THE BONE MICROSTRUCTURE IDENTIFICATION MODEL BASED ON BACKSCATTER MODE OF ULTRASOUND

Osteoporosis is defined by a decrease in bone mass and a deterioration in bone microstructure. It is a major public health issue and a significant economic burden for both individuals and society. Thus, monitoring bone mass and structure is necessary to prevent bone fragility and osteoporosis. This study aimed to develop a prototype of quantitative ultrasound (QUS) and to evaluate the feasibility of backscatter mode for the bone assessment. Ultrasound (US) signals that propagate through the bone can be characterized by comparing the signal from both transmitter and receiver transducers. The US backscattered signal depends on the characteristic of both medium and transducer. In this study, we analyzed the attenuated signal based on the parameters: type of bone (compact and spongy), type of coupling medium (air, starch, and gel), the angle between transducers and bone (30o, 60o, and 90o), and transducer distance (0, 10, 5, 15, 20 and 25 cm). We use only 1 MHz transducer frequency. The prototype has been evaluated by Digital Oscilloscope and LabVIEW user interface to observe received signals. The results of this study showed that there was a difference in amplitude of the US signal from compact and spongy bones. The amplitude is directly proportional to acoustic impedance and inversely proportional to the distance between transducers. There is a negative correlation between bone microstructure to attenuation, and compact bones have a greater attenuation coefficient than spongy bones.

Techniques for Improving Ultrasound Visualization of Biopsy Markers in Axillary Lymph Nodes

Objective: Biopsy markers are often placed into biopsy-proven metastatic axillary lymph nodes to ensure later accurate node excision. Ultrasound is the preferred imaging modality in the axilla. However, sonographic identification of biopsy markers after neoadjuvant therapy can be challenging. This is due to poor conspicuity relative to surrounding parenchymal interfaces, treatment-related alteration of malignant morphology during neoadjuvant chemotherapy, or extrusion of the marker from the target. To the authors’ knowledge, the literature provides no recommendations for ultrasound scanning parameters that improve the detection of biopsy markers. The purpose of this manuscript is 3-fold: (1) To determine scanning parameters that improve sonographic conspicuity of biopsy markers in a phantom and cadaver model; (2) to implement these scanning parameters in the clinical setting; and (3) to provide strategies that might increase the likelihood of successful ultrasound detection of biopsy markers in breast imaging practices. Materials and Methods: An ex vivo study was performed using a phantom designed to simulate the heterogeneity of normal mammary or axillary soft tissues. A selection of available biopsy markers was deployed into this phantom and ultrasound (GE LOGIQ E9) was performed. Scanning parameters were adjusted to optimize marker conspicuity. For the cadaver study, the biopsy markers were deployed using ultrasound guidance into axillary lymph nodes of a female cadaver. Adjustments in transducer frequency, dynamic range, cross-beam (spatial compound imaging), beam steering, speckle reduction imaging, harmonic imaging, colorization, and speed of sound were evaluated. Settings that improved marker detection were used clinically for a year. Results: Sonographic scanning settings that improved biopsy marker conspicuity included increasing transducer frequency, decreasing dynamic range, setting cross-beam to medium hybrid, turning on beam steering, and setting speckle reduction imaging in the mid-range. There was no appreciable improvement with harmonic imaging, colorization, or speed of sound. Conclusion: On a currently available clinical ultrasound scanning system, ultrasound scanning parameters can be adjusted to improve the conspicuity of biopsy markers. Overall, optimization requires a balance between techniques that clinically increase contrast (dynamic range, harmonic imaging, and steering) and those that minimize graininess (spatial compound imaging, speckle reduction imaging, and steering). Additional scanning and procedural strategies have been provided to improve the confidence of sonographic detection of biopsy markers closely associated with the intended target.

The standard facility for the transmission the unit of sound pressure at ultrasonic frequencies

Information is provided on a standard facility for calibrating hydrophones at frequencies from 100 kHz to 3 MHz, which created to expand the frequency range of the State primary standard GET 55-2017 to the area of high-frequency ultrasound. The actuality of the standard facility creation is justified. The possibilities of measurements and operation principles of the facility are briefly reviewed. The requirements to the characteristics of ultrasonic transducers are discussed. When selecting standard transducers, priority was given to their temporal stability, since the unevenness of the transducer frequency response is not of fundamental importance when calibrating using a tone signal. To reduce the influence of directivity, a precision four-coordinate positioning system of transducers applies, which including the control of transducers mutual position using laser beam. Attention is paid to the problems related with the mastering of higher frequencies.

Frequency Response Characterization for Dynamic Measurement of Pressure

Transducer requirements for making true dynamic pressure measurements point to a miniature point-level sensing element that is exposed to the flow. Meeting this requirement, however, is often challenged by transducer size constraints, integration at the location of measurement, and packaging, especially when one considers applications in harsh environments where protection of the sensing element may be needed. As part of an effort towards the development of a high frequency pressure measurement device for use in harsh environments (ultra-high temperature), an investigation was performed to evaluate the effect of sensing element packaging and geometry at the point of measurement on the dynamic response of a nominal transducer. Frequency and time domain calculations were performed to assess variations on the magnitude and phase between an input signal and a “measured” signal at the sensing element location for a range of probe tip parameters. The results offer insights and metrics that can govern transducer sensing element and probe tip implementation for optimum frequency response and strategies for compensation.

ANALYSIS OF THE INFLUENCE OF TRANSDUCER FREQUENCY ON THE ULTRASONIC MEASUREMENT OF CONCRETE HOMOGENEITY

The paper analyses the influence of transducer frequency on the determination of concrete homogeneity using the ultrasonic pulse velocity test. Transit time measurements were made on a 590×590mm concrete slab, with 110mm in thickness, in a raster of 5×5 points, which means the slab was tested in 25 places. The tests were made using a Pundit PL-200 ultrasonic tester using transducers set at 54, 82, and 150 kHz. Two types of measurements were performed – spot measurements of the ultrasonic pulse transit time at each point and full area scanning. The paper is concluded by an evaluation of the concrete slab’s homogeneity measured by different transducers and techniques in addition to a statistical analysis of how the results are affected by the transducer frequency.

ASSESSMENT OF GESTATIONAL AGE

Objective: To compare correct assessment of gestational age betweenTranscerebeller diameter versus femur length in third trimester (28-40) using first day of lastmenstrual period for actual period of gestation. Study Design: Cross-sectional descriptive study.Place and Duration of Study: Department of Obstetrics and Gynecology, Bahawal VictoriaHospital, Bahawalpur from Jun 2012 to Dec 2012. Methodology: This study was performed on327 patients in third trimester of pregnancy from 28-40 weeks fulfilling the inclusion criteria.Ultrasound measurements of transcerebellar diameter (TCD) and femur (FL) were made withcommercially available real time ultrasound equipment Toshiba Nemio-10 model 2009,Transducer frequency 50/60 Hz. Collected data was analyzed by SPSS version 10. Results: Outof 327 patients, TCD was found to give correct assessment corresponding to the gestational ageby LMP in 262 (80.1%) patients, while in 232 (70.9%) patients FL was found to give correctassessment corresponding to the gestational age by LMP. Conclusions: Transcerebellardiameter is more reliable method of gestational age determination in third trimester of pregnancythan femur length. TCD can be used as a tool to assist in the assessment of gestational age inthird trimester.