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1.
PLoS One ; 10(6): e0127580, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26039354

RESUMEN

BACKGROUND AND PURPOSE: Transcranial near-infrared laser therapy (TLT) is a promising and novel method to promote neuroprotection and clinical improvement in both acute and chronic neurodegenerative diseases such as acute ischemic stroke (AIS), traumatic brain injury (TBI), and Alzheimer's disease (AD) patients based upon efficacy in translational animal models. However, there is limited information in the peer-reviewed literature pertaining to transcranial near-infrared laser transmission (NILT) profiles in various species. Thus, in the present study we systematically evaluated NILT characteristics through the skull of 4 different species: mouse, rat, rabbit and human. RESULTS: Using dehydrated skulls from 3 animal species, using a wavelength of 800nm and a surface power density of 700 mW/cm2, NILT decreased from 40.10% (mouse) to 21.24% (rat) to 11.36% (rabbit) as skull thickness measured at bregma increased from 0.44 mm in mouse to 0.83 mm in rat and then 2.11 mm in rabbit. NILT also significantly increased (p<0.05) when animal skulls were hydrated (i.e. compared to dehydrated); but there was no measurable change in thickness due to hydration. In human calvaria, where mean thickness ranged from 7.19 mm at bregma to 5.91 mm in the parietal skull, only 4.18% and 4.24% of applied near-infrared light was transmitted through the skull. There was a slight (9.2-13.4%), but insignificant effect of hydration state on NILT transmission of human skulls, but there was a significant positive correlation between NILT and thickness at bregma and parietal skull, in both hydrated and dehydrated states. CONCLUSION: This is the first systematic study to demonstrate differential NILT through the skulls of 4 different species; with an inverse relationship between NILT and skull thickness. With animal skulls, transmission profiles are dependent upon the hydration state of the skull, with significantly greater penetration through hydrated skulls compared to dehydrated skulls. Using human skulls, we demonstrate a significant correlation between thickness and penetration, but there was no correlation with skull density. The results suggest that TLT should be optimized in animals using novel approaches incorporating human skull characteristics, because of significant variance of NILT profiles directly related to skull thickness.


Asunto(s)
Encefalopatías/cirugía , Rayos Infrarrojos , Terapia por Láser , Cráneo , Animales , Femenino , Humanos , Masculino , Ratones , Conejos , Ratas
2.
Comput Med Imaging Graph ; 38(8): 675-82, 2014 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-25069430

RESUMEN

In this paper we report how thickness and density vary over the calvarium region of a collection of human skulls. Most previous reports involved a limited number of skulls, with a limited number of measurement sites per skull, so data in the literature are sparse. We collected computer tomography (CT) scans of 51 ex vivo human calvaria, and analyzed these in silico using over 2000 measurement sites per skull. Thickness and density were calculated at these sites, for the three skull layers separately and combined, and were mapped parametrically onto the skull surfaces to examine the spatial variations per skull. These were found to be highly variable, and unique descriptors of the individual skulls. Of the three skull layers, the thickness of the inner cortical layer was found to be the most variable, while the least variable was the outer cortical density.


Asunto(s)
Absorciometría de Fotón/métodos , Densidad Ósea/fisiología , Imagenología Tridimensional/métodos , Interpretación de Imagen Radiográfica Asistida por Computador/métodos , Cráneo/diagnóstico por imagen , Cráneo/fisiología , Tomografía Computarizada por Rayos X/métodos , Anciano , Anciano de 80 o más Años , Cadáver , Simulación por Computador , Humanos , Masculino , Persona de Mediana Edad , Modelos Biológicos , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Cráneo/anatomía & histología
3.
Crit Ultrasound J ; 6(1): 3, 2014 Feb 27.
Artículo en Inglés | MEDLINE | ID: mdl-24572006

