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Linear Transducer (linear + transducer)
Selected AbstractsAssessment of Carotid Compliance Using Real Time Vascular Ultrasound Image Analysis in Marfan SyndromeECHOCARDIOGRAPHY, Issue 4 2009Anatoli Kiotsekoglou M.D. Background: Fibrillin-1 deficiency, dysregulated cytokine transforming growth factor-,, and increased collagen deposition related to fibrillin-1 gene mutations could predispose to impaired carotid compliance (CC) in Marfan syndrome (MFS). We sought to detect any alterations in CC using the vascular image analysis system (VIA). Methods and Results: Thirty-two MFS patients, 20 men and 12 women (mean age 34.2 ± 12.05 years), and 29 controls matched for age, sex, and body surface area (BSA) were recruited. The entire length of each carotid system was initially scanned longitudinally using a 14 MHz linear transducer. Then, a stereotactic clamp held the transducer in contact with the carotid artery. Arterial diameter changes during the cardiac cycle were recorded for 1 minute from both right (RCCA) and left common carotid arteries (LCCA) separately using the VIA system. RCCA and LCCA compliance and distensibility measurements were significantly reduced in MFS patients when compared to controls, P < 0.05. RCCA and LCCA intima-media thickness did not differ between patients and controls, P > 0.05. MFS diagnosis and age were associated with reduced CC in both carotid arteries after adjusting for variables such as, sex, BSA, heart rate, beta-blockade, intima-media thickness, and aortic root size. Conclusions: Our findings showed a reduction in CC in adult patients with MFS. This could be attributed to fibrillin-1 deficiency resulting in structural abnormalities in the carotid arterial wall. [source] Evaluation of the hepatic artery anastomosis by intraoperative sonography with high-frequency transducer in right-lobe graft living donor liver transplantationJOURNAL OF CLINICAL ULTRASOUND, Issue 1 2010Han Song Mun MD Abstract Objective To describe the usefulness of intraoperative ultrasonography (IOUS) with high-frequency transducer in living donor liver transplantation (LDLT) using right-lobe graft (RLG). Method This retrospective study was approved by our institutional review board. We performed IOUS in 22 patients (17 men and 5 women, aged 51 ± 9.0 years) during LDLT with RLG using a Sequoia 512 scanner with an 8,12-MHz linear transducer. Hepatic artery (HA) anastomosis was identified on gray-scale US, and the diameter and percentage of stenosis of the anastomosis were measured. The HA was evaluated to detect thrombus or dissection in the region of anastomosis. Doppler study of the graft HA was also performed. Patients were divided into those with and without abnormalities, including thrombosis, dissection, and abnormal Doppler parameters (peak systolic velocity < 30 cm/s or > 2 m/s, resistance index < 0.5, and systolic acceleration time > 80 msec). Result On gray-scale and Doppler IOUS study, abnormalities were found in 10 of 22 patients. Diagnoses were anastomotic stenosis (n = 2), celiac stenosis (n = 1), compromise of HA inflow due to systemic hypotension (n = 1), HA thrombosis (n = 2), and HA dissection (n = 4). Re-anastomoses were done in 3 case (2 stenoses and 1 thrombosis). Uneventful postoperative recovery occurred in the other 7 patients without re-anastomosis. Conclusion IOUS with high-frequency transducer is a useful method to make an early diagnosis of HA complications of LDLT with RLG. © 2009 Wiley Periodicals, Inc. J Clin Ultrasound, 2010 [source] Sonography of the shoulder in hemiplegic patients undergoing rehabilitation after a recent strokeJOURNAL OF CLINICAL ULTRASOUND, Issue 4 2009Ya-Ping Pong MD Abstract Purpose. To examine the hemiplegic shoulders for soft-tissue injury by musculoskeletal sonography and to determine the relationship between the motor functions of the upper extremity and these injuries, which play an important role in hemiplegic shoulder pain and may impede rehabilitation. Methods. The following characteristics of 34 acute stroke patients were recorded: age, gender, height, body weight, side of hemiplegia, type and duration of stroke, Brunnstrom stage, subluxation, and degree of spasticity of the upper extremity. On the basis of the Brunnstrom stage, the patients were divided into 2 groups. Patients with stages I, II, or III were categorized under the lower Brunnstrom stage (LBS) group (n = 21), and those with stages IV, V, or VI were allocated to the higher Brunnstrom stage (HBS) group (n = 13). Both shoulders of each patient were examined by musculoskeletal sonography with a 5,10-MHz linear transducer on 2 separate occasions (i.e., at admission and 2 weeks after rehabilitation). Results. With the exception of age, there were no significant differences in the demographic and clinical characteristics of the patients in the 2 groups. Shoulder musculoskeletal sonography revealed soft-tissue injury in 7 patients (33%) and 15 patients (71%) in the LBS group at admission and 2 weeks after rehabilitation, respectively (p < 0.05), and in 4 patients (31%) in the HBS group both at admission and 2 weeks after rehabilitation. Conclusions. Acute stroke patients with poor upper limb motor functions are more prone to soft-tissue injury of the shoulder during rehabilitation. © 2009 Wiley Periodicals, Inc. J Clin Ultrasound, 2009. [source] Reverse correlation in neurophysiologyCOGNITIVE SCIENCE - A MULTIDISCIPLINARY JOURNAL, Issue 2 2004Dario Ringach Abstract This article presents a review of reverse correlation in neurophysiology. We discuss the basis of reverse correlation in linear transducers and in spiking neurons. The application of reverse correlation to measure the receptive fields of visual neurons using white noise and m-sequences, and classical findings about spatial and color processing in the cortex resulting from such measurements, are emphasized. Finally, we describe new developments in reverse correlation, including "sub-space" and categorical reverse-correlation. Recent results obtained by applying such methods in the orientation, spatial-frequency and Fourier domains have revealed the importance of cortical inhibition in the establishment of sharp tuning selectivity in single neurons. [source] | ||||||||||