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C.N.S.
Pituitary Gland
Mohamed Zaitoun
Assistant Lecturer-Diagnostic Radiology Department , Zagazig University Hospitals
EgyptFINR (Fellowship of Interventional
Neuroradiology)[email protected]
Knowing as much as possible about your enemy precedes successful battle
and learning about the disease process precedes successful management
Pituitary Gland-The pituitary gland is formed from Rathke’s pouch which
is a superior invagination from the primitive oral cavity-The pituitary gland sits in the sella turcica, a cup-shaped
depression of the basisphenoid-The pituitary is composed of anterior and posterior lobes-Rathke’s pouch closes off to form a vesicle that involutes,
sometimes, the involution is incomplete and a cleft can be left behind which may give rise to craniopharyngioma or Rathke’ cleft cyst
The mandibular nerve (V3) is the only segment of the trigeminal nerve that doesn’t traverse the cavernous sinus , it exits inferiorly from Meckel’s cave through the foramen ovale
The abducens nerve (VI) enters the petrous portion of the temporal bone through Dorello’s canal and is the only nerve that travels in the medial venous sinusoids
The maxillary nerve (V2) is the only nerve of the cavernous sinus that doesn’t exit the superior orbital fissure , instead , it exits the foramen rotundum
Small Pituitary Fossa1-Normal Variant2-Dystrophia Myotonica :
-Hereditary-Usually starts in early adult life
-Cataracts , frontal baldness , testicular atrophy , thick skull and large frontal sinus3-Radiotherapy as child4-Hypopituitarism
Expanded Pituitary Fossaa) Definitionb) Causes
a) Definition :1-Size : Normal range is : height 6.5-11 mm , length 9-16 mm , breadth 9-19
mm2-Double floor : can be a normal variant
(asymmetrical development) but a tumor should be suspected
3-Elevation / destruction of clinoid processes 4-Loss of lamina dura
b) Causes :1-Parasellar / intrasellar mass 2-Raised intracranial pressure due to dilated
third ventricle 3-Empty sella
4-Nelson's syndrome : post-adrenalectomy for Cushing's syndrome
J-Shaped Sellaa) Definitionb) Causes
a) Definition :-Where the tuberculum sellae is flattened , thus
forming the straight edge of the "J“ , the dorsum sellae remains rounded and forms the loop of the "J“
Macrocephaly with J-shaped sella
Normal (1=tuberculum , 2=dorsum sella , 3=pituitary fossa) J-shaped sella
J shaped sella
-Causes :1. Normal : 5% of normal children2. Optic chiasm glioma : if the chiasmatic sulcus is
markedly depressed (W- or omega-shaped sella) , the tumor may be bilateral
3. Neurofibromatosis4. Achondroplasia5. Mucopolysaccharidoses
6 .Chronic hydrocephalus : bone erosion occurs due to the downward pressure of an enlarged third ventricle
Empty Sellaa) Incidenceb) Radiographic Features
a) Incidence :-Relatively common incidental finding -The hallmark of the finding is as the name suggests , a pituitary
fossa which is largely empty of tissue , replaced by CSF-Empty sella is a component of the constellation of findings in
pseudotumor cerebri -Pseudotumor cerebri also known as idiopathic (benign)
intracranial hypertension, is a syndrome associated with elevated CSF pressure , visual changes and headaches that is typically seen in obese black females
*Imaging findings include :1-Empty sella2-Flattening of posterior sclera of globes3-Protruding optic nerve papilla4-Tortous optic nerve with enlarged fluid-filled nerve sheath 5-The ventricles are normal in size or slightly reduced in caliber6-The sigmoid or transverse sinus may be stenotic
Empty sella
Flattening of posterior sclera of globes , protruding optic nerve papilla & tortuous optic nerve
Slit like ventricles
Stenotic transverse sinuses
b) Radiographic Features :-MRI will shows the sella to be filled with CSF
and the infundibulum can be seen to traverse the space , thereby excluding a cystic mass , this is known as the infundibulum sign
T1 T2
T1 T2
