Acoustic imaging of objects buried in soil.

In this study, we demonstrate an acoustic system for high-resolution imaging of objects buried in soil. Our goal is to image cultural artifacts in order to assess in a rapid manner the historical significance of a potential construction site. We describe the imaging system and present preliminary images produced from data collected from a soil phantom. A mathematical model and associated computer software are developed in order to simulate the signals acquired by the system. We have built the imaging system, which incorporates a single element source transducer and a receiver array. The source and receiver array are moved together along a linear path to collect data. Using this system, we have obtained B-mode images of several targets by using delay-and-sum beamforming, and we have also applied synthetic aperture theory to this problem.

High contrast ultrasound images of defects in food package seals.

Previous work to detect defects in food packaging seals using pulse-echo ultrasound inspired the backscattered amplitude integral (BAI) imaging technique, which could reliably identify channels with diameters 38 microm or larger at a center frequency of 17.3 MHz (lambda=86 microm). The current study presents two new processing techniques that more reliably reveal smaller channels ( approximately 6 microm in diameter). The RF sampling technique (RFS) displays a single, time-gated, pressure value from the received (not envelope-detected) RF waveform at each transducer position. The RF correlation technique (RFC) calculates the correlation coefficients of the RF signals with a reference signal that does not pass through a channel. The correlation coefficient can be calculated for the entire RF signal (RFCE) or over a short segment of the RF signal (RFCS). The performance of these imaging methods for detecting channel defects is investigated for plastic and aluminum foil trilaminate films with 6, 10, 15, 38, and 50 microm channels filled with water or air. Data are collected with a focused ultrasound transducer (17.3 MHz, 6.35 mm in diameter, f/2, 173 microm -6 dB pulse-echo lateral beamwidth at the focus) scanned over a rectangular grid, keeping the package in the focus. Performance is measured using detection rates, image contrast, and contrast-to-noise ratio (CNR). Both RFS and RFCS have improved detection rates relative to BAI for channels 15 microm or smaller. The RFCS technique is the most effective at smoothing the background, leading to the greatest CNR improvements.

Synthetic aperture techniques with a virtual source element.

A new imaging technique has been proposed that combines conventional B-mode and synthetic aperture imaging techniques to overcome the limited depth of field for a highly focused transducer. The new technique improves lateral resolution beyond the focus of the transducer by considering the focus a virtual element and applying synthetic aperture focusing techniques. In this paper, the use of the focus as a virtual element is examined, considering the issues that are of concern when imaging with an array of actual elements: the tradeoff between lateral resolution and sidelobe level, the tradeoff between system complexity (channel count/amount of computation) and the appearance of grating lobes, and the issue of signal to noise ratio (SNR) of the processed image. To examine these issues, pulse-echo RF signals were collected for a tungsten wire in degassed water, monofilament nylon wires in a tissue-mimicking phantom, and cyst targets in the phantom. Results show apodization lowers the sidelobes, but only at the expense of lateral resolution, as is the case for classical synthetic aperture imaging. Grating lobes are not significant until spatial sampling is more than one wavelength, when the beam is not steered. Resolution comparable to the resolution at the transducer focus can be achieved beyond the focal region while obtaining an acceptable SNR. Specifically, for a 15-MHz focused transducer, the 6-dB beamwidth at the focus is 157 mum, and with synthetic aperture processing the 6-dB beamwidths at 3, 5, and 7 mm beyond the focus are 189 mum, 184 mum, and 215 mum, respectively. The image SNR is 38.6 dB when the wire is at the focus, and it is 32.8 dB, 35.3 dB, and 38.1 dB after synthetic aperture processing when the wire is 3, 5, and 7 mm beyond the focus, respectively. With these experiments, the virtual source has been shown to exhibit the same behavior as an actual transducer element in response to synthetic aperture processing techniques.

Cefpodoxime proxetil in the treatment of skin and soft tissue infections.

Patients with skin and soft tissue infections were enrolled in a study comparing 2 dosage regimens of orally administered cefpodoxime proxetil; 204 patients with mild to moderate infections received cefpodoxime proxetil 200mg twice daily and 47 patients with severe infections received 400mg twice daily. Both dosage regimens were given for 7 to 14 days. 132 of 142 (93.0%) evaluable patients in the 200mg group and 22 of 29 (75.9%) in the 400mg group were clinically cured post-therapy, the remainder in both groups being classified as improved. The pathogen eradication rate at the end of therapy in the 200mg group was 161 of 165 (97.6%), and 38 of 38 (100%) in the 400mg group. Adverse reactions (drug-related) were reported by 20 (8.0%) patients overall, and there was no apparent relationship between the dosage group and the incidence of adverse reactions. The most commonly reported reactions involved the gastrointestinal tract (diarrhoea) or female genital tract (vaginitis). Cefpodoxime proxetil appears to be a useful and safe agent in the therapy of skin and soft tissue infections.

Tendon repairs with dacron vascular graft suture: a follow up report.

This paper is a follow-up report on the subject of the use of dacron vascular graft material to repair major tendons. This paper examines the long term fate of one of these grafts, based on an examination at autopsy of an Achilles tendon repaired with this type of graft.

Hemangioma of the fingertip.

This article describes a case of hemangioma of the fingertip that the patient said had been treated previously without success. A satisfactory result was achieved after using a V-Y pedicle flap.

Major tendon repairs with dacron vascular graft suture.

Achilles and patellar tendon tears in nine patients were repaired with 5 mm Dacron vascular grafts. There have been no failures with this method of fixation. In the patients we studied this method permitted earlier mobilization of joints.

Acute renal failure after total hip replacement.

Eight of forty-one patients undergoing total hip replacement experienced acute but not fatal renal failure postoperatively. All forty-one patients received transfusions of frozen blood and albumin and their wounds were irrigated with a bacitracin-neomycin-polymyxin solution. All subsequently had some relative hypotension. None of a second, prospective group of fifty-five patients who received the transfusion of albumin, but not frozen blood or the bacitracin-neomycin-polymyxin irrigant, had renal failure. The incidence of hypotension in this group was comparable to that in the first group, yet no cases of renal failure were seen. We therefore recommend that the combination of frozen blood and potentially nephrotoxic drugs be avoided in patients undergoing total hip replacement.