The role of nonconventional magnetic resonance imaging techniques in demyelinating disorders

Abstract

The use of nonconventional magnetic resonance imaging techniques (eg, magnetization transfer, magnetic resonance spectroscopy, and diffusion weighted imaging) allows for an accurate characterization of lesions as compared with conventional or standard approaches in demyelinating diseases. Magnetization transfer, magnetic resonance spectroscopy, and diffusion weighted imaging have revolutionized our understanding of demyelinating diseases because these techniques have been used to identify pathologic changes of normal-appearing brain tissue and characterize the differences in lesions. Metrics derived from these methods correlate with clinical disability and provide more accurate tools for monitoring disease activity and treatment effect over time. Quantitative T1 and T2 relaxation time maps provide additional information on demyelinating diseases, allowing for the evaluation of myelin water and distribution of water within tissues. Finally, the measurement of central nervous system atrophy has become a valuable element in determining the course of multiple sclerosis.

Thalamic Involvement and Its Impact on Clinical Disability in Patients with Multiple Sclerosis: A Diffusion Tensor Imaging Study at 3T

“…WM lesion load, however, is only weakly correlated with the disability of patients with MS. 1,2 Given the limited sensitivity of conventional MR imaging, researchers oriented their focus also to subtle damage to the so-called normal-appearing WM (NAWM) and normalappearing gray matter (NAGM), aiming to better explain neurologic impairments of these patients. 3,4 Postmortem and in vivo studies have demonstrated that the deep gray matter (GM) is also affected in MS. Diffuse microscopic damage in the absence of macroscopic MS lesions can be present in the thalamus and basal ganglia. 5,6 The thalamus, in particular, is a critical structure for a wide range of neurologic functions, including motor, sensory, and cognitive abilities.…”

Uncovering and Characterizing Multiple Sclerosis Lesions: The Aid of Fluid‐Attenuated Inversion Recovery Images in the Presence of Gadolinium Contrast Agent

“…An additional limitation of conventional MRI sequences is their inability to identify the effects of MS worsening beyond visible lesions or detecting pre‐lesion formation in CNS tissue appearing as normal. For many years, using non‐conventional quantitative MRI techniques 3 greatly aided in uncovering and quantifying pathology of normal‐appearing CNS tissue. Non‐conventional MRI techniques, however, may be labor‐intensive, thus often difficult to use in daily clinical practice.…”

Advanced magnetic resonance techniques for evaluating white matter

“…MTI provides a distinct contrast by measuring the exchange of magnetization between free, mobile protons with the bound, macromolecular protons in tissues [10]. MTI is accomplished by applying an off-resonance radiofrequency pulse to selectively saturate the pool of protons in the bound components of tissue [11]. By comparing the signal intensity using the applied offresonance pulse with that without the pulse, a magnetization transfer ratio (MTR) can be determined.…”