RESUMEN

BACKGROUND: Transcranial color-coded sonography (TCCS) has proved to be a fast and reliable tool for the detection of middle cerebral artery (MCA) occlusions in a hospital setting. In this feasibility study on prehospital sonography, our aim was to investigate the accuracy of TCCS for neurovascular emergency diagnostics when performed in a prehospital setting using mobile ultrasound equipment as part of a neurological examination. METHODS: Following a '911 stroke code' call, stroke neurologists experienced in TCCS rendezvoused with the paramedic team. In patients with suspected stroke, TCCS examination including ultrasound contrast agents was performed. Results were compared with neurovascular imaging (CTA, MRA) and the final discharge diagnosis from standard patient-centered stroke care. RESULTS: We enrolled '232 stroke code' patients with follow-up data available in 102 patients with complete TCCS examination. A diagnosis of ischemic stroke was made in 73 cases; 29 patients were identified as 'stroke mimics'. MCA occlusion was diagnosed in ten patients, while internal carotid artery (ICA) occlusion/high-grade stenosis leading to reversal of anterior cerebral artery flow was diagnosed in four patients. The initial working diagnosis 'any stroke' showed a sensitivity of 94% and a specificity of 48%. 'Major MCA or ICA stroke' diagnosed by mobile ultrasound showed an overall sensitivity of 78% and specificity of 98%. CONCLUSIONS: The study demonstrates the feasibility and high diagnostic accuracy of emergency transcranial ultrasound assessment combined with neurological examinations for major ischemic stroke. Future combination with telemedical support, point-of-care analysis of blood serum markers, and probability algorithms of prehospital stroke diagnosis including ultrasound may help to speed up stroke treatment.

5.
Expert Rev Med Devices ; 10(2): 201-13, 2013 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-23480089

RESUMEN

Transcranial ultrasound and high intensity focused ultrasound technologies have been developed as a method of thrombolysis to be applied to the treatment of acute ischemic stroke. The originating idea to apply ultrasound to treat disease states dates back from the 1930s to 1940s when seminal research findings suggested that ultrasound could have an effect on biological systems and the brain, but the mechanism(s) involved in the effects were unknown. This exciting field of research has flourished since the potential exists to effectively utilize ultrasound to induce thrombolysis noninvasively or perhaps in combination with a thrombolytic agent, such as tissue plasminogen activator or secondary pharmaceutical such as microbubbles to promote cerebral reperfusion and clinical improvement. While there is great enthusiasm in this field of stroke treatment, specific parameters required for optimal sonothrombolysis such as output power, duty cycle, pulse width, and exposure time, as well as the impact of skull bone characteristics and flow mechanics, remain to be defined. This article analyzes relevant ultrasound studies to provide a synthesis of insight in the field of sonothrombolysis to attempt to provide direction for possible future use in stroke patients.


Asunto(s)
Fibrinolíticos/administración & dosificación , Trombolisis Mecánica/métodos , Accidente Cerebrovascular/terapia , Terapia Trombolítica/métodos , Terapia por Ultrasonido , Animales , Circulación Cerebrovascular , Diseño de Equipo , Ultrasonido Enfocado de Alta Intensidad de Ablación/instrumentación , Humanos , Trombolisis Mecánica/instrumentación , Microburbujas , Accidente Cerebrovascular/fisiopatología , Terapia Trombolítica/instrumentación , Resultado del Tratamiento , Terapia por Ultrasonido/instrumentación
6.
Am J Emerg Med ; 31(4): 743-7, 2013 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-23415600

RESUMEN

Stroke is the second common cause of death and the primary cause of early invalidity worldwide. Different from other diseases is the time sensitivity related to stroke. In case of an ischemic event occluding a brain artery, 2000000 neurons die every minute. Stroke diagnosis and treatment should be initiated at the earliest time point possible, preferably at the site or during patient transport. Portable ultrasound has been used for prehospital diagnosis for applications other than stroke, and its acceptance as a valuable diagnostic tool "in the field" is growing. The intrahospital use of transcranial ultrasound for stroke diagnosis has been described extensively in the literature. Beyond its diagnostic use, first clinical trials as well as numerous preclinical work demonstrate that ultrasound can be used to accelerate clot lysis (sonothrombolysis) in presence as well as in absence of tissue plasminogen activator. Hence, the use of transcranial ultrasound for diagnosis and possibly treatment of stroke bares the potential to add to current stroke care paradigms significantly. The purpose of this concept article is to describe the opportunities presented by recent advances in transcranial ultrasound to diagnose and potentially treat large vessel embolic stroke in the prehospital environment.


