Showing papers by "Osama M. Mukdadi published in 2011"

High-resolution ultrasound imaging for jawbone surface

Abstract: Although medical specialties have recognized the importance of using ultrasonic imaging, dentistry is only beginning to discover its benefit. This has particularly been important in the field of periodontics, which studies infections in the gum and bone tissues that surround the teeth. This study investigates the feasibility of using a custom-designed high-frequency ultrasound imaging system to reconstruct high-resolution (<50 µm) 3D surface images of periodontal defects in human jawbone. The system employs single-element focused ultrasound transducers with center frequencies ranging from 30 to 60 MHz. Continuous acquisition using a 1 GHz data acquisition card is synchronized with a high precision two-dimensional positioning system of ±1 µm resolution for acquiring accurate measurements of the mandible, in vitro. Signal and image processing algorithms are applied to render 3D surface images of the jawbone. In vitro experiments were performed to assess the system performance using mandibles with teeth (dentate) or without (non-dentate). The system was able to reconstruct 3D images for the mandible's outer surface with superior spatial resolution down to 24 µm, and to perform the whole scanning in less than 30 s. All anatomical landmarks were detected and fully described as 3D images using this novel ultrasound imaging technique, whereas the 2D X-ray radiographic images suffered from poor contrast.

High-resolution quantitative ultrasound imaging for soft tissue classification

Abstract: Mouse models have been widely used in cardiovascular research when investigating the progression or treatment of various diseases. It is always challenging to find non-invasive tools for early detection of diseases. This led us to the development of small animal models for diagnostic imaging techniques, such as high-frequency quantitative ultrasound imaging. This work describes the development of an ultrasound tissue classification technique that could be used to quantitatively assess atherosclerotic plaques in mouse heart. Signal and image processing of radiofrequency ultrasound data have been performed in time, frequency, and wavelet domains to quantitatively assess the severity of atherosclerosis in an APOE-KO mouse model fed with high fat diet. Multiple in vitro experiments were conducted, and ultrasound images of high contrast-resolution were obtained using parameters from various domains. For example, images reconstructed using the time variance (Tσ2), and frequency skewness (PD skew ) parameters showed high-contrast resolutions of approximately 17.95±2.98 dB, and 9.67±0.24 dB (n=4) between normal tissue and atherosclerotic lesions. The technique is integrated with a custom-designed high-frequency ultrasound imaging system and is able to provide parametric images of high contrast and special resolution down to 24 microns.

Ultrasonic Evaluation of CFRP-Concrete Interface for Specimens under Temperature and Water-Immersion Aging Effects

Abstract: Ultrasonic non-destructive evaluation (NDE) techniques are widely used for structural health monitoring of concrete/FRP structures. In this study, experimental and processing schemes of surface acoustic waves (SAW) are described for assessing concrete/CFRP specimens subjected to accelerated aging conditions. Ultrasonic waves are generated and received at one side using narrow-band transducers of 110 kHz center frequency. The received signals are filtered and amplified then digitized and processed to extract various parameters in both time and frequency domains. These parameters include ultrasound propagation speed, maximum amplitude, total power, and the slope at maximum power spectrum. Changes in these parameters due to water immersion aging at different temperatures were monitored over 10 weeks. Results indicated a notable decrease in measured ultrasonic parameters over time, particularly after the first 2 weeks. This may indicate a debonding or deterioration in the concrete/FRP samples. This behavior showed good agreement with the findings of a parallel destructive study on Mode-II fracture loading of CFRP-concrete samples, tested to obtain fracture energy and define traction-separation response under temperature and water-immersion aging effects.