O60	New Pharmacological Applications and Extra- and Intracranial Ultrasound Methods László Csiba, Dept. of Neurology, Debrecen University, Hungary The lecture overviews the potential applications of extra- and intracranial ultrasound techniques for the assessment of efficacy of pharmacological therapy. Diabetes, smoking, hypertension, hypercholesterolemia and hormon replacement might increase the intima-media-thickness of the carotids. The effects of cholesterol lowering, antihypertensive and hormon replacement drugs were systematically investigated with high resolution ultrasound. The long-term follow up of IMT (with or without therapy) might have an important role in primary prevention and in treatment monitoring. The vasodilating capacity of cerebral arterioles might be impaired by chronic hypertension, diabetes, vasculitis etc. The improvement of vasodilatation after pharmacological therapy (atenolol, perindopril, acebutolol etc), could be assessed and followed by TCD (alone or combined with CO2, breath holding or acetazolamide test). The cessation of TCD embolic signals after antithrombotic agents was also demonstrated. In acute stroke, the TCD is an auxiliary technique for the selection of patients for reperfusion treatment, following and enhancing thrombolysis. The hemodynamic data of the TCD could be useful in the monitoring of intracranial hypertension treatments. In conclusion, TCD will possibly be more widely used in the future in the acute phase of cerebral infarction as a guide to diagnostic procedures, for treatment selection and for monitoring of cerebral hemodynamics. The extracranial ultrasound techniques and also the TCD will become the diagnostic and monitoring technique of choice to select the optimal treatment and dosage for primary and secondary prevention of stroke.
O61	New Developments in Neurosonology - Ultrasound techniques in the analysis of the venous system and the cerebral circulation time J.M. Valdueza, Dept. of Neurology, University Hospital Charité, Berlin, Germany In recent years the neurosonologic fields of interest have, mainly due to the rapid technical development, continuously increased. While the analysis of the cerebral arterial vessel system is now well established, venous signal analysis has been rather neglected for a long time. Today’s technical equipment allows the blood flow analysis of several intracerebral veins and sinuses by means of transcranial Doppler (TCD) or transcranial colour-coded duplex-sonography (TCCS). This resulted in the consequent application of the techniques in clinical conditions like arteriovenous malformations or sinus venous thrombosis. The gathered knowledge about the physiology of the cerebral venous drainage was also the foundation for hemodynamic ultrasound studies, based on the principle of echo-contrast bolus-tracking. A variety of a approaches, analysing either a regional or a global cerebral circulation time after intravenous echo-contrast application have since been presented. They seem to lead to promising results, comparable to data, known from established methods of hemodynamic analysis like angiography or MRI. The combination of ultrasound parameters like the global circulation time and the global blood volume flow, generated by extracranial duplex sonography opens a new door towards the assessment of global cerebral blood volume. Combined with the new approaches of brain perfusion analysis, ultrasound might become a very competitive tool for the evaluation and characterisation of the cerebral hemodynamic status.
O62	INNOVATIVE NON-INVASIVE METHOD FOR ABSOLUTE INTRACRANIAL PRESSURE MEASUREMENT A.Ragauskas, G.Daubaris, A. Dziugys Kaunas University of Technology, Kaunas, Lithuania Background: The ideas of the measurement of intracranial pressure (ICP) absolute value non-invasively have been appearing since 1980. However, the major problem of absolute ICP non-invasive measurement is the necessety to calibrate non-invasively and individually the system "individual patient – non-invasive ICP monitor". In this study a new method [1] is proposed which does not need the individual calibration of non-invasive absolute ICP measurement. Methods: A new noninvasive absolute ICP measurement method [1] includes a means based on the transcranial Doppler (TCD) two depth technique for a non-invasive absolute ICP and external absolute pressure comparison. The intracranial segment of eye artery (EA) is compressed by ICP. The extracranial segment of EA is compressed by the controlled external pressure Pe. In the case of pressures balance Pe=ICP the pulsating blood flow parameters in the extracranial and intracranial EA segments are approximately the same. Two depth special TCD is an indicator of balance Pe=ICP. Computer modeling of EA blood velocity pulsation under pressure balance and disbalance has been performed using especially designed mathematical model of EA blood flow. Preliminary clinical comparative study of simultaneous invasive and non-invasive absolute ICP measurements has been performed on ICU patients with traumatic brain injuries. Results: The pulsatility indexes (PI) were used for the pressure balance indication applying two depth TCD device. The experimental dependences of PI on extracranial pressure Pe and ICP show the pressure balance point when Pe is close to ICP and it is possible to resolve 1 mmHg absolute ICP changes using proposed method. The same resolution has been confirmed applying PC modeling of EA blood velocity pulsation. It is also shown that the results of non-invasive absolute ICP measurements do not depend on individual anatomical properties of the patient or an individual state of the EA blood flow. Conclusions: In this ongoing study it is shown that it is possible to measure absolute ICP value non-invasively without the individual calibration of the system "individual patient -- non-invasive ICP meter". 1. A. Ragauskas, G. Daubaris, A. Dziugys. US Patent No. 5951477, 1999. This work is supported by US DAMD Award 17-00-2-0065.
