[Carotid artery screening for stroke prevention]. / Gefäßscreening zur Schlaganfallprävention.

CLINICAL/METHODICAL ISSUE: The aim was to identify the risk of impending stroke originating from diseases of the carotid artery. STANDARD RADIOLOGICAL METHODS: Duplex scanning is the standard method for clinical examination of carotid arteries. METHODICAL INNOVATIONS: By implementing the new standardized German Society for Ultrasound in Medicine (DEGUM) criteria, ultrasound examination enables reliable grading of carotid artery disease and identification of the progression of stenosis. PERFORMANCE: Current guidelines recommend duplex scanning as the standard method. In consequence of finding atherosclerosis, intensive monitoring and therapy of cardiovascular risk factors is mandatory. In cases showing rapid progression of stenosis or a very high degree of stenosis indicating increased risk of stroke, carotid endarterectomy or stenting is warranted. ACHIEVEMENTS: Detection of carotid artery atherosclerosis is uncomplicated and the method is not demanding; however, identification of high-risk carotid disease by exact grading of carotid stenosis requires investigation by an experienced examiner. PRACTICAL RECOMMENDATIONS: Screening is recommended for patients exhibiting cardiovascular risk factors but is not recommended for the general population. On detection of carotid stenosis an exact grading of stenosis by an experienced examiner is absolutely essential.

[Revision of DEGUM ultrasound criteria for grading internal carotid artery stenoses and transfer to NASCET measurement]. / Ultraschallkriterien zur Graduierung von Stenosen der A. carotis interna - Revision der DEGUM-Kriterien und Transfer in NASCET-Stenosierungsgrade.

Since 1986, German ultrasound criteria for grading carotid stenosis have followed the local diameter reduction percentage consistent with the definition used in the European Carotid Surgery Trial (ECST) definition. To overcome the confusion caused by the coexisting grading method used in the North American Symptomatic Carotid Endarterectomy Trial (NASCET), a German interdisciplinary council on carotid artery stenosis has recommended the implementation of the NASCET grading system (distal diameter reduction percentage) as the standard. The multi-parametric German "DEGUM ultrasound criteria" consisting of combined Doppler and imaging criteria have consequently been revised and transferred to the NASCET definition. In addition, a novel differentiation between main (primary) and additional (secondary) criteria has been proposed. When these ultrasound criteria are combined, vascular sonography allows reliable grading of carotid disease.

[Duplex ultrasound of external carotid artery branches for the detection of dural arteriovenous fistulae]. / Duplexsonographie von A.-carotis-externa-Asten zum Nachweis duraler AV-Fisteln.

PURPOSE: To evaluate duplex ultrasonography of external carotid artery branches for the non-invasive diagnosis of dural AV fistulae (DAVFs). MATERIALS AND METHODS: A total of 126 patients suffering from pulsatile tinnitus underwent duplex ultrasonography of the cervicocephalic vasculature including external carotid artery branches. DAVFs were identified by increased flow velocity and reduced pulsatility. Patients with ultrasound findings of DAVFs were considered for selective angiography. RESULTS: Of the 23 patients that fulfilled the ultrasound criteria of AV fistula, 5 did not undergo angiography and were excluded from the study. The ultrasound findings of AV fistula were confirmed in all remaining patients (17 DAVFs, 1 extracranial AV fistula). Duplex ultrasound detected a DAVF of the common carotid artery in 29 %, of the external carotid artery in 65 % and of the external carotid artery branches in 100 % of the cases. CONCLUSION: Duplex ultrasonography of external carotid artery branches improves the non-invasive detection of DAVFs. For the evaluation of the venous drainage, however, selective angiography is necessary.

[Spontaneous dissection of the subclavian artery and its branches]. / Spontane Dissektion der A. subclavia und ihrer Aste.

