Ultrasound in medicine & biology
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Ultrasound Med Biol · Aug 2009
Sensitivity of linear endobronchial ultrasonography and guided transbronchial needle aspiration for the identification of nodal metastasis in lung cancer staging.
The aim of this study is to determine the sensitivity of real-time endobronchial ultrasonography (EBUS)-guided transbronchial needle aspiration (TBNA) in lung cancer staging. Short- and long-axis node diameters were measured during EBUS in patients referred for lung cancer staging and sensitivities for the identification of nodal malignancy at TBNA determined. Three hundred fifteen real-time EBUS-guided TBNA nodal sampling procedures were performed in 161 patients and in 87 of them, N2/N3 metastasis was confirmed (50.9%), eliminating the need for mediastinoscopy. ⋯ In 18 out of 50 patients with a normal mediastinal computed tomography (CT) scan, the technique identified enlarged nodes in the mediastinum (36%), mainly in the subcarinal region and confirmed mediastinal malignancy in 8 (10%). Real-time EBUS-guided TBNA obtains satisfactory node samples in almost 90% of cases and improves the identification of enlarged nodes in patients with a normal mediastinum at CT. If sampling all nodes with a short-axis diameter of > or =5 mm and a short- to long-axis ratio > or =0.5, a sensitivity of 100% for the cytologic identification of malignant nodes can be expected.
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Ultrasound Med Biol · Aug 2009
Reduction of echo decorrelation via complex principal component filtering.
Ultrasound motion estimation is a fundamental component of clinical and research techniques that include color flow Doppler, spectral Doppler, radiation force imaging and ultrasound-based elasticity estimation. In each of these applications, motion estimates are corrupted by signal decorrelation that originates from nonuniform target motion across the acoustic beam. In this article, complex principal component filtering (PCF) is demonstrated as a filtering technique for dramatically reducing echo decorrelation in blood flow estimation and radiation force imaging. ⋯ At the location of peak blood velocity, complex PCF improved the correlation of consecutive echo signals from an average correlation of 0.94 to 0.998. The improved echo correlation for both sonorheometry and blood flow estimation yielded motion estimates that exhibited more consistent responses with less noise. Complex PCF reduces speckle decorrelation and improves the performance of ultrasonic motion estimation.
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Ultrasound Med Biol · Aug 2009
Blood-brain barrier (BBB) disruption using a diagnostic ultrasound scanner and Definity in Mice.
The objective of this work was to determine whether diagnostic ultrasound and contrast agent could be used to transcranially and nondestructively disrupt the blood-brain barrier (BBB) in mice under ultrasound image guidance and to quantify that disruption using magnetic resonance imaging (MRI) and magnetic resonance (MR) contrast agent. Each mouse was placed under isoflurane anesthesia and the hair on top of its skull was removed before treatment. A diagnostic ultrasound transducer was placed in a water bag coupled with gel on the mouse skull. ⋯ Opening was achieved at higher frequencies than previously reported and was localized under ultrasound image guidance. A typical, ultrasound imaging mode (pulsed wave [PW] Doppler) with specific settings (transmit frequency=5.7 MHz, gate size=15 mm, pulse repetition frequency=100 Hz, system power=15%) successfully opened the BBB, which facilitates implementation using the most of commercially available clinical diagnostic scanners. Localized opening of the BBB may have potential clinical utility for the delivery of diagnostic or therapeutic agents to the brain.