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The aim of this study was to assess polyethylene wear in a total hip prosthesis by digitized radiography of the whole pelvis in the anteroposterior (AP) plane. The three-dimensional (3-D) pose of the nonmetal-backed acetubular cup, materialized by its metal ring and the femoral head made of metal or ceramic, was estimated using iterative algebraic algorithms with inner bias correction and bootstrapping for variance reduction. Points of interest were obtained by maximizing the correlation between sampled density profiles and 3-D geometric models degraded by the modulation transfer function (MTF) of the radiographic system and the film scanner. The error in the maximal correlation estimate were inferred from noise power spectra (NPS) and allowed the calculation of the point covariance matrix. Both NPS and MTF were modeled for each stage and estimated using least-square fitting of the overall NPS model to the autospectral density function calculated in stationary regions. Comparison of the radiographic time series was made possible by the high accuracy level and 3-D matching from the cup orientation. The feasibility of the full 3-D measurement, the assumption of negligible lateral wear and its influence on AP wear are discussed on simulated and real radiographic data.

In previously published studies, blood flow velocity from x-ray biplane angiography was measured by solving an inverse advection problem, relating velocity to bolus densities summed across sections. Both spatial and temporal velocity variations were recovered through a computationally expensive parameter estimation algorithm. Here we prove the existence and uniqueness of the solution on three sub-domains of the plane defined by the axial position along the vessel and the time of the angiographic sequence. A fast direct scheme was designed in conjunction with a regularization step stemming from the volume flow conservation law applied on consecutive segments. Its accuracy and immunity towards noise were tested on both simulated and real densitometric data. The relative error between the estimated and expected velocities was less than 5% for more than 90% of the points of the spatiotemporal plane with simulated densities normalized to 1.0 and a Gaussian additive noise of standard deviation 0.01. For densities reconstructed from a biplane angiographic sequence, increase in velocity is used as a functional index for the stenosis ratio and to characterize the sharing of flow at bifurcation.

This paper reports a new automated method for the segmentation of internal cerebral structures using an information fusion technique. The information is provided both by images and expert knowledge, and consists in morphological, topological, and tissue constitution data. All this ambiguous, complementary and redundant information is managed using a three-step fusion scheme based on fuzzy logic. The information is first modeled into a common theoretical frame managing its imprecision and incertitude. The models are then fused and a decision is taken in order to reduce the imprecision and to increase the certainty in the location of the structures. The whole process is illustrated on the segmentation of thalamus, putamen, and head of the caudate nucleus from expert knowledge and magnetic resonance images, in a protocol involving 14 healthy volunteers. The quantitative validation is achieved by comparing computed, manually segmented structures and published data by means of indexes assessing the accuracy of volume estimation and spatial location. Results suggest a consistent volume estimation with respect to the expert quantification and published data, and a high spatial similarity of the segmented and computed structures. This method is generic and applicable to any structure that can be defined by expert knowledge and morphological images.

We evaluated the direct location in the globus pallidus (GP) under stereotactic MRI (sMRI) guidance in five parkinsonians treated with chronic deep brain stimulation (four bilaterally). The sMRI consisted of three orthogonal (horizontal, frontal, sagittal) sets of images obtained with a stereotactic frame and its localiser. The sMRI was coupled with ventriculography to compare the location with the classic indirect method based on commissural landmarks. The target was defined on T2-weighted slices in the anterior part of the medial GP, at the vertex of the nucleus. It was reached via one track with a semi-micro-electrode and step by step high frequency stimulation, then replaced by a quadripolar electrode once we located the site enabling the optimal clinical improvement. Stereotactic x-rays localised the final position of the electrode. A company software matched sMRI, ventriculography, and peroperative (perop) x-rays, with reference to the stereotactic location boxes. We analysed the effects of acute (perop) and chronic (six-month follow-up) stimulation of active plots (acplots), i.e. leading to optimal clinical improvement. Three distances with reference to the acplots were measured both on sMRI and ventriculography: the laterality from the median sagittal plane of the third ventricle; the anterior position from the midpoint of the intercommissural line (Icl), and the vertical position with regard to the Icl. We then compared the differences in measurements (n = 64) with the Bland and Altman method. The mean difference was 0.09 mm with 95% of the values between +/- 1 mm, but only the laterality had a statistically significant agreement (all the differences included between +/- two times the standard deviation of the mean). The acplots distances from the dorsal, ventral, and medial boundaries of GP (defined by manual surrounding on frontal and horizontal planes) were measured on sMRI. With one exception, the acplots were all included in the nucleus. The six-month acplots were located dorsally with reference to the perop ones. Clinical benefit at six-months follow-up showed results comparable to the literature. Direct location of GP target based on sMRI seems a simple and reliable method.

