Development Of A Novel Pneumatic Driver Based On Low Field Magnetic Resonance Elastography

Palpation is a traditional medical method for tissue lesions diagnosis and it has been used for many years.However,this method is inexact and unobjective.Magnetic Resonance Elastography(MRE)is a non-invasive imaging system that can measure the mechanical properties of tissues in vivo and diagnose some early diseases,such as liver fibrosis,cirrhosis and so on.It has been found that MR imaging can be enhanced when an oscillation stress is applied to the object being imaged.The oscillating stress produce shear waves that propagate through the organ,or tissues,and it has to synchronize with the phase of MR signals in MRE experiments,also the mechanical properties of the target organ can be determined by shear waves.The pneumatic supercharging method has obvious advantages such as good magnetic compatibility,simple design and low cost.Due to the compressibility and delayed of air lead to low vibration efficiency and image quality.The traditional pneumatic drivers cannot vibrate deeper tissue within the body reliably and adequately.In this thesis,we demonstrated a novel pneumatic boost driver used for MRE.The mechanical waves responded faster and deeper by increasing the tube pressure.Our result shows that the boost driver enhanced vibration efficiency,which conveyed the uniform shear wave with less attenuation into deeper tissue,and improved MRE efficiency and quality.The experiment of this paper is based on the 0.36 T low field MRI system.The homogenous phantom experiment shows that the efficiency of boosting driver were improved 86% compared with the non-pressurized driver.The volunteers' liver test is also presented in this MRE system.The improved passive driver is designed to conform to the shape of the subject and be coupled the region of interest.This patient-friendly passive driver is easy to wear and relieves physical pain by long time scanning in low-field MR system.The experimental result shows that the system improvs the accuracy of the image and is absolutely feasible for humans.