) better recovery than the control group (n = 8). No significant differences occurred in animals without neurological deficits (flunarizine: n = 6, control: n = 4). So the effect of the drug is not due to a non-specific activation; it may partially cure neurological deficits caused by intracerebral hematoma.

Animals↗
PubMed1989

The Doppler CO2 test to exclude patients not in need of extracranial/intracranial bypass surgery.

In patients with an internal carotid artery (ICA) occlusion who suffer from ipsilateral transient ischaemic attacks or minor stroke extra/intracranial (EC/IC) bypass surgery may be useful only where there is insufficient collateral supply. The transcranial Doppler CO2 test offers a simple method of investigating the residual autoregulatory capacity which gives quantitative information about the efficiency of the collaterals. In 155 patients with 162 ICA occlusions there was a significant correlation between a markedly decreased or exhausted autoregulatory capacity and a recent ipsilateral ischaemic event (p less than 0.001). The Doppler CO2 test may enable the exclusion of patients not in need of EC/IC bypass surgery. In the reported series this affected more than 80% of all ICA occlusions.

Adult↗
PubMed1988

[X-ray diagnosis of intimal ruptures of the internal carotid artery. A pathologico-anatomic controlled study].

In a prospective study to determine the accuracy of intravenous DSA in the diagnosis of ulcerative lesions of the internal carotid artery, preoperative findings obtained from DSA in patients with suspected cerebrovascular disease were reviewed and compared with thrombendarterectomy specimen (n = 74). The radiological parameters employed for the assessment of ulcerations were excavations of the vascular contour, ill defined vessel walls and steep plaque surfaces. Overall sensitivity of DSA was 66%, specificity 52%. The depth of excavations proved to be the most accurate sign in detecting ulcerative lesions (sensitivity 83%). However, in rare cases mural recesses with the angiographic appearance of ulceration corresponded to re-endothelialized cavities. Small intimal disruptions with a depth of 0.1 to 1 mm. could not be detected by intravenous DSA.

Arteriosclerosis↗
PubMed1987

[Determination of the degree of stenosis in carotid artery stenoses: ultrasound and i.v. DSA in comparison to surgical findings].

The specimens from 116 consecutive carotid thrombendarterectomies were taken as "gold standard" to evaluate the accuracy of ultrasound methods (duplex scanning + extra-/transcranial Doppler sonography) and intravenous digital subtraction angiography (i.v. DSA) in carotid artery stenoses. In 65 cases, in which the specimens could be gauged reliably, sonography estimated the degree of stenosis in 85% within a range of +/- 10%, in 97% within +/- 20% i.v. DSA was accurate in 52 respectively in 94%. High-grade stenoses were correctly assessed by ultrasound in 90%, by i.v. DSA in 64%. Sonography identified 4/10 kinkings and coilings of the carotid artery, i.v. DSA 9/10. Current available ultrasound methods enable estimation of the diameter reduction of carotid artery stenoses with low deviations. I.v. DSA seems to be less reliable, but can be used favourably as a complementary method to sonography.

Carotid Artery Diseases↗
PubMed1986

Transcranial Doppler CO2 test for the detection of hemodynamically critical carotid artery stenoses and occlusions.

Cerebral CO2-reactivity was tested by transcranial Doppler sonography (Doppler CO2 test) in 232 patients. Time averaged flow velocity in the middle cerebral artery at the 40 mm Hg blood pCO2 level was taken as a reference point, and the relative increase of flow in hypercapnia of 46.5 mm Hg pCO2 was defined as "Normalized Autoregulatory Response" (NAR). A total of 82 patients with no evidence of cerebrovascular disease gave "normal" values for NAR (23.2 +/- 5.2 SD). In 150 patients with 233 stenoses and occlusions of the internal carotid artery NAR was significantly decreased in higher-grade stenoses (P = 0.01 for 80% diameter reduction, P less than 10(-6) for 90% or more). In such stenoses, patients with NAR less than 14 had suffered more frequently (P less than 0.01) from ipsilateral transient ischemic attacks and/or stroke during the previous 6 months than patients with "normal" NAR. Preoperative NAR less than 14 always improved to "normal" values following carotid surgery, while preoperative NAR greater than 19 remained unchanged (60 cases). The transcranial Doppler CO2 test is thought to be a reliable noninvasive method to detect hemodynamically critical carotid stenoses and occlusions. This may be of interest in selecting patients for superficial temporal artery-middle cerebral artery bypass and carotid surgery. For practical use 4 categories of NAR are suggested.

Arterial Occlusive Diseases↗
PubMed1986

[Morphologic and Doppler sonographic criteria for determining the degree of stenosis of the internal carotid artery].

There is no standard classification for quantifying the degree of internal carotid artery stenoses by means of Doppler sonography. Above all this requires a clear concept of how to define the degree of stenosis morphologically, which can be described as the local lumen narrowing or the residual lumen compared with the distal internal carotid artery. Because two different physical principles are applied, the correlation between morphologic findings and hemodynamic criteria assessed by Doppler sonography can be only rough. A classification into 5 categories is presented that is practicable also with Duplex scanning and which also takes Doppler frequency analysis into account.

Carotid Artery Diseases↗
PubMed1985

[Simple extension of an ultrasound B image device to a cw duplex scanner for carotid artery studies].

In contrast to cw-Doppler sonography, ultrasound B-mode imaging is rarely applied in routine examinations for carotid artery stenosis. This may be due to the fact that B-mode imaging without accompanying Doppler sonography lacks reliability, and that Duplex scanners with pulsed Doppler modules are expensive. In this paper a method is described for constructing a cw-Duplex scanner by slight modification and combination of conventional B-mode and cw-Doppler devices. Our experience with this equipment shows that it facilitates clear distinction of the carotid branches on the B-mode image, and that it is capable of visualising carotid occlusions as well as overlapping and atypical vascular courses, all of which frequently limit the diagnostic potential of Doppler sonography. For routine examinations of the carotid bifurcation, ease of application and considerably lower costs make the cw-Duplex scanner preferable to pulsed Duplex devices.

Brain Ischemia↗
PubMed1985

A new sensitive method for the quantification of internal carotid stenoses by means of ultrasound Doppler signal processing.

A new way of processing the ultrasound Doppler spectrum is presented. By introducing a Disturbance Index (DI), based on a double Fourier transformation, the quantitative evaluation of blood flow disturbance is possible. The integral value of this index over the whole cardiac cycle can be used to quantify the degree of lower grade internal carotid artery (ICA) stenoses and plaques. In a preliminary study, this new method has been tested in 18 normal and 10 atherosclerotic carotid arteries against Duplex-scan and angiography. The results were compared with 5 alternative methods of processing the Doppler spectrum.

Carotid Arteries↗
PubMed1984

[Potentialities and limitations of B-mode sonography of the carotid artery].

By the development of multi-purpose ultrasonic devices with exchangeable probes, high resolution B-mode-sonography of the carotid arteries gains increasing applicability. Combined with bidirectional Doppler sonography, stenoses and occlusions of the extracranial carotid arteries can be readily identified. With regard to some new criteria, accuracy in detecting ulcerated lesions has nearly the same amount for both B-mode-sonography and angiography. Sonography is superior to angiography in postoperative controls, in the differential diagnosis of pulsatile tumours of the neck as well as in arteritides, and in follow-up studies of asymptomatic plaques during antithrombotic treatment and reduction of risk factors. The results discussed base on the data of more than 15 000 carotid sonograms, investigated during the last 3 years.

Adult↗