In this paper, a method for the detection of myocardium contractility defect from transthoracic echocardiography is proposed. Speckle phenomenon is considered here as useful functional information and not only as a multiplicative noise. Its distribution and frequential characteristics are used to derive boundary and regional energy terms in order to track myocardium walls with deformable contour models. Moreover, ultrasound density is also estimated from speckle moments to calculate myocardial displacement field from the solution of an inverse continuity equation problem. The clinical feasibility of local and global indices and a prospective study for the multisite stimulation are presented.

A microcomputer program to analyse ICP signal in the frequential domain is described. It allows the detection and quantification of especially slow pressure waves (A, B, and C). 212 ICP data recordings were analysed with our software, and gave pertinent frequential informations. The status report and lessons learned are discussed.

N -Acetic acid derivatives of 4-carboxy-6-arylpyridazin-3-ones were synthesized for the dual purpose of inhibiting aldose reductase and exhibiting antioxidant properties. All the prepared compounds showed a significant in vitro aldose reductase inhibitory effect (10 −5 M ≤ IC 50 ≤ 10 −4 M). The spatial configuration of the most active derivative 4f (4- i -PrC 6 H 4 at C 6 , IC 50 = 0 95 × 10 −5 M) was compared with pharmacophore requirements of the aldose reductase inhibitor site using a molecular modeling system. The antioxidant action of 4a–f was also studied in vitro . Compound 4c (4-ClC 6 H 4 at C 6 , IC 50 = 1.56 × 10 −3 M) was the most effective at scavenging the superoxide anion whereas compound 4a (C 6 H 5 at C 6 , IC 50 = 1.28 × 10 −3 M) was the most active at inhibiting lipid peroxidation. In addition, biological activities (log 1/IC 50 ) for most of the data sets could be correlated directly to lipophilic, electronic and steric parameters.

To determine the contribution of computerized tomography (CT) to the management of nontraumatic acute abdomen, to evaluate interobserver agreement and the contribution of CT to cost control, to look for the predictive factors of CT.and method. Ninety prospectively included patients, admitted for nontraumatic acute abdomen and examined by a surgeon, received CT examination. Diagnosis and treatment 1) envisioned before and 2) defined after CT, and 3) finally retained were compared, and the interobserver agreement was calculated after the second reading. The predictive value of the clinical and biological criteria as well as the radiological criteria characterizing these patients was sought.CT was contributive in 68.9% of cases, with a reliable diagnosis and treatment strategy, defined after CT examination, for 92.2% and 90%, respectively. Interobserver agreement was 93.3%. CT contributed to reducing costs in 15.5% of patients, for an additional cost estimated at 104-139 euros. The positive predictive factors of the CT contribution were age over 70 years, localized symptoms, fever, and high CRP.In agreement with the literature, in our study CT appears to be a choice examination to guide patient care in nontraumatic acute abdomen.

Slow waves in intracranial pressure (ICP) and related signals seems of interest to evaluate the dynamic autoregulation, i.e. by comparison of the frequency links between an intracranial signal, e.g. ICP, cerebral blood velocity (CBV), and arterial blood pressure (ABP). To clarify the links, we compared two frequency methods based on coherence function to estimate the influence of ICP, ABP and CBV on couples, respectively CBV-ABP, ICP-CBV and ICP-ABP, of slow waves in the B and the UB bands. We found that B and UB waves activity in ICP, CBV and ABP had reciprocal influences, except for the UB activity in ICP-CBV link which seems to be less sensitive to ABP. These data confirmed the interest of to analyse the slow wave activity to evaluate dynamic autoregulation. The interest of taking into account the reciprocal influence of the signals must be evaluated.

A method for pericardial and endocardial edge extraction of the left ventricle (LV) in 2-D short axis echocardiographic sequence is presented. The proposed algorithm consists in two steps: nonlinear anisotropic diffusion filtering and directional geodesic active contours. These step are based on both PDE and tensors. Tensor formalism gives access to structure orientation of the acoustic density field. This provides a more robust algorithm by using the whole image information. Sample experimental results are shown for myocardium edge detection in 2-D short-axis ultrasound sequences.