A 51-year-old woman suffering from vertigo presented to our cerebrovascular laboratory. MRI revealed a right-sided cerebellar infarction. On ultrasound examination, we found a dissection with wall hematoma of the right subclavian artery extending to the first segment of the vertebral artery and to the thyrocervical trunc, as well as a dissection of the left vertebral artery in the cranio-cervical junction. On follow-up evaluation, all stenoses resulting from dissection were recanalized within 2 months and findings of wall hematoma disappeared completely within 7 months. There was no evidence of a traumatic or iatrogenic cause of dissection; an aortic dissection was excluded by MRI. So we diagnosed a spontaneous dissection of the subclavian artery--an extremely rare but apparently existing vascular condition.

Neurometabolic effects of psilocybin, 3,4-methylenedioxyethylamphetamine (MDE) and d-methamphetamine in healthy volunteers. A double-blind, placebo-controlled PET study with [18F]FDG.

The neurometabolic effects of the hallucinogen psilocybin (PSI; 0.2 mg/kg), the entactogen 3,4-methylenedioxyethylamphetamine (MDE; 2 mg/kg) and the stimulant d-methamphetamine (METH; 0.2-0.4 mg/kg) and the drugs' interactions with a prefrontal activation task were investigated in a double-blind, placebo-controlled human [F-18]fluorodeoxyglucoseFDG-positron emission tomographicPET study (each group: n = 8). Subjects underwent two scans (control: word repetition; activation word association) within 2-4 weeks. Psilocybin increased rMRGlu in distinct right hemispheric frontotemporal cortical regions, particularly in the anterior cingulate and decreased rMRGlu in the thalamus. Both MDE and METH induced cortical hypometabolism and cerebellar hypermetabolism. In the MDE group, cortical hypometabolism was more pronounced in frontal regions, with the exception of the right anterior cingulate, which tended to be hyperactive. Cognitive activation-related increases in left frontocortical regions were attenuated under all three psychoactive substances, but less so under MDE. Taking into account performance data and subjective reports on task difficulty, these effects may result from different mechanisms across the three groups. Our PSI data are in line with studies on acute schizophrenic patients suggesting frontal overactivity at rest, but diminished capacity to activate prefrontal regions upon cognitive demand. The MDE data support the hypothesis that entactogens constitute a distinct psychoactive substance class, which takes an intermediate position between stimulants and hallucinogens.

Floating thrombus in the internal carotid artery disclosed by B-mode ultrasonography.

In a 44-year-old patient with transient cerebral ischaemia a large floating thrombus in the carotid bifurcation was detected by B-mode ultrasonography. To prevent further embolization the floating thrombus was removed by endarterectomy. The sonography findings were confirmed by operation and microscopy. Although migrating clots have long been recognized as a frequent cause of cerebrovascular accident, comparable cases have been rarely published. The problems involved in visualizing thrombi in the carotid artery by B-mode ultrasonography are discussed.

The diagnostic relevance of colour Doppler artefacts in carotid artery examinations.

PURPOSE: Physical and technical artefacts of the colour Doppler method are examined with regard to their diagnostic relevance for the carotid artery. MATERIALS AND METHODS: After recording all diagnostic problems arising from physical and technical artefacts in 30,000 consecutively carotid arteries, the quantitative significance of relevant artefacts was determined in minor subgroups of the collective. RESULTS: Acoustic shadowing causes diagnostic problems in morphological and haemodynamic evaluation of stenoses. Mirror image artefacts simulate flow in cases of actual vessel occlusion or mimic vessel wall ulceration in carotid plaques and stenoses. Insonation angle artefacts inhibit detection of flow or mimic flow reversal. Problems of spatial resolution lead to incorrect demonstration of the vessel lumen in stenotic findings. Aliasing, perivascular colour artefacts, and ghosting do not cause any diagnostic problems. Relevant shadowing artefacts occurred in 14.7%, and relevant mirror image artefacts in 2.5% of the pathological cases. Insonation angle artefacts occurred in 17.3% of the cases (when using standard apparatus setting). However, with an exact knowledge of the artefact phenomena, insonation angle artefacts could be eliminated and mirror image artefacts were recognized in all cases. Resolution artefacts resulted in underestimation of carotid stenoses by on average 13.3% of the degree of stenosis. CONCLUSION: In principle, four artefact phenomena give rise to diagnostic problems; however, with a good knowledge of the phenomena, only artefacts due to acoustic shadowing and limited spatial resolution are of diagnostic significance.