Infundibulum sign
Post-Surgical Sella-Small tumors are often removed via a
transsphenoidal approach (anterior wall of sphenoid sinus → sella) , typically , sella and sphenoid sinus are packed with Gelfoam , muscle and fat , postsurgical fluid may be seen in the sphenoidal sinus
-Radiographic Features :*Image sella soon after surgery (3-7 days) to
establish baseline imaging appearance for further follow-up
-Gd-DTPA fat-suppression MRI techniques are helpful to suppress bright signal from surgical fat plug in the sella and to enhance pituitary tissue
Ectopic Neurohypophysisa) Incidenceb) Radiographic Features
a) Incidence :-Ectopic posterior pituitary reflects an disruption
of normal embryogenesis and is one of the more common causes of pituitary dwarfism
-May be associated with septo-optic dysplasia , optic nerve hypoplasia & agenesis of the corpus callosum
b) Radiographic Features :-High T1 signal 3-8 mm tissue nodule at the
median eminence (floor of third ventricle)-Absent normal posterior pituitary bright spot ,
it is important to note that a posterior pituitary bright spot is not identified in 100% of patients
Median eminence
T1
T1
T1 shows callosal dysgenesis with ectopic posterior pituitary
T1 shows ectopic posterior pituitary with septo-optic dysplasia
Intrasellar Massesa) Neoplasticb) Non-Neoplastic
Neoplastic 1-Pituitary microadenoma2-Pituitary macroadenoma3-Meningioma4-Craniopharyngioma5-Invasion by skull base
tumor 6-Pituitary metastases
Non-Neoplastic 1-Pituitary hyperplasia2-Pituitary Apoplexy3-Internal carotid artery aneurysm4-Ectatic carotid artery5-Rathke’s cleft cyst6-Infundibular Non-Neoplastic
Masses :a) Sarcoidosisb) Langerhans cell histiocytosisc) Lymphocytic hypophysitis 7-Pituitary abscess
a) Neoplastic :1-Pituitary microadenoma2-Pituitary macroadenoma3-Meningioma4-Craniopharyngioma5-Invasion by skull base tumour 6-Pituitary metastases
1-Pituitary Microadenoma :a) Sizeb) Typesc) Radiographic Features
a) Size :-Adenomas < 10 mm-75% are endocrinologically functional
b) Types :1-Prolactinoma (most common : galactorrhea ,
amenorrhea , decreased libido)2-Growth hormone (GH) (acromegaly , gigantism)3-Adrenocorticotropic hormone (ACTH) (Cushing's
syndrome)4-Gonadotroph (infertility or menstrual problems in
women , follicle-stimulating hormone)5-Mixed (prolactin , GH , thyroid-stimulating
hormone least common)
c) Radiographic Features :1-T1 noncontrast Appearance2-Contrast enhancement (Gd-DTPA)
1-T1 Noncontrast Appearance :-Microadenomas are hypointense / isointense
relative to pituitary-Gland asymmetry-Gland is convex superiorly (normal : flat or
concave)-Stalk deviation-Depression of sella floor
2-Contrast Enhancement (Gd-DTPA) :-Dynamic imaging is required-Low dose (0.05 mmol Gd/kg) : evaluation of
microadenomas-Normal dose (0.1 mmol Gd/kg) : evaluation of
macroadenomas-Adenoma enhances less rapidly than normal
pituitary
*N.B. : Dynamic Study :-After a bolus injection of intravenous gadolinium ,
six consecutive sets of three images are obtained in coronal plane every 10 seconds
-The enhancement occurs first in the pituitary stalk , then in the pituitary tuft (the junction point of the stalk and gland) and finally there is centrifugal opacification of the entire anterior lobe
-Within 30-60 seconds the entire gland shows homogenous enhancement
-The maximum image contrast between the normal pituitary tissue and microadenomas is attained about 30-60 seconds after the bolus injection of the intravenous contrast
High-resolution dynamic T1+C (at 60 seconds) shows a small nonenhancing (dark) microadenoma (thin black arrow) lateralized to the right side of the pituitary gland , the normal pituitary gland shows marked homogenous enhancement and there is no deviation of pituitary stalk (thin white arrow)
2-Pituitary Macroadenoma :a) Sizeb) Radiographic Featuresc) Extensiond) Differential Diagnosis
a) Size :-Adenomas > 10 mm-Symptomatic because of their mass effect (e.g.
