Este trabajo es apoyado en parte por el Comando de Material de Investigación Médica del Ejército de los Estados Unidos bajo W81XWH-08-1-0503 y W81XWH-12-1-0066, por las subvenciones de la AHA no 0655441U y 15SDG25740015, así como por NIH R21 HL081892, R21 HL130899, R21 HL089175, RC1 DK087365, R01 DK098526, R01 DK118964, R01 CA140338, R01 CA234428, por Lantheus Medical Imaging y por GE Healthcare, Oslo, Noruega.

Las juntas de revisión institucional de la Universidad Thomas Jefferson y el Hospital de la Universidad de Pensilvania aprobaron este protocolo. El protocolo cumple con la Ley de Portabilidad y Responsabilidad del Seguro de Salud. La Administración de Alimentos y Medicamentos de los Estados Unidos (FDA) emitió una aprobación de nuevo fármaco en investigación (IND # 124,465 a F. Forsberg) para este protocolo. GE Healthcare (Oslo, Noruega) proporcionó la UCA utilizada en esta investigación (Sonazoid; Tabla 1). El sonazoide no está aprobado por la FDA para ninguna aplicación clínica en los Estados Unidos, por lo que era necesario un IND. Otras UCA con aprobación de la FDA1 se pueden usar fuera de etiqueta a discreción del médico tratante si se considera potencialmente clínicamente útil.
NOTA: El protocolo completo y el plan de análisis estadístico están disponibles en https:// clinicaltrials.gov/ct2/show/NCT02489045. Número de registro del ensayo: NCT # 02489045.
1. Preparación de la asignatura
<ol><li>Revise las alergias o intolerancias conocidas a los medicamentos del sujeto, en particular cualquier alergia conocida a la UCA que se esté utilizando.</li>
	<li>Excluir sujetos con condiciones cardiopulmonares inestables o que son generalmente médicamente inestables.</li>
	<li>Coloque al sujeto en una camilla en posición supina.</li>
	<li>Coloque una cánula de calibre 18 a 22 en una vena del brazo derecho o izquierdo del sujeto para la infusión de UCA.</li>
	<li>Asegúrese de que los servicios de emergencia (por ejemplo, un carro de choque) estén disponibles dentro del hospital en caso de reacciones adversas agudas. NOTA: Los UCA son muy seguros con reacciones graves de tipo anafilactoide reportadas a una tasa de menos del 0.01%. 20</li>
</ol>2. Preparación de UCA (Específico para Sonazoide)
<ol><li>Preparar tres (3) viales con 48 μL de microburbujas (6 mL) para cada sujeto resuspendiendo de acuerdo con las instrucciones del fabricante. El UCA se suministra como polvo seco dentro de viales sellados de 10 ml. El espacio de cabeza de los viales contiene perfluorobutano.<ol><li>Perforar el tapón del vial de UCA con un quimiospike.</li>
		<li>Retire la tapa protectora del puerto de la jeringa del quimiospike y agregue 2 ml de agua estéril.</li>
		<li>Con la jeringa adherida al quimiopico, agite inmediatamente el producto durante 1 minuto para garantizar un producto homogéneo.</li>
		<li>Extraiga el producto en la jeringa y vuelva a inyectar el producto en el vial. Esto es para evitar la dilución del producto debido al volumen de espacio muerto en el quimiospike.</li>
		<li>Retire la jeringa del puerto de la jeringa y vuelva a colocar la tapa protectora. La concentración del UCA reconstituido es de 8 μL microburbujas/mL.</li>
		<li>Repita el procedimiento de reconstitución para los otros 2 viales.</li>
	</ol></li>
	<li>Use solución salina (solución de NaCl al 0,9%) para llenar los tubos de conexión antes de conectarlos a una llave de paso de 3 vías. La llave de paso se conectará al tubo de extensión que conduce a la cánula.</li>
	<li>Extraiga los tres (3) viales de UCA suspendido en una jeringa de 10 ml, colóquela en una bomba de jeringa al mismo nivel o debajo del paciente, y conéctela directamente a la llave de paso.</li>
	<li>Después de la ecografía inicial y después de que se haya abierto la llave de paso, infundir la solución de NaCl a una velocidad de 120 ml / hora y coinfundir sonazoide a una velocidad de 0.024 μL por kg de peso corporal por minuto (velocidad de infusión de suspensión de 0.18 ml / kg / hora). NOTA: Esta velocidad de infusión fue seleccionada en base a las experiencias previas de nuestro grupo con infusión de Sonazoide en sujetos con hipertensión portal sometidos a SHAPE13,14,21. El procedimiento exacto de resuspensión y el método de infusión variarán según la UCA utilizada.</li>
</ol>3. Imágenes de ultrasonido iniciales
