MRI is a powerful imaging technique that produces detailed, high quality, and high-resolution images of the brain’s anatomical structure without radiation. It is particularly well-suited to imaging the soft tissues of the body, and constant advances in technology have made it an essential tool for brain diagnosis and research.
Within the field of MRI, two imaging techniques are proving particularly valuable: functional MRI and diffusion tensor imaging (DTI). Functional MRI can observe brain structures and scan the brain while patients perform cognitive tasks, such as solving math problems or responding to stimuli such as sounds or flashing lights. It visualizes neural activity in the brain and spinal cord and is a popular imaging technology for neuroscience research.
DTI is unique among imaging modalities in its ability to visualize white matter tracts in the brain, which are the most vulnerable to damage and disconnection. DTI can visualize conditions such as traumatic brain injury that conventional MRI can’t.
MRI’s ability to penetrate soft tissue makes it invaluable in the diagnosis and treatment of multiple sclerosis (MS), brain tumors, stroke, aneurysms, abscesses, congenital abnormalities, hydrocephalus, and many other brain diseases. MRI is also helpful in diagnosing:
Herniated or degenerated discs of the spinal cord
Malformations of veins and/or arteries of the brain or spinal cord
Hemorrhage in the brain or spinal cord
Functional MRI can determine the specific location in the brain where a certain function, such as speech or memory, occurs, which varies slightly for each patient. Knowing where these functional areas are located is critical in planning surgery or other treatments for diseases such as epilepsy. DTI can image traumatic brain injury, psychiatric conditions, and neurodegenerative diseases.
Using MRI technology, researchers have developed related procedures that can diagnose specific types of neurological conditions:
Magnetic Resonance Angiography (MRA): Used for noninvasive evaluation of blood flow through arteries, MRA can also detect aneurysms and other blood vessel abnormalities within the brain and spinal cord.
Magnetic Resonance Spectroscopy (MRS): Used for assessing chemical abnormalities in body tissues, MRS can examine disorders such as HIV infection of the brain, stroke, head injury, coma, Alzheimer’s disease, tumors, and MS.
MRI advances enhance visualization
Since its introduction, MRI technology has been constantly advancing, producing sharper, clearer images in less time. The most powerful MRI scanners offer ultra-high magnetic fields of 7T which can visualize the brain in unprecedented detail through enhanced contrast mechanisms, such as blood oxygen level-dependent (BOLD) and flow-dependent contrast. At 7T, MRI increases lesion visibility and more accurately characterizes brain abnormalities. For example, it can help delineate the brain area where epileptic seizures originate, visualize brain tumor pathology, measure metabolic markers in tumor tissue, identify neuron loss in the hippocampus in Alzheimer’s disease, and detail the pathologic features of MS.
Other advances in MRI technology are improving brain scan speed, ease, and accuracy:
3D volume scans offer thin-slice, SNR-rich studies with exquisite detail to help visualize small and subtle lesions;
3D arterial spin labeling (ASL) delivers quantitative perfusion assessment to reliably rule out focal or global perfusion defects and evaluate tumor, stroke, and other cerebrovascular diseases;
automated brain exams help reduce workload and improve consistency;
and real-time acquisition, processing, and display of functional results enables a single technician to manage all aspects of BOLD fMRI studies acquired with synchronized stimuli.
Also, susceptibility-weighted imaging (SWI) can detect substances with different susceptibilities, such as deoxygenated blood, better than conventional MRI techniques.
Artificial intelligence -- the future of neuroimaging
As in other areas of radiology, artificial intelligence (AI) will play an increasingly important role in neuroimaging. Artificial neural networks may reduce perceptual and interpretive errors through computer analysis of images augmented by artificial intelligence.
Technological advances will continue to produce stronger MRI magnetic fields and improve contrast mechanisms for greater accuracy in diagnosing neurologic disorders, more effective treatment, and deeper understanding of the brain and how diseases develop. Scans will also be quieter and faster for greater patient comfort and better outcomes.
1. IMV MR Market Outlook Report. November 2014