Filter-based coded-excitation system for high-speed ultrasonic imaging. (1/3731)

We have recently presented a new algorithm for high-speed parallel processing of ultrasound pulse-echo data for real-time three-dimensional (3-D) imaging. The approach utilizes a discretized linear model of the echo data received from the region of interest (ROI) using a conventional beam former. The transmitter array elements are fed with binary codes designed to produce distinct impulse responses from different directions in ROI. Image reconstruction in ROI is achieved with a regularized pseudoinverse operator derived from the linear receive signal model. The reconstruction operator can be implemented using a transversal filter bank with every filter in the bank designed to extract echoes from a specific direction in the ROI. The number of filters in the bank determines the number of image lines acquired simultaneously. In this paper, we present images of a cyst phantom reconstructed based on our formulation. A number of issues of practical significance in image reconstruction are addressed. Specifically, an augmented model is introduced to account for imperfect blocking of echoes from outside the ROI. We have also introduced a column-weighting algorithm for minimizing the number of filter coefficients. In addition, a detailed illustration of a full image reconstruction using subimage acquisition and compounding is given. Experimental results have shown that the new approach is valid for phased-array pulse-echo imaging of speckle-generating phantoms typically used in characterizing medical imaging systems. Such coded-excitation-based image reconstruction from speckle-generating phantoms, to the best of our knowledge, have not been reported previously.  (+info)

Utility of ultrasound of the upper urinary tract in elderly men with indicators of obstructive symptoms or abnormal flow: how often can silent hydronephrosis be detected in general practice? (2/3731)

BACKGROUND AND OBJECTIVE: While the prevalence of hydronephrosis is very low in obduction studies, a prevalence of 3-13% is reported for patients with an obstruction who are listed for prostatectomy. In order to evaluate the usefulness of transabdominal ultrasound in primary care, we determined the occurrence of hydronephrosis in males with symptoms of urinary obstruction in a general practice setting. METHOD: A micturition questionnaire (a modified Boyarsky) was sent to all men of 55 years or more who were registered in 10 general practices in Maastricht, and was followed by an examination at their general practice. Men with obstructive symptoms and/or with a free-flow abnormality were examined in the hospital with transabdominal ultrasound in order to detect dilatation of the upper urinary tract. This ultrasound was repeated approximately 15 months later. RESULTS: At the first measurement, none of the examined men (n = 178) had hydronephrosis, and this was still the case for 94 men 15 months later. CONCLUSION: Renal ultrasound is not necessary in general practice for men with uncomplicated obstructive complaints.  (+info)

Ultrasonic characterisation of malignant melanoma of choroid. (3/3731)

An in-vitro study of wave spectral analysis in 8 enucleated eyes was conducted in order to differentiate histological subtypes of malignant melanoma. To obtain the backscattering coefficient for the tissues, we used a broadband focussed transducer with a frequency range of 7-12 MHz and a centre frequency of 10 MHz. Experimental measurement of backscattering coefficient and attenuation coefficient at various frequencies was done by substitution techniques. The backscattering coefficient, scatterer size, and root mean square velocity fluctuation were derived by the numerical method, while the attenuation coefficient at 1 MHz was derived from attenuation coefficient at different frequencies. This study revealed that backscattering coefficient and attenuation coefficient, over a frequency range of 7-12 MHz, show an increase in the spindle cell type compared to the mixed cell type of malignant melanoma. Particularly, the scatterer size was significantly higher in the spindle cell group (p = 0.013) in contrast to the mixed cell type. Spindle cells have uniform and compact histological pattern which contributes to an increase in scatterer size and root mean square velocity fluctuation. The ultrasonically obtained parameters have been shown to have a good correlation with the histology of malignant melanoma.  (+info)

A new sonographic technique for assessing carotid artery disease: extended-field-of-view imaging. (4/3731)

We describe a new sonographic technique, extended-field-of-view imaging, and its clinical application for carotid artery disease. The technique identifies identical structures on two successive images for position registration to make a panoramic image in real time without position sensors. In 39 of 41 subjects, this technique provided high-quality panoramic images that could not be obtained with conventional real-time sonography, and made findings in the carotid artery more interpretable.  (+info)

An echocardiographic study of right and left ventricular adaptation to physical exercise in elite female orienteers. (5/3731)

