Technology evaluation: Belatacept, Bristol-Myers Squibb

Bristol-Myers Squibb is developing belatacept, a soluble fusion protein of the B7-binding domain of CTLA4 with amino acid changes A29Y and L104E and an Ig tail, which inhibits lymphocyte co-stimulation through CD28, for the potential treatment of solid organ transplant rejection. Belatacept is currently undergoing phase III clinical trials.     

Intracranial aneurysms treated with Guglielmi detachable coils: usefulness of 6-month imaging follow-up with contrast-enhanced MR angiography

BACKGROUND AND PURPOSE: This study was undertaken to assess the utility of contrast-enhanced MR angiography at 6 months after endovascular treatment of intracranial aneurysms with Guglielmi detachable coils. METHODS: Contrast-enhanced MR angiography was performed in 47 patients at 6 and 12 months after endovascular treatment of intracranial aneurysms (48 aneurysms). Digital subtraction angiography (DSA) was used as reference and was performed at 12 months after the treatment in all patients. MR angiographs were analyzed independently by two senior radiologists. DSA and MR angiography findings were assigned into one of three categories: complete obliteration, residual neck, or residual aneurysm. RESULTS: All examinations were assessable. Interobserver agreement was judged as very good for contrast-enhanced MR angiography (kappa=0.96), with one discrepancy between examiners. Comparison between MR angiography at 6 months and DSA at 12 months showed an excellent agreement between techniques (kappa=0.93). Two cases of complete occlusion at DSA were misclassified as a residual neck at 6-month MR angiography. All aneurysm recanalizations at DSA already were detected on MR angiography at 6 months. The size of aneurysm recanalization did not increase between both MR angiographs performed at 6 and 12 months. CONCLUSION: Contrast-enhanced MR angiography after selective embolization of intracranial aneurysm seems to predict properly early aneurysm recanalizations.     

Three-dimensional packing with complex orbit coils for the endovascular treatment of intracranial aneurysms

BACKGROUND AND PURPOSE: Endovascular treatment of intracranial aneurysms is too often associated with aneurysm recurrence due to coil compaction. High packing of coils prevents compaction. To increase the packing attenuation, we sought to evaluate the results of selective embolization of aneurysms with complex-shaped coils alone. METHODS: Twenty consecutive patients with an intracranial aneurysm were treated by selective embolization. There were 12 women and eight men, with a mean age of 48 years. Fourteen patients presented with subarachnoid hemorrhage, whereas six were asymptomatic. Mean size of aneurysms was 5 mm (range, 3-11 mm). In all cases, we tried to pack the aneurysm with complex coils only (Orbit, Cordis, Miami Lakes, FL), delivered in a concentric fashion. Remodeling technique was used in two cases of wide-neck aneurysms. Clinical and anatomic outcome were assessed by using the modified Glasgow outcome scale and 6-month MR angiography (MRA). RESULTS: From two to five complex coils were delivered within the aneurysms. Occlusion by using complex coils alone was successful in 16 patients, and resulted in 14 complete occlusions and two neck remnants. In four patients, additional helical Orbit coils or Guglielmi detachable coils were required to complete aneurysm obliteration. No technical complication occurred, and clinical outcome was excellent in 14 cases and good in two. Follow-up MRAs were obtained in all patients and showed only one slight recanalization. CONCLUSIONS: Intracranial aneurysms may be treated by selective embolization with complex coils only. Imaging follow-up at 6 months shows a low rate of coil compaction.     

Lower-limb activity during the power serve in tennis: effects of performance level

PURPOSE: The aim of the present study was to investigate the differences in lower-limb activity during the tennis power serve between players of different performance levels. METHODS: Thirty-two participants distributed in three groups (beginner, B; intermediate, I; elite, E) performed countermovement jumps to measure leg power (P(max)) and 15 power serves from a force platform. Lateral, horizontal, and vertical forces (Fx, Fy, and Fz) were sampled simultaneously with EMG signals from six leg muscles. Racquet-ball impact height (I(height)) and maximum velocity of the ball (V(max) were measured with video analysis and radar, respectively. The total duration of the serve was fractioned into four phases: preparation (Pre), eccentric (Ecc), concentric (Con), and suspension (Sus). RESULTS: Pmax was similar in the three groups. The duration of Pre was longer (P < 0.05) in E than in B, whereas Con was shorter (P < 0.05). Vmax (169.4 +/- 11.3 vs 107.2 +/- 6.1 kmxh, P < 0.001), I(height) (149.2 +/- 2.7 vs 142.6 +/- 4.7% of standing height, P < 0.05), and Fz(max) (2.12 +/- 0.36 vs 1.68 +/- 0.33 of body weight, P < 0.01) were higher in E than in B. I(height) was correlated (r = 0.85, P < 0.001) with Fz(max) in E. Peaks EMG occurred earlier (P < 0.05) in E (79 +/- 17% of Con) than in other groups (B: 94 +/- 11% and I: 94 +/- 15%). CONCLUSION: The vertical forces and coordination in lower extremities during the tennis serve were different between players of different skill levels but with the same P(max). This may partly explain the differences in serve efficiency.     

