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Biomedical subjects

Marie Muller

Publications and source records attributed to Marie Muller.

4 recordsLinked to original sources
PubMed2006

Diagnosis of Cushing's syndrome: A retrospective evaluation of clinical practice.

BACKGROUND: The aim of this study was to evaluate the efficiency of the clinical diagnosis of Cushing's syndrome (CS). METHODS: A retrospective study was conducted of 72 consecutive patients with CS who, from 1995 to 2002, had been referred to the endocrinology department of a University Hospital by either endocrinologists or non-endocrinologists. Symptoms, signs, and biochemical screening tests used for confirmation of the diagnosis were recorded. Symptoms that led patients to a consultation were defined as reasons for consultation and were distinguished from other symptoms identified only by the referring physician. RESULTS: Fifty-one patients requested a consultation for reasons related to CS, predominantly weight gain (44%) and muscle weakness (21%). In contrast, 21 patients did not request a consultation for symptoms related to CS. Assessment of physical signs demonstrated that the clinical presentation of patients was similar in both groups. However, endocrinologists referred significantly more patients who had not expressed symptoms related to CS than non-endocrinologists (38% vs. 17%, p<0.05). Appropriate screening tests (overnight 1-mg dexamethasone suppression test and/or urinary free cortisol) were used in all patients referred by endocrinologists and in 45% of patients referred by non-endocrinologists. CONCLUSION: Our data show that many patients with CS do not spontaneously request a consultation for symptoms related to their condition. These patients are mostly identified by endocrinologists, who seem to have a better knowledge of physical signs and screening tests. Because endocrinologists are highly dependent upon non-endocrinologists for the recruitment of their patients, an improvement in the educational program is needed at the non-endocrinologist level. Our results may be of help in drafting the lines of this improvement by stressing the importance of the most specific physical signs and the most relevant screening tests for CS.

Journal Article↗
PubMed2005

Nonlinear resonant ultrasound spectroscopy (NRUS) applied to damage assessment in bone.

Nonlinear resonant ultrasound spectroscopy (NRUS) is a resonance-based technique exploiting the significant nonlinear behavior of damaged materials. In NRUS, the resonant frequency(ies) of an object is studied as a function of the excitation level. As the excitation level increases, the elastic nonlinearity is manifest by a shift in the resonance frequency. This study shows the feasibility of this technique for application to damage assessment in bone. Two samples of bovine cortical bone were subjected to progressive damage induced by application of mechanical cycling. Before cycling commenced, and at each step in the cycling process, NRUS was applied for damage assessment. For independent assessment of damage, high-energy x-ray computed tomography imaging was performed but was only useful in identifying the prominent cracks. As the integral quantity of damage increased, NRUS revealed a corresponding increase in the nonlinear response. The measured change in nonlinear response is much more sensitive than the change in linear modulus. The results suggest that NRUS could be a potential tool for micro-damage assessment in bone. Further work must be carried out for a better understanding of the physical nature of damaged bone and for the ultimate goal of the challenging in vivo implementation of the technique.

Animals↗
PubMed2004

The role of viscosity in the impulse diffraction field of elastic waves induced by the acoustic radiation force.

Several ultrasound-based techniques for the estimation of soft tissue elasticity are currently being investigated. Most of them study the medium response to dynamic excitations. Such responses are usually modeled in a purely elastic medium using a Green's function solution of the motion equation. However, elasticity by itself is not necessarily a discriminant parameter for malignancy diagnosis. Modeling viscous properties of tissues could also be of great interest for tumor characterization. We report in this paper an explicit derivation of the Green's function in a viscous and elastic medium taking into account shear, bulk, and coupling waves. From this theoretical calculation, 3D simulations of mechanical waves in viscoelastic soft tissues are presented. The relevance of the viscoelastic Green's function is validated by comparing simulations with experimental data. The experiments were conducted using the supersonic shear imaging (SSI) technique which dynamically and remotely excites tissues using acoustic radiation force. We show that transient shear waves generated with SSI are modeled very precisely by the Green's function formalism. The combined influences of out-of-plane diffraction, beam shape, and shear viscosity on the shape of transient waves are carefully studied as they represent a major issue in ultrasound-based viscoelasticity imaging techniques.

Acoustics↗