<ol><li>Encienda un escáner de ultrasonido (por ejemplo, Logiq E10, versión R2) y seleccione la sonda curvilínea C1-6-D.</li>
	<li>Seleccione un ajuste preestablecido abdominal en el ecógrafo y utilice una matriz curvi-lineal (típicamente con un ancho de banda de 1-6 o 2-8 MHz) para adquirir imágenes en escala de grises tanto del portal como de una vena hepática en el mismo plano de imagen y a profundidades similares (Figura 1). Esto generalmente se logra mejor a través de un enfoque subcostal.</li>
	<li>Optimizar las imágenes en base a las Buenas Prácticas Clínicas y tener cuidado de seleccionar la región de la vena hepática lejos de la vena cava inferior para evitar la influencia del flujo retrógrado.</li>
</ol>4. Imágenes SHI y SHAPE
<ol><li>Active el modo de imagen de contraste SHI en modo de pantalla dual (es decir, ejecutando el modo B en tiempo real y SHI simultáneamente) utilizando el botón del panel táctil Contraste subarmónico y active el modo Contraste. A continuación, seleccione SUBH-AM en el control giratorio.<ol><li>Realizar SHI a una frecuencia de transmisión de 2,5 MHz y obtener las señales recibidas a 1,25 MHz.</li>
		<li>Utilice la forma de pulsos para maximizar la generación de señales de microburbujas subarmónicas, como una onda cuadrada filtrada binomial de ventana gaussiana con Sonazoide,21 pero esto depende del escáner y la UCA. 17 NOTA: Es posible que la elección de la frecuencia de imagen y la forma del pulso no esté disponible para los usuarios finales.</li>
	</ol></li>
	<li>Confirme la permeabilidad de la vena portal y hepática, así como la presencia de microburbujas, que pueden tardar hasta 1-2 minutos desde el inicio de la infusión.</li>
	<li>Active el código de optimización automatizada de SHAPE para optimizar SHAPE compensando la profundidad y la atenuación variables. 22,23 Seleccione Análisis TIC en el panel táctil seguido de F6 y, a continuación, el botón k.</li>
	<li>El algoritmo de optimización SHAPE adquirirá datos subarmónicos para cada nivel de salida acústica. Una vez completada la adquisición de datos, coloque un ROI en la vena del portal en la ventana de muestra de contraste (arriba a la izquierda en la pantalla Análisis TIC).<ol><li>Trazar los datos subarmónicos promedio dentro del ROI en función de la salida acústica y ajustar una curva logística a los datos. Seleccione el punto de inflexión de esta curva (o más bien el pico en la curva derivada que se muestra debajo) como la potencia optimizada, ya que se ha demostrado que este es el punto de mayor sensibilidad SHAPE. 22,23 Uno de estos conjuntos de curvas se muestra en la Figura 2.</li>
	</ol></li>
	<li>Ajuste la potencia de salida acústica al valor identificado en el paso 4.4.1, lo que garantizará el cambio máximo en las amplitudes subarmónicas en función de la presión ambiental (es decir, maximizar la sensibilidad de SHAPE).</li>
	<li>Adquirir datos subarmónicos de las microburbujas (es decir, SHAPE) en segmentos de 5-15 s durante la infusión de la suspensión UCA (Figura 3).</li>
</ol>5. Tratamiento de datos SHAPE
<ol><li>Una vez adquirido el cine-loop SHI optimizado (paso 5.6), seleccione "TIC Analysis" (Análisis TIC) en el panel táctil.<ol><li>Asegúrese de que "Seguimiento de movimiento" esté activado en el panel táctil, que ajusta la posición ROI de cada fotograma para compensar cualquier respiración u otro movimiento.</li>
		<li>Asegúrese de que dB está seleccionado como unidad para el eje Y en las trazas de la ventana de análisis.</li>
	</ol></li>
	<li>En la ventana de muestra de contraste (arriba a la izquierda de la pantalla) seleccione ROI idénticos (las regiones elípticas son predeterminadas) dentro de las venas hepática y porta. En la ventana de análisis (a la derecha) la señal subarmónica (en dB) dentro de cada recipiente se promedia en todas las tramas en un ancho de banda de 0,5 MHz alrededor de 1,25 MHz.</li>
	<li>Calcule el gradiente SHAPE final (en dB) como la diferencia en la señal subarmónica media entre el ROI de la vena hepática y la vena porta. Según los estudios actuales, el punto de operación óptimo para identificar CSPH es -0.11 dB y la ecuación de regresión lineal es HVPG = 0.81 x SHAPE + 9.43. 14 Es importante tener en cuenta que este límite y ecuación dependen tanto del escáner como de la UCA.</li>
</ol>