hypopituitarism , visual problems) rather than endocrine dysfunction
b) Radiographic Features :-Heterogeneous appearance because of solid
and cystic components-Enhancement : Intense but heterogeneous-Intratumoral necrosis , hemorrhage (T1W
hyperintense)
T1
T2
T1+C
Axial T2W (a) and T1W (b) images show a large inhomogeneous T1-hypointense and T2-hyperintense pituitary mass (arrow) , which causes a lateral displacement of bilateral internal carotid arteries (cavernous part) , on post contrast coronal (c) and sagittal (d) images , the lesion exhibits marked but heterogeneous contrast enhancement
Axial T2W (a) and T1W (b) images demonstrate a large inhomogeneous , T1-hypointense , T2- hyperintense pituitary mass (arrow) which shows marked enhancement on post contrast coronal (c) and sagittal (d) images
Axial T2 (a) and T1 (b) show a large inhomogeneous isointense pituitary mass (arrow) encroaching bilateral cavernous sinus regions, on postcontrast coronal (c) and sagittal (d) images, the lesion exhibits moderate contrast enhancement, left ICA (cavernous part) appears to be displaced laterally by the mass while the right ICA is seen traversing through the mass, thereby showing invasion of ipsilateral cavernous sinus, however, both the arteries demonstrate normal contrast opacification with mild luminal compromise
Intratumoral Necrosis T1
Intratumoral Necrosis T2
Intratumoral Necrosis T1+C
-Pituitary macroadenoma-The lesion starts in the sella , which is enlarged and extends into the suprasellar cistern-Note the classic snowman configuration caused by constriction by the diaphragma sellae-Notice the blood-fluid level, indicating hemorrhage
Hemorrhagic pituitary macroadenoma T1
Hemorrhagic pituitary macroadenoma T2
Hemorrhagic pituitary macroadenoma T1+C
Coronal T1W (a) and Sagittal T2W (b) images reveal a pituitary mass (arrow) showing intratumoral hemorrhage , on post contrast coronal (c) and sagittal (d) images , the lesion demonstrates mild enhancement with left cavernous sinus invasion
Pituitary apoplexy (pituitary macroadenoma with hemorrhage) Axial T1W (a) , T2W (b) and GRE (c) images reveal a pituitary mass with intratumoral hemorrhage (arrow)
c) Extension :Large tumor extending beyond the confines of the sella1-Intrasellar expansion (ballooning of sella)2-Extension into suprasellar cistern :-Figure eight shape-Thickening of cavernous sinus-Encasement / narrowing of cavernous ICA flow void ,
cavernous sinus involvement can be difficult to determine unless tumor surrounds the vessel / cavernous sinus
-Compression of optic chiasm-Upward displacement of third ventricle-Obstruction of foramen of Monro with
hydrocephalus , 10%-Compression of frontal horn of lateral
ventricles-Splaying of cerebral peduncles
T1+C showing a pituitary adenoma with elevation and compression of the optic chiasm (arrow indicates area of optic chiasm)
Extension into sphenoid bone T1
Extension into sphenoid bone T2
Extension into sphenoid bone T1+C
Suprasellar extension CT
Invasion of the base of the skull T1+C
Invasion of the base of the skull T1+C
Invasion of the base of the skull T1+C
d) Differential Diagnosis : From Meningioma
-In Pituitary Macroadenoma :-Because they are soft tumors , they usually
indent at the diaphragma sellae giving them a (snowman or figure of 8 configuration )
-Enlargement of the sella turcica , this generally only occurs with pituitary macroadenomas that originate in the sella
-In Meningioma :-There are dural tail usually visible-Enhancement more vivid-Hyperdense on non-contrast CT-Typically narrow arteries which they encase
while macroadenoma doesn’t
-Pituitary macroadenoma-The lesion starts in the sella , which is enlarged and extends into the suprasellar cistern-Note the classic 'snowman' configuration caused by constriction by the diaphragma sellae-Notice the blood-fluid level, indicating hemorrhage
-In meningioma , there is no diaphragmatic constriction and there is uniform enhancement after the administration of intravenous gadolinium
