Automated identification of minimal myocardial motion for improved image quality on MR angiography at 3 T

OBJECTIVE: Imaging during a period of minimal myocardial motion is of paramount importance for coronary MR angiography (MRA). The objective of our study was to evaluate the utility of FREEZE, a custom-built automated tool for the identification of the period of minimal myocardial motion, in both a moving phantom at 1.5 T and 10 healthy adults (nine men, one woman; mean age, 24.9 years; age range, 21-32 years) at 3 T. CONCLUSION: Quantitative analysis of the moving phantom showed that dimension measurements approached those obtained in the static phantom when using FREEZE. In vitro, vessel sharpness, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were significantly improved when coronary MRA was performed during the software-prescribed period of minimal myocardial motion (p < 0.05). Consistent with these objective findings, image quality assessments by consensus review also improved significantly when using the automated prescription of the period of minimal myocardial motion. The use of FREEZE improves image quality of coronary MRA. Simultaneously, operator dependence can be minimized while the ease of use is improved.

To differentiate complementary mri sequences to standard protocol in detecting degenerative inflammatory lumbar spine lesions

Purpose: To compare the additional informations obtainedwith axial and sagittal T2 weighted with fat saturation(T2FS) and T1 weighted with Gadolinium iv sequenceswith fat saturation (T1FSGd) to detect degenerativeinflammatory lumbar spine lesions.Materials and Methods: Our retrospective study included73 patients (365 lumbar levels) with lumbar spinedegenerative disease (25 males, 48 females, mean age56 years). MRI protocol was performed with T1 and T2weighted sagittal and T2 weighted axial sequences(standard protocol), axial and sagittal T2FS and T1FSGd.Images were independently analyzed by two musculoskeletalradiologists and a neurosurgeon. Two groups ofsequences were analyzed: standard + T2FS sequences(group 1), standard + T1FSGd sequences (group 2).Degenerative inflammatory lumbar spine lesions werenoted at each level in: anterior column (vertebralendplate), spinal canal (epidural and peri-radicular fat)and posterior column (facet joint with capsular recessand subchondral bone).Results: Degenerative inflammatory lesions were present in18% (66/365) of levels in group 1, and 48% (175/365) oflevels in group 2. In details, lesions were noted in group 1 and2 respectively:-in 44 and 66 levels for anterior column,-in22 and 131 levels for posterior column,-in 0 and 36 levelsfor spinal canal. All these differences were statisticallysignificant. Intra and Interobserver agreements were good.Conclusion: The T1FSGd sequence is more sensitive thanT2FS to show the degenerative inflammatory lumbar spinelesions, especially in spinal canal and posterior column.

The value of intraoperative ultrasound in oblique corpectomy for cervical spondylotic myelopathy and ossified posterior longitudinal ligament.

Intraoperative ultrasound (IOUS) has been described to be useful during central corpectomy for compressive cervical myelopathy. This study aimed at documenting the utility of IOUS in oblique cervical corpectomy (OCC). Prospective data from 24 patients undergoing OCC for cervical spondylotic myelopathy and ossified posterior longitudinal ligament (OPLL) were collected. Patients had a preoperative cervical spine magnetic resonance (MR) image, IOUS and a postoperative cervical CT scan. Retrospective data from 16 historical controls that underwent OCC without IOUS were analysed to compare the incidence of residual compression between the two groups. IOUS identified the vertebral artery in all cases, detected residual cord compression in six (27%) and missed compression in two cases (9%). In another two cases with OPLL, IOUS was sub-optimal due to shadowing. IOUS measurement of the corpectomy width correlated well with these measurements on the postoperative CT. The extent of cord expansion noted on IOUS after decompression showed no correlation with immediate or 6-month postoperative neurological recovery. No significant difference in residual compression was noted in the retrospective and prospective groups of the study. Craniocaudal spinal cord motion was noted after the completion of the corpectomy. IOUS is an inexpensive and simple real-time imaging modality that may be used during OCC for cervical spondylotic myelopathy. It is helpful in identifying the vertebral artery and determining the trajectory of approach, however, it has limited utility in patients with OPLL due to artifacts from residual ossification.

A realistic Computed Tomography simulator for small motion analysis of cerebral aneurysms.

This paper describes a realistic simulator for the Computed Tomography (CT) scan process for motion analysis. In fact, we are currently developing a new framework to find small motion from the CT scan. In order to prove the fidelity of this framework, or potentially any other algorithm, we present in this paper a simulator to simulate the whole CT acquisition process with a priori known parameters. In other words, it is a digital phantom for the motion analysis that can be used to compare the results of any related algorithm with the ground-truth realistic analytical model. Such a simulator can be used by the community to test different algorithms in the biomedical imaging domain. The most important features of this simulator are its different considerations to simulate the best the real acquisition process and its generality.

Vectorisation intra-oculaire [Drug delivery to target the posterior segment of the eye].

