Improvement on detectability of early ischemic changes for acute stroke using nonenhanced computed tomography: Effect of matrix size

Pitfalls in the analysis conditions of canine brain perfusion computed tomography

This study aimed to investigate the impact of selected analysis conditions on blood flow values and color maps in canine brain perfusion computed tomography (PCT) and to propose optimal analysis conditions. Dynamic computed tomography imaging was performed on six beagle dogs. Color maps were generated using a combination of analysis algorithms (box-modulation transfer function (Box-MTF) and singular value deconvolution plus (SVD+) methods), slice thicknesses (4.0 and 8.0 mm), analysis matrix sizes (512 × 512, 256 × 256, and 128 × 128), and noise reduction levels (strong and weak). Cerebral blood flow (CBF) and cerebral blood volume (CBV) were calculated for gray matter, white matter, basal ganglia, hippocampus, thalamus, and cerebellum in each map. CBF and CBV values obtained using SVD+ were significantly higher than those obtained using Box-MTF. Noise reduction was more effective with larger matrix sizes; however, excessive noise reduction led to the blurring of anatomical structures in the color map. Across all analysis algorithms, anatomical structures were challenging to visualize at 8.0 mm. For canine brain PCT, it is essential to choose a straightforward algorithm that remains unaffected by circulatory velocity or intracranial bone structure. Given the brain's size, the slice thickness should be minimal, noise reduction level should be suitable for the targeted area, and matrix size should be maximized.

Diet gel-based oral drug delivery system for controlled dosing of small molecules for microglia depletion and inducible Cre recombination in mice

Small molecules like PLX5622 for microglia depletion and Tamoxifen for inducible Cre recombination are commonly used in mouse research. Traditional application methods, such as chow or oral gavage and injections, have limitations, including uncontrolled dosage and risk of injury. To address this issue, we have developed an alternative oral drug delivery system using a gel-based rodent maintenance diet that allows for controlled consumption and adjustment of dosage and is suitable for water-insoluble small molecules. We tested DietGel® 93M (93M) infused with PLX5622 (0.8 mg/g and 2.0 mg/g) in the Cx3cr1 gfp/+ retinal microglia reporter mouse and Tamoxifen-infused 93M (0.3125 mg/g) in the Rlbp1-CreERT2 ;Rosa ai14 mouse with an inducible tdTomato reporter in retinal Müller glia. Mice were single-caged and received daily batches of PLX5622-infused 93M over 14 days or Tamoxifen-infused 93M for one or three days followed by a 14-day observation period. Longitudinal scanning laser ophthalmoscopy in vivo and fixed tissue imaging were used to track GFP and tdTomato expression. Following evaluation of a suitable 93M consumption rate (g/d) to sustain body weight, the PLX5622-93M diet at both concentrations showed a 94% microglia depletion rate at 3 days and >99% after one and two weeks. The Tamoxifen-93M diet confirmed suitability for inducible Cre recombination, with significant treatment-time dependent efficacy and a positive correlation between total Tamoxifen dose and tdTomato expression. This study demonstrates that a diet gel-based drug delivery system offers a controllable and less invasive alternative to current drug application methods for PLX5622 and Tamoxifen.

Recovery of CT stroke hypodensity--An adaptive variational approach

The present research was directed to effective image restoration with the extraction of ischemic edema signs. Computerized support of hyperacute stroke diagnosis based on routinely used computerized tomography (CT) scans was optimized to visualize the infarct extent more precisely. In particular, a beneficial support of time-limited appropriate decision of whether to treat the patient by thrombolysis is expected. Because of a limited accuracy in determining the area of core infarction, particularly in the early hours of symptoms' onset, a variational approach to sensed data recovery was applied. Proposed methodology adjusts fidelity norms and regularization priors integrated with simulated sensing procedures in a compressed sensing framework. Experimental study confirmed almost perfect recognition of ischemic stroke in a test set of over 500 CT scans.