Asunto(s)
Servicios Médicos de Urgencia , Accidente Cerebrovascular/diagnóstico , Accidente Cerebrovascular/terapia , Ambulancias Aéreas , Ambulancias , Humanos , Accidente Cerebrovascular/diagnóstico por imagen , Ultrasonografía
7.
J Ther Ultrasound ; 1: 18, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-25512862

RESUMEN

The goal was to test the effects of various combinations of pulse widths (PW) and duty cycles (DC) on high-intensity focused ultrasound (HIFU)-induced sonothrombolysis efficacy using an in vitro flow model. An ExAblate™ 4000 HIFU headsystem (InSightec, Inc., Israel) was used. Artificial blood clots were placed into test tubes inside a human calvarium and exposed to pulsatile flow. Four different duty cycles were tested against four different pulse widths. For all study groups, an increase in thrombolysis efficacy could be seen in association with increasing DC and/or PW (p < 0.0001). Using transcranial HIFU, significant thrombolysis can be achieved within seconds and without the use of lytic drugs in vitro. Longer duty cycles in combination with longer pulse widths seem to have the highest potential to optimize clot lysis efficacy.

8.
J Ther Ultrasound ; 1: 22, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-25512864

RESUMEN

BACKGROUND: The primary goal of this study was to investigate the relationship between increasing output power levels and clot fragmentation during high-intensity focused ultrasound (HIFU)-induced thrombolysis. METHODS: A HIFU headsystem, designed for brain applications in humans, was used for this project. A human calvarium was mounted inside the water-filled hemispheric transducer. Artificial thrombi were placed inside the skull and located at the natural focus point of the transducer. Clots were exposed to a range of acoustic output power levels from 0 to 400 W. The other HIFU operating parameters remained constant. To assess clot fragmentation, three filters of different mesh pore sizes were used. To assess sonothrombolysis efficacy, the clot weight loss was measured. RESULTS: No evidence of increasing clot fragmentation was found with increasing acoustic intensities in the majority of the study groups of less than 400 W. Increasing clot lysis could be observed with increasing acoustic output powers. CONCLUSION: Transcranial sonothrombolysis could be achieved in vitro within seconds in the absence of tPA and without producing relevant clot fragmentation, using acoustic output powers of <400 W.

9.
Cerebrovasc Dis ; 33(3): 262-71, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-22261817

RESUMEN

BACKGROUND AND PURPOSE: The primary aim of this study was to investigate the diagnostic accuracy and time frames for neurological and transcranial color-coded sonography (TCCS) assessments in a prehospital '911' emergency stroke situation by using portable duplex ultrasound devices to visualize the bilateral middle cerebral arteries (MCAs). METHODS: This study was conducted between May 2010 and January 2011. Patients who had sustained strokes in the city of Regensburg and the surrounding area in Bavaria, Germany, were enrolled in the study. After a '911 stroke code' call had been dispatched, stroke neurologists with expertise in ultrasonography rendezvoused with the paramedic team at the site of the emergency. After a brief neurological assessment had been completed, the patients underwent TCCS with optional administration of an ultrasound contrast agent in cases of insufficient temporal bone windows or if the agent had acute therapeutic relevance. The ultrasound studies were performed at the site of the emergency or in the ambulance during patient transport to the admitting hospital. Relevant timelines, such as the time from the stroke alarm to patient arrival at the hospital and the duration of the TCCS, were documented, and positive and negative predictive values for the diagnosis of major MCA occlusion were assessed. RESULTS: A total of 113 patients were enrolled in the study. MCA occlusion was diagnosed in 10 patients. In 9 of these 10 patients, MCA occlusion could be visualized using contrast-enhanced or non-contrast-enhanced TCCS during patient transport and was later confirmed using computed tomography or magnetic resonance angiography. One MCA occlusion was missed by TCCS and 1 atypical hemorrhage was misdiagnosed. Overall, the sensitivity of a 'field diagnosis' of MCA occlusion was 90% [95% confidence interval (CI) 55.5-99.75%] and the specificity was 98% (95% CI 92.89-99.97%). The positive predictive value was 90% (95% CI 55.5-99.75%) and the negative predictive value was 98% (95% CI 92.89-99.97%). The mean time (standard deviation) from ambulance dispatch to arrival at the patient was 12.3 min (7.09); the mean time for the TCCS examination was 5.6 min (2.2); and the overall mean transport time to the hospital was 53 min (18). CONCLUSION: Prehospital diagnosis of MCA occlusion in stroke patients is feasible using portable duplex ultrasonography with or without administration of a microbubble contrast agent. Prehospital neurological as well as transcranial vascular assessments during patient transport can be performed by a trained neurologist with high sensitivity and specificity, perhaps opening an additional therapeutic window for sonothrombolysis or neuroprotective strategies.


