MRI Anatomy Flashcards · Neuro

Pituitary Anatomy

Learn to identify every labeled structure on a Pituitary MRI, plane by plane.

Studying as a guest, so progress saves on this device only.

Pituitary anatomy, structure by structure

A dedicated pituitary MRI is a small, high-detail study of the sella turcica and the structures packed around it, and reading it well starts with knowing the normal anatomy cold. This reference walks through every structure in our pituitary flashcard deck across the planes the deck uses (sagittal, coronal, and axial), with a plain-language definition, how each structure looks on MRI, and the pathology you will actually run into at the scanner.

Pituitary gland and stalk

The gland in the sella and the stalk that suspends it. The midline sagittal shows the gland front to back; thin coronals split the anterior and posterior lobes side to side.

Pituitary Gland

The "master gland" sitting in the sella turcica below the optic chiasm; it controls growth, metabolism, stress response, and reproduction.

On MRI: A small soft-tissue structure filling the sella, isointense to gray matter on T1 and T2 and seen on all three planes; dedicated pituitary protocols use thin dynamic coronals through the gland. The top border is normally flat or slightly concave; an upwardly convex gland can be normal in young women and pregnancy.

Common pathology: Microadenomas and macroadenomas, Rathke cleft cysts, and apoplexy are common reasons for a dedicated sella study.

Tip: On thin dynamic coronals a microadenoma typically enhances slower than the rest of the gland, so it looks relatively dark in the early post-contrast frames.

Adenohypophysis

The anterior lobe of the pituitary, which makes the hormones that regulate growth, thyroid, adrenal, and reproductive function.

On MRI: Forms the larger, front portion of the gland; isointense to gray matter on T1 and T2 and the part that enhances avidly and uniformly after contrast.

Common pathology: Most pituitary adenomas arise here; diffuse enlargement can occur with hyperplasia (for example in pregnancy or end-organ failure).

Neurohypophysis

The posterior lobe of the pituitary, a downward extension of the hypothalamus that stores and releases ADH and oxytocin.

On MRI: Sits at the back of the sella and is normally bright on unenhanced T1, the so-called posterior pituitary bright spot, which reflects stored hormone.

Common pathology: Loss of the bright spot is associated with central diabetes insipidus; an ectopic bright spot at the stalk or median eminence suggests an interrupted stalk.

Tip: Confirm the posterior bright spot on the unenhanced (pre-contrast) T1; after contrast the whole gland enhances and the bright spot can be masked.

Pituitary Stalk

The thin infundibular stalk connecting the hypothalamus above to the pituitary gland below, carrying the portal vessels and the hypothalamic axons.

On MRI: A slender midline structure descending from the floor of the third ventricle to the gland; it enhances uniformly and should taper smoothly, normally no thicker than the basilar artery.

Common pathology: Stalk thickening or enhancement raises concern for hypophysitis, sarcoidosis, Langerhans cell histiocytosis, or germinoma; deviation can be a clue to a small adenoma.

Tip: Check the stalk for midline position and uniform caliber on coronal; abrupt thickening is the abnormal finding to flag.

Sellar and parasellar bone

The bony floor and walls that house the gland, best traced on the midline sagittal at the skull base.

Sella Turcica

The saddle-shaped depression in the sphenoid bone that holds the pituitary gland.

On MRI: A midline bony recess on sagittal with bright fatty marrow in its walls on T1; the gland sits within it and the sphenoid sinus lies directly beneath.

Common pathology: An empty sella (CSF filling the sella with a flattened gland) is a common incidental finding; bony remodeling or floor erosion suggests a longstanding macroadenoma.

Sphenoid Sinus

The deepest paranasal sinus, sitting directly below the sella turcica and pituitary gland.

On MRI: An air-filled (dark) space beneath the sella on midline sagittal; mucosal thickening or trapped fluid stands out as bright T2 signal.

Common pathology: Sinusitis and mucoceles, and the surgical corridor for trans-sphenoidal pituitary surgery; its degree of pneumatization affects the surgical approach.

Clivus

The sloping skull-base bone (part of the sphenoid and occipital bones) behind the sella and in front of the brainstem.

