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Biomedical subjects

J Ophir

Publications and source records attributed to J Ophir.

At least 73 records · Page 4Linked to original sources
PubMed1994

Eosinophilic pustular folliculitis: a sterile folliculitis of unknown cause?

BACKGROUND: Eosinophilic pustular folliculitis (EPF) was initially defined as a sterile folliculitis of unknown cause. Because attempts to demonstrate bacterial organisms have been unsuccessful, and antibiotic therapy is usually ineffective, a bacterial infection is not considered a plausible causative factor for this disease. OBJECTIVE: Our purpose was to describe five patients with the clinical and histologic characteristics of EPF and to report the results of bacterial cultures. METHODS: Biopsy specimens were examined and pustules were cultured. RESULTS: In three of the five patients, Pseudomonas infection of the hair follicle was the cause of the disease as proven by repeated cultures and the response to specific therapy. Three patients had a systemic disorder known to cause immunologic alteration: AIDS in one and a myeloproliferative disorder in two. CONCLUSION: Although EPF was initially defined as a sterile folliculitis of unknown origin, three of our patients had an identifiable and treatable cause. We believe that these cases warrant the diagnosis of EPF.

Adult↗
PubMed1993

SAPHO syndrome.

Four women with pustulosis palmoplantaris (PPP) and associated sternocostoclavicular hyperostosis are described. The connection between the two diseases is not coincidental: it is encountered in 9.4% of PPP patients, and was reported in the French literature as part of the SAPHO (synovitis acne pustulosis hyperostosis osteomyelitis) syndrome. This syndrome is linked to the spondyloarthropathies, having an increased prevalence of HLA B27 and occurrence of sacroiliitis. None of our patients had HLA B27, but HLA A26 was found in the 3 patients examined. No conclusion can be drawn from this finding, however, since this antigen is found in 21.7% of Ashkenazi Jews. Recognition of this syndrome by dermatologists will improve diagnosis and treatment.

Acne Vulgaris↗
PubMed1993

Elastography: elasticity imaging using ultrasound with application to muscle and breast in vivo.

Changes in tissue elasticity are generally correlated with its pathological state. In many cases, despite the difference in elasticity, the small size of a lesion or its location deep in the body preclude its detection by palpation. In general, such a lesion may or may not possess echogenic properties that would make it ultrasonically detectable. Elastography is an ultrasonic method for imaging the elasticity of compliant tissues. The method estimates the local longitudinal strain of tissue elements by ultrasonically assessing the one dimensional local displacements. This information can be combined with first order theoretical estimates of the local stress to yield a quantitative measure of the local elastic properties of tissue. The elasticity information is displayed in the form of a gray scale image called an elastogram. An experimental system for elastography in phantoms based on a single element transducer has been described previously [1]. Here we introduce a new elastography system based on a linear array transducer that is suitable for in vivo scanning. We describe tissue mimicking phantom experiments and preliminary in vivo breast and muscle elastograms confirming the feasibility of performing elastography in vivo. An elastogram of a breast containing an 8 mm palpable cancer nodule clearly shows the lesion. Elastograms and their corresponding sonograms show some similarities and differences in the depiction of tissue structures.

Adult↗
PubMed1993

Reduction of image noise in elastography.

Elastography is a method for imaging the elastic properties of compliant tissues which produces gray scale elasticity images called elastograms. The elastograms of phantoms with homogeneous elastic properties exhibit a noisy appearance. We demonstrate that this noisy appearance of the elastograms is due to the nonstationary relationship between the pre- and postcompression signals that results in an artifactual modulation of the strain estimates by the amplitude variations of the envelope of the rf signal. We have identified two methods to reduce the strain modulation artifact. The first method consists of reducing the signal amplitude swings within the observation windows by logarithmically or otherwise compressing the rf signal. The sensitivity of this method to amplitude compression strength and the ability to reduce the noise in the elastograms without affecting the spatial resolution are investigated through simulations. The second method to reduce the strain modulation artifact consists of temporal stretching of the signal obtained after physical compression to approximate the shape of the signal obtained before compression. In this paper, we discuss the first method. The results show that significant improvement in image noise can be obtained with logarithmic amplitude compression. This improvement is obtained in conjunction with improved spatial resolution.

Computer Simulation↗
PubMed1993

Cutaneous paraneoplastic syndromes.

A review of a variety of cutaneous paraneoplastic conditions is presented. Although the conditions discussed appear in only 7-15% of cancer patients, they are considered indicators of possible underlying malignancy.

Humans↗
PubMed1992

On the feasibility of pulse-echo speed of sound estimation in small regions: simulation studies.