Asunto(s)
Ambulancias , Servicios Médicos de Urgencia/métodos , Accidente Cerebrovascular/diagnóstico por imagen , Ultrasonografía Doppler Transcraneal/instrumentación , Anciano , Anciano de 80 o más Años , Estudios de Factibilidad , Femenino , Alemania , Humanos , Masculino , Arteria Cerebral Media/diagnóstico por imagen , Valor Predictivo de las Pruebas , Estudios Retrospectivos , Sensibilidad y Especificidad , Factores de Tiempo
10.
Transl Stroke Res ; 3(3): 397-407, 2012 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-23275798

RESUMEN

The goal of this study was to develop an in vivo sonothrombolysis model for stroke research. The rabbit carotid artery has average vessel diameters similar to human M1/M2 segments and allows generation of a thrombotic occlusion using various kinds of thrombus material as well as thrombus placement under visual control. It further allows real-time monitoring of flow and clot mechanics during the sonothrombolysis procedure using high-frequency diagnostic ultrasound. In the present study, the model will be introduced and first results to show feasibility using diagnostic as well as high-intensity focused ultrasound will be presented.

11.
Cerebrovasc Dis ; 28(4): 365-70, 2009.
Artículo en Inglés | MEDLINE | ID: mdl-19641311

RESUMEN

BACKGROUND: The main aim was to study the effects of ultrasound (US) alone, in combination with an US contrast agent (UCA), tissue plasminogen activator (tPA), or the combination of both upon blood clots. METHODS: In order to learn about sonothrombolysis with diagnostic duplex US, a simplified in vitro test model, using human whole blood clots in Petri dishes, was established. RESULTS: A total of 286 blood clots were analyzed. Improved sonothrombolysis due to insonation with diagnostic duplex US could be achieved, whether it was used alone or in combination with tPA. Although already described, a beneficial effect of UCA microbubbles on sonothrombolysis could not be confirmed due to the study design. CONCLUSION: Diagnostic duplex US improves thrombolysis significantly, even when it is used without tPA. To study the effect of UCA microbubbles on sonothrombolysis appropriately, any experimental design should provide continuous replenishment of microbubbles at the target site.


Asunto(s)
Coagulación Sanguínea/efectos de los fármacos , Fibrinolíticos/farmacología , Terapia Trombolítica/métodos , Trombosis/terapia , Activador de Tejido Plasminógeno/farmacología , Terapia por Ultrasonido , Ultrasonografía Doppler Dúplex , Terapia Combinada , Medios de Contraste , Productos de Degradación de Fibrina-Fibrinógeno/metabolismo , Fluorocarburos , Humanos , Microburbujas , Proyectos Piloto , Trombosis/sangre , Trombosis/diagnóstico por imagen , Factores de Tiempo
12.
Cerebrovasc Dis ; 26(6): 659-63, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-18984953