Retinal diseases are nowadays the most common causes of vision threatening in developed countries. Therapeutic advances in this field are hindered by the difficulty to deliver drugs to the posterior segment of the eye. Due to anatomical barriers, the ocular biodisponibility of systemically administered drugs remains poor, and topical instillation is not adequate to achieve therapeutic concentrations of drugs in the back of the eye. Ocular drug delivery has thus become one of the main challenges of modern ophthalmology. A multidisciplinary research is being conducted worldwide including pharmacology, biomaterials, ophthalmology, pharmaceutics, and biology. New promising fields have been developed such as implantable or injectable slow release intravitreal devices and degradable polymers, dispersed polymeric systems for intraocular drug delivery, and transscleral delivery devices such as iontophoresis, osmotic pumps or intra-scleraly implantable materials. The first clinical applications emerging from this research are now taking place, opening new avenues for the treatment of retinal diseases.

Anterior Segment Angiography in Strabismus Surgery

Background: Anterior ciliary arteries travelling along recti muscles provide anterior segment vascularization, which can be compromised by surgery involving more than 2 muscles.Patients and Methods: We studied retrospectively the files of 10 patients in whom a fluorescein angiography of the iris had been performed as a pre-operative assessment prior to a second or third oculomotor surgery.Results: The median age of the patients was 47.5 years (range 15 to 73 years). Relative iris ischemia was present in 4 patients following multiple surgeries, none of them presenting any general cardiovascular risk. The initial surgical protocol was modified according to angiographic results in these 4 patients.Conclusion: When further surgery has to be performed on previously multi-operated patients, anterior segment angiography can be useful in the planning of surgery in order to minimize the risks of anterior segment ischemia.

Systèmes de délivrance des médicaments pour le segment antérieur: bases fondamentales et applications cliniques [Drug delivery systems to target the anterior segment of the eye: fundamental bases and clinical applications].

The development of new drug delivery systems to target the anterior segment of the eye may offer many advantages: to increase the biodisponibility of the drug, to allow the penetration of drug that cannot be formulated as solutions, to obtain constant and sustained drug release, to achieve higher local concentrations without systemic effects, to target more specifically one tissue or cell type, to reduce the frequency of instillation and therefore increase the observance and comfort of the patient while reducing side effects of frequent instillation. Several approaches are developed, aiming to increase the corneal contact time by modified formulation or reservoir systems, or by increasing the tissue permeability using iontophoresis. To date, no ocular drug delivery system is ideal for all purposes. To maximize treatment efficacy, careful evaluation of the specific pathological condition, the targeted Intraocular tissue and the location of the most severe pathology must be made before selecting the method of delivery most suitable for each individual patient.

A randomised controlled clinical trial and gait analysis of fixed- and mobile-bearing total knee replacements with a five-year follow-up.

This study compared the outcome of total knee replacement (TKR) in adult patients with fixed- and mobile-bearing prostheses during the first post-operative year and at five years' follow-up, using gait parameters as a new objective measure. This double-blind randomised controlled clinical trial included 55 patients with mobile-bearing (n = 26) and fixed-bearing (n = 29) prostheses of the same design, evaluated pre-operatively and post-operatively at six weeks, three months, six months, one year and five years. Each participant undertook two walking trials of 30 m and completed the EuroQol questionnaire, Western Ontario and McMaster Universities osteoarthritis index, Knee Society score, and visual analogue scales for pain and stiffness. Gait analysis was performed using five miniature angular rate sensors mounted on the trunk (sacrum), each thigh and calf. The study population was divided into two groups according to age (≤ 70 years versus > 70 years). Improvements in most gait parameters at five years' follow-up were greater for fixed-bearing TKRs in older patients (> 70 years), and greater for mobile-bearing TKRs in younger patients (≤ 70 years). These findings should be confirmed by an extended age controlled study, as the ideal choice of prosthesis might depend on the age of the patient at the time of surgery.

Disc degeneration: current surgical options.

Chronic low back pain attributed to lumbar disc degeneration poses a serious challenge to physicians. Surgery may be indicated in selected cases following failure of appropriate conservative treatment. For decades, the only surgical option has been spinal fusion, but its results have been inconsistent. Some prospective trials show superiority over usual conservative measures while others fail to demonstrate its advantages. In an effort to improve results of fusion and to decrease the incidence of adjacent segment degeneration, total disc replacement techniques have been introduced and studied extensively. Short-term results have shown superiority over some fusion techniques. Mid-term results however tend to show that this approach yields results equivalent to those of spinal fusion. Nucleus replacement has gained some popularity initially, but evidence on its efficacy is scarce. Dynamic stabilisation, a technique involving less rigid implants than in spinal fusion and performed without the need for bone grafting, represents another surgical option. Evidence again is lacking on its superiority over other surgical strategies and conservative measures. Insertion of interspinous devices posteriorly, aiming at redistributing loads and relieving pain, has been used as an adjunct to disc removal surgery for disc herniation. To date however, there is no clear evidence on their efficacy. Minimally invasive intradiscal thermocoagulation techniques have also been tried, but evidence of their effectiveness is questioned. Surgery using novel biological solutions may be the future of discogenic pain treatment. Collaboration between clinicians and basic scientists in this multidisciplinary field will undoubtedly shape the future of treating symptomatic disc degeneration.