-On the coronal images (T1 and T1-postcontrast) a compressed pituitary gland can be identified at the bottom of the sella turcica-Above it lies a large mass , partially intrasellar and partially suprasellar-Although the diaphragma sellae can not be identified on these images , it is probably a suprasellar mass growing downwards-When pituitary macroadenomas get this size they usually have areas of hemorrhage or necrosis , in mengiomas this is less often
3-Meningioma :-Tuberculum or diaphragma sellae meningioma
may extend into the sella (See Suprasellar Masses)
-Purely intrasellar tumor rare
4-Craniopharyngioma :-See (Suprasellar Masses)
5-Invasion by Skull Base Tumor :Chordoma & Chondrosarcoma
1-Chordoma :a) Incidenceb) Radiographic Features
a) Incidence :-Occurs at any age but are usually seen in adults
(20-40 years)-Expansile lytic mass arising from the central skull
base (clivus)-Typically the mass projects in the mid-line
posteriorly indenting the pons , this characteristic appearance has been termed the thumb sign
-The clivus is a combination of two bones , the body of the sphenoid and the anterior aspect of the occipital bone
-Together they form a bony slope anterior to the brainstem which extends from the dorsum sella to the anterior aspect of the foramen magnum
3D CT shows the sites of origin of intracranial chordomas : the upper (yellow) , middle (red) and lower (green) clivus
Sagittal T1-weighted MR images demonstrate involvement of the upper clivus
Sagittal T1-weighted MR images demonstrate involvement of the middle clivus
Sagittal T1-weighted MR images demonstrate involvement of the lower clivus
b) Radiographic Features :1-CT2-MRI3-MRA4-Conventional Angiography
1-CT :-Centrally located well-circumscribed expansile
soft-tissue mass that arises from the clivus with associated extensive lytic bone destruction
-The bulk of the tumor is usually hyperattenuating relative to the adjacent neural axis
-Intratumoral calcifications appear irregular at CT and are usually thought to represent sequestra from bone destruction rather than dystrophic calcifications in the tumor itself
-There is moderate to marked enhancement
CT
CT+C
Sagittal reformatted CT scan reveals bone sequestra at the distal end of a lytic clival lesion (arrows)
Axial CT scan of the skull base demonstrates the lesion with a clival origin and extension to the prepontine cistern with typical trabecular entrapment (arrow) , dystrophic calcification is also seen (arrowhead)
CT scan shows a chondroid chordoma in the clivus with intratumoral calcifications (arrow)
2-MRI :*T1 :-Intermediate to low signal intensity-Small foci of hyperintensity (intratumoral
hemorrhage or a mucus pool)
T1
Axial T1-weighted MR image shows a small hypointense mass in the right side of the clivus (arrow)
Sagittal T1-weighted MR shows a large hypointense soft-tissue mass that arises from the distal clivus with anterior extension into the nasopharynx (arrows) and extradural extension into the posterior fossa (arrowhead)
Sagittal T1-weighted MR image shows a retroclival mass (arrows) that has a hyperintense rim and projects posteriorly , a finding that represents highly proteinaceous material or blood products
*T2 :-Most exhibit very high signal (reflects the high fluid
content of vacuolated cellular components )-The intratumoral areas of calcification ,
hemorrhage and a highly proteinaceous mucus pool usually demonstrate heterogeneous hypointensity
-Low signal intensity septations that separate high signal intensity lobules are commonly seen
T2
Axial T2 shows an intracranial chordoma with diffuse homogeneous hyperintensity
Axial T2 shows a multiseptate hyperintense mass with extension into the sellar area and left cavernous sinus , the mass also exhibits areas of hypointensity possibly secondary to calcification , hemorrhage or a mucus collection
Axial T2 shows a septate tumor with a pseudoencapsulated appearance