RESUMEN

BACKGROUND: To test whether portable duplex ultrasound devices can be used in a prehospital '911' emergency situation to assess intracranial arteries. METHODS: Non-contrast-enhanced transcranial duplex ultrasound studies were performed either immediately at the site of the emergency (i.e. private home) or after transfer into the emergency helicopter/ambulance vehicle. RESULTS: A total of 25 patients were enrolled. In 5/25 cases, intracranial vessels could not be visualized due to insufficient quality of the temporal bone window. In 20/25 cases, bilateral visualization and Doppler flow measurements of the middle cerebral artery could be assessed in a mean time less than 2 min. CONCLUSION: Emergency assessment of intracranial arteries using portable duplex ultrasound devices is feasible shortly after arrival at the patient's site.


Asunto(s)
Servicios Médicos de Urgencia/métodos , Accidente Cerebrovascular/diagnóstico por imagen , Ultrasonografía Doppler Transcraneal , Ambulancias Aéreas , Ambulancias , Diagnóstico Diferencial , Diagnóstico Precoz , Medicina de Emergencia , Estudios de Factibilidad , Alemania , Humanos , Infarto de la Arteria Cerebral Media/diagnóstico por imagen , Persona de Mediana Edad , Infarto del Miocardio/diagnóstico , Neurología , Grupo de Atención al Paciente , Sistemas de Atención de Punto , Convulsiones/diagnóstico , Factores de Tiempo
13.
Ultrasound Med Biol ; 34(6): 973-80, 2008 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-18255216

RESUMEN

In the scope of therapeutic ultrasound applications in the adult brain, such as sonothrombolysis in stroke, a better understanding of the intracranial acoustic properties during insonation through the temporal bone is warranted. Innovative ultrasound imaging techniques, like transcranial duplex sonography, may open new avenues to apply ultrasound for therapeutic purposes and to visually monitor the effect using the same device. The aim was to study the transcranial sound field aberrations and the changes of acoustic parameters, using a high-end duplex machine. Six cadaver skulls were insonated through the temporal bone window, using a diagnostic duplex ultrasound device. The measurements were done in a water tank, using a needle hydrophone to assess and compute acoustic parameters, such as peak intensity, peak-to-peak, peak-positive, peak-negative acoustic pressure, beam area etc. in a 2-D plane. It could be shown that the absorption and wavefront distortion effects of the temporal bone are variable among different skulls. Because of signal absorption of the bone, the mechanical index of the incident ultrasound wave drops by a factor > or =10 in most cases. However, the beam area might be increased by a factor of almost 4, because of phase aberration (i.e., defocusing). (


Asunto(s)
Interpretación Estadística de Datos , Ultrasonografía Doppler Transcraneal/métodos , Acústica , Anciano , Humanos , Trombosis Intracraneal/terapia , Masculino , Persona de Mediana Edad , Hueso Temporal/diagnóstico por imagen , Terapia Trombolítica/métodos , Terapia por Ultrasonido/métodos , Ultrasonografía Doppler Transcraneal/instrumentación
14.
Neurosurgery ; 60(4 Suppl 2): 382-6; discussion 386-7, 2007 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-17415178

