Citations

An integrated approach for the absorption of ultrasound by liquids and tissues is proposed from the solution of a one-dimensional wave equation of propagation. The proposed model explains the square and linear power dependence of absorption on frequency for liquids and tissues, respectively. The study also provides a new index, specific heat ratio (γ), in terms of which the physical and the chemical state and thus possibly the pathological state of a tissue can be defined quantitatively.

ABSTRACT Specimens submitted in M5 medium for cell culture detection of Chlamydia trachomatis were tested by nucleic acid amplification testing (NAAT) and in cell cultures. Of 35 (genital) and 26 (nongenital) specimens positive for C. trachomatis , 21 and 14 specimens, respectively, were detected exclusively by NAAT. NAAT is significantly ( P < 0.0001) more sensitive than cell culture and should be considered the new “gold standard” for the laboratory diagnosis of C. trachomatis infections.

Context: Testosterone (Te) depletion in aging men in principle could reflect deficits in the hypothalamus, pituitary gland, or testis. Available pharmacological studies of possible failure of Leydig cell steroidogenesis remain inconclusive. Objective: The objective of the study was to assess Te secretion in older and young men in response to near physiological LH stimulation. Intervention: Pulsatile iv infusion of recombinant human LH was administered for 2 d to stimulate Te secretion during suppression of endogenous LH concentrations with a potent selective GnRH receptor antagonist (ganirelix). Subjects/Context: Healthy older (aged 60–73 yr, n = 8) and young (19–30 yr, n = 13) men were studied in an academic setting. Measures: Pulsatile LH and Te concentrations on the second day of exogenous LH stimulation were measured. Results: Serum ganirelix concentrations and infused LH pulse increments were similar by age. In contrast, older subjects manifested: 1) reduced mean Te concentrations (P = 0.016), Te peak heights (P = 0.014), increments (P = 0.010), summed areas (P &lt; 0.013), and interpeak Te concentrations (P = 0.023); 2) decreased Te to LH concentration ratios (P = 0.002); 3) diminished LH-Te feed-forward synchrony (P = 0.020); and 4) a blunted amplitude (P = 0.036) and advanced phase (P = 0.013) of diurnal Te rhythms. Conclusion: A novel regimen of pulsatile LH stimulation for 48 h during GnRH receptor blockade unmasks deficits in pulsatile, basal, synchronous, and nyctohemeral Te secretion in healthy older men. These findings do not exclude concomitant defects in GnRH outflow and/or Te-negative feedback in the aging male.

Multi-frequency signals were transmitted using a plane-wave transducer, through a water immersed phantom consisting of two finger cots, one containing 50% isopropanol alcohol and the other containing normal saline. The scattered ultrasound was received with a small hydrophone and detected with a quadrature detection system. The resulting phase quadrature data were submitted to a reconstruction algorithm which utilized the Rytov approximation to the Helmholtz equation in order to obtain the inverse solution for the distribution of refraction index within the phantom. In one experiment pseudo-random noise was generated by loading a 256 by 8-bit memory with random numbers and then synchronously reading these values through a D/A converter into an EMI power amplifier which drove the plane-wave transducer. The data received from each of 60 angles of view were spectral analyzed and specific frequencies selected for the cw reconstruction algorithm. Multiple frequency reconstructions will be shown as will the effect of frequency on the various underlying assumptions for the approximation. [Supported in part by Grants CA 24085 and NCI and ECS 7296008 from NSF.]

Purpose Contralateral prophylactic mastectomy (CPM) is one option for reducing the risk of a second breast cancer in women with a personal and family history of breast cancer. Few data are available regarding satisfaction, psychological, and social function after CPM. The purpose of this research is to evaluate women’s long-term satisfaction with CPM, factors influencing satisfaction, and psychological and social function after CPM. Patients and Methods This was a descriptive study of all women with a family history of breast cancer, known to be alive, who elected CPM at Mayo Clinic (Rochester, MN) between 1960 and 1993 (n = 621). Ninety-four percent of the women (n = 583) completed a study-specific questionnaire. Results A mean of 10.3 years after the procedure, the majority of women (83%) were satisfied with their CPM. A smaller number were neutral (8%) or dissatisfied (9%). Women who had a subcutaneous mastectomy had more problems with reconstruction, and fewer of these women were satisfied than women with simple mastectomy. Decreased satisfaction with CPM was associated with decreased satisfaction with appearance, complications with reconstruction, reconstruction after CPM, and increased level of stress in life. The majority of women experienced no change or favorable effects in self-esteem (83%), level of stress in life (83%), and emotional stability (88%). Satisfaction with body appearance, feelings of femininity, and sexual relationships were the most adversely affected with 33%, 26%, and 23% of the women responding negatively. Conclusion Although most women are satisfied with CPM, each woman should weigh the benefits alongside the potential adverse effects.

Data and simulated data from circumscribing and linear sampled arrays has been used to form high resolution reflection images by two techniques. The first technique (synthetic focusing) uses the mathematical equivalent of a lense to focus the image at each point by adding either linear (uncompressed) or nonlinear (compressed) transforms of the data. Logarithmic and square root compression is studied. The lense effect is obtained by backprojecting convolved or other linear transformed versions of the data along equal time propagation surfaces in the image with appropriate corrections for refraction and frequency dependent attenuation. The choice of apodizing function and different wave forms can greatly improve image resolution. The second technique (reflection ART) is not based on a focusing model but rather on direct inversion of a matrix (linear transform) model of the object-acoustic field interaction and data acquisition process by a Kacmarz iterative inversion method. The two methods are compared.

Quantitative images of acoustic speed distribution in excised human tissues, in excised dog myocardium, and in in vivo female breasts were obtained by ultrasound computerized tomography. The in vitro study was carried over a temperature from 20° to 40 °C. Results indicate (1) acoustic speed in human tissues (except fat) increase monotonically with temperature in this range, (2) fat shows an anomalous decrease in acoustic speed around 35 °C, (3) average acoustic speed is higher in breasts with cancer and with fibrocystic disease compared to normal breasts, and (4) acoustic speed is a function of age. The reconstruction problem in ultrasound computerized tomography is unlike its x-ray analog because of the refraction and diffraction effects. Methods to correct for the consequent degradation are discussed. The backscattering properties of in vivo myocardial tissue of dogs were studied by a high-resolution B-scanner and the potential of (renovist and indocyanine green) as ultrasound contrast agents to quantitate perfusion in the myocardium will be discussed. [Work supported by NCI-CB-64041, HV 72928, HL-07111, HL-00060, HL-00170.]