Diagnostic Imaging for Pituitary Disorders
To diagnose pituitary disorders, magnetic resonance imaging (MRI) is performed either with or without contrast enhancement. The normal brain has a blood-brain-barrier through which contrast cannot pass, so contrast does not show up on magnetic resonance images of a normal brain. Tumors, especially vascular tumors, do not have a blood-brain-barrier. Therefore, contrast enters tumors and enhances (shows up as a bright area on magnetic resonance images) on a contrasted magnetic resonance image. The pituitary gland and stalk also do not have a blood-brain-barrier, so they too appear as bright areas on contrasted MRIs.
Left. Sagittal precontrast T1-weighted magnetic resonance image shows a normal-appearing pituitary gland. The anterior lobe of the pituitary is isointense and the posterior lobe is hyperintense. Right. Sagittal postcontrast T1-weighted magnetic resonance image shows normal diffuse enhancement of the pituitary gland.
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Left. Coronal precontrast T1-weighted magnetic resonance image shows the infundibulum, optic chiasm, and cavernous sinuses. Right. Fat-saturated coronal postcontrast T1-weighted magnetic resonance image is useful for assessing the pituitary gland for residual tumor or for a recurrence after surgery.
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