RESUMEN

OBJECTIVE: To study the feasibility of intraoperative ultrasound using the phase inversion harmonic imaging (PIHI) technique. METHODS: Eight patients with intracranial middle cerebral artery aneurysms and five patients with arteriovenous malformations were studied after written informed consent. A first ultrasound study was performed through the intact dura mater after cranial trepanation to assess the pathology, its feeding artery, and downstream segments. A second ultrasound study was performed immediately after intervention to monitor the success of the procedure. All patients were studied using a Siemens Sonoline Antares ultrasound machine (Siemens Medical Solutions USA, Inc., Malvern, PA) before and after intravenous administration of an ultrasound contrast agent (Optison; GE Healthcare, Milwaukee, WI). Other than conventional brightness mode, PIHI is sensitive to the nonlinear acoustic response of tissue, and especially to ultrasound contrast agent microbubbles. The latter enables contrast-specific vascular imaging. RESULTS: PIHI provided anatomically detailed information. In combination with an ultrasound contrast agent, angiography-like views of the vascular pathologies, including their surrounding vessels, could be obtained. Flow velocities in afferent and downstream vascular segments, as well as inside the pathology, could be assessed. Flow dynamics inside the aneurysm sac or the arteriovenous malformation could be studied in real-time. Postintervention, contrast-enhanced PIHI could be used to immediately monitor the success of the surgical procedure. CONCLUSION: PIHI enables intraoperative visualization and morphological assessment of neurovascular pathologies, such as middle cerebral artery aneurysms or arteriovenous malformations. In combination with an ultrasound contrast agent, the flow dynamics of these lesions can be displayed in real-time.


Asunto(s)
Aneurisma Intracraneal/diagnóstico por imagen , Malformaciones Arteriovenosas Intracraneales/diagnóstico por imagen , Ultrasonografía Doppler en Color/instrumentación , Ultrasonografía Intervencional/instrumentación , Velocidad del Flujo Sanguíneo , Circulación Cerebrovascular , Medios de Contraste/administración & dosificación , Estudios de Factibilidad , Humanos , Internet , Aneurisma Intracraneal/cirugía , Malformaciones Arteriovenosas Intracraneales/cirugía , Periodo Intraoperatorio , Ultrasonografía Doppler en Color/métodos , Ultrasonografía Intervencional/métodos , Grabación en Video
15.
Ultrasound Med Biol ; 32(9): 1307-13, 2006 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-16965970

RESUMEN

The aim was to evaluate the potential of contrast-enhanced ultrasound to visualize the hemodynamics in intracranial aneurysms during neurosurgical intervention and to quantify the ultrasound data using digital particle image velocimetry (DPIV) technique. Aneurysms were scanned through the intact dura mater, preclipping and again postclipping after closure of the dura. After intravenous injection of Optison, angio-like views of the vascular tree surrounding the aneurysm, including the aneurysm sac, were obtained. Single ultrasound contrast agent microbubbles could be visualized in the aneurysm sac and the flow dynamics could be assessed in vivo. Spatial and temporal distributions of the velocity in the aneurysm and in the parent vessels were measured with DPIV using the backscattered signals from the microbubbles. Subsequently, the fluid stresses, vorticity, circulation, etc., were calculated from the velocity fields. We demonstrate in this paper that intraoperative contrast-enhanced ultrasound can be used to quantify the flow dynamics within an aneurysm.


Asunto(s)
Circulación Cerebrovascular , Aneurisma Intracraneal/diagnóstico por imagen , Cuidados Intraoperatorios/métodos , Albúminas , Velocidad del Flujo Sanguíneo , Medios de Contraste , Ecoencefalografía/métodos , Fluorocarburos , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Aneurisma Intracraneal/fisiopatología , Aneurisma Intracraneal/cirugía , Microburbujas , Arteria Cerebral Media/diagnóstico por imagen , Arteria Cerebral Media/cirugía
16.
Stroke ; 36(10): 2283-5, 2005 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-16141430

RESUMEN

BACKGROUND AND PURPOSE: The purpose of this study was to assess brain perfusion with an ultrasound contrast-specific imaging mode and to prove if the results are comparable between 2 centers using a standardized study protocol. METHODS: A total of 32 individuals without known cerebrovascular disease were included in the study. Perfusion studies were performed ipsilaterally in an axial diencephalic plane after intravenous administration of 0.75 mL of Optison. Offline time intensity curves (TIC) were generated in different anatomic regions. Both centers used identical study protocols, ultrasound machines, and contrast agent. RESULTS: In both centers, the comparison of the parameter time to peak intensity (TPI) revealed significantly shorter TPIs in the main vessel structures compared with any parenchymal region of interest (ROI), whereas no significant differences were seen between the parenchymal ROIs. The parameter peak intensity (PI) varied widely interindividually in both centers, whereas the inter-ROI comparison revealed statistical significance (P < 0.05) in most of the cases according to the following pattern: (1) lentiforme nucleus > thalamus and white matter region, (2) thalamus > white matter region, and (3) main vessel > any parenchymal structure. Similar results were achieved in both centers independently. CONCLUSIONS: The study demonstrates that brain perfusion assessment with an ultrasound contrast-specific imaging mode is comparable between different centers using the same study protocol.


