see also Pituitary macroadenoma Magnetic resonance imaging
MRI is the mainstay of imaging for pituitary microadenomas and requires dedicated pituitary sequences (thin slice, small field of view, dynamic contrast acquisition). Contrast-enhanced MRIs have a sensitivity of 90%.
Post-contrast and especially thin-section dynamic contrast-enhanced imaging is an important part of a pituitary MRI and has significantly improved diagnostic accuracy. However, subtle morphology changes may still be identified in non-contrast images. These include bulkiness of the gland on the side of the microadenoma, subtle remodeling of the floor of the sella and deviation of the pituitary infundibulum away from the adenoma.
usually isointense to normal pituitary
dynamic sequences demonstrate a rounded region of delayed enhancement compared to the rest of the gland delayed images are variable, ranging from hypo-enhancement (most common) to isointense to the rest of the gland, to hyperintense (retained contrast)
variable, but often a little hyperintense An important fact of life needs to be kept in mind when reporting pituitary MRIs: small pituitary incidentalomas are relatively common, with up to 2-30% of autopsies identifying small asymptomatic microadenomas.