Low-field Magnetic Resonance Technique Research Articles

Laminar flow characterization using low-field magnetic resonance techniques

Laminar flow velocity profiles depend heavily on fluid rheology. Developing methods of laminar flow characterization, based on low-field magnetic resonance (MR), contribute to the widespread industrial application of the MR technique in rheology. In this paper, we outline the design of a low-cost, palm-sized permanent magnet with a 1H resonance frequency of 20.48 MHz to measure the laminar flow. The magnet consists of two disk magnets, which were each tilted at an angle of 1° from an edge separation of 1.4 cm to generate a constant gradient, 65 G/cm, in the direction of flow. Subsequently, a series of process methods, for MR measurements, were proposed to characterize Newtonian and non-Newtonian fluid flows in a pipe, including phase-based method, magnitude-based method, and a velocity spectrum method. The accuracy of the proposed methods was validated by simulations, and experiments in Poiseuille flow and shear-thinning flow with the designed magnet. The new velocity profile methods proposed are advantageous because the MR hardware and measurement methods are simple and will result in a portable instrument. Although the governing equations are complicated, the data analysis is straightforward.

Studies on Wheat Resistant Starch by NMR Technique

A low field magnetic resonance technique was used to analyze the water mobility character about wheat starch and its resistant starch (RS) suspensions at different water activity. RS was obtained from wheat starch by high temperature and high pressure method. Scanning electron microscopy(SEM), X-ray diffraction analysis and differential scanning calorimetry (DSC) analysis were used to evaluate the variation between the starch and RS after treatment. Compared with the original starch, it was suggested that the capacity of combining water of RS was stronger than starche from the NMR relaxation parameters, but RS’s water holding capacity (WHC) was lower than that of starch. Experiments indicated that water mobility character was lower in RS. This study on the water mobility character of starch and RS was significant for the starch industry, and showed the perspective of NMR and MRI technique potential utilization in the food science field.

Intracranial MR Venography Using L ow-Field Magnet: Normal Anatomy and Variations in Nepalese Population

Magnetic resonance (MR) venography is considered a reliable imaging modality for the evaluation of intracranial venous system. The purpose of this study was to evaluate the normal venous anatomy and its variations in Nepalese population using low field MR technique. One hundred patients with normal MR imaging of brain underwent MR venographic study. MR venograms were performed in 0.35 T MR scanner using a contiguous 2D time-of-flight MR angiographic technique. The flow gaps in the transverse sinus were seen in 47% of population, of which 91% occurred in the non-dominant side. Right transverse sinus was dominant in 73% population. Flow gap was observed in bilateral transverse sinus in one case, while it was seen in the dominant right transverse sinus in 6.3% population. Inferior sagittal sinus was observed in 11% cases. Internal cerebral vein was seen in 60 cases. Occipital sinus was observed in 4% of the cases. The basal vein of Rosenthal was observed in 34% of the cases, whereas vein of Labbe seen in 8% cases. Unilateralflow gap in the sigmoid sinus was seen in 5 cases. MR angiography done at low field MR unit is a reliable tool in cerebral venous sinus assessment, particularly major dural sinuses. The flow gaps in transverse sinus are frequently encountered anatomic variation. Visualization of small veins like inferior sagittal sinus, basal vein of Rosenthal, vein of Labbe, internal cerebral vein was inferior in our study compared to other studies done in high field MR unit.

Low field magnetic resonance techniques in the development of nanomaterials for biomedical applications

In recent years there has been rapid progress in the development of nanomaterials, and in particular magnetic nanomaterials, for magnetic resonance imaging and other biomedical applications. Using selected highlights from recent literature we describe the magnetic resonance methods that are used to measure the effects of agents on image contrast. We also show how these methods offer new insight into magnetic order in the colloidal state, a critical factor for all biomedical applications.