Ultrasound in medicine & biology
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Ultrasound Med Biol · Jan 2010
Cerebral blood flow characteristics and biometry in fetuses undergoing prenatal intervention for aortic stenosis with evolving hypoplastic left heart syndrome.
Children with hypoplastic left heart syndrome (HLHS) are at risk for neurodevelopmental dysfunction; prenatal factors may play a role in this predilection. Cerebral blood flow profiles are abnormal in fetuses with HLHS, raising the possibility that cerebral hemodynamics in utero may be related to neurodevelopmental abnormalities. Prenatal aortic valvuloplasty for fetal aortic stenosis with evolving HLHS is technically feasible and improves left heart hemodynamics. ⋯ Cerebral blood flow characteristics are abnormal in mid-gestation fetuses with evolving HLHS, suggesting low cerebral vascular impedance. The mechanisms and significance of these abnormalities are unknown. Prenatal aortic valvuloplasty did not have a major impact on these indices. (E-mail: doff.mcelhinney@cardio.chboston.org).
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Ultrasound Med Biol · Jan 2010
Molecules of various pharmacologically-relevant sizes can cross the ultrasound-induced blood-brain barrier opening in vivo.
Focused ultrasound (FUS) is hereby shown to noninvasively and selectively deliver compounds at pharmacologically relevant molecular weights through the opened blood-brain barrier (BBB). A complete examination on the size of the FUS-induced BBB opening, the spatial distribution of the delivered agents and its dependence on the agent's molecular weight were imaged and quantified using fluorescence microscopy. BBB opening in mice (n=13) was achieved in vivo after systemic administration of microbubbles and subsequent application of pulsed FUS (frequency: 1.525MHz, peak-rarefactional pressure in situ: 570 kPa) to the left murine hippocampus through the intact skin and skull. ⋯ However, high concentrations of 70 kDa dextran appeared more punctated throughout the targeted region. In conclusion, FUS combined with microbubbles opened the BBB sufficiently to allow passage of compounds of at least 70 kDa, but not greater than 2000 kDa into the brain parenchyma. This noninvasive and localized BBB opening technique could, thus, provide a unique means for the delivery of compounds of several magnitudes of kDa that include agents with shown therapeutic promise in vitro but whose in vivo translation has been hampered by their associated BBB impermeability. (E-mail: ek2191@columbia.edu).
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Ultrasound Med Biol · Nov 2009
A rotating cylinder phantom for flow and tissue color Doppler testing.
Ultrasound Doppler using two-dimensional (2D) techniques is commonly used to study blood flow and myocardial tissue motion. This use includes measurement of velocity and time intervals, often in relation to the electrocardiogram (ECG) signal. 2D Doppler is frequently considered a real-time technique but in reality the acquisition time can be as long as 200 ms per image. ⋯ The phantom can produce constant velocities for velocity testing, as well as accelerating movement for testing the timing characteristics of ultrasound systems. Our investigation shows that the cylinder phantom is especially suitable for timing measurements in 2D Doppler imaging and that time delays between the Doppler signals and the ECG signal exist in the tested ultrasound system.
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Ultrasound Med Biol · Oct 2009
New transcranial Doppler index in infants with hydrocephalus: transsystolic time in clinical practice.
Raised intracranial pressure (ICP) in infants with hydrocephalus may cause (ir)reversible damage to the brain parenchyma but can be present without clinical signs and/or symptoms. Therefore, new, favorably noninvasive, detection methods are needed to distinguish between compensated hydrocephalus with normal intracranial pressure and slowly progressive hydrocephalus with increased intracranial pressure. Because early ischemic changes in the brain parenchyma are associated with increased intracranial pressure, transcranial Doppler (TCD) indices may be useful to detect increased intracranial pressure in infants with hydrocephalus. ⋯ TST has a strong correlation with the ICP (p<0.005). Measuring TST with TCD can be helpful in the decision-making process about whether to perform CSF diversion in infants with hydrocephalus. Because TST is related solely to the relative changes in the flow velocity caused by intracranial physical properties, it has a closer relation to ICP than the PI and the RI.
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Ultrasound Med Biol · Sep 2009
Transthoracic ultrasonography in predicting the outcome of small-bore catheter drainage in empyemas or complicated parapneumonic effusions.
Thoracic sonography has been advocated as being complementary to small-bore catheter drainage in pleural effusions. However, it is not known whether the initial sonographic appearances of empyemas or complicated parapneumonic effusions (CPPEs) can predict the outcomes of small-bore catheter drainage for these pleural insults. This retrospective study investigated the outcomes of patients who had been diagnosed with empyema and CPPE and had received ultrasound-guided small-bore catheter (size from 12F to 16F) drainage in a tertiary university hospital from September 2005 to August 2007. ⋯ Moreover, patients with complex septated sonographic patterns also had higher intensive care unit admission rates compared with nonseptated sonographic patterns (22/81, 27%, vs. 8/60, 13%, respectively; p=0.0047), as well as infection-related mortality rates (17/81, 21% vs. 4/60, 7%, respectively; p=0.018). The appearance of sonographic septation is a useful sign to help predict the outcome of small-bore catheter drainage in cases of empyemas or CPPEs. Patients with a complex septated sonographic pattern have a poorer prognosis for a successful outcome, higher ICU admission rate and a higher mortality rate.