The Dynamics of Spontaneous Capillary Flow in Confined and Open Microchannels

Capillary microfluidics or capillarics is gaining importance in the biotechnological domain. It combines the advantages of capillary actuation that does not require pumps or syringes to move the fluids, with low-cost fabrication, user-friendliness, portability and telemedicine compatibility. In this work, we present expressions of the spontaneous capillary flow velocity in different geometrical configurations. It is shown that relatively large velocities - at the scale of microsystems — can be reached by capillary microflows. Consequently transport distances can be important

Symmetry-based reorientation algorithm for spinal cord 3T MR images

Congrès sous l’égide de la Société Française de Génie Biologique et Médical (SFGBM).National audienceImaging the spinal cord of spinal cord injury (SCI) patients is challenging due to pain and sores problems that could be caused by a prolonged lying position in the scanner. Once positioned within the MRI the subject cannot be displaced and therefore subject centering within the scanner (A-P and L-R directions) is not ensured. Thus, centering spinal cord images in the A-P and L-R directions is necessary to make group analysis and accurately quantifying cord atrophy in SCI patients. A Symmetry-based reorientation algorithm for the spinal cord 3T R images was proposed and evaluated on 32 data using both an imposed rotation angle and visual strategies. The proposed reorientation algorithm was proven to be efficient at C2 vertebral level

Fast and accurate semi-automated segmentation method of spinal cord MR images at 3T applied to the construction of a cervical spinal cord template.

To design a fast and accurate semi-automated segmentation method for spinal cord 3T MR images and to construct a template of the cervical spinal cord.A semi-automated double threshold-based method (DTbM) was proposed enabling both cross-sectional and volumetric measures from 3D T2-weighted turbo spin echo MR scans of the spinal cord at 3T. Eighty-two healthy subjects, 10 patients with amyotrophic lateral sclerosis, 10 with spinal muscular atrophy and 10 with spinal cord injuries were studied. DTbM was compared with active surface method (ASM), threshold-based method (TbM) and manual outlining (ground truth). Accuracy of segmentations was scored visually by a radiologist in cervical and thoracic cord regions. Accuracy was also quantified at the cervical and thoracic levels as well as at C2 vertebral level. To construct a cervical template from healthy subjects' images (n=59), a standardization pipeline was designed leading to well-centered straight spinal cord images and accurate probability tissue map.Visual scoring showed better performance for DTbM than for ASM. Mean Dice similarity coefficient (DSC) was 95.71% for DTbM and 90.78% for ASM at the cervical level and 94.27% for DTbM and 89.93% for ASM at the thoracic level. Finally, at C2 vertebral level, mean DSC was 97.98% for DTbM compared with 98.02% for TbM and 96.76% for ASM. DTbM showed similar accuracy compared with TbM, but with the advantage of limited manual interaction.A semi-automated segmentation method with limited manual intervention was introduced and validated on 3T images, enabling the construction of a cervical spinal cord template

Ground-Truth Segmentation of the Spinal Cord from 3T MR Images Using Evolutionary Computation

International audienceSpinal cord atrophy is one of the neuroimaging features associated with neurodegenerative diseases, inflammatory diseases and trauma. MR images segmentation can be used to assess cord atrophy, with varying degrees of manual intervention. However the accuracy of segmentation results highly depends on the operator’s experience: there is a clear need for methods that simplifies and facilitates expert intervention, while providing an accurate quantification of cord atrophy. We propose and test here a ground-truth segmentation based on a simple evolutionary algorithm. EAcord integrates a set of segmentation methods with varying accuracy and manual intervention (manual, semi-automated and automated methods), as well as knowledge about the spinal cord anatomy, its relative location, immediate surrounding environment and shape at C2 vertebral level. A lighter version, EAcord-light, is also proposed, using only segmentations from semi-automated and automated methods as inputs. An experimental analysis of both algorithms showed an improved reproducibility and similar or even better accuracies compared to manual outlining. More interestingly, in some cases, EAcord-light produced a ground-truth segmentation with minimal expert interventio

Accuracy of mean cross-sectional area measured at C2 vertebral level.

<p>Manual segmentation by the experienced operator was the ground truth for accuracy measurements.</p><p>Accuracy of mean cross-sectional area measured at C2 vertebral level.</p

Results of the visual evaluation.

<p>*Asymptomatic syrinx revealed by the visual evaluation.</p><p>Results of the visual evaluation.</p

Criteria and scores for the visual evaluation.

<p>¹Insufficient to moderate overlap in at least 3 vertebral levels.</p><p>²Insufficient to moderate overlap in less than 3 vertebral levels.</p><p>³Global substantial overlap agreement.</p><p>⁴Global perfect overlap agreement.</p><p>Criteria and scores for the visual evaluation.</p

Overview of DTbM steps (S).

<p>Slice 1 represents an example of a resampled axial image. Slices 2 and 3 represent the progressive contrast enhancement of slice 1.</p

Segmented spinal cord regions for each group of subjects (Upper–Lower vertebral level limits).

<p>Segmented spinal cord regions for each group of subjects (Upper–Lower vertebral level limits).</p

Cervical spinal cord template and probability tissue map.

<p>(a) Coronal (left), sagittal (middle) and axial views (right) of the cervical spinal cord template through mid-vertebral level from C2 to C7. (b) Probability tissue map. Views are arranged in the same order and orientation as in (a). A, anterior; I, inferior, L, left, P, posterior, R, right; S, superior.</p