Doppler Velocity Estimates of Internal Carotid Artery Stenosis: Angle Correction Parallel to the Color Doppler Lumen Versus Parallel to the Artery Wall.

OBJECTIVES: We compared internal carotid artery Doppler peak systolic velocities (PSVs) measured with angle correction parallel to the artery wall (// wall) on grayscale images and parallel to the direction of blood flow (// flow) on color Doppler images. METHODS: We studied 25 internal carotid lesions with PSVs higher than 125 cm/s. The PSVs were measured in the same imaging plane, at the stenosis orifice (0 cm) and at 0.5 and 1 cm downstream by both methods. Linear regression and correlation analyses were used to study the effects of the angle correction method on changes in PSVs as a function of the differences in angle adjustment and distance from the stenosis. RESULTS: The 23 patients studied included 9 women and 14 men. There was a mean difference in absolute PSVs ± SD of -17.2 ± 29.5 cm/s (P < .008) between methods at the stenosis. The difference in the PSVs was associated with the angle difference between the flow jet and the artery wall (P < .01). At 1 cm from the stenosis, // flow PSVs were more strongly correlated with PSVs at the stenosis (r = 0.61; 95% confidence interval, 0.28, 0.82; P = .001) than // wall PSVs (r = 0.39; 95% confidence interval, -0.003, 0.68; P = .052). CONCLUSIONS: Blood flow velocity measurements made with angle correction parallel to the direction of the color Doppler blood flow lumen remain more consistent with the distance from the stenosis than blood flow velocity measurements made with angle correction parallel to the outer artery walls.

Mirror Image from a Left Atrial Line Mimicking a Catheter in the Left Ventricle During Transesophageal Echocardiography.

We describe a case report where a left atrial catheter inserted intraoperatively produced an artifact, which mimicked a catheter in the left ventricle during transesophageal echocardiographic examination.

Medical ultrasound systems.

Medical ultrasound imaging has advanced dramatically since its introduction only a few decades ago. This paper provides a short historical background, and then briefly describes many of the system features and concepts required in a modern commercial ultrasound system. The topics addressed include array beam formation, steering and focusing; array and matrix transducers; echo image formation; tissue harmonic imaging; speckle reduction through frequency and spatial compounding, and image processing; tissue aberration; Doppler flow detection; and system architectures. It then describes some of the more practical aspects of ultrasound system design necessary to be taken into account for today's marketplace. It finally discusses the recent explosion of portable and handheld devices and their potential to expand the clinical footprint of ultrasound into regions of the world where medical care is practically non-existent. Throughout the article reference is made to ways in which ultrasound imaging has benefited from advances in the commercial electronics industry. It is meant to be an overview of the field as an introduction to other more detailed papers in this special issue.