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Biomedical subjects

D R Foster

Publications and source records attributed to D R Foster.

At least 19 recordsLinked to original sources
PubMed1995

Interpretation of lymphoscintigrams in suspected lymphoedema: contribution of delayed images.

Interpretation of lymphoscintigrams in patients with extremity oedema may be adversely affected by any variation in the acquisition protocol. The purpose of this study was to determine whether delayed (2-24 h post-injection) views provide information incremental to the first 60 min of acquisition. In a 5-year period, 31 patients (10 males, 21 females, mean age 46 years) with extremity oedema or recurrent cellulitis underwent lymphoscintigraphy using 99Tcm-antimony trisulphide colloid (99Tcm-Sb2S3). All subjects underwent an initial dynamic acquisition of the pelvis and legs for 60 min, with further images obtained after 2-24 h. Films and reports were retrospectively reviewed by an experienced observer to determine whether delayed views provided information incremental to early images. Using standard qualitative criteria, lymphoscintigrams were classified as normal (n = 12) or consistent with lymphoedema (n = 19). However, 6 of 19 (32%) patients with lymphoedema displayed normal transit of radiopharmaceutical and a normal appearance of regional lymph nodes on views acquired up to 1 h after injection; localized dermal backflow (n = 5) or lymphocoele (n = 1) were seen only on delayed images (P < 0.02). These data indicate that delayed lymphoscintigraphy images are important for the diagnosis of lymphoedema and should be obtained even when lymphatic transit of 99Tcm-Sb2S3 and lymph node appearance at 1 h are normal.

Adolescent↗
PubMed1994

Case report: pulmonary calcification in smallpox handler's lung.

Smallpox handler's lung was first described by Morris Evans and Foreman in 1963. During the South Wales smallpox outbreak of 1962 several nurses were noted to develop a "flu-like" illness following an exposure to smallpox patients. The late development of pulmonary calcification in one of these nurses, who is now 74 years old, is described.

Calcinosis↗
PubMed1986

Quantitative contrast measurements in B-mode images comparison between experiment and theory.

Quantitative measurements of image contrast were carried out for B-mode images of anechoic spheres (cysts) embedded in a random scattering medium. Four transducer geometries were used: (a) f/5.7 spherical transducer in pulse echo mode, (b) f/2.4 spherical transducer in pulse echo mode, (c) f/2.4, 30 degrees cone (hybrid transducer), (d) f/5.7, 30 degrees cone (hybrid transducer). The image contrast was also calculated via two methods; (i) a three-dimensional computer simulation and (ii) a relatively simple numerical convolution which relates the image of a small point-like scatterer [point spread function (PSF)] to image contrast. Generally, good agreement was found between the experimental measurements and the values calculated via both theoretical methods. The results indicate that image contrast is not determined solely by the full width at half maximum (FWHM) of the PSF. In particular, the results demonstrate the importance of far off-axis contributions of the ultrasound beam to the significant degradation of contrast in images obtained with high resolution (low f-number) axicons.

Computers↗
PubMed1984

Operative cholangiography--techniques and inadequacies.

The effectiveness of three methods of operative cholangiography in outlining biliary anatomy was assessed in 60 patients undergoing routine cholecystectomy for gallbladder calculi. X-rays were scored according to bile duct visualization and an overall score calculated. There were no statistically significant differences between the three groups. However, ductal opacification was inadequate in a majority of patients. It is suggested that closer cooperation with the radiologist and more emphasis on technique are required if cholangiography is used to identify unsuspected calculi.

Adult↗
PubMed1983

Computer simulations of speckle in B-scan images.

The granularity or speckle in medical ultrasound images tends to mask the presence of small lesions. As well, artifactual filling in of anechoic regions such as cysts, reduces the diagnostic potential of the images. These effects depend not only on the acoustic properties of the tissue but also are strongly influenced by the imaging system, especially the transducer geometry. To study the effect of the transducer on the final B-scan image, a computer model has been developed simulating the interaction of ultrasound with a simple scattering medium. This model, incorporating the position dependence of the point response of the transducer, is based on single scattering from a collection of points positioned randomly in a three-dimensional volume. Using this approach, B-scan images showing speckle have been generated for different transducer geometries. Inclusion of a 2.6 mm void mimicking a cyst within the three-dimensional scattering volume has allowed us to predict the cyst contrast in the image for the different transducer systems. Experimental B-scan images of a scattering phantom were obtained using the different pulse echo systems. Quantitative assessment using first and second order statistics of the images shows good agreement between experiment and theory.

Acoustics↗
PubMed1982

Localized giant pseudo-polyposis in ulcerative colitis.

Localized giant pseudo-polyposis is a rare complication of ulcerative or granulomatous colitis. A case illustrating the typical radiological findings is described. Recognition of this condition is important since it may simulate malignancy.

Adult↗