Imaging in Anterior Pituitary Gland Diseases (Without Images)

8/22/2019 Imaging in Anterior Pituitary Gland Diseases (Without Images)

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IMAGING IN ANTERIOR PITUITARY

GLAND DISEASES

PROF D.A. NZEHDEPARTMENT OF RADIOLOGY

UNIVERSITY OF ILORINILORIN


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ANATOMICAL CONSIDERATIONS IN THE

PITUITARY GLAND

ANTERIOR PITUITARY GLAND (ADENOHYPOPHYSIS)

Highly vascular

Very cellular: Consists of chromophobe, eosinophilic and

basophylic cells.

POSTERIOR PITUITARY GLAND (NEUROHYPOPHYSIS)

Made up of nerve fibres connected to the hypothalamus.

PARS INTERMEDIA

Contains large colloid vesicles similar to the thyroid gland.


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PHYSIOLOGICAL CONSIDERATIONS IN THE

PITUITARY GLAND

ANTERIOR PITUITARY GLAND

Hormones secreted (six)

Growth hormone.

Adrenocoticotrophin hormone (ACTH).

Thyroid stimulating hormone (TSH).

Follicle stimulating hormone (FSH). Luteinizing hormone (LH).

Prolactin.

POSTERIOR PITUITARY GLAND

Hormones secreted (two) Antidiuretic hormone (ADH)

Oxytocin


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PATHOLOGICAL CONSIDERATIONS IN THE

PITUITARY GLAND

Pituitary tumours are generally classified as either endocrine active orendocrine inactive.

TUMOURS OF THE PITUITARY GLAND

MACROADENOMA

Usually > 10mm in size.

Form intracranial space-occupying lesions.

May compress the optic chiasma and cause visual disturbances (Typically causes bitemporal hemianopia).

MICROADENOMA

Usually < 10mm in size.

Cause endocrine disturbances.


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CLINICAL FEATURES IN

PITUITARY GLAND DISEASESCHROMOPHOBE ADENOMA

Tumour itself is non-secretory but destroys normal functioning gland.

Patient develops hypopituitarism with loss of sex characteristics, hypothyroidism and

hypoadrenalism.

In childhood, there is arrest of growth.

Extension of tumour to the hypothalamus results in diabetes insipidus and obesity.

EOSINOPHIL ADENOMA

Secretes GH.

When it is present before puberty (unusual), gigantism occurs.

After puberty it causes acromegaly.

BASOPHIL ADENOMA Small and does not produce pressure effect.

May be associated with Cushings syndrome.

PROLACTINOMAS

Manifests with gonadal malfunction sometimes causing galactorrhea.


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IMAGING MODALITIES TO EVALUATE DISEASES THE

PITUITARY GLAND

Computed Tomography.

Magnetic Resonance Imaging.

Angiography

Plain Skull Radiograph.

Single photon Emission ComputedTomography (SPECT).

Positron Emission Tomography (PET).


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DISEASES OF THE ANTERIOR PITUITARY GLAND

COMPUTED TOMOGRAPHYPITUITARY MACROADENOMA

Shows destruction of sella floor by tumour.

Demonstrates enlarged sella.

Shows extent of suprasellar extension in large tumours.

Sagittal and coronal reformation after i.v. contrast helps

to outline of a adenoma due to good enhancement.Demonstrates chiasmal compression in large tumours.


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COMPUTED TOMOGRAPHY

PITUITARY MICROADENOMA

Difficult to demonstrate on CT due to beam hardening

artefacts.

Requires high resolution CT with direct coronal sections.

Contiguous 1.5mm sections are obtained after contrast

enhancement.

Appears as a small hypodense area within the enhancinggland.

May show deviation of the infundibulum.

Bulging of the upper surface of the gland may be present.


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MAGNETIC RESONANCE IMAGINGPITUITARY MACROADENOMA

Preferred imaging modality for pituitary gland assessment.

Demonstrates chiasmal compression in large tumours.

MRI shows relationship of tumor with sphenoid sinus and carotid

vessels well.

High signal intensity of marrow fat in the clivus is well shown.

Tumor is of relatively lower signal intensity to normal brain on T1Wand higher signal intensity on T2W images.

Areas of cyst formation or necrosis may show low signal intensity

on T1W or high signal intensity of T2W sequences.

Recent hemorrhage inside a tumor mass shows signal intensity onT2W ima es.


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MAGNETIC RESONANCE IMAGING


Difficult to differentiate microadenoma from

normal gland tissue.

Gadolinium-DTPA injection shows delayed

enhancement of the adenoma compared to

normal gland.

Dynamic contrast enhanced MRI may improve

sensitivity in detection of microadenomas.


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PLAIN SKULL RADIOGRAPH

PITUITARY MACROADENOMA Increase in size,expansion and erosion of a ballooned sella.

Backward bowing of the dorsum.

Undercutting of the anterior clinoid process.

Downward protrusion of the sella floor into the sphenoid bone or

sinus.

In acromegaly the skull may show grossly enlarged sinuses,

thickening of the skull vault, and prognathous jaw.


May produce local bulging of the sella floor.

Double floor sella but this sign may also be present in

the normal skull.


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PLAIN SKULL RADIOGRAPHDIFFERENTIAL DIAGNOSIS OF PITUITARY MACROADENOMA

It may be difficult to differentiatepituitary tumor from raised intracranial

pressure .

The empty sella shows more globular

and symmetrical enlargement but the

cortex of the sella remains intact.


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CATHETER ANGIOGRAPHYPITUITARY MACROADENOMA

Lateral displacement of the both carotid arteries

in the frontal view.

Upward bowing of the anterior cerebral artery in

the lateral view.

Tumour blush may be present in a large mass.


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Imaging in Anterior Pituitary Gland Diseases (Without Images)