On MRI: A bright fatty-marrow ramp on midline sagittal T1, just behind the sphenoid sinus and in front of the pons.

Common pathology: Chordoma, metastases, and skull-base fractures; replacement of the normal bright marrow signal can be an early clue.

Suprasellar structures

The structures sitting just above the gland that a pituitary study must clear, plus nearby midline landmarks.

Optic Chiasm

The X-shaped crossing of the optic nerves that sits in the suprasellar cistern directly above the pituitary stalk.

On MRI: A gray-matter-signal band suspended above the sella, surrounded by bright CSF on T2; coronal shows its relationship to the gland and stalk best.

Common pathology: Upward extension of a macroadenoma can compress and elevate the chiasm, causing bitemporal visual field loss; gliomas and meningiomas also involve it.

Tip: On coronal, judge how close the top of the gland comes to the chiasm; chiasmal contact or compression is the key surgical and visual concern.

Hypothalamus

The region forming the floor and lower walls of the third ventricle that controls the pituitary, body temperature, appetite, and circadian rhythm.

On MRI: Sits above the pituitary stalk forming the floor of the third ventricle on midline sagittal; gray-matter signal on all sequences.

Common pathology: Hypothalamic hamartomas (gelastic seizures), gliomas, and involvement by suprasellar germinoma or Langerhans cell histiocytosis.

Mamillary Body

A pair of small rounded nuclei on the underside of the hypothalamus that are part of the limbic memory circuit.

On MRI: Two small bumps on the floor of the third ventricle behind the stalk, just in front of the midbrain on midline sagittal; gray-matter signal.

Common pathology: Bright T2/FLAIR signal and atrophy in Wernicke-Korsakoff syndrome; a useful midline landmark on the sagittal.

Pineal Gland

A small midline gland at the back of the third ventricle that secretes melatonin and helps regulate the sleep-wake cycle.

On MRI: A small structure in the posterior midline behind the third ventricle on sagittal; it lacks a blood-brain barrier and so enhances, and frequently calcifies with age.

Common pathology: Pineal cysts (common and usually incidental) and pineal region tumors such as germinoma and pineocytoma, which can obstruct the aqueduct.

Frequently asked questions

What structures are seen on a pituitary MRI?

A dedicated pituitary MRI shows the pituitary gland with its anterior lobe (adenohypophysis) and posterior lobe (neurohypophysis), the pituitary stalk, the bony sella turcica with the sphenoid sinus below and clivus behind, and the suprasellar structures above: the optic chiasm, hypothalamus, mamillary bodies, and the pineal gland in the posterior midline. This page labels each one with its MRI appearance.

Which planes and sequences are best for imaging the pituitary?

Thin coronal images through the sella are the workhorse, since they separate the gland, stalk, optic chiasm, and cavernous sinuses side to side. Sagittal shows the gland, stalk, and posterior bright spot front to back. Dedicated protocols add small fields of view, thin slices, and a dynamic post-contrast coronal series to catch microadenomas by their delayed enhancement.

Why is the posterior pituitary normally bright on T1?

The neurohypophysis (posterior lobe) is normally bright on unenhanced T1, the posterior pituitary bright spot, which reflects stored hormone. Always confirm it on the pre-contrast T1, because after contrast the whole gland enhances and can mask the spot. A missing bright spot is associated with central diabetes insipidus.

What landmarks help orient a pituitary study?

On the midline sagittal, follow the floor of the third ventricle from the optic chiasm and stalk back to the mamillary bodies, with the sella turcica and sphenoid sinus below and the clivus behind. On coronal, the gland sits in the sella with the stalk descending in the midline and the optic chiasm directly above, which is the relationship that matters most for surgical planning.

Do I need an account to use these pituitary MRI flashcards?

No. The interactive flashcards and this full labeled reference are open to use, with no account required to start. Creating an account lets you save your progress across devices and track which packs you have mastered.

Tesla MR Institute

Training to become an MRI technologist?

These flashcards come from our MRI tech program — learn online and train at a clinical site near you, in 12 to 18 months.

Explore the program

Pituitary Anatomy