James C Ryva

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Pulsed Doppler (PD) devices to compute blood flow volume and velocity have not been used in newborn infants. We studied CCA diameter (D), flow velocity (V), and volume (Q), in 17 healthy term and 3 preterm (30-33 wks) infants, with a PD device (ATL, Mark IV). Infants were placed on their sides and a 7.5 MHZ transducer was used. The Doppler line and cursor(More)
Using a commercial pulsed Doppler (PD) system we measured common carotid artery (CCA) flow velocities in 19 healthy and 6 stable preterm infants and computed volume flow rates based on the time-averaged flow velocities and vessel diameter. The mean (+/- SEM) time-averaged CCA velocities in the term and preterm infants were 33.04 +/- 3.0 and 23.3 +/- 1.3(More)
Four hundred and fifty-four kidneys were evaluated by real time ultrasound for appearance of renal cortical echogenecity, medullary pyramids and central sinus echoes. These renal parameters were correlated with age in 227 patients ranging in age from 0–15 years. The renal parenchymal echogenicity was observed to change not abruptly at a certain age but(More)
Systematic evaluation of blood clot echogenicity was performed with five different transducer frequencies in two experiments. In the first experiment, blood clots were insonified at five different time periods; from immediately after clotting up to 96 hours after clotting. In the second experiment, blood clots of four different hematocrits (48 to 20%) and(More)
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