The phase differences between visual evoked responses and electroretinograms were studied. Colored sinusoidal stimulation was obtained using a Vo van Toi and Grounauer papillometer (modulation: 100%; flicker frequency: 5 Hz and 20 Hz; fields size: 6 degrees and 60 degrees ; color: white, red, green and blue). Recordings were made using cutaneous electrodes and averaging (analysis time: 0.6 s; number of sweeps: 100). Fourier series analysis showed the red to be slower than the blue using stimulation at 5-Hz and 60 degrees . This result was reversed for both the 20-Hz, 60 degrees and 5-Hz, 6 degrees cases, where the central retina is at less of a disadvantage. >

We propose in this article to compute White Matter (WM), Gray Matter (GM) and Cerebrospinal Fluid (CF) volumes from MR images of a human brain using possibilistic logic and a fusion scheme. The fusion process is divided into three steps: fuzzy tissue maps are first computed on all images using a possibilistic clustering algorithm. Fusion is then achieved for all tissues with a context based fusion operator. The final segmentation allows for the computation of brain tissue volumes. Applications on a brain model show a great agreement between the results and the true segmentation, thus affording a relevant tissue classification on clinical data.

Slowly varying pressure oscillations in the cranial enclosure are well known, especially intracranial pressure waves as best described by the pioneering works of Janny and Lundberg. Nevertheless, in spite of over twenty five years research on intracranial pressure waves, their origin and regulation remain unclear but are often considered only as pathological. Our aim was to review data on these phenomena to clarify their biological status and the role that they could play in the management of patients suffering from such intracranial neurosurgical diseases as intracranial hypertension, severe head injury, and hydrocephalus. It appears that these pressure waves reveal important information on the function of the cerebral vasculature and as such have significance for influencing intracranial compliance. Pressure waves are also closely associated with autoregulation, in particular dynamic autoregulation. It seems evident that they are not only pathophysiological but also physiological, linked with other biological parameters such as the neurovegetative cardiovascular system, breathing, and sleeping. This study shows that it is not only important to continue to explore these slow waves, but also the methods of analysis in order to more fully clarify their clinical significance.

An algorithm for the segmentation of a single sequence of three-dimensional magnetic resonance (MR) images into cerebrospinal fluid, gray matter, and white matter classes is proposed. This new method is a possibilistic clustering algorithm using the fuzzy theory as frame and the wavelet coefficients of the voxels as features to be clustered. Fuzzy logic models the uncertainty and imprecision inherent in MR images of the brain, while the wavelet representation allows for both spatial and textural information. The procedure is fast, unsupervised, and totally independent of any statistical assumptions. The method is tested on a phantom image, then applied to normal and Alzheimer's brains, and finally compared with another classic brain tissue segmentation method, affording a relevant classification of voxels into the different tissue classes.

Pelizaeus-Merzbacher Disease (PMD) is an X-linked developmental defect of myelination affecting the central nervous system and segregating with the proteolipoprotein (PLP) locus. Investigating 82 strictly selected sporadic cases of PMD, we found PLP mutations in 77%; complete PLP-gene duplications were the most frequent abnormality (62%), whereas point mutations in coding or splice-site regions of the gene were involved less frequently (38%). We analyzed the maternal status of 56 cases to determine the origin of both types of PLP mutation, since this is relevant to genetic counseling. In the 22 point mutations, 68% of mothers were heterozygous for the mutation, a value identical to the two-thirds of carrier mothers that would be expected if there were an equal mutation rate in male and female germ cells. In sharp contrast, among the 34 duplicated cases, 91% of mothers were carriers, a value significantly (chi2=9. 20, P

