Ultrasound in medicine & biology
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Ultrasound Med Biol · Oct 2004
Correlations among critical closing pressure, pulsatility index and cerebrovascular resistance.
We attempted to explore the relationships among critical closing pressure (CrCP), resistance-area product (RAP) and traditional resistance indices of cerebral hemodynamics. Twenty healthy volunteers were studied. Blood pressure was obtained with servo-controlled plethysmography. ⋯ RAP reliably reflected cerebrovascular resistance. The changes in CrCP were valuable in assessing cerebrovascular regulation. Estimating changes in CrCP and RAP provided better understanding of the nature of cerebrovascular regulation.
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Hibernating myocardium is viable myocardium that recovers after revascularization. The observation of loss of contractile proteins (myofibrils) and accumulation of glycogen in hibernating cardiomyocytes provide the basis for diagnosing hibernating myocardium. ⋯ Acoustic microscopy of normal cardiomyocytes showed intracellular linear echoes suggestive of myofibrils, and cardiomyocytes of hibernating myocardium revealed absence of myofibrils and dense intracellular echoes that corresponded to glycogen accumulation on optical microscopy. This modality of visualization allows a definitive diagnosis of hibernating myocardium.
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Ultrasound Med Biol · May 2004
Evaluation of vertebral artery hypoplasia and asymmetry by color-coded duplex ultrasonography.
Distinguishing stenosis and hypoplasia of the extracranial vertebral artery (VA) is clinically important, but there is no agreement in defining VA hypoplasia. We endeavored to attain reference values for VA flow volume by color Doppler ultrasonography (CDU), analyze age and gender effects on VA flow volume and develop a definition of VA hypoplasia. CDU was performed in 447 subjects free of cerebrovascular diseases or carotid stenosis. ⋯ We defined hypoplasia as a significant decrease in flow velocities and increase in RI for VA diameters < 0.22 cm. This definition is supported by findings of an increase in ipsilateral flow resistance (RI >/= 0.75), contralateral diameter (side-to-side diameter difference >/= 0.12 cm), and flow volume (side-to-side flow volume ratio >/= 5). This definition and these reference values may lead to better differentiation between congenital variation and steno-occlusion clinically.
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Ultrasound Med Biol · May 2004
Enhancement of needle visibility in ultrasound-guided percutaneous procedures.
The visibility of a needle in ultrasound (US)-guided percutaneous procedures is often limited by dispersion of the needle's reflections away from the probe. A needle enhancement algorithm is developed that maximizes the received reflections by steering the US beam precisely perpendicular to the needle. The resulting image clearly depicts the needle as a bright line. ⋯ Implementation of the needle-enhancement algorithm was made possible by using the programmable ultrasound platform and interface library (PUPIL). PUPIL is capable of acquiring digital images, processing the images in real-time, controlling the beam angle, and displaying the fused image. The results demonstrate significantly improved needle visibility in both breast phantoms and turkey breast samples.
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Ultrasound Med Biol · Mar 2004
Randomized Controlled Trial Clinical TrialComplex tibial fracture outcomes following treatment with low-intensity pulsed ultrasound.
A clinical study was conducted to investigate the effect of low-intensity pulsed ultrasound (US) stimulation (LIPUS) on the healing of complex tibial fractures. Thirty complex tibial fractures were randomly assigned to the treatment with LIPUS (n = 16) or by a dummy machine (sham-exposed: n = 14). The fractures were immobilized by either internal or external fixations according to the clinical indications. ⋯ There were two cases of infection in the control group. The delayed-union cases were subsequently treated by LIPUS and the infection cases were treated with standard protocol. Fracture healing in these patients was again treated by LIPUS.