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R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chronic+liver+disease:+noninvasive+subharmonic+aided+pressure+estimation+of+hepatic+venous+pressure+gradient.">Chronic liver disease: noninvasive subharmonic aided pressure estimation of hepatic venous pressure gradient.</a> Radiology. 268 (2), 581-588 (2013).</li><li>Gupta, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diagnosing+portal+hypertension+with+noninvasive+subharmonic+pressure+estimates+from+an+ultrasound+contrast+agent.">Diagnosing portal hypertension with noninvasive subharmonic pressure estimates from an ultrasound contrast agent.</a> Radiology. , (2020).</li><li>Nam, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monitoring+neoadjuvant+chemotherapy+for+breast+cancer+by+using+three-dimensional+subharmonic+aided+pressure+estimation+and+imaging+with+US+contrast+agents:+preliminary+experience.">Monitoring neoadjuvant chemotherapy for breast cancer by using three-dimensional subharmonic aided pressure estimation and imaging with US contrast agents: preliminary experience.</a> Radiology. 285 (1), 53-62 (2017).</li><li>Dave, J. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-invasive+intra-cardiac+pressure+measurements+using+subharmonic-aided+pressure+estimation:+proof+of+concept+in+humans.">Non-invasive intra-cardiac pressure measurements using subharmonic-aided pressure estimation: proof of concept in humans.</a> Ultrasound in Medicine and Biology. 43 (11), 2718-2724 (2017).</li><li>Esposito, C., Dickie, K., Forsberg, F., Dave, J. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Developing+an+interface+and+investigating+optimal+parameters+for+real-time+intra-cardiac+subharmonic+aided+pressure+estimation.">Developing an interface and investigating optimal parameters for real-time intra-cardiac subharmonic aided pressure estimation.</a> IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control. , (2020).</li><li>Bosch, J., Groszmann, R. J., Shah, V. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolution+in+the+understanding+of+the+pathophysiological+basis+of+portal+hypertension:+How+changes+in+paradigm+are+leading+to+successful+new+treatments.">Evolution in the understanding of the pathophysiological basis of portal hypertension: How changes in paradigm are leading to successful new treatments.</a> Journal of Hepatology. 62, 121-130 (2015).</li><li>Procopet, B., Berzigotti, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diagnosis+of+cirrhosis+and+portal+hypertension:+imaging,+non-invasive+markers+of+fibrosis+and+liver+biopsy.">Diagnosis of cirrhosis and portal hypertension: imaging, non-invasive markers of fibrosis and liver biopsy.</a> Gastroenterology Report. 5 (2), 79-89 (2017).</li><li>Dietrich, C. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Guidelines+and+good+clinical+practice+recommendations+for+contrast-enhanced+ultrasound+(CEUS)+in+the+liver-update+2020+WFUMB+in+cooperation+with+EFSUMB,+AFSUMB,+AIUM,+and+FLAUS.">Guidelines and good clinical practice recommendations for contrast-enhanced ultrasound (CEUS) in the liver-update 2020 WFUMB in cooperation with EFSUMB, AFSUMB, AIUM, and FLAUS.</a> Ultrasound in Medicine and Biology. , (2020).</li><li>Gupta, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+pulse+shaping+on+subharmonic+aided+pressure+estimation+in+vitro+and+in+vivo.">Effect of pulse shaping on subharmonic aided pressure estimation in vitro and in vivo.</a> Journal of Ultrasound in Medicine. 36 (1), 3-11 (2017).</li><li>Dave, J. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+the+implementation+of+an+automated+acoustic+output+optimization+algorithm+for+subharmonic+aided+pressure+estimation.">On the implementation of an automated acoustic output optimization algorithm for subharmonic aided pressure estimation.</a> Ultrasonics. 53 (4), 880-888 (2013).</li><li>Gupta, I., Eisenbrey, J. R., Machado, P., Stanczak, M., Wallace, K., Forsberg, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+factors+impacting+subharmonic-+aided+pressure+estimation+(SHAPE).">On factors impacting subharmonic- aided pressure estimation (SHAPE).</a> Ultrasonic Imaging. 41 (1), 35-48 (2019).</li><li>Eisenbrey, J. R., Daecher, A., Kramer, M. 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Forsberg, Gupta, Wallace y Eisenbrey tienen una patente pendiente sobre la tecnología SHAPE. El Dr. Wallace es empleado de GE.

