Using second harmonic generation (SHG) imaging microscopy, we have examined the effect of optical clearing with glycerol to achieve greater penetration into specimens of skeletal muscle tissue. We find that treatment with 50% glycerol results in a 2.5-fold increase in achievable SHG imaging depth. Signal processing analyses using fast Fourier transform and continuous wavelet transforms show quantitatively that the periodicity of the sarcomere structure is unaltered by the clearing process and that image quality deep in the tissue is improved with clearing. Comparison of the SHG angular polarization dependence also shows no change in the supramolecular organization of acto-myosin complexes. By contrast, identical treatment of mouse tendon (collagen based) resulted in a strong decrease in SHG response. We suggest that the primary mechanism of optical clearing in muscle with glycerol treatment results from the reduction of cytoplasmic protein concentration and concomitant decrease in the secondary inner filter effect on the SHG signal. The lack of glycerol concentration dependence on the imaging depth indicates that refractive index matching plays only a minor role in the optical clearing of muscle. SHG and optical clearing may provide an ideal mechanism to study physiology in highly scattering skeletal or cardiac muscle tissue with significantly improved depth of penetration and achievable imaging depth.

Background-Quantitative measures derived from MRI have been widely investigated as noninvasive biomarkers in multiple sclerosis (MS). However, the correlation of single measures with Expanded Disability Status Scale (EDSS) is poor, especially for studies with large population samples.

Diffusion spectrum imaging (DSI) is capable of resolving crossing and touching fiber bundles in a given voxel. Acquisition of DSI data involves sampling large number of points in the q-space which significantly increases scan times. The scan times can be reduced by exploiting the symmetry of the q-space. In this study the fiber pathways for five (fornix, cingulum, superior longitudinal fasciculus, corticospinal tract, and crossing fibers in the centrum semiovale region) fiber bundles derived using three subsampled data sets of different sizes derived from the 257 samples in the q-space are compared. The coefficient of variation of the ratio of the number of fiber pathways for each subsample data set to the original data points, averaged over all the 10 subjects, was used for quantitatively investigating the effect of subsampling on the tractography. The effect of threshold angles on tractography is also investigated. The effect of subsampling on the orientation distribution function (ODF) was quantitatively evaluated using both scalar and vector measures derived from the ODF. A streamline tractography method that improves the curvature problem and reduces the local truncation error to further improve the mapping of fiber pathways is adapted. Analysis of the fiber pathways in ten normal subjects, based on qualitative and quantitative methods, shows that the 129 and 198 q-space points provide very similar result with angle of threshold between 41° and 45°. Based on the scan time advantage, 129 subsampled points appear to be adequate for tractography.

Purpose: The purpose of this study was to build diffusion phantoms and employ post‐processing techniques for validating the diffusion spectrum imaging (DSI)‐derived fiber orientation distribution function (ODF) in the crossing regions. Methods: To establish a ground truth, we constructed a phantom with a fixed crossing fiber configuration of 45° and another with 3 crossing fibers at 60°. Phantom construction involved hollow plastic capillaries which were filled with water and wrapped around a plastic plate to form a number of interleaved parallel layers resulting in fibers crossing at the desired angle. We also implemented a technique to de‐convolve the response function of an individual peak from the overall ODF. The technique involves representing a DSI derived ODF with its spherical harmonic coefficients and performing the de‐convolution using the Funk‐ Hecke theorem. Unlike the methodology in which deconvolution is applied to the spherical q‐ball signal by Descoteaux et. al, (2009), our method applies it directly on the ODF derived from DSI.DSI data was acquired on the phantom on a Philips 3.0 T Intera scanner (with SENSE Flex M coil) using spin‐echo echo‐planar imaging (EPI) sequence with b‐value of 6000 and 515 sampling points. Results: Our deconvolution methodology greatly improves the angular resolution of the otherwise un‐resolvable peaks in the ODF. Quantification of a crossing region with 10±10 pixels in the 45° and 60° phantoms resulted in a successful detection with mean ± sd of 44.6°±1.6° and 59.4°±6.8° respectively, while simultaneously sharpening the ODFs in regions containing single fibers. Conclusions: We developed a diffusion phantom with 3 crossing fibers for the first time. Our proposed methodologies significantly improved the angular accuracy of the crossing fibers and are applicable to ODFs obtained from other high angular resolution diffusion imaging such as Q ball imaging.

Introduction Cell therapy is an investigational modality to enhance recovery after stroke. We completed a Phase I clinical trial of 25 patients assessing the safety and feasibility of autologous bone marrow derived mononuclear cells (MNCs). Study participants underwent a bone marrow harvest and were intravenously administered autologous MNCs 24-72 hours after stroke onset. We report an ordinal analysis that compares 90-day outcomes of study patients with retrospectively generated controls. Methods We compared the study patients to a group of patients derived from our stroke registry who presented to our center during the same time period as the clinical trial. The control group was initially matched for age and NIHSS and was further refined based on other inclusion / exclusion criteria of the trial, generating a final set of 185 patients. Between the two groups, we compared demographics, clinical characteristics, baseline lab values, co-morbidities and adverse events. An ordinal logistic regression model, utilizing the full range of outcome scores, was fitted to compare 90-day mRS scores. Results: The bone marrow harvest and infusion of MNCs was completed successfully in all study patients without any definitive study related severe adverse event. Table 1 shows the balance of tested co-variates between the stem cell and control groups. After controlling for 24-48 hour NIHSS, t-PA, rehab, length of stay, cardiac disease, and PTT, the final model estimated a greater odds of having a higher mRS at 90 days in the control group compared with the study patients (OR: 3.25, 95% CI: 1.48 - 7.14). Our model did not violate the proportionality of odds assumption (likelihood-ratio, p=0.1). Figure 1 shows the proportion of patients for each level of discharge and day 90 mRS score. Conclusion: Intravenous infusion of autologous MNCs is safe in the setting of acute stroke. This analysis suggests that patients receiving MNCs may also be exhibiting a signal of enhanced functional recovery.