[Investigations on the effect of "ecstasy" on cerebral glucose metabolism: an 18-FDG PET study]. / Untersuchungen zum Einfluss von "Ecstasy" auf den zerebralen Glukosemetabolismus: eine 18-FDG-PET-Studie.

PURPOSE: The aim of the present study was to determine the acute effects of the "Ecstasy" analogue MDE (3, 4-methylendioxyethamphetamine) on the cerebral glucose metabolism (rMRGlu) of healthy volunteers. METHOD: In a randomised double-blind trial, 16 healthy volunteers without a history of drug abuse were examined with 18-FDG PET 110-120 minutes after oral administration of 2 mg/kg MDE (n = 8) or placebo (n = 8). Beginning two minutes prior to radiotracer injection, a constant cognitive stimulation was maintained for 32 minutes using a word repetition paradigm in order to ensure constant and comparable mental conditions during cerebral 18-FDG uptake. Individual brain anatomy was represented using T1-weighted 3D flash MRI, followed by manual regionalisation into 108 regions-of-interest and PFT/MRI overlay. Absolute quantification of rMRGlu and comparison of glucose metabolism under MDE versus placebo were performed using Mann-Whitney U-test. RESULTS: Absolute global MRGlu was not significantly changed under MDE versus placebo (MDE: 41.8 +/- 11.1 mumol/min/100 g, placebo: 50.1 +/- 18.1 mumol/min/100 g, p = 0.298). The normalised regional metabolic data showed a significantly decreased rMRGlu in the bilateral frontal cortex: left frontal posterior (-7.1%, p < 0.05) and right prefrontal superior (-4.6%, p < 0.05). On the other hand, rMRGlu was significantly increased in the bilateral cerebellum (right: +10.1%, p < 0.05; left +7.6%, p < 0.05) and in the right putamen (+6.2%, p < 0.05). CONCLUSIONS: The present study revealed acute neurometabolic changes under the "Ecstasy" analogon MDE indicating a fronto-striato-cerebellar dysbalance with parallels to other psychotropic substances and various endogenous psychoses respectively.

Nonatherosclerotic disease of the cervical arteries: role of ultrasonography for diagnosis.

On the basis of morphological and hemodynamic criteria, color-coded duplex sonography enables diagnostic evaluation of non-atheromatous lesions of the cervical arteries. Ultrasonography is the method of first choice for Takayasu's arteritis, radiation angiopathy, and common carotid artery dissections. Internal carotid and vertebral artery dissections are detected in up to 95% and 79%, respectively; in some of these cases, however, ultrasonography delivers unspecific findings so that dissections can only be confirmed when typical clinical symptoms are present, too. Detection of vasospasms of the cranial arteries is extremely difficult, on account of their tendency for rapid regression; however, sonography is in principle a suitable method. In cases of fibromuscular dysplasia ultrasound has furnished less positive results on account of the unfavourable localisation for duplex sonography. As the disease has a relatively good prognosis, only symptomatic cases need to be detected. On the whole, sonography is a suitable method for the diagnosis of nonatherosclerotic diseases of the cervical arteries.

[Arteriovenous fistula of the jugular vein: detection and follow-up with color-coded duplex ultrasound]. / Arteriovenöse Fistel an der V. jugularis: Nachweis und Verlaufsbeobachtung mit farbkodierter Duplexsonographie.

