A new technique, the laser-doppler flowmetry. has been used intraoperatively to measure blood flow responses in the normal brain tissue, the traumatic brain tissue and so on. The flow estimate by this technique is based on the assessment of the doppler shift of the low power laser light, which is scattered by moving red blood cells.
Brain ; Craniotomy* ; Doppler Effect ; Erythrocytes ; Homeostasis ; Laser-Doppler Flowmetry

PURPOSE: The aim of this experimental study was to evaluate whether the acoustic radiation force (ARF) is a potential source of twinkling artifacts in color Doppler images. METHODS: Color Doppler images were obtained using a clinical ultrasonic scanner (Voluson e, GE Healthcare) for a high contrast (+15 dB) circular scattering phantom at pulse repetition frequencies (PRFs) ranging from 0.1 to 13 kHz. Ultrasound transmissions resulting in ARF were measured using a hydrophone at the various PRFs considered. The influence of ARF on the appearance of twinkling colors was examined via the common parameter PRF. This methodology is based on the fact that alternating positive and negative Doppler shifts induced by the ARF are centered at a PRF twice the maximum Doppler frequency on the color scale bar, whereas the twinkling color aliasing is expected to remain similar regardless of PRF. RESULTS: Color twinkling artifacts were observed to be most conspicuous at the lowest PRF of 0.1 kHz. The extent of twinkling rapidly decreased as the PRF increased, eventually disappearing when the PRF > or =0.6 kHz. The measured ultrasound transmissions, however, were found to be insensitive to the PRF, and therefore it can be inferred that the PRF was insensitive to the ARF. CONCLUSION: Based on our experimental observations, the ARF may not be a source of color Doppler twinkling artifacts.
Acoustics* ; Artifacts* ; Doppler Effect ; Ultrasonics ; Ultrasonography ; Ultrasonography, Doppler, Color

Determination of peripheral artery disease by using a simple automatic blood pressure device with ankle-brachial indexes (ABIs) was feasible for the doctors who couldn’t use Doppler method. 219 patients were examined at Cardiovascular Department, Hospital 108 and were measured ABIs. Results: The correlations between ABI in both methods were good in left legs (r=0.66,p<0.001) and in right legs (r=0.61, p<0.001). This method is inexpensive, easy to use, and can detect peripheral artery disease in early stage
Peripheral Vascular Diseases ; Blood Pressure ; Doppler Effect ; diagnosis ; Equipment and Supplies

BACKGROUND/AIMS: Clinical validation is required to determine whether Doppler measurements are comparable before and after administering ultrasound contrast agent (USCA). The purpose of this study is to explore whether the use of USCA affects spectral Doppler analysis in recipients of liver transplantation (LT). METHODS: For this study, 36 patients were examined using Doppler ultrasonography (US) along with a contrast-enhanced US for surveillance of vascular complications after LT. The following spectral Doppler US parameters were measured before and after administration of USCA: peak systolic velocity, end-diastolic velocity, resistive index, and systolic acceleration time of the graft hepatic artery; peak flow velocity of the graft portal vein; and peak flow velocity and venous pulsatility index of the graft hepatic vein. RESULTS: The mean peak systolic and end-diastolic velocities of the hepatic artery and the peak flow velocity of the portal and hepatic veins were increased after intravenously administration of the USCA, ranging from 10% to 13%. However, the changes were not statistically significant (P=0.097, 0.103, 0.128, and 0.190, respectively). There were no significant differences in other measured parameters, including the resistive index (P=0.205) and systolic acceleration time (P=0.489) of the hepatic artery and venous pulsatility index (P=0.494) of the hepatic vein. CONCLUSIONS: The measured velocities of graft hepatic vessels tended to increase after administration of USCA, but without statistical significance. The comparison of serial Doppler parameters with or without injection of USCA is valid during Doppler surveillance in recipients of LT.
Acceleration ; Contrast Media* ; Doppler Effect ; Hepatic Artery ; Hepatic Veins ; Humans ; Liver Transplantation* ; Liver* ; Microbubbles ; Portal Vein ; Transplants ; Ultrasonography* ; Ultrasonography, Doppler

BACKGROUND AND OBJECTIVES: P300 has been studied with a variety of stimuli. However, the nature of P300 has not been investigated for deviant stimuli which change its characteristics from standard stimuli after a period of time from onset. SUBJECTS AND METHODS: Nine young adults with normal hearing participated in the study. The P300 was elicited using an oddball paradigm, the probability of standard and deviant stimuli was 80% and 20% respectively. Six stimuli were used to elicit P300, it included two pure-tones (1,000 Hz and 2,000 Hz) and four tone-complexes (tones with frequency changes). Among these stimuli, 1,000 Hz tone served as standard while others served as deviant stimuli. The P300 was recorded in five separate blocks, with one of the deviant stimuli as target in each block. Electroencephalographic was recorded from electrode sites Fz, Cz, C3, C4, and Pz. Latency and amplitude of components of the cortical auditory evoked potentials were measured at Cz. RESULTS: Waveforms obtained in the present study shows that, all the deviant stimuli elicited obligatory P1-N1-P2 for stimulus onset. 2,000 Hz deviant tone elicited P300 at a latency of 300 ms. While, tone-complexes elicited acoustic change complex (ACC) for frequency changes and finally elicited P300 at a latency of 600 ms. In addition, the results showed shorter latency and larger amplitude ACC and P300 for rising tone-complexes compared to falling tone-complexes. CONCLUSIONS: Tone-complexes elicited distinct waveforms compared to 2,000 Hz deviant tone. Rising tone-complexes which had an increase in frequency elicited shorter latency and larger amplitude responses, which could be attributed to perceptual bias for frequency changes.
Acoustics ; Bias (Epidemiology) ; Doppler Effect ; Electrodes ; Evoked Potentials* ; Evoked Potentials, Auditory ; Hearing ; Humans ; Young Adult