Le mariage des prêtres, ou Récit de ce qui s'est passé à trois séances des assemblées générales du district de Saint-Étienne-du-Mont, où l'on a agité la question du mariage des prêtres , avec la motion principale et Les opinions des honorables membres qui ont appuyé la motion...

Comprend : Les opinions des honorables membres qui ont appuyé la motion

The fixation of the cemented femoral component. Effects of stem stiffness, cement thickness and roughness of the cement-bone surface.

After cemented total hip arthroplasty (THA) there may be failure at either the cement-stem or the cement-bone interface. This results from the occurrence of abnormally high shear and compressive stresses within the cement and excessive relative micromovement. We therefore evaluated micromovement and stress at the cement-bone and cement-stem interfaces for a titanium and a chromium-cobalt stem. The behaviour of both implants was similar and no substantial differences were found in the size and distribution of micromovement on either interface with respect to the stiffness of the stem. Micromovement was minimal with a cement mantle 3 to 4 mm thick but then increased with greater thickness of the cement. Abnormally high micromovement occurred when the cement was thinner than 2 mm and the stem was made of titanium. The relative decrease in surface roughness augmented slipping but decreased debonding at the cement-bone interface. Shear stress at this site did not vary significantly for the different coefficients of cement-bone friction while compressive and hoop stresses within the cement increased slightly.

Automated Traffic/Truck Weight Monitoring Equipment (Weigh-in-Motion), HR-282, 1988

This report documents work undertaken in the demonstration of a low-cost Automatic Weight and Classification System (AWACS). An AWACS procurement specification and details of the results of the project are also included. The intent of the project is to support and encourage transferring research knowledge to state and local agencies and manufacturers through field demonstrations. Presently available, Weigh-in-Motion and Classification Systems are typically too expensive to permit the wide deployment necessary to obtain representative vehicle data. Piezo electric technology has been used in the United Kingdom and Europe and is believed to be the basic element in a low-cost AWACS. Low-cost systems have been installed at two sites, one in Portland Cement Concrete (PCC) pavement in Iowa and the other in Asphaltic Cement Concrete (ACC) pavement in Minnesota to provide experience with both types of pavement. The systems provide axle weights, gross vehicle weight, axle spacing, vehicle classification, vehicle speed, vehicle count, and time of arrival. In addition, system self-calibration and a method to predict contact tire pressure is included in the system design. The study has shown that in the PCC pavement, the AWACS is capable of meeting the needs of state and federal highway agencies, producing accuracies comparable to many current commercial WIM devices. This is being achieved at a procurement cost of substantially less than currently available equipment. In the ACC pavement the accuracies were less than those observed in the PCC pavement which is concluded to result from a low pavement rigidity at this site. Further work is needed to assess the AWACS performance at a range of sites in ACC pavements.

Gravity-driven slug motion in capillary tubes

The velocity of a liquid slug falling in a capillary tube is lower than predicted for Poiseuille flow due to presence of menisci, whose shapes are determined by the complex interplay of capillary, viscous, and gravitational forces. Due to the presence of menisci, a capillary pressure proportional to surface curvature acts on the slug and streamlines are bent close to the interface, resulting in enhanced viscous dissipation at the wedges. To determine the origin of drag-force increase relative to Poiseuille flow, we compute the force resultant acting on the slug by integrating Navier-Stokes equations over the liquid volume. Invoking relationships from differential geometry we demonstrate that the additional drag is due to viscous forces only and that no capillary drag of hydrodynamic origin exists (i.e., due to hydrodynamic deformation of the interface). Requiring that the force resultant is zero, we derive scaling laws for the steady velocity in the limit of small capillary numbers by estimating the leading order viscous dissipation in the different regions of the slug (i.e., the unperturbed Poiseuille-like bulk, the static menisci close to the tube axis and the dynamic regions close to the contact lines). Considering both partial and complete wetting, we find that the relationship between dimensionless velocity and weight is, in general, nonlinear. Whereas the relationship obtained for complete-wetting conditions is found in agreement with the experimental data of Bico and Quere [J. Bico and D. Quere, J. Colloid Interface Sci. 243, 262 (2001)], the scaling law under partial-wetting conditions is validated by numerical simulations performed with the Volume of Fluid method. The simulated steady velocities agree with the behavior predicted by the theoretical scaling laws in presence and in absence of static contact angle hysteresis. The numerical simulations suggest that wedge-flow dissipation alone cannot account for the entire additional drag and that the non-Poiseuille dissipation in the static menisci (not considered in previous studies) has to be considered for large contact angles.