ABSTRACT
Periodic quality control (QC) for ultrasound scanners checks their overall performance, reducing the risk of inaccurate diagnoses. Data from routine annual QC activity were analyzed to optimize the scheduling and the criteria of further QC programs. Among all the ultrasound scanners (68 transducers) in use at the Regional Medical Department of the Aosta Valley, which are currently tested, 48.6% showed problems, mainly (35.3%) related to defects detectable by physical and mechanical inspection. Nearly two-thirds of these problems impacted QC parameters. Failures were significantly related to the workload and to the "technological level" of the equipment. QC scheduling should therefore include a daily/weekly physical inspection in addition to a more complete, objective and software algorithms-based test, the frequency of which should be tailored on the basis of the equipment characteristics. © 2012 Wiley Periodicals, Inc. J Clin Ultrasound, 2012.
Subject(s)
Ultrasonography/instrumentation , Ultrasonography/standards , Equipment Design , Quality Control , Ultrasonography, Doppler/instrumentation , Ultrasonography, Doppler/standardsABSTRACT
Ultrasound (US) energy combined with gas-filled microbubbles has been used for several years in medical imaging. This study investigated the ability of oxygen-loaded chitosan bubbles to exchange oxygen in the presence or in the absence of US. Oxygen delivery is enhanced by sonication and both frequency and time duration of US affected the exchange kinetics.
Subject(s)
Chitosan/chemistry , Microbubbles , Oxygen/administration & dosage , Sonication/methods , Cell Line, Tumor , Humans , Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , Time Factors , UltrasonicsABSTRACT
Chitosan-coated oxygen microbubbles of average diameter 2.5 mum, narrow size distribution and spherical shape were prepared. A core-shell structure was evidenced by fluorescence microscopy using fluorescent microbubbles. Such microbubbles can be a therapeutic device for vehiculating oxygen to hypoxic tissues, provided they show proper permeability and diffusivity properties and are non-toxic. Our study proves that oxygen is efficiently delivered both in 'in vitro' and 'in vivo' preparations, and can be conveniently metabolized reversing the cellular hypoxic response. Moreover, toxic effects were investigated in human blood and in cultured cells and no evidence for them was found.
Subject(s)
Drug Carriers , Hypoxia/therapy , Microbubbles , Oxygen/therapeutic use , Animals , Cells, Cultured , Chitosan/chemistry , Eggs , Humans , Hypoxia-Inducible Factor 1, alpha Subunit/analysisABSTRACT
Doppler indices are widely used to assess normal versus pathologic haemodynamics. In obstetrics, the assessment of abnormal values in some critical compartments, such as the umbilical arteries (UA), may be crucial in the clinical management of growth-restricted foetuses. It was recently proposed that the UA should be sampled in their perivesical portion (PVC), i.e., where they surround the foetal urinary bladder. However, measurements at this site could be biased by the degree of curvature of the vessel due to bladder filling. We investigated this possibility in vivo and in vitro, i.e., measurements on rubber tubes at different radii of curvature R(c). There was significant dependence of the Doppler indices A/B and PI on the vessel curvature and insonation angle; in fact, we recorded errors of about 25% when R(c) was 10 times larger than the radius of the vessel and about 100% when R(c) was five times larger than the radius of the vessel. Therefore, measurements of the UA at the PVC site should only be performed when the foetal bladder is empty.