Asunto(s)
Encéfalo/patología , Ultrasonografía Doppler Transcraneal/métodos , Adulto , Circulación Cerebrovascular , Medios de Contraste/farmacología , Cuerpo Estriado/patología , Humanos , Interpretación de Imagen Asistida por Computador , Microburbujas , Persona de Mediana Edad , Perfusión , Reproducibilidad de los Resultados , Tálamo/patología , Factores de Tiempo , Ultrasonido
17.
Ultrasound Med Biol ; 31(8): 1001-6, 2005 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-16085089

RESUMEN

The goal was to develop an ultrasound contrast agent-specific imaging mode that offers an angiography-like view of the intracranial arteries and enables lower mechanical index MI settings compared to conventional transcranial duplex sonography. We studied 12 patients with transcranial ultrasound angiography (t USA) via the temporal bone window after an IV bolus injection of a perfluorocarbon-based microbubble contrast agent (Imagent). The aim was to display the intracranial vessel segments of the middle cerebral artery (M1, M2 and M3), the anterior cerebral artery (A1 and A2), the posterior cerebral artery (P1, P2 and P3) and the internal carotid artery (C1/2 and C3/4). t USA is a B-mode phase inversion imaging technique that uses wideband harmonic signals for image generation. We demonstrate, in this report, that t USA provides detailed anatomical display at native B-mode spatial resolution with fewer artifacts, yielding improved delineation of intracranial vessels that are in the 1- to 2-mm range.


Asunto(s)
Arterias Carótidas/diagnóstico por imagen , Arterias Cerebrales/diagnóstico por imagen , Ultrasonografía Doppler Transcraneal/métodos , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Medios de Contraste , Fluorocarburos , Humanos , Hidrocarburos Bromados , Aumento de la Imagen/métodos , Aneurisma Intracraneal/diagnóstico por imagen , Persona de Mediana Edad
18.
J Ultrasound Med ; 24(8): 1071-6, 2005 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-16040821

RESUMEN

OBJECTIVE: Paradoxical embolization by cardiac right-to-left shunts (RLS) is increasingly recognized as an important factor for embolic stroke. Contrast-enhanced transcranial Doppler sonography (ce-TCDS) is an established diagnostic tool for RLS detection but is frequently limited because of an inadequate temporal acoustic bone window. The purpose of this study was to determine whether extracranial sonography (ECS) using harmonic frequencies improves detection of RLS. METHODS: Extracranial color duplex sonography using harmonic frequencies enables visualization of even single ultrasound contrast agent microbubbles because of oscillation. Patients with stroke and positive RLS findings on transesophageal echocardiography underwent a simultaneous extracranial and transcranial sonographic examination of the proximal common carotid artery (CCA) and middle cerebral artery (MCA) on the same side. A Valsalva strain was performed for 10 seconds after intravenous bolus injection of a galactose-based nontranspulmonary contrast agent. The B-mode frame sequences of the transverse plane of the CCA obtained by harmonic ECS and the ce-TCDS recordings of high-intensity transient signals from the MCA were analyzed offline. RESULTS: In all patients with RLS, the shunts could be identified by harmonic ECS. A close correlation could be seen between the count of visualized microbubbles in the CCA and the number of high-intensity transient signals detected on ce-TCDS in the ipsilateral MCA. CONCLUSIONS: The results of this study indicate that contrast-enhanced ultrasound harmonic imaging of the CCA using a Valsalva strain might be an optional screening tool for detection of cardiac RLS in patients with insufficient acoustic bone windows.


