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Ultrasound Beam (ultrasound + beam)
Selected AbstractsAutomated Volumetric Flow Quantification Using Angle-Corrected Color Doppler ImageECHOCARDIOGRAPHY, Issue 5 2004Beomjin Kim Ph.D. We have developed a fully automated method for measuring volumetric blood flow with angle-corrected blood velocity from a color Doppler image. By computing the blood flow vector through a conduit, the angle of incidence between the direction of ultrasound beam and the direction of blood flow can be measured to correct the underestimated blood velocity. This correction immediately contributes to the improvement of measurement accuracy. The developed method also enhances the conduit identification procedure that is one of the most important factors affecting the accuracy of volumetric measurement. To evaluate the validity of the developed algorithm, experimental studies had been applied to 21 healthy subjects and 10 patients. Volumetric flows were measured from a color Doppler image of the left ventricular outflow track, which were compared with blood volumes that were measured by traditional pulsed-wave (PW)-Doppler technique. The mean stroke volume difference between two methods was ,0.45 ± 11.7 (mean ± SD). The proposed algorithm is a viable method for determining blood flow volume in an automated fashion. (ECHOCARDIOGRAPHY, Volume 21, July 2004) [source] The learning process of the hydrolocalization technique performed during ultrasound-guided regional anesthesiaACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 4 2010S. BLOC Background: Because poor echogenicity of the needle remains a safety issue, we decided to analyze the learning process of the hydrolocalization technique (Hloc) performed to continuously identify needle-tip anatomical position during many ultrasound-guided regional anesthesia procedures. Methods: Ten senior anesthesiologists naïve to the Hloc agreed to participate in the study. They were requested to perform 40 out-of-plane (OOP) approach ultrasound-guided axillary blocks (AB) each using the Hloc. The Hloc, which is a needle-tip localization principle, was performed by means of repetitive injections of a small amount of a local anesthetic solution (0.5,1 ml) under an ultrasound beam. Details of the learning process and skill acquisition of the Hloc were derived from the following parameters: the duration of block placement, a measure of the perceived difficulty of needle-tip visualization, a measure of block placement difficulty, and the amount of local anesthetics solution required for the technique. Results: Four hundred ABs were performed. The success rate of an ultrasound-guided AB was 98%. The Hloc was successful in all patients. Skill acquisition over time of the Hloc was associated with a significant reduction of both the duration and the perceived difficulty of ABs placement. Apprenticeship data revealed that 20 blocks were required to successfully place AB within 5 min in most cases using the Hloc. Conclusion: The Hloc performed during the OOP approach of ultrasound-guided regional anesthesia is a simple technique with a relatively short learning process feasible for efficient placement of ABs. [source] First-trimester sonography: Is the fetus exposed to high levels of acoustic energy?,JOURNAL OF CLINICAL ULTRASOUND, Issue 5 2007Eyal Sheiner MD Abstract Purpose. As a form of energy, diagnostic ultrasound has bioeffects on living tissues. The thermal index (TI), TIS (TI for soft tissue), TIB (TI for bone), TIC (TI for cranial bone) expresses the potential for rise in temperature at the ultrasound beam's focal point. The mechanical index (MI) indicates the potential for the ultrasound beam to induce inertial cavitation in tissues. The goal of this study was to characterize the acoustic output of clinical ultrasound instruments, as expressed by TI and MI, during routine first-trimester sonographic examinations. Methods. A prospective observational study was conducted. First-trimester patients were randomly selected from those scheduled for viability scans. An obstetrician collected data. Sonographers were blinded to the data being sought, which included gestational age, duration of the examination, and every variation in the MI and TI during each sonographic examination. Results. A total of 52 first-trimester examinations were evaluated. The mean gestational age was 8.9 ± 1.9 weeks. The mean duration of the sonographic examinations was 8.1± 1.4 minutes. During the examinations, there were 178 MI variations (mean ± SD, 0.9 ± 0.3) and 167 TI variations (mean ± SD, 0.2 ± 0.1). Conclusion. First-trimester sonographic examinations are associated with a negligible rise in TI. © 2007 Wiley Periodicals, Inc. J Clin Ultrasound, 2007 [source] Transabdominal sonography of the normal gastroesophageal junction in childrenJOURNAL OF CLINICAL ULTRASOUND, Issue 6 2001Francesco Esposito MD Abstract Purpose Because sonography identifies abnormalities of the gastroesophageal junction, it is essential to understand the normal sonographic anatomy. The aim of this study was to determine the normal sonographic appearance of the gastroesophageal junction and its variations and to provide measurements of the abdominal esophagus in asymptomatic, healthy children. Methods In this prospective study, 124 healthy children (75 boys and 49 girls), aged 2 days,12 years, underwent abdominal sonography. With the patient in a supine position, the transducer was placed under the xiphoid and the ultrasound beam was directed cephalad through the window of the left lobe of the liver. The length of the abdominal esophagus was measured from the point at which it penetrated the diaphragm to the gastroesophageal junction. The thickness was measured on the anterior wall at the midpoint of the abdominal esophagus. Results The gastroesophageal junction was identified by sonography in all of the children. The mean length of the abdominal portion of the esophagus ranged from 18 mm in the newborns to 34 mm in children older than 6 years. The wall thickness ranged from 2.4 mm to 5.7 mm. Conclusions Our results indicate that visualization of the gastroesophageal junction and measurement of the abdominal esophagus are readily achievable with real-time sonography in healthy children. © 2001 John Wiley & Sons, Inc. J Clin Ultrasound 29:326,331, 2001. [source] | ||||||||||