O63	The depth of microembolic signal direction change corresponds with vessel anatomy W.H.Mess(1), J.M.Willigers(2), Th.W.O.Elenbaas(1), R.G.A.Ackerstaff(3), A.P.G.Hoeks(2); University Hospital Maastricht (1). University Maastricht(2), St.Antonius Hospital, Nieuwegein(3) Background: Analysis of microembolic signals (MES), either based on FFT or time domain information of the demodulated Doppler signal or by use of the amplitude information of the radiofrequent (RF) signal, suggest a change of flow direction (CFD). The aim of the present study was to compare data of the second approach with the vascular anatomy as seen with transcranial color coded duplex (TCCD). Methods: Five patients undergoing heart valve surgery or aortic arch replacement were enrolled in this study. Preoperatively, TCCD of the distal part of the internal carotid artery, the middle and the anterior cerebral artery on the right side was performed to determine the depths of changes in flow direction. Peroperatively, a 2 MHz transcranial pulsed Doppler (TCD) monitoring probe was fixed over the right temporal bone. A customized RF based system, connected to the TCD device, captured and stored the occurring MES. Offline, the color coded amplitude of the clutter filtered RF signals was plotted as a function of time (sample interval 0.17 msec) and depth (sample interval 0.05 mm). A CFD was observed if an MES appeared first as a line of increased intensity directed towards the probe and consecutively as a line away from the probe. The depth of a CFD was visually estimated. Results: A total of 313 MES were recorded with 66 MES (21 %) in 4 patients showing a CFD. Taking a measurement error of 2 mm into account, in each patient all MES with CFD could be assigned to maximally three different depth values, irrespective of the number of MES. Six out of eight CFD depth values coincided with an accuracy of one mm with a turn in flow direction as estimated with TCCD. Conclusions: A CFD of MES occurred at a very limited number of depths and corresponded mostly with the intracranial vascular anatomy, namely a turn of the flow direction in the intracranial vessels as observed with TCCD. These findings confirm that it is possible to follow the course of MES in the basal cerebral arteries with an RF based acquisition system with a high spatial resolution.
O64	Correlations of flow velocity changes during simultaneous passive and active movements of the arms in post-stroke patients: a functional Transcranial doppler study. ^1M. Matteis, ^2F. Vernieri,, ^1,3C. Caltagirone, ^1E. Troisi, ^3F. Tibuzzi, ^4 M. Silvestrini. ^1IRCCS "S.Lucia", Roma; ^2AfaR: Dipartimento di Neuroscienze-Ospedale Fatebenefratelli, Isola Tiberina, Roma; ^3Clinica Neurologica Università di Roma "Tor Vergata";^4Clinica Neurologica Università di Ancona. Background: Restoration of full function to the stroke-affected upper limb remains a major problem in rehabilitation. Clinical observations prompted investigation of a novel approach using simultaneous identical bilateral movements performed independently. Bilateral movement appears to provide a novel method of intervention based on encouraging the involvement of the undamaged hemisphere in the recovery process. We report preliminary data from a Transcranial doppler investigation regarding the changes of cerebral blood flow velocity in the middle cerebral arteries during passive movement of the plegic arm performed alone or simultaneously to active movement of the unaffected arm in patients with hemiplegic stroke. Methods: The study included thirteen patients with single ischemic cerebral lesion confirmed by MRI ( 8 men and 5 women, mean age 65± 8) and severe motor deficit of the upper limb. Within 20 days (range 10 to 20 days) from stroke onset, all patients were examined for the effects of passive elbow movements of the paretic arm performed alone and with simultaneous movement of the unaffected arm on cerebral blood flow in the middle cerebral arteries by means of bilateral Transcranial doppler ultrasonography. For evaluating the clinical outcome, the Canadian Neurological Scale (CNS) and the Medical Research Council (MRC) for motor deficit of the plegic arm were performed on the same day of TCD assessment and after two months. Results: When the passive movements were performed simultaneously to active movements of the unaffected arm, the increase of mean flow velocity (MFV) in the affected hemisphere was significantly higher in all patients with respect to the increase recorded during passive movement of the plegic arm alone ( increase of MFV in the affected hemisphere during passive movement alone: 3,7%; increase of MFV in the affected hemisphere during passive movement of the plegic arm and simultaneous active movement of the unaffected arm: 6,4 %). After two months all patients showed a good clinical recovery. Conclusions: Our preliminary results suggest that bilateral movements increased the activation of the affected hemisphere. Further investigations are necessary for evaluating whether the bilateral motor performance could enhance recovery from hemiparesis The bilateral movement could be a significant addition to the the armamentarium for restorative therapeutic intervention.
