Wilson Mathias Junior et al. Sharon L. Mulvagh David Costa de Souza Le Bihan Miguel Osman Dias Aguiar Eliza de Almeida Gripp Jeane Mike Tsutsui Adenalva Lima de Souza Beck Alessandra Joslin Oliveira Alex dos Santos Felix Ana Caroline Reinaldo de Oliveira Ana Clara Tude Rodrigues Ana Cristina Camarozano Wermelinger Ana Gardenia Liberato Ponte Farias, Anderson da Costa Armstrong André Luiz Cerqueira de Almeida Angele Azevedo Alves Mattoso Arnaldo Rabischoffsky Carolina Stangenhaus Claudia Gianini Monaco Colandy G. O. Nunes Dourado Daniel Furtado Vidigal Daniela do Carmo Rassi Eliza Kaori Uenishi Fábio Cañellas Moreira Fábio Michalski Velho Guilherme Loureiro Fialho Jairo Pinheiro João Batista Masson Silva Joao Cesar Nunes Sbano Joicely Melo da Costa José Luis de Castro e Silva Pretto José Luiz Barros Pena Jose Maria Del Castillo José Sebastião de Abreu Juliana Etto Rolim Karen Saori Shiraishi Sawamura Marcelo Dantas Tavares de Melo Marcelo Haertel Miglioranza Marcelo Iorio Garcia Márcio Silva Miguel Lima Marco Stephan Lofrano-Alves Maria Estefânia Bosco Otto Mohamed Hassan Saleh Monica Luiza de Alcantara Rafael Bonafim Piveta Rodrigo Bellio de Mattos Barretto Salomon Israel do Amaral Sandra Nívea dos Reis Saraiva Falcão Silvio Henrique Barberato Tatiane Mascarenhas Santiago Emerich Petros Nihoyannopoulos Michael L. Main Jordan B. Strom Andrew Appis Roxy Senior Steven B. Feinstein
Introduction
In the last two decades, new perspectives have opened for a better evaluation of cardiovascular pathophysiology, especially coronary macro- and microvascular pathophysiology, due to the development of ultrasound-enhancing agents (UEAs) based on encapsulated microbubbles prepared for intravascular injections.
These microbubbles behave similarly to red blood cells, remain exclusively intravascular, and freely circulate through the macro-and microcirculation, causing opacification of cardiac chambers and the capillary microcirculation. The primary mechanism whereby these microbubbles produce blood-pool enhancement is the introduction of multiple gas-liquid interfaces into the circulation, increasing ultrasound reflection by creating small areas with significant differences in impedance. Modern microbubbles used for diagnostic purposes are approximately 2µm in diameter (smaller than half the width of a human capillary) and resonate at frequencies used in diagnostic ultrasound for humans, around 2 MHz.
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