T2 relaxation time (T2)

T2 relaxation time is a fundamental physical parameter in magnetic resonance imaging (MRI) that describes the rate at which the transverse component of the magnetization vector decays due to spin-spin interactions (StatPearls: MRI Physics, 2023 [1]). It is not a biological molecule, receptor, or enzyme, but rather a measurable property of tissue protons that reflects the local chemical and magnetic environment (Radiopaedia, 2023 [2]). In clinical practice, T2 relaxation time is used as a sensitive surrogate marker for various pathological states, as values typically increase in the presence of edema or inflammation and decrease in the presence of iron, hemorrhage, or certain minerals (NIH: National Institute of Biomedical Imaging and Bioengineering, 2022 [3]). While not a therapeutic target, it is the primary focus of diagnostic pharmacology involving T2 contrast agents, such as superparamagnetic iron oxide nanoparticles (SPIONs). These agents interact with the local magnetic field to significantly shorten the T2 relaxation time of surrounding water protons, thereby enhancing the contrast and visibility of specific tissues or lesions during imaging (PubChem: Ferumoxytol, 2023 [4]).

Other names

Transverse relaxation timeSpin-spin relaxation timeT2 decay timeT2 constant

Shortening of transverse relaxation time via local magnetic field inhomogeneities induced by paramagnetic or superparamagnetic substances