A 71-year-old man presented with a pulsating swelling in the lower right neck region. On clinical examination palpation revealed a local thrill and auscultation the typical systolic vascular sounds. On sonography the typical findings for an AV fistula with large widening of the jugular vein and entry of an extremely rapid jet stream into the vein were detected. The entry point was under a venous valve whose movements apparently influenced the jet stream since the inflow was only seen intermittently and only in the systolic phase. The shunt volume of the fistula was apparently small: indirect signs of an arteriovenous short circuit could not be seen on duplex sonography. The low-flow fistula was not demonstrated by arterial DSA. Thus, the arterial sources could not be identified. Sonographic monitoring over 5 years at first showed no changes while at the last follow-up the fistula was no longer detectable. The suspected cause of the arteriovenous fistula was a vascular wall perforation effected some years previously during insertion of a central venous catheter. We further assume that the anticoagulation therapy with Marcumar started at that time had prevented spontaneous closure of the fistula over a period of several years. This case illustrates the value of colour-coded duplex sonography for the differentiation of pulsating tumors in the neck. In individual cases of AV fistulas with low shunt volumes the method is apparently superior even to angiography.

Ultrasonographic criteria for diagnosing a dissection of the internal carotid artery.

AIM: To evaluate the usefulness of various sonographic criteria for detecting a dissection of the internal carotid artery (ICA). METHOD: Twenty-three consecutive patients displaying typical clinical symptoms of ICA dissection were identified. The diagnosis of dissection in these cases was confirmed by MRI/MRA or arteriography. The sonographic examination was the first technical investigation and involved the combined use of Doppler and duplex sonography. The value of different sonographic criteria was evaluated for the identification of ICA dissection: 1) Morphological criteria: intramural haematoma or double lumen. 2) Haemodynamic findings of distal stenosis/occlusion in combination with suddenly appearing clinical signs of a space-occupying lesion in the respective region (Horner's syndrome, lower cranial nerve palsies). 3) Haemodynamic signs of distal stenosis/occlusion with ensuing recanalisation within a few weeks. RESULTS: Morphological criteria alone allowed detection of a dissection in 47,8 % of patients. By the combined use of morphological and haemodynamic criteria ICA dissections were identified on admission in 73.9 % and after an average of 4.5 weeks (at the latest after 6 weeks) in 91.3 % of the patients. CONCLUSION: ICA dissections can be identified sonographically with high sensitivity. In some of the cases, however, definite diagnosis can only be provided by follow-up evaluation.

[Perivascular tissue vibrations: a criterium for high-grade stenoses of the internal carotid artery]. / Perivaskuläre Gewebsvibrationen: ein Kriterium hochgradiger Stenosen der A. carotis interna.

UNLABELLED: Perivascular tissue vibrations, an artefact of the colour Doppler method, are already known to be a sonographic sign of stenosis but have not yet been investigated systematically in the examination of the internal carotid artery. AIM: The present study is intended to assess the value of this artefact in the diagnosis of stenosis of the internal carotid artery. METHOD: A total of 167 consecutive cases including a stenosis of the internal carotid artery of at least 50% were diagnosed according to the usual haemodynamic criteria using Doppler and duplex sonography and classified into 10% categories. Intermediate groups were formed for findings that could not be assigned unambiguously. By means of suitable apparatus settings each finding was examined to test whether a perivascular colour artefact was detectable. RESULTS: In the stenosis categories of 50% to 70% no perivascular colour artefact was found, whereas in the stenosis categories of 80% to 90% this was the case in 80% of the findings, and in the intermediate 75% category in 42% of the findings. The perivascular colour artefact was recognizable even under poor sonographic conditions. CONCLUSION: When a perivascular colour artefact is seen the diagnosis of a high-degree stenosis (or an AV fistula) is certain. The phenomenon is particularly valuable as a supplementary criterion of stenosis in cases of unfavourable sonographic conditions. However, the perivascular colour artefact may only be used to confirm, but never to exclude, a high-degree stenosis.

[Does cw Doppler ultrasound still have a value for cerebrovascular diagnosis today?]. / Hat die cw-Dopplersonographie heute noch einen Wert für die Hirngefässdiagnostik?

