Muscle structure assessment using synchrotron radiation X-ray micro-computed tomography in murine with cerebral ischemia

Muscles are crucial for balance and walking, activities which depend specifically on the lower extremity muscles. Therefore, the evaluation of stroke induced atrophy and paralysis is essential; however, determining the extent of damage in the days after its occurrence remains challenging. In this study, we evaluated ischemic stroke-induced soleus muscle damage in gerbils using synchrotron radiation X-ray micro-computed tomography (SR-µCT), comparing a control group (n = 3), animals 7 days after stroke (7 d, n = 3), and animals 14 days after stroke (14 d, n = 3). The left muscle was paralyzed, whereas the right muscle was not. Subsequently, we quantified the assessment by segmenting the soleus muscle based on the extracellular space/matrix and fiber region to determine the degree of damage. The muscle fiber-to-extracellular space/matrix ratio were significantly damaged due to paralysis on the left side (control vs. 14 d, P = 0.040). Muscle area was significantly different at 14 d between the left and right sides (P = 0.010). Additionally, the left local fascicle surface area, thickness, global pennation angle, and local fascicle angle were significantly different between the control and 14 d groups (P = 0.002, P = 0.007, P = 0.005, and P = 0.014 respectively). These findings underscore the potential of post-stroke animal studies in improving rehabilitation treatment for the central nervous system by assessing the degree of muscle recovery.

Single fiber curvature for muscle impairment assessment: Phase contrast imaging of stroke-induced animals

There are technical challenges in imaging studies that can three-dimensionally (3D) analyze a single fiber (SF) to observe the functionality of the entire muscle after stroke. This study proposes a 3D assessment technique that only segments the SF of the right stroke-induced soleus muscle of a gerbil using synchrotron radiation x-ray microcomputed tomography (SR-μCT), which is capable of muscle structure analysis. Curvature damage in the SF of the left soleus muscle (impaired) progressed at 7-day intervals after the stroke in the control; particularly on the 7 days (1 week) and 14 days (2 weeks), as observed through visualization analysis. At 2 weeks, the SF volume was significantly reduced in the control impaired group (p = .033), and was significantly less than that in the non-impaired group (p = .009). We expect that animal post-stroke studies will improve the basic field of rehabilitation therapy by diagnosing the degree of SF curvature. RESEARCH HIGHLIGHTS: Muscle evaluation after ischemic stroke using synchrotron radiation x-ray microcomputed tomography (SR-μCT). Curvature is measured by segmenting a single fiber (SF) in the muscle. Structural changes in the SF of impaired gerbils at 7-day intervals were assessed.

Micro- and nano-tomography analysis of mouse soleus muscle using radiation

In this study, we analyze radiation images of muscle structure of mice soleus muscles using radiation source-based microtomography and nanotomography. Soleus muscle samples were collected for analysis from 8-week-old male Institute of Cancer Research mice. First, phase-contrast X-ray microtomography was employed in these experiments. Then to obtain images with excellent contrast, imaging was performed using monochromatic light with excellent transmission power. To analyze additional muscle structures in higher magnification images than these images, nanotomography was performed, which facilitated obtaining high-magnification and high-resolution images. Muscle tissue microstructures were confirmed through three-dimensional images obtained from phase-contrast X-ray microtomography. Thus, the muscle tissue's overall shape at microscopic level can be captured. Additionally, a single muscle fiber was examined using hard X-ray nano-imaging, through which we could observe the alignment of countless myofibrils, that is, actin and myosin filaments in the muscle fibers. Thus, the methodology adopted here proved to be advantageous in analyzing the muscle tissue's overall structure with microtomography and in observing the myofibrils in detail using nanotomography.

Three-dimensional analysis of injury conditions of single muscle fibers in small animals using phase-contrast X-ray imaging

Muscle damage can reduces the biological functions and lead to ultimately a disease state. For the reason, it is important to accurately check the state of an injury such as atrophy, and it is required to identify the state of fibers constituting the muscle. This study describes a novel method of analyzing single muscle fibers with injury conditions in three-dimensions. The muscle fibers of the mice were visualized using phase-contrast X-ray projection the microstructure. In additions, it was possible to confirm the status by quantitatively analyzing the injury severity of muscle fibers. Significantly, the muscle conditions of multiple individuals were individually determined. This study could contributes to areas where it is very important to identify microdetailed and quantitative changes of state, such as new drug development.

Synchrotron radiation imaging analysis of neural damage in mouse soleus muscle

Damage to lower limb muscles requires accurate analysis of the muscular condition via objective microscopic diagnosis. However, microscopic tissue analysis may cause deformation of the tissue structure due to injury induced by external factors during tissue sectioning. To substantiate these muscle injuries, we used synchrotron X-ray imaging technology to project extremely small objects, provide three-dimensional microstructural analysis as extracted samples. In this study, we used mice as experimental animals to create soleus muscle models with various nerve injuries. We morphologically analyzed and quantified the damaged Section and Crush muscles, respectively, via three-dimensional visualization using synchrotron radiation X-ray imaging to diagnose muscle injury. Results of this study can also be used as basic data in the medical imaging field.

Using X-ray computed tomography and micro-Raman spectrometry to measure individual particle surface area, volume, and morphology towards investigating atmospheric heterogeneous reactions

Heterogeneous reactions on the aerosol particle surface in the atmosphere play important roles in air pollution, climate change, and global biogeochemical cycles. However, the reported uptake coefficients of heterogeneous reactions usually have large variations and may not be relevant to real atmospheric conditions. One of the major reasons for this is the use of bulk samples in laboratory experiments, while particles in the atmosphere are suspended individually. A number of technologies have been developed recently to study heterogeneous reactions on the surfaces of individual particles. Precise measurements on the reactive surface area, volume, and morphology of individual particles are necessary for calculating the uptake coefficient, quantifying reactants and products, and understanding the reaction mechanism better. In this study, for the first time we used synchrotron radiation X-ray computed tomography (XCT) and micro-Raman spectrometry to measure individual CaCO₃ particle morphology, with sizes ranging from 3.5-6.5μm. Particle surface area and volume were calculated using a reconstruction method based on software three-dimensional (3-D) rendering. The XCT was first validated with high-resolution field-emission scanning electron microscopy (FE-SEM) to acquire accurate CaCO₃ particle surface area and volume estimates. Our results showed an average difference of only 6.1% in surface area and 3.2% in volume measured either by micro-Raman spectrometry or X-ray tomography. X-ray tomography and FE-SEM can provide more morphological details of individual CaCO₃ particles than micro-Raman spectrometry. This study demonstrated that X-ray computed tomography and micro-Raman spectrometry can precisely measure the surface area, volume, and morphology of an individual particle.