BACKGROUND: A considerable body of echocardiographic studies has described how athletic training induces morphological adaptation of the left ventricle in male endurance athletes, but only a few studies have described left ventricular adaptation in female endurance athletes. In contrast to changes in the left ventricle far less attention has been directed towards right ventricular changes due to extensive physical exercise. The purpose of this study was to obtain normal values and to determine if there are any differences in right and left ventricular cavity and wall dimensions between female orienteers and females with a mainly sedentary lifestyle. METHODS: Echocardiography was performed in 42 highly trained elite female orienteers and 32 healthy female students with a predominantly sedentary lifestyle. The 74 females had no history of cardiac disease, a normal electrocardiogram and showed no echocardiographic abnormalities. M-mode and two-dimensional measurements of the right and left ventricular cavity and wall were obtained in elite orienteers and sedentary females. For the right ventricle and wall, multiple cross-sections were used and measurements were obtained from the right ventricular inflow and outflow tract. RESULTS: The left ventricular end-diastolic cavity dimension and the left ventricular wall thickness were significantly greater in the athletes compared with the sedentary controls. The right ventricular inflow tract measurements were all significantly greater in the orienteers compared with the controls but the right ventricular outflow tract measurements were comparable in the study groups. The right ventricular wall thickness, calculated as the mean of three different wall measurements was an average of 13% greater in the athletes compared with the sedentary controls. CONCLUSION: This study suggests symmetrical cardiac enlargement with a concomitant increase in both the right and left ventricular wall, probably reflecting the increased haemodynamic loading in the female athletes.  (+info)

Transrectal ultrasonography in the assessment of congenital vaginal canalization defects. (6/3731)

Our aim was to evaluate the reliability of transrectal ultrasonography in the preoperative assessment of congenital vaginal canalization defects. We studied nine patients, six with suspected Rokitansky syndrome and three with suspected complete transverse septum. Before corrective surgery all the patients underwent pelvic examination, transabdominal and transrectal ultrasonography. The ultrasonographic findings were compared with the surgical ones. Transrectal ultrasonography provided an accurate map of the pelvic organs showing the precise distances between the urethra and bladder anteriorly, rectum posteriorly, retrohymenal fovea caudally, and pelvic peritoneum cranially. Transrectal ultrasonography produced a picture that corresponded perfectly with the real anatomical situation. Conversely, abdominal ultrasonography provided inadequate images in six of our nine patients, and magnetic resonance imaging was responsible for a mistaken diagnosis in one patient with suspected transverse vaginal septum. In conclusion, if our results are confirmed in larger series, transrectal ultrasonography could be considered as a diagnostic procedure of choice in the assessment of vaginal canalization defects.  (+info)

Evaluation of carcass, live, and real-time ultrasound measures in feedlot cattle: I. Assessment of sex and breed effects. (7/3731)

Carcass and live-animal measures from 1,029 cattle were collected at the Iowa State University Rhodes and McNay research farms over a 6-yr period. Data were from bull, heifer, and steer progeny of composite, Angus, and Simmental sires mated to three composite lines of dams. The objectives of this study were to estimate genetic parameters for carcass traits, to evaluate effects of sex and breed of sire on growth models (curves), and to suggest a strategy to adjust serially measured data to a constant age end point. Estimation of genetic parameters using a three-trait mixed model showed differences between bulls and steers in estimates of h2 and genetic correlations. Heritability for carcass weight, percentage of retail product, retail product weight, fat thickness, and longissimus muscle area from bull data were .43, .04, .46, .05, and .21, respectively. The corresponding values for steer data were in order of .32, .24, .40, .42, and .07, respectively. Analysis of serially measured fat thickness, longissimus muscle area, body weight, hip height, and ultrasound percentage of intramuscular fat using a repeated measures model showed a limitation in the use of growth models based on pooled data. In further evaluation of regression parameters using a linear mixed model analysis, sex and breed of sire showed an important (P < .05) effect on intercept and slope values. Regression of serially measured traits on age within animal showed a relatively larger R2 (62 to 98%) and a smaller root mean square error (RMSE, .09 to 8.85) as compared with R2 (0 to 58%) and RMSE (.31 to 67.9) values when the same model was used on pooled data. We concluded that regression parameters from a within-animal regression of a serially measured trait on age, averaged by sex and breed, are the best choice in describing growth and adjusting data to a constant age end point.  (+info)

Ultrasonography as an aid in the diagnosis and management of surgical diseases of the pelvis: special emphasis on the genitourinary system. (8/3731)

Technological advances, particularly the advent of the gray scale technique, has greatly extended the application and usefulness of this modality to clinical diagnoses and surgery. The ultrasonic beam uniquely provides anatomical profiles in the transverse (cross-sectional) and sagittal (longitudinal) planes of the body. Intra-rectal and intra-vaginal ultrasonic probes have provided unique definition of both the normal and pathologic anatomy of the pelvic organs. The present report is drawn from a continuing experience with ultrasonography of the genitourinary system with an update of current technological advances. Ultrasonography has proven especially valuable in the following clinical applications: 1) Early diagnosis of cancer (especially of the prostate); 2) Accurate staging of cancer of the bladder and prostate; 3) Monitoring of the response of the pathologic process to therapy.  (+info)