Epidemiology :
· Average age : 32 years.
· 28 women/15 men.
Clinical signs :
- The clinical symptomatology consisted mainly in hormonal and neurological troubles.
- Other means of revelation :
o Intracranial hypertension syndrome.
o Hormonal troubles.
o Vision troubles.
o Hyperprolactinemia.
o Galactorrhea-amenorrhea.
o Primary infertility.
o Acromegalia.
o Epilepsy.
o Cushing syndrome.
Imaging :
INTRASELLAR PATHOLOGY :
Pituitary adenoma is a benign tumor which develops from anterior hypophyseal cells.
v Microadenomas : 18 cases.
- Intra-sellar lesion.
- T1: Iso or hyposignal / normal hypophysis.
- T2: Variable signal (haemorrhagic or liquid content).
- Enhancement after gadolinium injection :
o Slow on the dynamic sequences/normal hypophysis.
o Rarely,
precocious enhancement.
o Late acquisition (30 or 40 minutes after injection) : late enhancement.
- Indirect signs (if the microadenoma is not seen) :
o Asymmetrical height increase.
o Bulging of the diaphragma sellae.
o Lowering of the sellar floor.
o Controlateral deviation of the pituitary stalk.
v Macroadenomas : 16 cases.
1-Solid macroadenoma :
- Intra and suprasellar mass :
o Distorsion of the glandular outlines.
o Expanding of the sella turcica.
o Lateral erosion of the sellar floor.
- Shape : oval or polycyclic with a stricture at the diaphragma sellae.
- T1 : isointense (as the cerebral cortex)
- T2 : iso or hypointense,
heterogeneous.
- Normal gland : more intense signal.
- Enhancement : mild,
compared to the normal hypophyseal parenchyma.
- Surrounding dura mater : thickened and enhanced.
- Extension of the macroadenoma : (coronal sections in T1 and T2 weighting without contrast dye+++) :
o Suprasellar : towards the opto-chiasmatic cisterns and the optic chiasm.
o Infrasellar : towards the sphenoidal sinus.
o Laterosellar : towards the cavernous loggiae.
- Diffusion imaging gives us an idea about the texture of the adenoma by measuring the ADC :
o Low ADC : soft tumor.
o High ADC : hard tumor.
2-Necrotic macroadenoma :
a- Central part :
· T1: Hypointense,
· T2,
Flair and proton data : highly hyperintense,
· Annular peripheral enhancement.
b-Haemorrhagic necrosis :
· T1: Hyperintense with liquid-liquid level.
Differential diagnosis :
o Rathke’s pouch cysts,
o Cystic craniopharyngioma,
o Giant thrombosed aneurysm.
SUPRASELLAR PATHOLOGY :
v Sellar meningioma 7 cases.
- 10 % of intracranial meningiomas.
- Origin: arachnoidal cells.
- Women > 40 years.
- Asymptomatic or revealed by vision troubles,
rarely by hormonal or neurological signs (intracranial hypertension syndrome).
- MRI aspects :
- T1: Isosignal (to the grey matter),
- T2: Iso or hypersignal (40%),
- Enhancement :
o Intense and homogenous.
o Surrounding dura mater : thickened with « comet-like » enhancement.
- Important sign : visualization of cerebrospinal fluid between the tumor and the cerebral parenchyma.
- Calcifications and hyperostosis surrounding the meningioma insertion : hardly seen on MRI.
- MRA : studies the meningioma’s relation with the visual pathways and carotid siphons.
v Craniopharyngioma : 2 cases.
- Benign tumor,
represents :
o 3% of intracranial tumors in adults.
o 6 to 9% in children.
o 50% of sellar and suprasellar tumors.
- Origin : epithelial residue of Rathke’s pouch.
- Two peaks :
o Children : 5-10 years.
o Adults : 40-60 years.
- Location :
o Suprasellar (90% of the cases).
o Rarely intra or infrasellar
o Exceptionally in the 3rd ventricle.
- MRI aspect : three components : cystic,
tissular and calcic.
*Cysts:
- Always present,
well-defined.
- Signal : depends on the physicochemical composition.
- Only the lining is enhancement.
*Tissular part:
- Irregular outlines.
- Signal : isointense to the cerebral parenchyma in T1 weighting.
- Is enhanced after gadolinium injection.
*Calcifications :
- Very frequent.
- Signal lacunas on all sequences.
- More easily seen on CT scan.
v Chiasm gliomas :
- Chiasm and hypothalamus gliomas : very frequently associated.
- Peak : 1st decade.
- Low grade piocytic astrocytomas+++
- Clinical picture : café-au-lait spots and visual troubles.
- Unpredictable evolutionary potential.
- MRI aspect :
o Enlarged chiasm : « dumbbell-like »
o T1 weighting : iso or hypointense.
o T2 and FLAIR : hyperintense.
o Typical signs : extension to the optic nerve and no cystic component.
o Enhancement :
§ Discreet in type 1 neurofibromatosis.
§ Intense if posterior extension towards the optic radiations.
- T1: iso ou hypointense.
- T2 et Flair: hyperintense.
v RARE SUPRASELLAR LESIONS :
- Rathke’s pouch cysts.
- Arachnoid cysts.
- Teratomas.
- Germinomas.
- Suprasellar dermoid cysts.
- Suprasellar epidermoid cysts.