Magnetic Resonance Imaging (MRI) is an imaging modality that relies on the radiofrequency signals emits from particles in the body in response to being displaced by a strong magnetic field.
In other words, MRI is a modality that does not involve ionizing radiation. Unlike CT scans, MRI images do not represent structures based on their density but rather, their magnetic properties. As such, it is not appropriate to refer to different levels of brightness in MRI as differences in density.
The terminology used for MRI is ‘intensity’, with high signal intensity referring to brighter structures and low signal intensity referring to darker structures.
Terms like ‘hyperintense’, ‘isointense’ and ‘hypointense’ can also be used but, strictly speaking, they are meant to compare the relative intensities of two structures. Therefore, it would not be appropriate to say that a lesion is hyperintense without clarifying what structure is the hyperintensity relative to.
- Eg. The lesion is hyperintense. (X)
- Eg.2. The lesion is hyperintense relative to the cerebral white matter. (V)
