Magnetic Resonance Elastography as a Method to Estimate Stiffness of Soft Tissues

Overview

Magnetic resonance elastography is a novel non-invasive MRI technique to obtain stiffness of soft tissues such as liver, heart, kidneys, etc. In this imaging technique a person is laid in an MR scanner and a paddle (plastic drum) is put on the area of interest to send sound vibration via a speaker placed outside the scan room which is connecting plastic drum via a plastic tube. These vibrations are scanned using MRI to estimate the stiffness of soft tissues such as liver, heart, kidneys, breast etc.

Recently a new and novel noninvasive imaging-based technique known as Magnetic Resonance Elastography (MRE) was developed that is capable of quantifying stiffness of soft tissues such as liver, spleen, kidney, heart brain, breast, aorta etc. In MRE a person is laid into an MR scanner which is similar to all MR scans. In addition, a drum (passive driver) is placed on the body (area close to the region of interest), which is connected by a long plastic tube that runs outside the scan room. This drum is tightly strapped by a Velcro to the body for better contact. Then the other end of the plastic tube is connected to an active driver that produces vibrations of frequencies in the range of 20Hz -2kHz. These frequencies of vibrations are transferred to the passive driver which produces vibrations on the body. These vibrations are tracked using MR scanner to produce wave images. A post-processing of these wave images are performed to obtain spatial stiffness maps. Currently, MRE is a clinical tool to assess hepatic fibrosis at many institutions. MRE is superior to many invasive techniques (i.e. biopsies, catheter based Pressure-Volume measurements) and mechanical testing in that it is noninvasive and can be performed in vivo under physiologic conditions. MRE could make stiffness widely available and could revolutionize the diagnosis and treatment of numerous diseases affecting stiffness of soft tissues. For example in Liver: diagnosis of hepatic fibrosis, Non-alcoholic fatty liver disease, liver tumors etc. Heart: diagnosis of diastolic dysfunction, myocardial infarction, hypertrophic cardiomyopathy, contractility etc. Aorta: Aortic aneurysms, hypertension etc. This technology is completely noninvasive and the vibrational energy is way below the required standards. Previous experiences of these vibrations are like massaging the body. The risks of this research study are minimal, which means that we do not believe that they will be any different than what you would experience at a routine clinical visit or during your daily life. This study will not make participants' health better. It is for the benefit of research.The specific aim of this study is that MRE can be used as a noninvasive tool to diagnose different disease states in soft tissues. In this study we will be applying this technique in adult volunteers to test the feasibility and validation of the technique in different organs.