Region-growing segmentation of brain vessels: an atlas-based automatic approach

PURPOSE: To propose an atlas-based method that uses both phase and magnitude images to integrate anatomical information in order to improve the segmentation of blood vessels in cerebral phase-contrast magnetic resonance angiography (PC-MRA). MATERIAL AND METHODS: An atlas of the whole head was developed to store the anatomical information. The atlas divides a magnitude image into several vascular areas, each of which has specific vessel properties. It can be applied to any magnitude image of an entire or nearly entire head by deformable matching, which helps to segment blood vessels from the associated phase image. The segmentation method used afterwards consists of a topology-preserving, region-growing algorithm that uses adaptive threshold values depending on the current region of the atlas. This algorithm builds the arterial and venous trees by iteratively adding voxels that are selected according to their grayscale value and the variation of values in their neighborhood. The topology preservation is guaranteed because only simple points are selected during the growing process. RESULTS: The method was performed on 40 PC-MRA images of the brain. The results were validated using maximum-intensity projection (MIP) and three-dimensional surface rendering visualization, and compared with results obtained with two non-atlas-based methods. CONCLUSION: The results show that the proposed method significantly improves the segmentation of cerebral vascular structures from PC-MRA. These experiments tend to prove that the use of vascular atlases is an effective way to optimize vessel segmentation of cerebral images.     

Hidden Markov event sequence models: toward unsupervised functional MRI brain mapping

RATIONALE AND OBJECTIVES: Most methods used in functional MRI (fMRI) brain mapping require restrictive assumptions about the shape and timing of the fMRI signal in activated voxels. Consequently, fMRI data may be partially and misleadingly characterized, leading to suboptimal or invalid inference. To limit these assumptions and to capture the broad range of possible activation patterns, a novel statistical fMRI brain mapping method is proposed. It relies on hidden semi-Markov event sequence models (HSMESMs), a special class of hidden Markov models (HMMs) dedicated to the modeling and analysis of event-based random processes. MATERIALS AND METHODS: Activation detection is formulated in terms of time coupling between (1) the observed sequence of hemodynamic response onset (HRO) events detected in the voxel's fMRI signal and (2) the "hidden" sequence of task-induced neural activation onset (NAO) events underlying the HROs. Both event sequences are modeled within a single HSMESM. The resulting brain activation model is trained to automatically detect neural activity embedded in the input fMRI data set under analysis. The data sets considered in this article are threefold: synthetic epoch-related, real epoch-related (auditory lexical processing task), and real event-related (oddball detection task) fMRI data sets. RESULTS: Synthetic data: Activation detection results demonstrate the superiority of the HSMESM mapping method with respect to a standard implementation of the statistical parametric mapping (SPM) approach. They are also very close, sometimes equivalent, to those obtained with an "ideal" implementation of SPM in which the activation patterns synthesized are reused for analysis. The HSMESM method appears clearly insensitive to timing variations of the hemodynamic response and exhibits low sensitivity to fluctuations of its shape (unsustained activation during task). Real epoch-related data: HSMESM activation detection results compete with those obtained with SPM, without requiring any prior definition of the expected activation patterns thanks to the unsupervised character of the HSMESM mapping approach. Along with activation maps, the method offers a wide range of additional fMRI analysis functionalities, including activation lag mapping, activation mode visualization, and hemodynamic response function analysis. Real event-related data: Activation detection results confirm and validate the overall strategy that consists in focusing the analysis on the transients, time-localized events that are the HROs. CONCLUSION: All the experiments performed on synthetic and real fMRI data demonstrate the relevance of HSMESMs in fMRI brain mapping. In particular, the statistical character of these models, along with their learning and generalizing abilities are of particular interest when dealing with strong variabilities of the active fMRI signal across time, space, experiments, and subjects.     

Enterprise-wide PACS: beyond radiology, an architecture to manage all medical images

RATIONALE AND OBJECTIVES: Picture archiving and communication systems (PACS) have the vocation to manage all medical images acquired within the hospital. To address the various situations encountered in the imaging specialties, the traditional architecture used for the radiology department has to evolve. MATERIALS AND METHODS: We present our preliminarily results toward an enterprise-wide PACS intended to support all kind of image production in medicine, from biomolecular images to whole-body pictures. Our solution is based on an existing radiologic PACS system from which images are distributed through an electronic patient record to all care facilities. This platform is enriched with a flexible integration framework supporting digital image communication in medicine (DICOM) and DICOM-XML formats. In addition, a generic workflow engine highly customizable is used to drive work processes. RESULTS: Echocardiology; hematology; ear, nose, and throat; and dermatology, including wounds, follow-up is the first implemented extensions outside of radiology. CONCLUSION: We also propose a global strategy for further developments based on three possible architectures for an enterprise-wide PACS.