La medición no invasiva y precisa de las presiones dentro del cuerpo humano ha sido durante mucho tiempo un objetivo clínico importante pero difícil de alcanzar. El protocolo para mediciones SHAPE presentado aquí logra este objetivo. El componente más crítico del procedimiento SHAPE es el algoritmo de optimización, ya que los datos subarmónicos no adquiridos en la potencia acústica óptima se correlacionarán mal con las presiones hidrostáticas. 17,22,23 La versión inicial de este soft...

Varios agentes de contraste de ultrasonido (UCA) diferentes están aprobados para uso clínico en cardiología (en particular opacificación ventricular izquierda) y radiología (en particular caracterización de lesiones hepáticas adultas y pediátricas) en todo el mundo. 1 La sensibilidad y la especificidad de las imágenes de ultrasonido pueden mejorarse mediante la inyección intravenosa (IV) de microburbujas llenas de gas (diámetro < 10 μm) encapsuladas por una cubierta lipídica o proteica como UCA que atraviesan toda la vasculatura y mejoran las señales hasta en 30 dB. 1 Estos UCA no solo mejoran las señales de ultrasonido retrodispersadas, sino que a presiones acústicas suficientes (> 200 kPa) también actúan como osciladores no lineales. Por lo tanto, se producirán componentes de energía significativos en los ecos recibidos que van desde frecuencias subarmónicas y armónicas hasta ultraarmónicas. 1,2 Estos componentes de señal no lineales pueden extraerse de ecos de tejido y burbujas lineales (por ejemplo, utilizando inversión de pulso) y usarse para crear modalidades de imagen específicas de contraste, como imágenes subarmónicas (SHI), que reciben a la mitad de la frecuencia de transmisión (es decir, a f 0/2). 3 Nuestro grupo ha demostrado en ensayos clínicos en humanos que el SHI puede detectar el flujo sanguíneo en neovasos y arteriolas asociados con una variedad de tumores y tejidos. 4,5,6,7,8,9 
Hemos abogado por el uso de UCAs no como trazadores vasculares, sino como sensores para la estimación no invasiva de la presión en el sistema circulatorio mediante la monitorización de las variaciones de amplitud de burbujas de contraste subarmónicas. 10 Esta técnica innovadora, llamada estimación de presión asistida por subarmónicos (SHAPE), se basa en la correlación lineal inversa entre la amplitud de las señales subarmónicas y la presión hidrostática (hasta 186 mmHg) medida para la mayoría de los UCA comerciales in vitro (r2 > 0.90) como se resume en la Tabla 1. 10,11 Sin embargo, cabe señalar que no todas las UCA presentan este comportamiento. En particular, se ha demostrado que las señales subarmónicas de la UCA SonoVue (conocida como Lumason en los Estados Unidos) aumentan inicialmente con aumentos de presión hidrostática, seguidos de una meseta y una fase decreciente. 12 No obstante, SHAPE ofrece la posibilidad de permitir que los gradientes de presión en el corazón y en todo el sistema cardiovascular, así como la presión del líquido intersticial en los tumores, se obtengan de forma no invasiva. 13,14,15,16,17 Recientemente, implementamos una versión en tiempo real del algoritmo SHAPE en un escáner de ultrasonido comercial y proporcionamos una prueba de concepto de que SHAPE puede proporcionar estimaciones de presión in vivo con errores de menos de 3 mmHg en los ventrículos izquierdo y derecho de los pacientes. 16,17
La mayor experiencia con SHAPE hasta la fecha ha sido para diagnosticar la hipertensión portal con más de 220 sujetos inscritos y los hallazgos iniciales confirmados en un ensayo multicéntrico. 13,14 La hipertensión portal se define como un aumento en el gradiente de presión entre la vena porta y las venas hepáticas o la vena cava inferior superior a 5 mmHg, mientras que la hipertensión portal clínicamente significativa (CSPH) requiere un gradiente o su equivalente, un gradiente de presión venosa hepática (GPVV) ≥ 10 mmHg. 18 La CSPH se asocia con un mayor riesgo de várices gastroesofágicas, ascitis, descompensación hepática, descompensación postoperatoria y carcinoma hepatocelular. 18,19 Los pacientes que desarrollan ascitis tienen una mortalidad del 50% a tres años y los que desarrollan infección espontánea del líquido ascitis tienen una mortalidad del 70% al año. Los pacientes con cirrosis tienen una incidencia anual del 5-10% de formación de várices gastroesofágicas y una incidencia anual de hemorragia del 4-15%; Cada episodio hemorrágico conlleva hasta un 20% de riesgo de muerte. 18,19
Este manuscrito describe cómo llevar a cabo un estudio SHAPE utilizando equipos disponibles comercialmente y UCA con énfasis en la identificación de la hipertensión portal en el hígado de los pacientes. El procedimiento de calibración crítico requerido para lograr la mayor sensibilidad para estimar los cambios de presión se explica en detalle.

<table>
	<tbody>
		<tr>
			<td>2 mL syringe</td>
			<td>Becton Dickinson</td>
			<td>309637</td>
			<td>Used for reconstituting Sonazoid</td>
		</tr>
		<tr>
			<td>10 mL saline-filled syringe</td>
			<td>Becton Dickinson</td>
			<td>306545</td>
			<td>Used for flushing line to verify IV access</td>
		</tr>
		<tr>
			<td>500 mL saline bag</td>
			<td>Baxter Healthcare Corp</td>
			<td>2131323</td>
			<td>Used for co-infusion with Sonazoid</td>
		</tr>
		<tr>
			<td>C1-6-D curvi-linear proble</td>
			<td>GE Healthcare</td>
			<td>H40472LT</td>
			<td>Used for liver imaging</td>
		</tr>
		<tr>
			<td>Chemoprotect Spike</td>
			<td>Codan USA</td>
			<td>C355</td>
			<td>Chemospike used for reconstituting Sonazoid</td>
		</tr>
		<tr>
			<td>Discofix C Blue</td>
			<td>B. Braun Medical Inc</td>
			<td>16494C</td>
			<td>3-way stopcock</td>
		</tr>
		<tr>
			<td>Intrafix Safeset 180 cm</td>
			<td>B. Braun Medical Inc</td>
			<td>4063000</td>
			<td>Infusion tubing</td>
		</tr>
		<tr>
			<td>Logiq E10 ultrasound scanner</td>
			<td>GE Healthcare</td>
			<td>H4928US</td>
			<td>Used for conventional ultrasound imaging as well as for SHI and SHAPE</td>
		</tr>
		<tr>
			<td>Luer lock 10 mL syringe</td>
			<td>Becton Dickinson</td>
			<td>300912</td>
			<td>For infusion of Sonazoid</td>
		</tr>
		<tr>
			<td>Medfusion 3500 syringe pump</td>
			<td>Smiths Medical</td>
			<td>3500-500</td>
			<td>Used for infusing Sonazoid at 0.18 mL/kg/hour</td>
		</tr>
		<tr>
			<td>Perfusor-leitung tubing 150 mm</td>
			<td>B. Braun Medical Inc</td>
			<td>8722960</td>
			<td>Extension line enabling syringe connection to patient&#39;s IV access</td>
		</tr>
		<tr>
			<td>SHI/SHAPE software</td>
			<td>GE Healthcare</td>
			<td>H4920CI</td>
			<td>Contrast-specific imaging software</td>
		</tr>
		<tr>
			<td>Sigma Spectrum infusion system</td>
			<td>Baxter Healthcare Corp</td>
			<td>35700BAX</td>
			<td>Pump used for co-infusing saline at 120 mL/hour</td>
		</tr>
		<tr>
			<td>Sonazoid</td>
			<td>GE Healthcare</td>
			<td></td>
			<td>Gas-filled microbubble based ultrasound contrast agent</td>
		</tr>
		<tr>
			<td>sterile water, 2 mL</td>
			<td>B. Braun Medical Inc</td>
			<td></td>
			<td>Used for reconstituting Sonazoid</td>
		</tr>
		<tr>
			<td>ultrasound gel</td>
			<td>Cardinal Health</td>
			<td>USG-250BT</td>
			<td>Used for contact between probe and patient</td>
		</tr>
		<tr>
			<td>Venflon IV cannula 22GA</td>
			<td>Becton Dickinson</td>
			<td>393202</td>
			<td>Cannula needle for obtaining IV access</td>
		</tr>
	</tbody>
</table>

contrast-enhanced subharmonic aided pressure estimation (shape) using ultrasound imaging with a focus on identifying portal hypertension

