An Introduction to Magnetic Resonance Imaging: From Image Acquisition to Clinical Diagnosis

Magnetic resonance imaging provides a comprehensive and non-invasive view of the structural features of living tissue at very high resolution (typically on the 1-2 mm scale). A variety of pulse sequences have been developed that provide quantitative information regarding the structural features of a variety of tissue classes, providing details that are extremely beneficial in a clinical setting. Unlike positron emission tomography (PET), MRI as it does not deploy the use of radioactive isotopes, and hence can be performed repeatedly. Modern day MRI scanners can provide extremely high resolution images in a relatively short period of time (approximately 20 minutes) on average in a typical diagnostic scan. A variety of measurements can be made in a single scanning session through the application of serial pulse sequences. These pulse sequences are computer programmes that control the scanner parameters, which in turn control factors such as tissue contrast. By deploying the appropriate pulse sequence, One can obtain detailed information about the vasculature of a region of the body (magnetic resonance angiogram), deep tissue injury, and more recently one can obtain information regarding the microstructural features of the brain. Indeed, MRI is routinely used to identify and/or confirm the diagnosis of a variety of brain parenchyma or vasculature diseases such as multiple sclerosis and stroke respectively. With further improvements in the electronics and pulse sequences, more detailed and accurate imaging techniques may provide medical science with the opportunity to automate the diagnosis of a variety of diseases which present ultastructural changes.