Ultrasound in medicine & biology
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Ultrasound Med Biol · Jun 2006
Sympathectomy-like effects of brachial plexus block in arteriovenous access surgery.
We used color Doppler ultrasonography to prospectively study the effects of supraclavicular brachial plexus block (BPB) on blood flow and vein diameter in patients undergoing arteriovenous access surgery. BPB might produce a sympathectomy-like effect that could have a role in improving patencty. Thirty-one consecutive patients who underwent arteriovenous access surgery with BPB were studied prospectively, in addition to 5 patients with BPB having other operations and 5 patients undergoing general anesthesia for elective surgery. ⋯ In the nonaccess BPB group the PI remained low after the block for at least 5 h. Brachial plexus block causes significant venous dilation and a significant decrease in the pulsatility index. This appears to be due to a beneficial sympathectomy-like effect of the block that might prevent early failure and improve patency in vascular access surgery.
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Ultrasound Med Biol · Nov 2005
A needle tracking device for ultrasound guided percutaneous procedures.
A novel tracking device is proposed for measuring the position and orientation of a needle with respect to an ultrasound probe. This device is intended to guide an operator during a percutaneous needle insertion so that the needle trajectory can be visually aligned with the target before insertion. The tracking device uses a pair of cameras to track the needle location so that a standard needle can be used without attaching a separate sensor to the needle. ⋯ A series of tests show that an overall error of 3.1 +/- 1.8 mm is achieved with two commercial cameras and an error of 6.5 +/- 5.7 mm is achieved with two inexpensive consumer cameras. An analysis of the source of errors reveals that the errors arise from all of the calibration steps. Overall system accuracy is therefore determined by both the quality of the cameras and the performance of calibration.
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Ultrasound Med Biol · Jan 2005
Low back pain, the stiffness of the sacroiliac joint: a new method using ultrasound.
Abnormal biomechanical properties of the sacroiliac joints are believed to be related to low back and pelvic pain. Presently, physiotherapists judge the condition of the sacroiliac joints by function and provocation tests, and palpation. No objective measuring device is available. ⋯ Vibration amplitudes from 0.25 microm to 3 microm could be measured. The US technique was able to detect bone vibration in vivo. In conclusion, the principle based on US waves can be used to develop a new measurement tool, instrumental in studying the relation between the biomechanical properties of the sacroiliac joints and low back pain.
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Ultrasound Med Biol · Nov 2004
Validation of a sensitivity performance index test protocol and evaluation of colour Doppler sensitivity for a range of ultrasound scanners.
The ability to detect flow is the most crucial aspect of an ultrasound (US) system because, if flow cannot be detected, no other aspect of performance matters. The objectives of this study were to validate a Doppler "sensitivity performance index," a figure of merit, and to determine if it could be used to differentiate colour Doppler sensitivity performance in scanners of varying complexity. The sensitivity performance index was developed to give a combined measure of related aspects of sensitivity, such as the lowest detectable velocity, the vessel size and the penetration depth. ⋯ The effect of instrument settings was assessed for two transducers, the 4C3 curvilinear general-purpose transducer (Aspen) and the PVM375AT curvilinear general-purpose transducer (Nemio). The colour Doppler sensitivity performance was found to be significantly dependent on the clutter filter setting and the output power setting for both transducers tested. Users need to be aware of the effect of these settings on the colour Doppler sensitivity performance of their US scanner when interpreting the clinical significance of the colour Doppler information.
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Ultrasound Med Biol · Nov 2004
Intracranial collateral pathways assessed by contrast-enhanced three-dimensional transcranial color-coded sonography.
Individual parameter settings of the duplex machine and limited insonation angles may influence the visualization of small intracranial vessels in 2-D transcranial color-coded sonography. The aim of our study was the morphologic assessment of intracranial collateral pathways (first auditory area celiac artery, A(1)CA; anterior communicating artery, AComA; first parental generation celiac artery P(1)CA; posterior communicating artery, PComA) using 3-D transcranial color-coded duplex sonography (3-D TCCS) and digital subtraction angiography (DSA). A total of 41 patients with large vessel disease and 30 patients who had suffered subarachnoidal hemorrhage (mean age 52 +/- 15 years) were involved. ⋯ Compared with angiography or magnetic resonance (MR) angiography, 3-D sonography can be performed easily in critically ill patients on stroke units or intensive care units. The noninvasive assessment of the circle of Willis may be useful in patients who undergo carotid surgery without angiography. Combined with hemodynamic information, contrast-enhanced 3-D TCCS might increase the diagnostic impact of transcranial US.