An excerpt from Professeur Jean-François Bonneville, Departments of Medical Imaging and Endocrinology, Centre Hospitalier Universitaire de Liège, Liège, Belgium: Unless you are practicing in a Pituitary Center, you, my dear colleagues radiologists, you did not manage a pituitary MRI every day and probably not one every week: it is a very special examination with possible crucial issues that require your full attention. If it is the first pituitary MRI of your patient and not a follow-up, some recommendations are welcome.
- Take a short time to greet your patient and ask a few questions: undoubtedly, you will learn more than what you have read on the MRI prescription.
- You must know what you are looking for—for instance, macro (visual field defect), micro (hyperprolactinemia), or possible picoadenoma (Cushing disease), and you have to adapt your technical protocol.
- The localizer image may sometimes tell you in seconds if there is a mass of the sellar region or not: do not neglect its reading to adapt possibly your protocol (Fig. 1.1).
- Be personally present during the examination to modify, if necessary, the choice of the sequences in real time. For instance, deciding to inject gadolinium (it is not compulsory!); adding an axial T1W or a sagittal T2W sequence to elucidate an unexplained intrasellar image; changing the thickness of the reformat to confirm a tiny lesion or understand an artifact; obtaining an additional FLAIR sequence to precise a liquid-looking image. Your presence during a pituitary MRI may seem like a heavy burden but is for me key to best helping the clinician and the patient.
- Allow at least 15–20 min for a pituitary MRI: again, it could be a complex examination.
- If a brain MRI is also ordered or is considered necessary, it will be scheduled in a different session.
The first MRI could be often the first of many follow-up studies: comparison will be easy and accurate if the same rigorous projections are chosen. We perform all coronal sequences perpendicularly to a line joining the genu and the splenium of the corpus callosum. This line is easier to draw than the classical bicommissural line (Fig. ). Our landmark being distant from the sellar area is immovable at the difference of the sellar floor or the pituitary stalk which could be modified after surgery or medical treatment. It has the advantage to be applicable to any MR scanner whatever the firm.1.2
- The most informative sequence is most of the time T2W, not a gadolinium-enhanced one. Favor a long acquisition time to get the best information
- Dynamic imaging must never be systematic and reserved for exceptional cases or research purpose.
Hyperprolactinemia is certainly one of the most frequent indications for pituitary MRI in your practice. Symptomatology is secondary amenorrhea, often after stopping the pill, galactorrhea, or infertility. A lot of “microincidentalomas” can mimic microprolactinomas. Fortunately, there is an excellent correlation between prolactin level and pituitary adenoma size—except when the lesion is liquid or hemorrhagic. Most microprolactinomas (less than 10 mm) correspond to a prolactin level between 35 and 120 μg/L, but an intrasellar prolactinoma invading the cavernous sinus can be responsible of a 1000 μg/L prolactinemia. A tiny millimetric image associated with a 100 μg/L prolactin level or more is not a prolactinoma but probably an artifact or an incidentaloma.
- Therefore, knowledge of the prolactin level is essential and must be always requested. If it is not available at the time of the MRI, ask your secretary to call the laboratory.
- Pituitary MRI follow-up is another frequent indication: after medical treatment of prolactinomas, after surgery or radiotherapy, or just for monitoring a non-secreting adenoma. Tumoral volume and signal changes are well seen on T2WI (Fig. ). Gadolinium injection is usually unnecessary. 1.3
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