A novel interpolation strategy for estimating subsample speckle motion.

Multidimensional, high-resolution ultrasonic imaging of rapidly moving tissue is primarily limited by sparse sampling in the lateral dimension. In order to achieve acceptable spatial resolution and velocity quantization, interpolation of laterally sampled data is necessary. We present a novel method for estimating lateral subsample speckle motion and compare it with traditional interpolation methods. This method, called grid slopes, requires no a priori knowledge and can be applied to data with as few as two samples in the lateral dimension. Computer simulations were performed to compare grid slopes with two conventional interpolation schemes, parabolic fit and cubic spline. Results of computer simulations show that parabolic fit and cubic spline performed poorly at translations greater than 0.5 samples, and translations less than 0.5 samples were subject to an estimation bias. Grid slopes accurately estimated translations between 0 and 1 samples without estimation bias at high signal-to-noise ratios. Given that the grid slopes interpolation technique performs well at high signal-to-noise ratios, one pertinent clinical application might be tissue motion tracking.

Ensemble tracking for 2D vector velocity measurement: Experimental and initial clinical results.

We describe a new method, called ensemble tracking, for estimating two-dimensional velocities with ultrasound. Compared to previous speckle tracking techniques, ensemble tracking measures motion over smaller times and distances, increasing maximum velocities and reducing errors due to echo decorrelation. Ensemble tracking uses parallel receive processing, 2D pattern matching, and interpolation of the resulting tracking grid to estimate sub-pixel speckle translations between successive ultrasonic acquisitions. In this study, small translations of a tissue mimicking phantom were quantified at transducer angles of 0 degrees , 45 degrees , and 90 degrees . Measurements over three parallel beam spacings and all transducer angles had mean errors from -4% to +11%, when parallel beam amplitudes were normalized. Such amplitude normalization substantially improved results at 45 degrees and 90 degrees . The amplitude, spacing, and correlation between the parallel beams were quantified, and their effects on the accuracy and precision of estimates are discussed. Finally, initial clinical results demonstrate the ability to track and display blood flow in the carotid artery.

Familial occurrence of alpha 1-antitrypsin deficiency and Weber-Christian disease.

Severe panniculitis of the Weber-Christian type occurred in two brothers, both with marked alpha 1-antitrypsin (alpha 1-AT) deficiency and phenotype PiZZ. Studies of inflammatory and immunologic function were undertaken in these two patients as well as in a third brother with severe alpha 1-AT deficiency but without Weber-Christian disease. The findings of these investigations were suggestive of exaggerated immunologic and inflammatory function with enhanced lymphocyte responsiveness to phytohemagglutinin, enhanced activation of neutrophils and monocytes, and accelerated delayed hypersensitivity responses in all three subjects. This hyperreactivity may explain the apparent association of alpha 1-AT deficiency with Weber-Christian disease.