-T1+C : Heterogeneous enhancement with a honeycomb appearance corresponding to low T1 signal areas within the tumor , occasionally , the enhancement is slight or even absent , such a finding likely represents necrosis and a large amount of mucinous material in the tumor
-GE (gradient echo) : Confirms hemorrhage if present with blooming
T1+C
Axial unenhanced T1-weighted MR image shows an isointense mass along the right side of the clivus and petrous apex
Axial contrast-enhanced T1-weighted MR image shows the mass with marked enhancement
Axial contrast-enhanced T1-weighted MR image shows a large midclival mass with variable enhancement (honeycomb appearance) and extension to the sellar area and adjacent cavernous sinuses , note the lateral displacement of the right cavernous internal carotid artery (arrow)
Sagittal unenhanced T1-weighted MR image shows a large isointense soft tissue mass in the distal clivus (arrows)
Sagittal T1+C , the mass exhibits little or no enhancement (arrows)
Note the normal enhancement of the nasal , nasopharyngeal and palatal mucosa
3-MRA : -Allows better evaluation of vascular encasement
and obviates cerebral angiography which does not allow detection of encasement without luminal narrowing or occlusion
-Tumoral displacement or partial encasement of intracranial arteries is common being visualized in up to 80 % of intracranial chordomas
Normal MRAMRA shows posterior displacement of the
right PCA (arrowhead) and lateral displacement of the right cavernous ICA (arrow)
Sagittal T1-weighted MR image demonstrates posterior and superior elevation of the right cavernous internal carotid artery (arrows)
Coronal T1-weighted MR shows a tumor with extension to the right cavernous sinus and concomitant displacement and partial encasement of the right cavernous internal carotid artery (arrow)
Sagittal T1+C shows a large irregularly enhancing mass (arrow) with retroclival extension that encases the left ICA (arrowhead)
4-Conventional Angiography :-Angiographic evaluation is reserved for cases in which
there is significant displacement , encasement or narrowing of the ICA or vertebral artery at MRA
-Cerebral angiography can better demonstrate the degree of luminal narrowing or occlusion and the extent of collateral circulation
-Temporary balloon occlusion of the ICA is frequently used to determine whether patients are at risk for neurologic injury during surgery due to permanent vessel occlusion
Left carotid arteriogram shows narrowing of the distal left ICA (arrow) and upward displacement of the left MCA (arrowhead)
Sagittal T1-weighted MR image shows a mass that involves the posterior fossa (arrows) with extracranial soft-tissue extension to the face
Left ECA arteriogram demonstrates recurrent tumor with vasculature from the branches of the posterior auricular artery (arrow) , note the occlusion of the ICA (arrowhead)
2-Chondrosarcoma :a) Incidenceb) Radiographic Features
a) Incidence :-Paramedian arising from the petro-occipital
fissure and infiltrate the cavernous sinus
-Drawing of a sagittal section through the head depicts a large chondrosarcoma arising from the clivus-The tumor is exerting mass effect on the pons and midbrain without direct invasionWhitish areas within the tumor represent matrix mineralization
b) Radiographic Features :1-CT2-MRI
1-CT :-Shows a stippled and / or amorphous calcified
matrix
CT Showed peripheral Calcification
-MRI :*T1 :-The tumor shows variable signal intensity-The areas of high T1 signal intensity may reflect
hemorrhage or mucin
*T2 : -Characteristic high T2 signal intensity-The heterogeneous T2 signal intensity may be
due to fibrocartilaginous foci or areas of chondroid mineralization
T2 revealed a retroclival mass which was intensely hyperintense , clival invasion was note
*T1+C :-Enhancement is moderate to marked and
usually heterogeneous , though occasionally it is homogeneous
Coronal T1+C of a chondrosarcoma , this is an enhancing mass involving the left side of the sella and the cavernous sinus but arising from the skull base just off midline