Computer simulations are used to study the feasibility of the estimation of sound speed in small regions with precision better than 1% using the Beam Tracking method. The speed of sound is estimated in a 10-mm by 10-mm region by considering a number of parallel tracks confined to the small region. The transducer focusing and the step sizes for the tracking and tracked transducers required to extract the maximum amount of uncorrelated data from the 10-mm by 10-mm region is evaluated. The results show that the speed of sound can be estimated with error less than 1% in a small region using a typical medical transducer. The statistical comparison of estimates in small areas with different speed of sound is also considered.

Acoustics↗
PubMed1992

Axial stress distributions between coaxial compressors in elastography: an analytical model.

We describe an analytical model to study the behavior of stress along the compression axis for different configurations of opposing circular compressors, as applied to elastography. The method is based on a hypothesis that the axial stress at any point on the axis is the superposition of the individual components of the stresses derived from the boundary conditions at either end. The determination of the axial stress behavior according to the model permits the correction of certain elastograms for depth-dependent stress. Experimental results have been presented to corroborate the model.

Elasticity↗
PubMed1992

Correction of diffraction errors in attenuation estimation with Dynamic Beam Translation.

We describe computer simulations for the estimation of the attenuation coefficient in scattering media using the Dynamic Beam Translation (DBT) method. DBT refocuses a variable aperture transducer to maintain the focal characteristics of the transducer at different depths in order to reduce diffraction errors. The efficacy of DBT is evaluated for transducers with different focal powers and under the influence of phase aberration due to the body wall. DBT shows robustness in the elimination of diffraction errors and resistance to the effects of aberration.

Computer Simulation↗
PubMed1992

Nonbullous bullous pemphigoid.

Three patients had a rare form of bullous pemphigoid, clinically similar to the erythematous type of bullous pemphigoid without vesiculobullous lesions. All the patients displayed immunofluorescence features of bullous pemphigoid. This form of the disease presents a substantial diagnostic problem because it lacks the principal morphologic feature of bullous pemphigoid, namely the vesicles and bullae.

Aged↗
PubMed1992

Squamous cell carcinoma--70 years after irradiation.

The rare event of invasive squamous cell carcinoma 70 years after irradiation to the scalp for tinea capitis, occurred in a 75-year-old Caucasian male. The clinical, histological, roentgenologic and magnetic resonance imaging picture are described, and the literature is reviewed.

Aged↗
PubMed1992

Systemic amyloidosis secondary to chronic leg ulcers.

Chronic leg ulcers due to any cause are almost invariably associated with an inflammatory process. As with any long-standing inflammation, leg ulcers may be complicated by systemic amyloidosis, which occurs in rheumatoid arthritis, cystic fibrosis, tuberculosis, and other disorders. There are, however, very few reports on the association between these two conditions. We report a patient with severe leg ulcers of twenty years' duration in whom reactive systemic amyloidosis presented as a nephrotic syndrome.

Aged↗
PubMed1991

Pemphigus gestationis (herpes gestationis): a case report.

Pemphigus gestationis is a rare disease, probably of immunologic origin, that causes the placenta to absorb immunoglobulins and deposit them in its basement membrane. The resulting placental insufficiency leads to increased morbidity and mortality among the offspring of such patients. A case of pemphigus gestationis is presented, and the importance of early diagnosis is discussed.

Adult↗
PubMed1991

Pulse-echo ultrasound speed measurements: progress and prospects.

The data on the relationship of sound speed to tissue condition, and the development of methods for measurement of sound speed in vivo, are outlined. The methods developed by the authors are discussed. These include methods which use the spatial shift in images of targets viewed from different directions, time-of-flight measurements along incrementally tracked beams and echo tracking during transaxial compression of tissue. The reported sound-speed values are discussed, discrepancies noted and suggestions made on the potential clinical applications of in vivo sound-speed estimation.

Humans↗
PubMed1991

Elastography: a quantitative method for imaging the elasticity of biological tissues.

We describe a new method for quantitative imaging of strain and elastic modulus distributions in soft tissues. The method is based on external tissue compression, with subsequent computation of the strain profile along the transducer axis, which is derived from cross-correlation analysis of pre- and post-compression A-line pairs. The strain profile can then be converted to an elastic modulus profile by measuring the stresses applied by the compressing device and applying certain corrections for the nonuniform stress field. We report initial results of several phantom and excised animal tissue experiments which demonstrate the ability of this technique to quantitatively image strain and elastic modulus distributions with good resolution, sensitivity and with diminished speckle. We discuss several potential clinical uses of this technique.

Abdomen↗