Imaging for Intractable Headache with Suspected Pituitary Adenoma
Order an MRI of the sella with high-resolution pituitary protocol without IV contrast as your first-line imaging study. This is the gold standard for evaluating suspected pituitary adenomas and will provide comprehensive diagnostic detail for both microadenomas and macroadenomas 1.
Why MRI Without Contrast is First-Line
MRI using high-resolution pituitary protocols is the preferred diagnostic imaging modality for all suspected pituitary pathology, as it directly visualizes the pituitary gland and can detect even small hormone-secreting microadenomas (<10 mm) 1.
The protocol should include pre-contrast T1 and T2 thin-sliced sequences with high-resolution, focused field-of-view sequences specifically targeted for sellar and parasellar assessment 1, 2.
MRI is significantly more sensitive than CT for detecting pituitary pathology, even with optimized CT technique, and better demonstrates critical anatomical relationships including cavernous sinus invasion and optic chiasm compression 2, 3.
When to Add Contrast
Add IV gadolinium contrast (T1 post-contrast sequences) if the initial non-contrast MRI is negative or equivocal and clinical suspicion remains high, as contrast increases the conspicuity of small adenomas which typically appear as hypoenhancing lesions 1.
Consider adding volumetric gradient (recalled) echo sequences after contrast administration, as this increases sensitivity for adenoma detection 1, 2.
Contrast is particularly useful for characterizing lesions, assessing cavernous sinus invasion, and surgical planning, but should not be considered a first-line test 1.
Critical Clinical Context for Intractable Headache
Intractable headache with pituitary adenoma warrants urgent imaging because it may indicate pituitary apoplexy (hemorrhage or infarction of the tumor), which is a neurosurgical emergency 4.
MRI without contrast is highly sensitive for detecting hemorrhage, showing T1 hyperintensity, low T2 signal, or fluid-hemorrhage levels characteristic of apoplexy 3, 4.
CT head may miss acute pituitary infarction, making MRI the most sensitive imaging modality even in emergency presentations 4.
Technical Specifications
Use thin-section imaging (2 mm slices) with spin echo T1-weighted sequences and fast/turbo spin echo T2-weighted sequences 1.
3-Tesla MRI provides superior anatomical delineation and enhances surgical planning when available, though it does not increase sensitivity for adenoma detection compared to standard MRI 1, 2.
Ensure the study is reported by a neuroradiologist familiar with pituitary pathology 1.
What NOT to Order
Do not order CT as first-line imaging – while CT can identify large pituitary tumors, it is insensitive compared to MRI and may miss microadenomas entirely 1.
Do not order CTA or MRA for initial evaluation – these are reserved for surgical planning or when vascular lesions are suspected, not for initial diagnosis 1.
Do not order plain radiography of the sella – it is insensitive and nonspecific for evaluating pituitary pathology 1.
Additional Urgent Evaluations
Obtain comprehensive pituitary hormone testing before initiating any steroids, including prolactin, IGF-1, TSH, free T4, morning cortisol, ACTH, and gonadal hormones, as steroid administration will confound interpretation 5, 4.
Perform urgent visual assessment including visual acuity, visual fields (ideally Goldmann perimetry), and fundoscopy if the patient has any visual symptoms or if imaging reveals suprasellar extension with potential optic chiasm compression 1.
Consider immediate neurosurgical consultation if imaging reveals apoplexy, significant mass effect, or acute visual compromise 4.
Common Pitfalls to Avoid
Do not delay MRI in favor of CT in a patient with intractable headache and suspected pituitary pathology – the superior sensitivity of MRI is critical, and CT may provide false reassurance 4.
Do not give steroids before obtaining baseline pituitary hormone levels, as this is a common pitfall that makes subsequent diagnosis of hypopituitarism and Cushing's disease impossible to assess accurately 4.
Do not assume a normal CT rules out pituitary pathology – up to 16% of patients presenting with headache and meningeal signs may have pituitary adenomas that are occult on CT 4.