-A , Coronal T1+C shows a large inhomogeneous-appearing mass involving the left CS , sella , suprasellar region , ipsilateral middle cranial fossa and intratemporal region , the mass has a cystic lateral component-B , Axial T2 shows that the solid portion of the mass is hyperintense , a finding that is typical of chondrosarcoma
6-Pituitary Metastases :a) Incidenceb) Clinical Picturec) Radiographic Features
a) Incidence :-Rare (breast most common)-May appear identical to pituitary adenomas
b) Clinical Picture :Hormonal dysfunction and mass effect
c) Radiographic Features :-Although larger lesions are visible on CT ,
appearing as enhancing soft tissue masses , MRI is the modality of choice for assessment of the pituitary region
-MRI : usually encountered in two pattern :1-Sizeable mass arising from the pituitary fossa
(similar to a macroadenoma)2-Infundibular lesion
1-Sizeable mass arising from the pituitary fossa (similar to a macroadenoma) :
-These masses typically involve both the intra and suprasellar compartments , as they are usually rapidly growing they have a number of features which are helpful in distinguishing them from pituitary macroadenomas :
1-Relatively normal size fossa2-Bony destruction rather than remodelling3-Dural thickening4-Dumb-bell shape as the diaphragma sella has
not had time to be stretched5-Irregular edges
2-Infundibular Lesion :-Involvement of the infundibulum typically
appears as nodular / irregular thickening and enhancement , the posterior pituitary bright spot may also be absent , either from interruption of the normal transport of neurosecretory granules down the infundibulum or due to concurrent infiltration of the posterior lobe
T1
T1
T2
T1+C
-Patient with lung cancer who presented with a sixth cranial nerve palsy-The abnormality is in the clivus which should have a high signal intensity on this sagittal T1-weighted-A low signal intensity means the normal fatty marrow has been replaced by some other tissue-In this case by tumor metastasis-Also lymphomas , myelomas or diffuse bone abnormalities can give this appearance-Therefore always take a minute to look at the clivus
-T1 showing the disappearance of the characteristic high signals of the posterior pituitary and increased size of the pituitary stalk
- MRI T1+C showing the nodular lesions below the hypothalamus region , the posterior pituitary continued to lack the characteristic high signal
b) Non-Neoplastic :1-Pituitary Hyperplasia2-Pituitary Apoplexy3-Internal Carotid Artery aneurysm4-Ectatic Carotid Artery5-Rathke’s cleft cyst6-Infundibular Non-Neoplastic Masses :a) Sarcoidosisb) Langerhans cell histiocytosisc) Lymphocytic hypophysitis7-Pituitary Abscess
1-Pituitary Hyperplasia :a) Definition b) Etiology
a) Definition :-Generalized homogeneous enlargement of the
gland
b) Etiology :1-Pregnancy & Lactation2-Nelson’s syndrome (infrequently develop
following total bilateral adrenalectomy (TBA) for the treatment of Cushing's disease )
(a) Non-enhanced T1 shows normal pituitary gland (thin arrows) , (b) T1+C shows pituitary hyperplasia (thick arrows) , the enlarged pituitary gland abuts the optic chiasm superiorly (dotted arrows) , typical feature of physiologic enlargement is a triangular shape to the gland with the apex pointing toward the optic apparatus
Coronal contrast-enhanced MRI shows the enlarged gland without any visible adenoma
Sagittal contrast-enhanced MRI shows the enlarged gland without any visible adenoma
2-Pituitary Apoplexy :a) incidenceb) Causes c) Radiographic Features
a) Incidence :-Is an acute clinical syndrome caused by either
hemorrhage or infarction of the pituitary gland
- An existing pituitary macroadenoma is usually present (60-90%) but it can occur with healthy glands in few isolated cases
-Manifests as acute onset of terrible headache , ptosis , vision changes , diplopia , nausea & vomiting
b) Causes :1-Acute onset of hemorrhage into pituitary
adenoma with necrosis and infarction of the pituitary gland
2-Sheehan's syndrome : postpartum infarction of anterior pituitary gland
