Magnetization Transfer Imaging

Magnetization transfer (MT)–magnetic resonance imaging (MRI) techniques can provide access to visualizing macromolecular content of tissues, otherwise not assessable using conventional MRI. MT contrast is generated by the interaction between mobile water protons and the protons associated with tissue macromolecules. Given substantial variation between macromolecular compositions of tissues, this interaction differs by tissue type and results in macromolecular-sensitive contrast in MT-weighted images. MT contrast is generated by applying radiofrequency pulses to selectively saturate the macromolecular protons, and this saturation is transferred to the water protons resulting in an observed signal attenuation. The MT effect can be characterized via the MT ratio (MTR) and, more recently, via quantitative MT (qMT) methods. MT-MRI indices may be useful to detect and quantify macromolecular alterations, potentially offering unique opportunities to link pathophysiologic and clinical outcomes in disorders of the central nervous system (CNS), and response to treatments.