Asunto(s)
Arteria Carótida Interna/diagnóstico por imagen , Defectos del Tabique Interatrial/diagnóstico por imagen , Ultrasonografía Doppler en Color , Ultrasonografía Doppler Transcraneal , Medios de Contraste , Ecocardiografía Transesofágica , Embolia Paradójica/diagnóstico por imagen , Embolia Paradójica/etiología , Estudios de Factibilidad , Defectos del Tabique Interatrial/complicaciones , Humanos , Embolia y Trombosis Intracraneal/diagnóstico por imagen , Embolia y Trombosis Intracraneal/etiología , Masculino , Microburbujas , Persona de Mediana Edad , Polisacáridos , Estadísticas no Paramétricas
19.
J Ultrasound Med ; 23(8): 1035-40, 2004 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-15284461

RESUMEN

OBJECTIVE: To validate the potential of ultrasonographic depletion imaging for semiquantitatively visualizing cerebral parenchymal perfusion with contrast burst depletion imaging (CODIM) in comparison with phase inversion harmonic depletion imaging (PIDIM) in healthy volunteers. METHODS: Thirteen healthy adults were examined with both CODIM and PIDIM in accordance with previously described criteria. In addition to the perfusion coefficient, the time to decrease image intensity to 10% above equilibrium intensity from the initial value and the relative error (deviation of measured data from the fitted model) were evaluated to compare the reliability of both techniques in 3 different regions of interest. RESULTS: Perfusion coefficient values did not show significantly differing values in both groups (1.57-1.64 * 10(-2) s(-1) for CODIM and 1.42-1.58 * 10(-2) s(-1) for PIDIM). The relative error was significantly smaller in the PIDIM group (0.38-0.53 for CODIM and 0.18-0.25 for PIDIM; P < .002). CONCLUSIONS: Phase inversion harmonic depletion imaging proved to be more reliable than CODIM because values of the relative error were significantly lower in PIDIM even in this relatively small cohort. This is of interest because the underlying technique, phase inversion harmonic imaging, is more widely available than contrast burst imaging.


Asunto(s)
Encéfalo/irrigación sanguínea , Ecoencefalografía/métodos , Adulto , Encéfalo/diagnóstico por imagen , Circulación Cerebrovascular , Medios de Contraste/administración & dosificación , Femenino , Fluorocarburos/administración & dosificación , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Masculino , Microburbujas , Persona de Mediana Edad , Valores de Referencia , Reproducibilidad de los Resultados , Estadísticas no Paramétricas , Tomografía Computarizada por Rayos X/métodos
20.
J Neuroimaging ; 13(4): 303-6, 2003 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-14569821

RESUMEN

BACKGROUND AND PURPOSE: The aim of this study was to test a new ultrasound software tool to assess pathological perfusion in a brain tumor patient. METHODS: Tissue harmonic imaging (THI) enables an improved depiction of brain morphology, employing nonlinear parenchyma and ultrasound contrast agent (UCA) backscatter information. With specialized software, morphological information can be separated from perfusion information. Both can be superimposed at a preferred mixing ratio in a single image. RESULTS: Using THI and a perfluoropropane-based UCA, a pathologic perfusion pattern described by abnormal perfused areas in the tumor region could be demonstrated. After superimposing morphologic and perfusion information, subtle structural tumor inhomogeneities were depicted. Craniopharyngioma structure and perfusion defect were confirmed by T2-weighted and perfusion-weighted magnetic resonance imaging. CONCLUSION: Transcranial duplex sonography in combination with contrast specific imaging methods might be helpful to visualize perfusion defects without loss of morphological information.


Asunto(s)
Encéfalo/irrigación sanguínea , Craneofaringioma/diagnóstico por imagen , Neoplasias Hipofisarias/diagnóstico por imagen , Ultrasonografía Doppler Transcraneal , Adulto , Albúminas , Circulación Cerebrovascular/fisiología , Medios de Contraste , Femenino , Fluorocarburos , Humanos , Microesferas , Ultrasonografía Doppler Transcraneal/métodos
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