La medición no invasiva y precisa de las presiones dentro del cuerpo humano ha sido durante mucho tiempo un objetivo clínico importante pero difícil de alcanzar. Los agentes de contraste para imágenes de ultrasonido son microburbujas encapsuladas llenas de gas (diámetro < 10 μm) que atraviesan toda la vasculatura y mejoran las señales hasta en 30 dB. Estas microburbujas también producen oscilaciones no lineales a frecuencias que van desde el subarmónico (la mitad de la frecuencia de transmisión) hasta armónicos más altos. La amplitud subarmónica tiene una relación lineal inversa con la presión hidrostática ambiental. Aquí se presenta un sistema de ultrasonido capaz de realizar una estimación de presión asistida por subarmónicos (SHAPE) en tiempo real. Durante la infusión de agente de contraste por ultrasonido, se activa un algoritmo para optimizar las salidas acústicas. Después de esta calibración, las señales de microburbujas subarmónicas (es decir, SHAPE) tienen la mayor sensibilidad a los cambios de presión y se pueden usar para cuantificar la presión de forma no invasiva. La utilidad del procedimiento SHAPE para identificar la hipertensión portal en el hígado es el énfasis aquí, pero la técnica tiene aplicabilidad en muchos escenarios clínicos.

Al igual que con todos los exámenes de imágenes de ultrasonido, la primera consideración para la SHAPE hepática es obtener las mejores imágenes de escala de grises de referencia posibles de la región objetivo y asegurarse (utilizando imágenes Doppler) de que no haya derivaciones venosas portales intrahepáticas u otras anomalías vasculares presentes. En el caso de la imagen hepática para el diagnóstico de la hipertensión portal, la clave es visualizar tanto la vena porta como una vena hepática a la misma prof...

Watch this Scientific Journal Video about Contrast-Enhanced Subharmonic Aided Pressure Estimation SHAPE Using Ultrasound Imaging with a Focus on Identifying Portal Hypertension at JoVE.com

Contrast-Enhanced Subharmonic Aided Pressure Estimation SHAPE Using Ultrasound Imaging with a Focus on Identifying Portal Hypertension

Se describe un protocolo para estimar de forma no invasiva las presiones ambientales utilizando imágenes de ultrasonido subarmónico de microburbujas de contraste infundidas (después de la calibración adecuada) con ejemplos de pacientes humanos con enfermedad hepática crónica.

Estimación de la presión asistida por subarmónicos (SHAPE) con contraste mejorado mediante imágenes de ultrasonido con un enfoque en la identificación de la hipertensión portal

Noninvasive, accurate measurement of pressures within the human body has long been an important but elusive clinical goal. Contrast agents for ultrasound ...

contrast-enhanced-subharmonic-aided-pressure-estimation-shape-using

Research

JoVE Journal

Bioengineering

Contrast-Enhanced Subharmonic Aided Pressure Estimation (SHAPE) Using Ultrasound Imaging with a Focus on Identifying Portal Hypertension

2.2K vistas.  Thomas Jefferson University. Se describe un protocolo para estimar de forma no invasiva las presiones ambientales utilizando imágenes de ultrasonido subarmónico de microburbujas de contraste infundidas (después de la calibración adecuada) con ejemplos de pacientes humanos con enfermedad hepática crónica.

Video: Contrast-Enhanced Subharmonic Aided Pressure Estimation SHAPE Using Ultrasound Imaging with a Focus on Identifying Portal Hypertension

Shape Memory Polymers for Active Cell Culture

Shape memory polymers (SMPs) are a class of "smart" materials that have the ability to change from a fixed, temporary shape to a pre-determined permanent shape upon the application of a stimulus such as heat1-5. In a typical shape memory cycle, the SMP is first deformed at an elevated temperature that is higher than its transition temperature, Ttrans [either the melting temperature (Tm) or the glass transition temperature (Tg)]. The deformation is elastic in nature and mainly leads to a reduction in conformational entropy of the constituent network chains (following the rubber elasticity theory). The deformed SMP is then cooled to a temperature below its Ttrans while maintaining the external strain or stress constant. During cooling, the material transitions to a more rigid state (semi-crystalline or glassy), which kinetically traps or "freezes" the material in this low-entropy state leading to macroscopic shape fixing. Shape recovery is triggered by continuously heating the material through Ttrans under a stress-free (unconstrained) condition. By allowing the network chains (with regained mobility) to relax to their thermodynamically favored, maximal-entropy state, the material changes from the temporary shape to the permanent shape.
Cells are capable of surveying the mechanical properties of their surrounding environment6. The mechanisms through which mechanical interactions between cells and their physical environment control cell behavior are areas of active research. Substrates of defined topography have emerged as powerful tools in the investigation of these mechanisms. Mesoscale, microscale, and nanoscale patterns of substrate topography have been shown to direct cell alignment, cell adhesion, and cell traction forces7-14. These findings have underscored the potential for substrate topography to control and assay the mechanical interactions between cells and their physical environment during cell culture, but the substrates used to date have generally been passive and could not be programmed to change significantly during culture. This physical stasis has limited the potential of topographic substrates to control cells in culture.
Here, active cell culture (ACC) SMP substrates are introduced that employ surface shape memory to provide programmed control of substrate topography and deformation. These substrates demonstrate the ability to transition from a temporary grooved topography to a second, nearly flat memorized topography. This change in topography can be used to control cell behavior under standard cell culture conditions.

