In MRI, there are some terms so confused as enhancing and non enhancing lesions . Dose this mean an lesion should featured as enhancing and others lesion nonenhancing . Or enhancing mean acute while nonenhancing lesions are chronic?
In MRI field, usually the term "enhancing" is coupled with "gadolinium" or "contrast". Therefore, an enhancing lesion is a lesion that assumes contrast medium. In some cases this contrast-enhancing lesion may be acute (e.g. an acute multiple sclerosis lesion), but in other cases an enhancement may be even related to non-acute findings (e.g. vascular malformation)
In general, the terms 'enhancing' or 'non-enhancing' lesion refer to the uptake of Gadolinium-based contrast agent in the lesion. Typically, this property is assessed using a T1-weighted acquisition: Gd shortens the longitudinal relaxation rate of tissue, which causes a signal enhancement.
The difference between enhancing an non-enhancing is very pronounced in brain tissue, where the blood-brain barrier effectively hinders Gd-based contrast agent from accumulating in the tissue in normal circumstances. When the blood-brain barrier is leaking, e.g. due to an inflammatory process in a lesion or due to cancerous angiogenesis, Gd can extravasate and accumulate in the tissue.
Specifically in Multiple Sclerosis, 'active' and 'chronic' MS lesions are often differentiated based on their contrast enhancement, based on the fact that an active lesion exhibits acute inflammation and breakdown of the BBB, whereas chronic MS lesions usually don't enhance.
The differences between enhancing and nonenhancing lesions in MRI are obvious. Normally with T1 contrast agents at a usual dosage, the enhancing lesions appear hyperintense on MR images and nonenhancing lesions appear isointense or without signal changes in comparison to that on precontrast MR images. Whereas with T2 contrast agents, the enhancing lesions appear hypointense on MR images and nonenhancing lesions appear isointense or without signal changes relative to that on precontrast MR images. Whether a lesion is enhanced or not reflects the blood perfusion, vascular permeability and extracellular space of the lesion.
The differences between enhancing and nonenhancing lesions in MRI are obvious. Normally with T1 contrast agents at a usual dosage, the enhancing lesions appear hyperintense on MR images and nonenhancing lesions appear isointense or without signal changes in comparison to that on precontrast MR images. Whereas with T2 contrast agents, the enhancing lesions appear hypointense on MR images and nonenhancing lesions appear isointense or without signal changes relative to that on precontrast MR images. Whether a lesion is enhanced or not reflects the blood perfusion, vascular permeability and extracellular space of the lesion.
The differences between enhancing and nonenhancing lesions in MRI are obvious. Normally with T1 contrast agents at a usual dosage, the enhancing lesions appear hyperintense on MR images and nonenhancing lesions appear isointense or without signal changes in comparison to that on precontrast MR images. Whereas with T2 contrast agents, the enhancing lesions appear hypointense on MR images and nonenhancing lesions appear isointense or without signal changes relative to that on precontrast MR images. Whether a lesion is enhanced or not reflects the blood perfusion, vascular permeability and extracellular space of the lesion.
Any lesion able to increase vascularization or to be responsible of neoangyogenesis -inflamatory or tumoral are the most frequent - will produce an enhancing image at MRI.
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