Diffusion MRI With High to Ultrahigh b-Values: How It Will Benefit the Discovery of Brain Microstructure and Pathological Changes

Diffusion MRI (dMRI) has been widely utilized to probe the random motion of water molecules in tissues. In a dMRI acquisition protocol, diffusion weighting or b-value is one of the most important parameters to consider. In recent years, high and ultrahigh b-values have become popular partly due to advances in hardware. In this mini-review, we will discuss impacts of high/ultrahigh b-values in three different areas: brain microstructure, tractography, and clinical applications. We will emphasize advantages of high b-value in probing diffusion within highly restricted regions or fine structures with enhanced diffusion contrast. A short summary is included at the end of each section to illustrate both advantages and disadvantages of using a high/ultrahigh b-value for each purpose.

Diffusion Encoding Methods in MRI: Perspectives and Challenges

Diffusion MRI (dMRI) is an important imaging modality that is used extensively to diagnose and monitor diseases. dMRI measures random motion of water molecules and helps elucidate microstructural properties of tissues. Optimal diffusion encoding paradigms have been developed to reduce acquisition time, minimize artifacts, and acquire high fidelity data needed for advanced modeling of tissue properties. To further probe microstructural properties, joint diffusion-relaxometry and diffusion weighted MR fingerprinting have garnered interest. A thorough knowledge of different diffusion encoding methods is essential to accurately encode diffusion in MR experiments. Here, we review fundamental physics of diffusion encoding methods, their associated challenges, and how to address them. Advanced diffusion acquisition methods are also discussed.

EVALUATION OF PROTEIN DETERMINATION IN URINE FOR GLOMERULAR HEMATURIA DIAGNOSIS / 中华肾脏病杂志

To study the affection of blood on protein determining in urine, different volumes of blood from healthy volunteers was added to urine samples of varied osmolatites. Specimens were analyzed for protein concentration by the method of 3% sulfosalicylic acid. Microscopic hematuria was not associated proteinuria. In hypertonic urines, the protein of gross hematuria is low (30mg/100ml for the urine with 3% RBC, 32. 4mg/100ml for the urine with 1% blood), while in iso and hypotonic urines gross hematuria produced marked proteinuria (225—1090mg/100ml). Urine protein electrophoreses identified hemoglobin as the responsible protein. The protein concentration in urine may he used to distinguish glomerular hematuria from nonglomerular hematuria.