A method for developing cell culture substrates with the ability to change topography during culture is described. The method makes use of smart materials known as shape memory polymers that have the ability to memorize a permanent shape. This concept is adaptable to a wide range of materials and applications.

Los polímeros con memoria de forma para el cultivo celular activo

Shape memory polymers (SMPs) are a class of "smart" materials that have the ability to change from a fixed, temporary shape to a pre-determined permanent ...

Investigación

Bioingeniería

Wideband Optical Detector of Ultrasound for Medical Imaging Applications

Optical sensors of ultrasound are a promising alternative to piezoelectric techniques, as has been recently demonstrated in the field of optoacoustic imaging. In medical applications, one of the major limitations of optical sensing technology is its susceptibility to environmental conditions, e.g. changes in pressure and temperature, which may saturate the detection. Additionally, the clinical environment often imposes stringent limits on the size and robustness of the sensor. In this work, the combination of pulse interferometry and fiber-based optical sensing is demonstrated for ultrasound detection. Pulse interferometry enables robust performance of the readout system in the presence of rapid variations in the environmental conditions, whereas the use of all-fiber technology leads to a mechanically flexible sensing element compatible with highly demanding medical applications such as intravascular imaging. In order to achieve a short sensor length, a pi-phase-shifted fiber Bragg grating is used, which acts as a resonator trapping light over an effective length of 350 &#181;m. To enable high bandwidth, the sensor is used for sideway detection of ultrasound, which is highly beneficial in circumferential imaging geometries such as intravascular imaging. An optoacoustic imaging setup is used to determine the response of the sensor for acoustic point sources at different positions.

Optical detection of ultrasound is impractical in many imaging scenarios because it often requires stable environmental conditions. We demonstrate an optical technique for ultrasound sensing in volatile environments with miniaturization and sensitivity levels appropriate for optoacoustic imaging in restrictive scenarios, e.g. intravascular applications.

Banda ancha Detector óptico de ultrasonido para aplicaciones de imágenes médicas

Optical sensors of ultrasound are a promising alternative to piezoelectric techniques, as has been recently demonstrated in the field of optoacoustic ...

Microfluidic Fabrication of Polymeric and Biohybrid Fibers with Predesigned Size and Shape

A &#8220;sheath&#8221; fluid passing through a microfluidic channel at low Reynolds number can be directed around another &#8220;core&#8221; stream and used to dictate the shape as well as the diameter of a core stream.&#160;Grooves in the top and bottom of a microfluidic channel were designed to direct the sheath fluid and shape the core fluid.&#160;By matching the viscosity and hydrophilicity of the sheath and core fluids, the interfacial effects are minimized and complex fluid shapes can be formed.&#160;Controlling the relative flow rates of the sheath and core fluids determines the cross-sectional area of the core fluid.&#160;Fibers have been produced with sizes ranging from 300 nm to ~1 mm, and fiber cross-sections can be round, flat, square, or complex as in the case with double anchor fibers. Polymerization of the core fluid downstream from the shaping region solidifies the fibers.&#160;Photoinitiated click chemistries are well suited for rapid polymerization of the core fluid by irradiation with ultraviolet light.&#160;Fibers with a wide variety of shapes have been produced from a list of polymers including liquid crystals, poly(methylmethacrylate), thiol-ene and thiol-yne resins, polyethylene glycol, and hydrogel derivatives. Minimal shear during the shaping process and mild polymerization conditions also makes the fabrication process well suited for encapsulation of cells and other biological components.

Two adjacent fluids passing through a grooved microfluidic channel can be directed to form a sheath around a prepolymer core; thereby&#160;determining both shape and cross-section. Photoinitiated polymerization, such as thiol click chemistry, is well suited for rapidly solidifying the core fluid into a microfiber with predetermined size and shape.

Fabricación Microfluídica De Fibras Poliméricas Y Biohíbridas Con Tamaño y Forma Prediseñados

A &#8220;sheath&#8221; fluid passing through a microfluidic channel at low Reynolds number can be directed around another &#8220;core&#8221; stream and ...

Fabrication of a Bioactive, PCL-based "Self-fitting" Shape Memory Polymer Scaffold

Tissue engineering has been explored as an alternative strategy for the treatment of critical-sized cranio-maxillofacial (CMF) bone defects. Essential to the success of this approach is a scaffold that is able to conformally fit within an irregular defect while also having the requisite biodegradability, pore interconnectivity and bioactivity. By nature of their shape recovery and fixity properties, shape memory polymer (SMP) scaffolds could achieve defect &#8220;self-fitting.&#8221; In this way, following exposure to warm saline (~60 &#186;C), the SMP scaffold would become malleable, permitting it to be hand-pressed into an irregular defect. Subsequent cooling (~37 &#186;C) would return the scaffold to its relatively rigid state within the defect. To meet these requirements, this protocol describes the preparation of SMP scaffolds prepared via the photochemical cure of biodegradable polycaprolactone diacrylate (PCL-DA) using a solvent-casting particulate-leaching (SCPL) method. A fused salt template is utilized to achieve pore interconnectivity. To realize bioactivity, a polydopamine coating is applied to the surface of the scaffold pore walls. Characterization of self-fitting and shape memory behaviors, pore interconnectivity and in vitro bioactivity are also described.

