Precision Ultrasonic Wave Measurements With Simple Equipment.

We describe the design and construction of a relatively simple, inexpensive laser interferometer system for accurate measurements of ultrasonic surface displacement waveforms in reasonably friendly environments. We show how analysis of a single waveform can provide both the calibration constant required for absolute measurements and an estimate of the uncertainty of these measurements. We demonstrate the performance of this interferometer by measuring ultrasonic waveforms generated by a novel conical-element ultrasonic transducer.

Quality assurance in mammography: artifact analysis.

Evaluation of mammograms for artifacts is essential for mammographic quality assurance. A variety of mammographic artifacts (i.e., variations in mammographic density not caused by true attenuation differences) can occur and can create pseudolesions or mask true abnormalities. Many artifacts are readily identified, whereas others present a true diagnostic challenge. Factors that create artifacts may be related to the processor (eg, static, dirt or excessive developer buildup on the rollers, excessive roller pressure, damp film, scrapes and scratches, incomplete fixing, power failure, contaminated developer), the technologist (eg, improper film handling and loading, improper use of the mammography unit and related equipment, positioning and darkroom errors), the mammography unit (eg, failure of the collimation mirror to rotate, grid inhomogeneity, failure of the reciprocating grid to move, material in the tube housing, compression failure, improper alignment of the compression paddle with the Bucky tray, defective compression paddle), or the patient (e.g., motion, superimposed objects or substances [jewelry, body parts, clothing, hair, implanted medical devices, foreign bodies, substances on the skin]). Familiarity with the broad range of artifacts and the measures required to eliminate them is vital. Careful attention to darkroom cleanliness, care in film handling, regularly scheduled processor maintenance and chemical replenishment, daily quality assurance activities, and careful attention to detail during patient positioning and mammography can reduce or eliminate most mammographic artifacts.

How accurate is fine-needle biopsy in malignant neoplasia of the pancreas?

The accuracy of fine-needle aspiration biopsy of the pancreas in 77 patients was studied, in 47 by the percutaneous route and in 30 under direct vision at the time of operation. Seventeen (49%) of 35 pancreatic malignant neoplasms were detected percutaneously and 13 (65%) of 20 at surgery. The predictive value of a positive test was 100% in both situations. The sensitivity of the percutaneous test was 57%; the sensitivity of the test done at operation rose to 72%. No complications were encountered. The test, when positive, can be relied on in surgical decision making but is of limited value when negative. Our findings are essentially similar to those of others who have reported their experience in the literature.

Malignant lymphoma arising in a large congenital neurofibroma of the head and neck. Report of a case.

A lymphoma developed in a large neurofibroma in a young woman who had no other stigmata of neurofibromatosis. The neurofibroma was congenital and extensively involved the soft tissue and bone of the face and neck. Despite multiple attempts to excise the neurofibroma, it persistently recurred. At the age of 30 the patient underwent another resection of the lesion, and a follicular, mixed, small and large cell lymphoma was present within the neurofibroma. Over 3 years the lymphoma transformed into a diffuse large cell type despite the fact that it remained localized to the neurofibroma. After the lymphoma had transformed, the patient received multiagent chemotherapy. She responded well, and a repeat biopsy showed no residual lymphoma. She is alive and well 25 months after completion of chemotherapy. To the best of our knowledge, this is the first report of a lymphoma arising in a soft tissue neoplasm.

Seroconversion to human immunodeficiency virus (HIV) in hemophiliacs. Relation to lymphadenopathy.

The authors studied the natural history of human immunodeficiency virus (HIV) exposure in 187 hemophiliacs followed for an average of 45 months. Overall, 55 percent developed antibody specific for HIV and 21 percent developed persistent generalized lymphadenopathy. Most patients seroconverted sometime between early 1982 and the end of 1984. Four patients developed acquired immune deficiency syndrome (AIDS) and four seropositive patients developed idiopathic thrombocytopenia (ITP). One of the four patients who developed AIDS and three of the four with ITP had preexisting lymphadenopathy. None of the 10 patients with lymphadenopathy or the 20 asymptomatic patients was seropositive for human T-lymphotropic virus, type I. Although seropositivity and lymphadenopathy have been found in many of the authors' patients, few have developed clinical disease that can be related to HIV infection.

Three-dimensional real-time measurements of ultrasonic waves in transparent solids.

A Doppler-shifted light-scattering technique, long used in velocimetry to yield 3-D flow information about liquids and gases, has been used for the first time to measure ultrasonic fields in solids. Unlike Bragg diffraction and interferometric methods previously used in solids, Doppler methods require no a priori assumptions about the sound field in order to obtain 3-D resolution. In addition, Doppler methods determine not refractive index changes but particle motion directly; thus the need to use the photoelastic constants of the medium to calculate strain data is eliminated.

Cheyletiella dermatitis.

A mild dermatitis probably due to Cheyletiella yasguri was observed in 2 persons whose pet dog was infested with this parasite. Cheyletiella mites differ morphologically from sarcoptic mites, which cause canine and human scabies. Treatment of man and dog with 1% gamma benzene hexachloride is usually successful in clearing this condition.

Apocrine cystadenoma of the penile shaft.

What is to our knowledge the first apocrine cystadenoma reported on the penile shaft is described. Of 96 previously reported apocrine cystadenomas, more than 90% were located on the face, ears, or scalp; the remainder occurred on the chest, axilla, or prepuce. Apocrine cystadenoma should be considered in the differential diagnosis of solitary blue, gray, or flesh-colored cystic nodules in those areas.

Ultrasonic wave measurement by differential interferometry.

The theory and performance of a two beam differential interferometer for measurement of both surface and bulk waves are described. The system is insensitive to small errors (<1 mm) in focus or in specimen flatness. Both amplitude and phase measurements are demonstrated. The system has been absolutely calibrated and can detect 6 x 10(-4)-A surface wave displacements on glass.

Transmission of incoherent light between ronchi grids.

The use of Ronchi grids for the detection or measurement of small angular changes is well known. In some applications, such as instruments for the measurement of strain or displacement, the question of linearity of calibration over an extended angular range is important. In this paper we treat the question of such linearity on the basis of physical optics. We conclude that although arbitrary combinations of wavelength or wavelength range, grating space, focal length, and beam width generally yield a nonlinear calibration, special combinations of these parameters result in a highly linear curve over an extended range.

Anomalous behavior of blazed gratings.

A numerical integration method based on Kirchhoff's diffraction integral is used to determine the approximate location and shape of so-called anomalies of a blazed grating in both polarizations. Although a scalar theory is used, the phase shift on reflection accounts for the differences in polarization. Multiple diffraction within the single grating groove accounts for the anomalous behavior. The theory is compared with new experimental data on two microwave gratings.

Differential optical strain gauge for torsion measurements.

An optical strain gauge has been built to measure extremely small torsion strains in cylindrical specimens. Moiré fringe techniques are used to measure the differential angular changes between two sensing mirrors supported on two rings attached to the specimen. The present instrument has a useable linear range of about 0.5 mrad with a sensitivity of 500 mV/mrad. Angular changes as small as 2 microrad are easily detected. Risley prisms are used to extend the range to 10 mrad as well as to verify the calibration procedure.

Anomalous behavior of gratings at skew incidence.

A new formula has been developed and verified to account for the location of possible anomalous behavior of a plane diffraction grating when illuminated at skew incidence as in the Grieg and Ferguson mounting. It is shown that for their mounting, in contrast to both Littrow and Ebert mountings, blaze angles can be chosen which eliminate possible anomalous behavior in the observed spectra.