When do you perform an MRI (Magnetic Resonance Imaging) head with pituitary (gland) protocol?

When to Perform MRI Head with Pituitary Protocol

MRI of the sella using high-resolution pituitary protocols is the gold standard for evaluating any suspected pituitary disorder, and MRI without IV contrast is the first-line imaging test that provides comprehensive diagnostic detail for all pituitary pathologies. 1

Primary Clinical Indications

Suspected Pituitary Dysfunction

Hypopituitarism and Growth Hormone Deficiency

• MRI sella without IV contrast is the preferred initial imaging for adults with hypopituitarism, growth hormone deficiency, growth deceleration, panhypopituitarism, or hypogonadotropic hypogonadism 2
• The noncontrast study provides sufficient diagnostic detail to assess pituitary morphology, detect hypoplasia, confirm ectopic posterior pituitary, and identify empty sella 1
• Approximately 30% of patients with empty sella demonstrate some degree of hypopituitarism upon testing 3

Hyperfunctioning Pituitary Adenomas

• MRI without contrast is the gold standard for suspected hyperfunctioning adenomas including Cushing's disease (high ACTH), acromegaly/gigantism (high growth hormone), hyperprolactinemia, and TSH-secreting tumors 1
• These are typically microadenomas (<10 mm) requiring high-resolution, thin-section imaging with focused field-of-view sequences 1
• Approximately 65% of pituitary adenomas secrete hormones: 50% prolactin, 10% growth hormone, and 6% corticotropin 4

Diabetes Insipidus

• MRI with and without contrast using high-resolution pituitary or skull base protocols is preferred to detect hypothalamic-neurohypophyseal axis abnormalities 1
• The study identifies absent T1 hyperintensity of the posterior pituitary (a marker of neurohypophyseal functional integrity) and characterizes infiltrative or mass lesions 1

Pituitary Apoplexy

• MRI without contrast is the optimal first-line test for suspected pituitary apoplexy, as it is highly sensitive for detecting hemorrhage 1
• Noncontrast imaging demonstrates T1 hyperintensity, low T2 signal, or fluid-hemorrhage levels characteristic of hemorrhage 1
• Pituitary apoplexy refers to sudden onset of neurological symptoms and hormonal dysfunction related to hemorrhagic or vascular impairment of the pituitary gland 2
• This can occur as the initial manifestation of an adenoma or in the setting of treated adenoma, prior radiation, pregnancy, anticoagulation, or trauma 2, 5

Precocious Puberty

• Imaging should always follow hormonal studies that suggest a central origin 2
• Girls <6 years and boys <9 years with central precocious puberty should be screened with MRI, as they are most likely to show a central nervous system abnormality 2
• For girls 6-8 years of age, the likelihood of identifying a CNS lesion is lower (2-7%, neoplastic in 1%), making routine imaging controversial and requiring careful clinical consideration 2
• MRI is appropriate irrespective of age in patients with precocious puberty and concurrent CNS symptoms such as severe headaches, visual changes, or seizures 2

Postoperative Surveillance

• Postoperative imaging is typically performed >3 months following transsphenoidal surgery for patients with known subtotal resection or nonfunctioning adenomas 2
• Delayed surveillance is guided by tumor pathology and patient symptoms 2

Pituitary Incidentalomas

• Pituitary incidentalomas are lesions detected incidentally during imaging for unrelated causes 6
• Most (approximately 90%) are benign adenomas, with micro-incidentalomas having a mean prevalence of around 10% in normal individuals 6
• MRI is essential for determining the nature and extent of the lesion, particularly for macro-incidentalomas (≥1 cm) which require more extensive initial investigation and closer surveillance 6

Technical Specifications

Essential Protocol Elements

• High-resolution, focused field-of-view sequences targeted specifically for sellar and parasellar assessment are essential 1
• Thin-section imaging is critical, particularly for detecting hormone-secreting microadenomas 1
• Spoiled gradient-echo 3-D T1 sequences demonstrate increased sensitivity for detecting hormone-secreting adenomas 1
• 3-Tesla MRI provides superior anatomical delineation and enhances surgical planning when available 1

Contrast Administration

• The addition of IV contrast is preferred for assessment of pituitary lesions when characterization is needed 2
• However, MRI without contrast provides comprehensive diagnostic detail for initial evaluation of most pituitary pathologies 1
• Small pituitary lesions such as adenomas and Rathke cleft cysts may be occult without postcontrast sequences 2
• For dynamic evaluation of suspected microadenomas, sequences with dynamic contrast administration may assess specific enhancement characteristics 4

Comparison with CT

MRI is significantly superior to CT for pituitary evaluation:

• MRI is more sensitive than CT for detecting pituitary pathology, even with optimized CT technique 1
• MRI directly visualizes the pituitary gland and differentiates anterior from posterior lobes 1
• MRI provides superior delineation of spatial relationships to the optic chiasm, third ventricle, adjacent brain, and parasellar vasculature 1
• MRI better demonstrates cavernous sinus invasion, which CT cannot reliably detect 1

Limited role of CT:

• CT has a very limited role in initial pituitary evaluation and should not be used as first-line imaging 1
• CT may be appropriate in emergency settings when rapid diagnosis is needed (such as excluding intracranial hemorrhage in acute pituitary apoplexy presentation), for preoperative planning, or for detecting calcifications 2, 1

Common Pitfalls to Avoid

• Do not order CT as first-line imaging for pituitary evaluation – MRI is the gold standard and CT provides little intrasellar and parasellar soft-tissue detail 1
• Do not skip imaging in young children with central precocious puberty – girls <6 and boys <9 have the highest likelihood of CNS abnormalities 2
• Do not order MRI before hormonal studies in precocious puberty – imaging should always follow hormonal confirmation of central origin 2
• Do not assume contrast is always necessary – noncontrast MRI provides comprehensive diagnostic detail for most initial pituitary evaluations 1
• Do not image too early postoperatively – wait >3 months after transsphenoidal surgery, as local complications are difficult to discern from normal postoperative changes 2