c) Radiographic Features :-MRI typically demonstrates a pituitary region mass*T1 : hyperintense due to blood *T2 : variable signal *T1+C : enhancement variable and may be difficult
to identify due to intrinsic high T1 signal*Diffusion : restricted diffusion may be present in
solid infarcted component
T1
T1
T1+C
3-Internal Carotid Artery Aneurysm :-Must not be mistaken for intrasellar tumor (see Parasellar masses)
4-Ectatic Carotid Artery :-Medially positioned ICAs may be bilateral and
produce (kissing carotids)
Ectasia of left ICA
Ectasia of left ICA
CTA 3D , intracranial intrasellar kissing carotids
5-Rathke’s Cleft Cyst :a) Incidenceb) Radiographic Featuresc) Differential Diagnosis
a) Incidence :-Common in adult females-Intrasellar , suprasellar or both-Cystic or solid -Arises from the embryologic remnants of
Rathke’s pouch in the pituitary gland (similar to craniopharyngioma)
b) Radiographic Features :1-CT2-MRI
1-CT :-Hyperdense on CT with rim enhancement-No enhancement (may be rim enhancement) ,
No calcification unlike craniopharyngioma which enhances and calcify
2-MRI :*T1 :-High T1W signal on MRI (the only two things that are this bright on
unenhanced T1-weighted images are either fluid ( blood or proteinaceous fluid) or fat
-Small intracystic nodules with high signal intensity at T1 and low signal intensity at T2 are present in approximately 45% of cases and are considered a characteristic feature of Rathke cleft cysts
*T2 :-High signal intensity*T1+C :-Peripheral enhancement is sometimes noted (The claw sign
represents enhancing pituitary tissue completely wrapped around the cyst)
T1 shows a well-marginated sellar mass , a Rathke cleft cyst , extending into the suprasellar cistern , note that the mass has homogeneous high signal intensity relative to the brain parenchyma
T2 shows the mass , a Rathke cleft cyst , is isointense relative to the cortex
After contrast enhancement , no significant enhancement is seen in the Rathke cleft cyst , note the normally enhancing pituitary infundibulum dorsal to the mass
T1+C shows hypointense mass (yellow arrows) with faint peripheral rim enhancement , the pituitary is displaced to the right and the optic chiasm is displaced superiorly (red arrow)
The red arrow points to the cyst , the yellow to the compressed and displaced pituitary stalk
Rathke cleft cyst in a 34 year old woman with a slightly elevated prolactin level, (a) Coronal T1shows a high signal intensity spheroid lesion (arrow) within the sella, (b) Coronal T2 shows a low signal intensity intracystic nodule (arrowhead) within the spheroid lesion
c) Differential diagnosis :From Craniopharyngioma1-Enhancement of the wall of a cystic
craniopharyngioma on contrast-enhanced MR images played an essential role in differentiating it from Rathke cleft cyst
2-Craniopharyngioma is usually suprasellar or have a suprasellar component
3-Craniopharyngioma tends to calcify
Craniopharyngioma ; suprasellar mass with rim enhancement
CT without contrast shows craniopharyngioma , suprasellar mass with calcification
Craniopharyngioma with suprasellar location
6-Infundibular Non-Neoplastic Masses :a) Sarcoidosisb) Langerhans cell histiocytosisc) Lymphocytic hypophysitis
a) Sarcoidosis :1-Incidence2-Location3-Clinical Picture4-Radiographic Features
1-Incidence :-Typically affecting patients 30-40 years of age
with a female predilection-Sarcoidosis is a great mimic , enhancing lesions
may involve dura , leptomeninges , brain parenchyma , hypothalamic pituitary axis and cranial nerves
2-Location :-Central nervous system involvement by
sarcoidosis is very variable with lesions potentially involving the leptomeninges , pituitary and parenchyma of all parts of the intracranial compartment
3-Clinical Picture :-Variable and non-specific , it includes :1-Signs and symptoms of raised ICP due to
hydrocephalus2-Cranial nerve palsies :-Optic nerve involvement (common)-Facial Nerve palsy4-Diabetes insipidus from pituitary involvement5-Seizures
