Emphysema index based on hyperpolarized xenon 129 diffusion MRI is introduced as a robust, nonionizing alternative to CT for quantifying emphysema burden in chronic obstructive pulmonary disease. Background Apparent diffusion coefficient (ADC) maps of inhaled hyperpolarized gases have shown promise in the characterization of emphysema in patients with chronic obstructive pulmonary disease (...

Separation and detection are ubiquitous in our daily life and they are two of the most important steps toward practical biomedical diagnostics and industrial applications. A deep understanding of working principles and examples of separation and detection enables a plethora of applications from blood test and air/water quality monitoring to food safety and biosecurity; none of which are irrelevant to public health. Microfluidics can separate and detect various particles/aerosols as well as cells/viruses in a cost-effective and easy-to-operate manner. There are a number of papers reviewing microfluidic separation and detection, but to the best of our knowledge, the two topics are normally reviewed separately. In fact, these two themes are closely related with each other from the perspectives of public health: understanding separation or sorting technique will lead to the development of new detection methods, thereby providing new paths to guide the separation routes. Therefore, the purpose of this review paper is two-fold: reporting the latest developments in the application of microfluidics for separation and outlining the emerging research in microfluidic detection. The dominating microfluidics-based passive separation methods and detection methods are discussed, along with the future perspectives and challenges being discussed. Our work inspires novel development of separation and detection methods for the benefits of public health.

This work describes the design, construction and testing of a 1.5 T cryogen-free low-temperature superconductor niobium–titanium whole-body magnet with a bore diameter of 850 mm that is suitable for clinical magnetic resonance imaging (MRI) applications. The magnet is actively shielded and passively shimmed to achieve confinement within a 0.5 mT stray magnetic field at 2.5/4 m radial/axial positions and 12.1 ppm field inhomogeneity over a 45 mm diameter of spherical volume. The magnet is conductively refrigerated using a two-stage Gifford–McMahon cryocooler and can be maintained at a steady temperature below 5.7 K during MRI scanning. The MRI scanner assembled with the designed cryogen-free magnet demonstrated stable performance and provided MRI images with good quality and high contrast.

Purpose: To determine whether helium‐3 diffusion MR can detect the changes in the lungs of healthy nonsmoking individuals who were regularly exposed to secondhand smoke.Materials and Methods: Three groups were studied (age: 59 ± 9 years): 23 smokers, 37 exposure‐to‐secondhand‐smoke subjects, and 29 control subjects. We measured helium‐3 diffusion values at diffusion times from 0.23 to 1.97 s.Results: One‐way analysis of variance revealed that the mean area under the helium‐3 diffusion curves (ADC AUC) of the smokers was significantly elevated compared with the controls and to the exposure‐to‐secondhand‐smoke subjects (P < 0.001 both). No difference between the mean ADC AUC of the exposure‐to‐secondhand‐smoke subjects and that of the controls was found (P = 0.115). However, application of a receiver operator characteristic‐derived rule to classify subjects as either a “control” or a “smoker,” based on ADC AUC, revealed that 30% (11/37) of the exposure‐to‐secondhand subjects were classified as “smokers” indicating an elevation of the ADC AUC.Conclusion: Using helium‐3 diffusion MR, elevated ADC values were detected in 30% of nonsmoking healthy subjects who had been regularly exposed to secondhand smoke, supporting the concept that, in susceptible individuals, secondhand smoke causes mild lung damage. J. Magn. Reson. Imaging 2014;39:77–84.

Arterial stiffness has been proved to be an important parameter in the evaluation of cardiovascular diseases, and Pulse Wave Velocity (PWV) is a strong indicator of arterial stiffness. Compared to regional PWV (PWV among different arteries), local PWV (PWV within a single artery) outstands in providing higher precision in indicating arterial properties, as regional PWVs are highly affected by multiple parameters, e.g., variations in blood vessel lengths due to individual differences, and multiple reflection effects on the pulse waveform. However, local PWV is less-developed due to its high dependency on the temporal resolution in synchronized signals with usually low signal-to-noise ratios. This paper presents a method for the noninvasive simultaneous measurement of two local PWVs in both left and right radial arteries based on the Fiber Bragg Grating (FBG) technique via correlation analysis of the pulse pairs at the fossa cubitalis and at the wrist. Based on the measurements of five male volunteers at the ages of 19 to 21 years old, the average left radial PWV ranged from 9.44 m/s to 12.35 m/s and the average right radial PWV ranged from 11.50 m/s to 14.83 m/s. What is worth mentioning is that a stable difference between the left and right radial PWVs was observed for each volunteer, ranging from 2.27 m/s to 3.04 m/s. This method enables the dynamic analysis of local PWVs and analysis of their features among different arteries, which will benefit the diagnosis of early-stage arterial stiffening and may bring more insights into the diagnosis of cardiovascular diseases.

The choroid plexus (ChP) is crucial for most cerebrospinal fluid (CSF) secretion. However, few studies have explored the morphology of ChP in a natural upright posture. This study investigated the positional, areal, and volumetric changes of the ChP in response to gravity when comparing supine and upright scanning postures. Thirty-one healthy volunteers underwent MRI scans using an innovative 1.5T rotatable MRI at pitch angles of 0 and 90 employing a 3D magnetization-prepared rapid gradient echo (MP-RAGE) sequence. Based on an in-house ChP segmentation pipeline, gap lengths between the ChP and lateral ventricles (LVEN), ChP surface area, volumes, and signal intensities in different directions were measured. The ChP exhibited a bottom gap decrease (-1.30 mm, P < 0.001), posterior gap increase (1.28 mm, P < 0.001), and bilateral gap growth (0.16 mm, P = 0.015) as well as downward centroidal shift (-1.31 mm, P < 0.001) relative to the LVEN when transitioning from lying to standing positions. Significant distance deviations were noted along the direction of gravity. Along with these positional changes, decreases in surface area (-5.30%, P = 0.021) and volume (-7.53%, P = 0.002) and an increase (11.46%, P < 0.001) in signal intensity of the ChP were observed from lying to standing. This study reveals the positional and volumetric change of the ChP within the LVEN with postural changes and demonstrates its morphology in a typical standing condition. These anatomic changes could provide additional evidence of CSF circulation and intracranial pressure in different postures.