Past few decades have witnessed a major technological revolution in diagnostic as well as therapeutic aspects of medical science. As a practising radiologist in a tertiary care super speciality organ transplant hospital, I take this opportunity to write about one such revolutionary technique which has truly made its mark in the diagnosis and management of chronic liver disease – MR elastography.
This MRI technique quantitatively evaluates tissue stiffness by propagating low frequency mechanical waves through the liver. It is performed using an MRI safe passive driver that is applied to the right upper abdomen and lower chest overlying the right lobe of the liver while the patient is being scanned in the MRI scanner. The MRE sequence is carried out with four short breath-holds and completed within one to two minutes, without the need for intravenous contrast injection.
An active driver generates low frequency mechanical waves (typically at 60 Hz) which are conducted to the passive driver through a long plastic tube. The passive driver vibrates and produces shear waves that are propagated across the liver. The wavelength of the propagating shear wave is directly proportional to the stiffness of the liver, that is, the stiffer the liver, the longer the wavelength...