Fabrication of a Bioactive, PCL-based &quot;Self-fitting&quot; Shape Memory Polymer Scaffold

Scaffolds capable of fitting within cranio-maxillofacial (CMF) bone defects while exhibiting osteoconductivity and bioactivity are of interest. This protocol describes the preparation of a shape memory scaffold based on polycaprolactone diacrylate (PCL-DA) using a solvent-casting particulate-leaching (SCPL) method employing a fused salt template and application of a bioactive polydopamine coating.

La fabricación de una memoria de forma &quot;Auto-ajuste&quot; basado en PCL Bioactivos, Polymer Andamios

Tissue engineering has been explored as an alternative strategy for the treatment of critical-sized cranio-maxillofacial (CMF) bone defects. Essential to ...

Real-time Monitoring of High Intensity Focused Ultrasound (HIFU) Ablation of In Vitro Canine Livers Using Harmonic Motion Imaging for Focused Ultrasound (HMIFU)

Harmonic Motion Imaging for Focused Ultrasound (HMIFU) is a technique that can perform and monitor high-intensity focused ultrasound (HIFU) ablation. An oscillatory motion is generated at the focus of a 93-element and 4.5 MHz center frequency HIFU transducer by applying a 25 Hz amplitude-modulated signal using a function generator. A 64-element and 2.5 MHz imaging transducer with 68kPa peak pressure is confocally placed at the center of the HIFU transducer to acquire the radio-frequency (RF) channel data. In this protocol, real-time monitoring of thermal ablation using HIFU with an acoustic power of 7 W on canine livers in vitro is described. HIFU treatment is applied on the tissue during 2 min and the ablated region is imaged in real-time using diverging or plane wave imaging up to 1,000 frames/second. The matrix of RF channel data is multiplied by a sparse matrix for image reconstruction. The reconstructed field of view is of 90&#176; for diverging wave and 20 mm for plane wave imaging and the data are sampled at 80 MHz. The reconstruction is performed on a Graphical Processing Unit (GPU) in order to image in real-time at a 4.5 display frame rate. 1-D normalized cross-correlation of the reconstructed RF data is used to estimate axial displacements in the focal region. The magnitude of the peak-to-peak displacement at the focal depth decreases during the thermal ablation which denotes stiffening of the tissue due to the formation of a lesion. The displacement signal-to-noise ratio (SNRd) at the focal area for plane wave was 1.4 times higher than for diverging wave showing that plane wave imaging appears to produce better displacement maps quality for HMIFU than diverging wave imaging.

Real-time Monitoring of High Intensity Focused Ultrasound HIFU Ablation of In Vitro Canine Livers Using Harmonic Motion Imaging for Focused Ultrasound HMIFU

This article describes real-time monitoring of HIFU ablation in canine liver with high frame rate ultrasound imaging using diverging and plane wave imaging. Harmonic Motion Imaging for Focused Ultrasound is used to image the decrease of acoustic radiation force induced displacement in the ablated region.

Monitoreo en tiempo real de Ultrasonido de alta intensidad (HIFU) Ablación de<em&gt; In Vitro</em&gt; Canine hígados Uso Movimiento armónico Imaging para Ultrasonido Focalizado (HMIFU)

Harmonic Motion Imaging for Focused Ultrasound (HMIFU) is a technique that can perform and monitor high-intensity focused ultrasound (HIFU) ablation. An ...

Double Emulsion Generation Using a Polydimethylsiloxane (PDMS) Co-axial Flow Focus Device

Double emulsions are useful in a number of biological and industrial applications in which it is important to have an aqueous carrier fluid. This paper presents a polydimethylsiloxane (PDMS) microfluidic device capable of generating water/oil/water double emulsions using a coaxial flow focusing geometry that can be fabricated entirely using soft lithography. Similar to emulsion devices using glass capillaries, double emulsions can be formed in channels with uniform wettability and with dimensions much smaller than the channel sizes. Three dimensional flow focusing geometry is achieved by casting a pair of PDMS slabs using two layer soft lithography, then mating the slabs together in a clamshell configuration. Complementary locking features molded into the PDMS slabs enable the accurate registration of features on each of the slab surfaces. Device testing demonstrates formation of double emulsions from 14 &#181;m to 50 &#181;m in diameter while using large channels that are robust against fouling and clogging.

Double Emulsion Generation Using a Polydimethylsiloxane PDMS Co-axial Flow Focus Device

Microfluidic double emulsions generation typically involves devices with patterned wettability or custom-fabricated glass components. Here we describe the fabrication and testing of an all polydimethylsiloxane (PDMS) double emulsion generator that does not require surface treatment or complicated fabrication processes, and is capable of producing double emulsions down to 14 &#181;m.

Generación de doble emulsión utilizando un flujo Focus Dispositivo de polidimetilsiloxano (PDMS) Co-axial

Double emulsions are useful in a number of biological and industrial applications in which it is important to have an aqueous carrier fluid. This paper ...

