Pituitary gland protocol (MRI)
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MRI protocol for pituitary gland is a group of MRI sequences put together to improve sensitivity and specificity for the assessment of lesions of the pituitary gland (e.g. pituitary adenoma) and other sellar and suprasellar abnormalities (check the article on pituitary region masses for some examples).
MRI is nowadays the imaging modality of choice for pituitary gland assessment, largely replacing CT, which is currently reserved for the assessment of bone destruction and surgically relevant bone anatomy 1. See the history of imaging the pituitary region.
To review a systematic approach to the pituitary region, please refer to the article on pituitary MRI (an approach).
NB: This article is intended to outline some general principles of protocol design. The specifics will vary depending on MRI hardware and software, radiologist's and referrer's preferences, institutional protocols, patient factors (e.g. contrast media adverse reactions) and time constraints.
The sequences for this purpose should be performed with small FOV (field of view) targeting the sella. A good protocol for this purpose involves at least:
- sequence: small FOV coronal and sagittal
- purpose: useful for anatomical depiction, in particular, the posterior pituitary bright spot
- sequence: usually coronal, but axial or sagittal can also be useful with high resolution/thin slices
- purpose: identify blood product or dot sign in Rathke cleft cyst and to visualize the diaphragma sellae and arterial flow-voids
T1 C+ dynamic
- sequence: small FOV coronal, obtained at multiple locations through the pituitary gland (e.g. 6) at multiple timepoints (e.g. 0, 30, 60, 90, 120 and 180 seconds)
- purpose: useful to identify microadenomas (which have delayed enhancement) and identify displaced normal pituitary gland by a sellar mass, and to help distinguish between a residual or a recurrent tumor from postoperative tissues 1
T1 C+ delayed
- sequence: small FOV coronal and sagittal (same as T1 non-contrast)
- purpose: valuable to assess the cavernous sinuses and to characterize other sellar region tumors
Some institutions also include some whole brain sequences (e.g. DWI/ADC and FLAIR).