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A scanning head is designed and fabricated that has incorporated a 20-MHz, 128-element linear transducer and the elements of PVDF film with an element. An imaging test has shown that the system has achieved axial and lateral resolutions and the entire scanning head has dissipated at a pulse repetition rate of 750 Hz.

An approach is described for measuring human subcutaneous fat thickness automatically by using ultrasound radio frequency (RF) signals. High correlations are observed between the manual and automatic ultrasound measurements and between the skinfold caliper and automatic ultrasound measurements.

A narrow band approximation using phase rotation is described to facilitate coefficient filtering for ultrasound speckle tracking in order to reduce the computational burden. The improvement in displacement estimation is achieved by combining correlation filtering with a new Viterbi-based displacement estimator.

Magnetic resonance imaging (MRI) is examined for monitoring small and large lesions created by high-intensity focused ultrasound (HIFU) in freshly excised lamb brain and in rabbit brain in vivo. The studies have shown that HIFU can be used for treating brain tumors in human and it could be done either by using a single-element transducer with a frequency around 1 MHz or using a multi-element transistor.

We describe a fully automated ultrasound analysis system that tracks and identifies the common carotid artery (CCA) and the internal jugular vein (IJV). Our goal is to prevent inadvertent damage to the CCA when targeting the IJV for catheterization. The automated system starts by identifying and fitting ellipses to all the regions that look like major arteries or veins throughout each B-mode ultrasound image frame. The spokes ellipse algorithm described in this paper tracks these putative vessels and calculates their characteristics, which are then weighted and summed to identify the vessels. The optimum subset of characteristics and their weights were determined from a training set of 38 subjects, whose necks were scanned with a portable 10 MHz ultrasound system at 10 frames per second. Stepwise linear discriminant analysis (LDA) narrowed the characteristics to the five that best distinguish between the CCA and IJV. A paired version of Fisher's LDA was used to calculate the weights for each of the five parameters. Leave-one-out validation studies showed that the system could track and identify the CCA and IJV with 100% accuracy in this dataset. Index Terms--Biomedical acoustic imaging, biomedical engineering, biomedical image processing, blood vessels.

The knowledge of skull bone thickness would be helpful for a great variety of surgical interventions of the head. Ultrasound (US) can offer this information intraoperatively in real time. A-mode US measurements of skull bone thickness were performed with different pulse characteristics: 1) in water and 2) by directly coupling a 2.25-MHz US transducer integrated in a handpiece with a soft delay line using coded excitation (CE) (SonoPointer). Mechanical measurements by calipers served as controls. The specimen were 16 nonselected human cadaveric skull bones preserved with formaldehyde. The average difference between the bone thickness measured by the SonoPointer and the mechanical control measurements was 0.04 [+ or -] 0.62 mm. The 95% limits of agreement between the two methods were -1.18 and 1.25 ram. However, even the gold standard of two repeated caliper measurements had limits of agreement of -0.4 and 0.42 mm. Using a standard US pulse in water, only 62.5% sample points were measurable, whereas the SonoPointer produced the thickness measurement in 97.9% of points. CE proved to be superior to single burst or needle US pulses. A-mode US measurements of skull bone thickness using the SonoPointer are feasible. It may provide valuable information on skull bone thickness, e.g., for osteosynthesis, calvarial split bone harvesting, implantation of hearing devices, osseointegrated titanium fixtures, and skull base surgery. Index Terms--Acoustic pulse compression, biomedical ultrasonics, coded excitation (CE), intraoperative navigation, RF data signal processing, skull bone, ultrasound (US).

A continuous representation of the echo signal is used to design a new class of time-delay estimator based on the tracking of individual samples. The sample tracking algorithm has higher sensitivity and resolution and is applied in medical ultrasound, including fine tissue motion estimation, strain estimation, elasticity estimation, and acoustic radiation force impulse imaging.

Several algorithms that use reciprocal signals are described for measuring the difference profile of the transmission and reception phase-aberration profiles. The transmission and reception phase-aberration profiles are derived separately and are used to correct phase-aberrations on transmission and reception.

Two different methods for motion compensation in intravascular ultrasound (IVUS) palpography are examined. The implementation of the hybrid strategy, which has combined the accuracy of the optical flow (OF) algorithm with the fast computational speed of the block matching (BM) method, is used for improving the diagnostic quality of IVUS palpography.

The article talks about a recently discovered dual high-frequency difference excitation technique, which is used for inducing low-frequency nonlinear scattering from microbubbles by using high-frequency ultrasound. The technique is shown to be widely used in microbubble fragmentation and cavitation with high-frequency ultrasound.

A modified version of more computationally efficient formulation of spline-based time delay estimator that directly determines subsample time delay estimates from sampled data is presented. The bias and the standard deviation of the newly designed algorithm were comparable to that of the original method with superior performance.

A new generation of miniature ring-array transducers integrated into the catheter deployment kits of interventional devices is developed. The newly constructed ring transducers integrated with an 8.5 French catheter sheath of a vena cava filter deployment device allow real-time 3-D ultrasound scanning for improved guidance of minimally invasive procedures.

A new technique is proposed for the robust estimation of relaxation-time distribution in tissue. Results suggest the feasibility of the proposed technique.

The relevance of quantitative ultrasound (QUS) methods for the assessment of bone quality is discussed.

The advantages and disadvantages of ultrasound, as a tool for determination of bone mechanical properties are discussed.

The clinical applications of quantitative ultrasound (QUS) in the detection and management of osteoporosis and osteoporosis-related fractures is discussed. Findings reveal that QUS is acceptable, low-cost and an accessible alternative in the management of osteoporosis.

The effect of preferred orientation of hydroxyapatite (HAp) crystallites on the spatial distribution of ultrasonic wave velocity is examined. Findings reveal that the velocity distribution pattern was similar to the distribution of integrated intensity of (0002) peak.

The application of a model-based estimation method to quantitative ultrasound (QUS) transmission measurements is discussed. Results suggest the detection of different wave types and its characterization in the trochanteric region.