O65	THREE-DIMENSIONAL HISTOLOGIC RECONSTRUCTION OF CAROTID ENDARTERECTOMY SPECIMENS- PATHOANATOMICAL CORRELATION WITH IN-VITRO THREE-DIMENSIONAL REAL-TIME COMPOUND IMAGING MA Ritter^1, C Hegedüs^1, R Kern^2, S Molnar^1,L Pourcelot^3, L Csiba^1, S Meairs^2 University of Debrecen, Hungary^1,Neurologische Klinik, Universitätsklinikum Mannheim, Germany^2, Méd. Nucléaire et Ultrasons. Unité INSERM U316, Tours, France^3 Background and purpose: Three-dimensional (3D) reconstruction methods have been developed for most imaging modalities, but only rarely have these been transferred to the pathological or histological level. We developed a technique for serial digitisation of images of native endarterectomy specimens using an epoxy resin embedding method. In a second step, we compared the results of 3D ultrasound reconstructions of carotid endartectomy specimens with the results of the new 3D histological technique Methods: 3D-ultrasound data of 24 carotid endartectomy specimens were acquired with a motor-driven parallel system using B-mode compound imaging with a 4-7 MHz linear array transducer on a Philips ATL HDI-5000 platform. Thus far, 6 specimens were then embedded in epoxy resin. Serial slices of 200m m thickness were cut with a hard tissue microtome and photographed with a digital camera mounted in fixed position above the tissue block. The resolution of the camera was 55 pixel per mm (3025 pixel per mm^2). Multimodal matching was performed with the Automated Image Registration® package. Slice images were reconstructed and rendered using the Volume Graphics Library®. Results: Quantitative evaluation of volumes, intraplaque haemorrhage and other pathological features was easily possible after reconstruction. Comparison with matched 3D-ultrasound reconstructions showed an excellent correlation for plaque volume. Although there was good agreement in tissue characterization, the extent of plaque rupture and hemorrhage was sometimes poorly described by ultrasound. Conclusions: Our 3D-histological work-up provides useful data for the comparison with 3D reconstructions of slice images acquired during ultrasound or other imaging modalities. Since major preparation of the endarterectomy specimen, e.g. decalcification, is not required, the morphological accuracy of our method is high. 3D-ultrasound reliably assesses plaque volume and most morphological characteristics of carotid artery plaques.
O66	AUTOMATED EMBOLUS DETECTION WITH THE ‘NOVEL FREQUENCY FILTERING APPROACH’ VERSUS HUMAN OBSERVERS A.G. Munts, W.H. Mess, E.F. Bruggemans, L. Walda, R.G.A. Ackerstaff St Antonius Hospital, Nieuwegein (Utrecht), The Netherlands Background: In 2000, a new automated method for online detection of micro-embolic signals (MESs), developed by Markus H. and Reid G. et al., proved to be successful. In the present study we investigated its performance in TCD monitoring after carotid endarterectomy (CEA) and carotid angioplasty and stenting (CAS). Methods: A 2-hours DAT study tape was analysed by the algorithm and 5 human experts of three different centres throughout the Netherlands. The software was set at a confidence level of 65%. Agreement between all human observers and the algorithm was calculated by using kappa statistics and the probability of specific agreement. Results: The human gold standard (agreement between at least 3 human observers) detected 107 MESs of which 90 were with an intensity of ³ 7 dB. The software detected 81 and 77 MESs, respectively. Using no intensity threshold, the software had 3 false positives and 29 false negatives. The mean probability of detecting a MES that was also found by another human observer was 0.88 for the human observers and 0.71 for the algorithm. Kappa values between human observers ranged from 0.84 to 0.91. The kappa value between human gold standard and software was 0.83. Conclusions: The interobserver agreement between human experts is better than the agreement between the tested software and the human gold standard. Nevertheless, the ‘novel frequency filtering approach’ algorithm is the first reliable automated method for online MESs detection after carotid surgery or stenting. This makes testing of the effectiveness of anti-platelet agents in the prevention of stroke after surgical and endovascular procedures of the carotid artery more practicable.