Although coronary stenting reduces the incidence of post-angioplasty restenosis, it remains a problem. The influence of lipoproteins on the development of atherosclerosis has been demonstrated but their role in restenosis is controversial. Contradictory results have been published on the subject of the influence of the APO E genotype. In an initial study, the authors showed a closer correlation between Lp (a) and coronary artery disease in women than in men. A sub-group of women who underwent angioplasty and whose lipid profile had been well established, was analysed with respect to APO E alleles. The 59 patients who underwent angioplasty included 35 single, 20 twin and 4 triple vessel diseases. Control coronary angiography was performed in 40 of these women. A telephonic interview was carried out between 12 and 22 months after dilatation on the whole population. The apolipoproteins A1, B, Lp (a) and Lp A1 were measured by immunological, turbidimetric or electroimmunological techniques. The APO E genotyping was performed with the Inno-Lipa kit. The results showed 18 angiographic restenoses (Group A), 20 coronary artery disease without restenosis (Group B), 41 without angiographic (20) or clinical (21) restenosis (Group C). In Group A, the Lp (a) was well above the threshold value of 0.30 g/l. The e4 allele was associated with the highest values of total and LDL cholesterol fractions. There was no significant difference between the APO E genotype of the different groups or with respect to the severity of lesions. The authors conclude that if the e4 is more commonly associated with high LDL-cholesterol and Lp (a), its role in the process of restenosis remains unproven. A greater number of patients is required and further studies are desirable to determine the inflammatory and/or immunological mechanisms through which APO E could influence restenosis.

The synthesis, labeling, and biodistribution of four 125I radiopharmaceuticals designed to localize in melanoma were tested. Uptake in tumors was demonstrated by autoradiography of whole-body sections and quantitated by measurement of radioactivity of selected tissues and tumors using melanoma-bearing mice. N-(2-diethylaminoethyl)-4-iodobenzamide was selected for its highest melanoma uptake: 60 min after IV injection of 6.5% and 4% ID/g, respectively for murine B16 and human melanotic melanoma. Tumor uptake showed the highest values of all analyzed tissues from 6 to 24 hr after injection. High uptake in melanotic tumor tissue with relatively low uptake in blood, muscle, brain, lung, and liver tissue resulted in high tumor/nontumor ratios (at 24 hr for B16, tumor/blood = 37, tumor/brain = 147, tumor/muscle = 95). This agent was compared with iodoamphetamine. Scintigraphic images of the tumor confirmed that external detection of melanoma is possible with this new radiopharmaceutical.

We measured the modulation depth of an interference pattern after double passage through the eye with different entry positions of the linearly polarized incident beam in the pupil plane. This shifting of the incident beam greatly modifies the mean irradiance and the modulation depth of the aerial image, whatever the direction of the polarizer. These measurements give a better understanding of the respective contributions of the retinal layers to the formation of the aerial image. Consequently, the modulation transfer function of the optics of the eye deduced from measurements with the aerial image must be considered cautiously.

After a light stimulation, the electrical potentials are recorded on the ocular zone (electroretinogram), on the temporal and parietal zones (electroaxogram), and on the occipital zone (electrovisiogram or visual evoked cortical potential). Using mathematical methods (with microcomputer) the morphology and the propagation of electrophysiological signals are studied. Apart from the future possibilities, a clinical application exists now: early detection of demyelinating diseases such as multiple sclerosis.

To study the relationship between peak latencies of visual electrograms and photostimulation parameters, the authors worked on two different stimulation protocols: flash and pattern reversal. The recording gave differents signals, all of them lost in noise. Starting from the study of this kind of signal, the authors carried out processing in five steps: averaging, filtering (digital), modeling, standardizing, and extracting of peak latencies. Next, statistical studies were conducted using an analysis of variance and a Tukey test. The main results are particularly interesting for a visual evoked response with pattern where peak latencies are selectively sensitive to luminance-color or contrast. This could be extended to pathological cases with a view to use as a diagnostic aid. >

The authors want to isolate e-waves using their Fourier spectrums. The electroretinograms are averaged. A 4 Hz flash stimulus is used and a first spectral set (the fundamental's amplitude at 4 Hz is taken as reference) is determined. Next, the e-waves are suppressed (linear interpolation) and a second spectral set is determined. e-wave characteristic spectrums are obtained from the difference between sets (linear operation). The true period of e-waves, in this case 7 ms, is determined theoretically. The energetic contribution of each harmonic is given. >

Proposes a new segmentation scheme to detect cerebral structures in MRI acquisitions using numerical information contained in the image and expert knowledge brought by a specialist. This process is divided in three steps: first, information contained in the MR image is extracted using a fuzzy clustering algorithm, and theoretical information concerning the structure to segment is modeled using possibility theory. Information fusion is then processed, followed by a decision step ending the structure segmentation. Heads of caudate nuclei and putamens are segmented using this method. Results are promising and validation is performed using both numerical indexes and assessment by an expert. This method can be applied to any cerebral structure in an MR image, provided that it can be described in terms of shape, direction and distance by an expert and that the contrast and resolution of the MRI are sufficient.