Conducting Multiple Imaging Modes with One Fluorescence Microscope

Fluorescence microscopy is a powerful tool to detect biological molecules in situ and monitor their dynamics and interactions in real-time. In addition to conventional epi-fluorescence microscopy, various imaging techniques have been developed to achieve specific experimental goals. Some of the widely used techniques include single-molecule fluorescence resonance energy transfer (smFRET), which can report conformational changes and molecular interactions with angstrom resolution, and single-molecule detection-based super-resolution (SR) imaging, which can enhance the spatial resolution approximately ten&#160;to twentyfold compared to diffraction-limited microscopy. Here we present a customer-designed integrated system, which merges multiple imaging methods in one microscope, including conventional epi-fluorescent imaging, single-molecule detection-based SR imaging, and multi-color single-molecule detection, including smFRET imaging. Different imaging methods can be achieved easily and reproducibly by switching optical elements. This set-up is easy to adopt by any research laboratory in biological sciences with a need for routine and diverse imaging experiments at a reduced cost and space relative to building separate microscopes for individual purposes.

Here we present a practical guide of building an integrated microscopy system, which merges conventional epi-fluorescent imaging, single-molecule detection-based super-resolution imaging, and multi-color single-molecule detection, including single-molecule fluorescence resonance energy transfer imaging, into one set-up in a cost-efficient way.

Realización de múltiples modos de la proyección de imagen con un microscopio de fluorescencia

Fluorescence microscopy is a powerful tool to detect biological molecules in situ and monitor their dynamics and interactions in real-time. In addition to ...

Material Formation of Recombinant Spider Silks through Aqueous Solvation using Heat and Pressure

Many spiders produce seven types of silks. Six of the silks are fiber in form when produced by the spiders. These fibers are not water soluble. In order to reproduce the remarkable mechanical properties of spider silks, they must be produced in heterologous hosts as spiders are both territorial and cannibalistic. The synthetic analogs of spider silk also tend to be insoluble in aqueous solutions. Thus, a large percentage of research in recombinant spider silks rely upon organic solvents that are detrimental to large scale production of materials. Our group&#8217;s method forces the solvation of these recombinant spider silks into water. Remarkably, when these proteins are prepared using this method of heat and pressure, a wide range of material forms can be prepared from the same solution of recombinant spider silk proteins (rSSp) including: films, fibers, sponge, hydrogel, lyogel, and adhesives. This article demonstrates the production of the solvated rSSp and material forms in a manner that is more easily understood than from written materials and methods alone.

Here, we present a protocol to produce water soluble recombinant spider silk protein solutions and the material forms that can be formed from those solutions.

Formación material de la araña recombinante sedas a través de la Solvación acuosa utilizando calor y presión

Many spiders produce seven types of silks. Six of the silks are fiber in form when produced by the spiders. These fibers are not water soluble. In order ...

Patient-Specific Polyvinyl Alcohol Phantom Fabrication with Ultrasound and X-Ray Contrast for Brain Tumor Surgery Planning

Phantoms are essential tools for clinical training, surgical planning and the development of novel medical devices. However, it is challenging to create anatomically accurate head phantoms with realistic brain imaging properties because standard fabrication methods are not optimized to replicate any patient-specific anatomical detail and 3D printing materials are not optimized for imaging properties. In order to test and validate a novel navigation system for use during brain tumor surgery, an anatomically accurate phantom with realistic imaging and mechanical properties was required. Therefore, a phantom was developed using real patient data as input and 3D printing of molds to fabricate a patient-specific head phantom comprising the skull, brain and tumor with both ultrasound and X-ray contrast. The phantom also had mechanical properties that allowed the phantom tissue to be manipulated in a similar manner to how human brain tissue is handled during surgery. The phantom was successfully tested during a surgical simulation in a virtual operating room.
The phantom fabrication method uses commercially available materials and is easy to reproduce. The 3D printing files can be readily shared, and the technique can be adapted to encompass many different types of tumor.

This protocol describes the fabrication of a patient specific skull, brain and tumor phantom. It uses 3D printing to create molds, and polyvinyl alcohol (PVA-c) is used as the tissue mimicking material.

Fabricación fantasma de alcohol polivinílico específica del paciente con ultrasonido y contraste de rayos X para la planificación de la cirugía de tumor cerebral

Phantoms are essential tools for clinical training, surgical planning and the development of novel medical devices. However, it is challenging to create ...

High-Dimensionality Flow Cytometry for Immune Function Analysis of Dissected Implant Tissues

The success of implanting laboratory-grown tissue or a medical device in an individual is subject to the immune response of the recipient host. Considering an implant as a foreign body, a hostile and dysregulated immune response may result in the rejection of the implant, while a regulated response and regaining of homeostasis can lead to its acceptance. Analyzing the microenvironments of implants dissected out under in vivo or ex vivo&#160;settings can help in understanding the pattern of immune response, which can ultimately help in developing new generations of biomaterials. Flow cytometry is a well-known technique for characterizing immune cells and their subsets based on their cell surface markers. This review describes a protocol based on manual dicing, enzymatic digestion, and filtration through a cell strainer for the isolation of uniform cell suspensions from dissected implant tissue. Further, a multicolor flow cytometry staining protocol has been explained, along with steps for initial cytometer settings to characterize and quantify these isolated cells by flow cytometry.

Isolation of cells from dissected implants and their characterization by flow cytometry can significantly contribute to understanding the pattern of immune response against implants. This paper describes a precise method for the isolation of cells from dissected implants and their staining for flow cytometric analysis.