The aim of this study was to assess the current value of extracranial continuous wave (cw) Doppler sonography in routine use as compared to color-coded duplex sonography. For this purpose, 500 carotid and 500 vertebral arteries were examined by a user experienced in both methods. The error rate of Doppler sonography was determined only when the methods allowed a clear decision to be made about the status of the vessel (normal findings including common variants, stenosis, and occlusion). In 85.4% of the carotid arteries and 88% of the vertebral arteries, the Doppler findings fulfilled the diagnostic differentiation unequivocally. For these cases, false findings were obtained in 1.9% of the carotid arteries and 0.2% of the vertebral arteries. Accordingly, a clear Doppler sonographic finding, normal or pathologic, is still of large diagnostic value. However, ambiguous or uncertain findings requiring further diagnostic workup are not uncommon. Thus, the sole use of cw Doppler sonography is no longer sufficient in a stroke center but still retains its utility in the practitioner's office.

[Possible errors caused by artefacts in the Doppler color image]. / Fehlermöglichkeiten durch Artefakte im Farb-Doppler-Bild.

The practical application of colour-coded duplex sonography shows that physico-technical artifacts of colour Doppler imaging may not be obvious in all cases and can lead to misinterpretation. Slice-thickness artifacts are due to restricted transversal resolution, as in the B-mode, and may cause false negative results in vascular occlusions. Specific problems in creating and processing the colour flow image interfere with lateral resolution and lead to errors in the quantification of stenoses from the colour Doppler image. Mirror image artifacts produce phantom pictures that can be easily identified as such in some cases, but may resemble recesses in the arterial wall in other cases. Phenomena of sound shadowing resulting from the same reasons as in B-mode may lead to assume vascular occlusions in cases of long-range stenoses. Artifacts of the sonication angle in case of blood vessel tortuosity may lead to misdiagnosis of a non-existent retrograde flow. The artifacts mentioned do restrict the capacity of colour coded duplex sonography for localising flow in the ultrasound image. Users of the method should therefore be familiar with these artifacts.

Mirror image artifacts of color Doppler images causing misinterpretation in carotid artery stenoses.

A knowledge of mirror image artifacts in color-coded duplex sonography is important as they can lead to diagnostic problems in the morphologic evaluation of stenoses and plaques. Mirror image artifacts were detectable in stenosed vessels when strongly reflecting plaques on the wall of the vessel distant from the transducer head were insonated obliquely. The artifacts were revealed in regions that were hypoechoic or anechoic on B-mode scans. Depending on the angle of insonation and the surface structure of the plaque, the mirror image artifact could be linked with the vessel lumen and thus imitate ulcerations or branches. The artifact appeared in both the longitudinal and the transverse projections and also occurred in the power Doppler and in pulsed Doppler sonographic modes. Mirror image artifacts with linkages to the vessel lumen that could result in a misinterpretation were seen in 2.5% of the stenosed vessels.

[Significance of Doppler ultrasound procedures for diagnosis of carotid stenoses]. / Stellenwert der Doppler-sonographischen Verfahren zur Diagnose der Karotisstenosen.

Determining degree and morphology of stenoses is important for surgical planning or stent implantation. Vascular ultrasound is usually the first modality to evaluate carotid artery stenosis. Due to rapid development various methods of vascular ultrasound are applied including continuous wave (CW) Doppler, duplex Doppler, colour-coded duplex sonography (CCDS), power Doppler and B-flow technique. For quantitative assessment of the degree of stenosis the most frequently used parameters are peak systolic velocity (PSV), end-diastolic velocity (EDV) in the internal carotid artery (ICA), as well as ICA to CCA ratios of PSV and EDV. Different results reported in the literature may reflect differences in defining the degree of stenosis and methodological differences in protocol or imaging techniques. Differences in defining the degree of stenosis, advantages and disadvantages of the different Doppler techniques and future developments are discussed in detail.