4-Radiographic Features :a) CT :-Plaque like dural thickening-Often the only finding is hydrocephalus due to
unseen leptomeningeal diseaseb) MRI :*T1 :-Iso or hypointense with respect to adjacent grey
matter
*T2 :-Variable-Most are hyperintense*T1+C :-Homogenous enhancement- Enhancement involving the optic apparatus / floor
of the third ventricle and pituitary infundibulum is particularly suggestive of sarcoidosis
Sagittal T1+C , shows a well-defined mass in the hypothalamic area and a thickened pituitary stalk
(a) Sagittal and (b) coronal images of pituitary and hypothalamus Involvement , there is extensive enhancement of the pituitary gland (arrow) and stalk (arrowhead) which is markedly enlarged
T1+C , A : shows a well enhanced mass in the hypothalamic area , thickening of the stalk and swelling of the pituitary gland , B : Shows improvement after treatment
Coronal T1+C , A : Shows an enhanced nodular lesions around the 3rd ventricle , optic tract and decreased intensity of the posterior pituitary gland , B : Shows disappearance of the nodular lesions after treatment
Leptomeningeal Involvement ( T1+C )
b) Lymphocytic Hypophysitis :-Lymphocytic infiltration of the anterior pituitary
occurring in pregnancy / postpartum period-Enlarged enhancing gland and infundibulum-Responds to steroid therapy
T1+C shows diffuse enhancement of the pituitary gland (black arrow) , also note the enlargement and enhancement of the infundibular stalk (white arrow)
Postcontrast T1W coronal (a) and sagittal (b) images show slight enlargement of pituitary gland and thickening of the infundibulum with minimal enhancement (arrow) , the fossa is not enlarged , also note the absence of posterior bright spot
c) Langerhans Cell Histiocytosis :-Disease of children-Commonest radiological presentation is a
thickened enhancing infundibulum with loss of the normal posterior pituitary bright spot
-Parenchymal , cranial nerve , meningeal and skull lesions also occur
T1+C shows remarkable thickening of the pituitary stalk resulting in slight compression of optic chiasm
Loss of normal T1 high signal in the posterior pituitary
Normal high signal of post p Loss of normal signal
T1+C (a) coronal and (b) sagittal images show a contrast-enhancing thickened pituitary stalk , an associated left frontal intradiploic skull lesion is noted
A. T1 shows a uniformly thickened pituitary stalk (arrow) , the posterior lobe no longer shows high signal intensity , B. T1+C shows strong enhancement of the lesion (arrow)
7-Pituitary Abscess :a) Incidenceb) Etiologyc) Clinical Pictured) Radiographic Findings
a) Incidence :-Rare , accounts for approximately 0.2-1% of all
pituitary lesions
b) Etiology :-Caused by hematogenous seeding of the pituitary
gland or possibly by direct extension of an adjacent infection such as meningitis , sphenoid sinusitis , cavernous sinus thrombophlebitis or as a result of a CSF fistula that has been contaminated
c) Clinical Picture :-The most common presenting symptoms are
headaches , visual problems and those of pituitary insuffiency such as diabetes insipidus
d) Radiographic Findings :-T1 : Typically show low intensity but may also
show marked T1 hyperintensity due to purulent content
-T2 : Demonstrates increased intensity-T1+C : Ring enhancement can be demonstrated
, which represents the abscess capsule-DWI : Restricted diffusion within the abscess
cavity may be seen-MRS : Lactate , aminoacid (valine , alanine and
leucine) and acetate peaks
T1 shows suprasellar mass with internal increased intensity
T2 coronal image shows suprasellar mass with increased intensity and compression of the optic chiasm is seen
T1+C sagittal image shows peripheral enhancement of the suprasellar lesion
Suprasellar Masses a) Neoplasticb) Non-Neoplastic
a) Neoplastic 1-Pituitary macroadenoma 2-Suprasellar Meningioma 3-Craniopharyngioma 4-Optic pathway glioma5-Hypothalamic hamartoma 6-Lymhoma & Leukemia7-Suprasellar Germ Cell
Tumors8-Suprasellar Lipoma9-Metastases
b) Non-Neoplastic1-Aneurysm of ICA2-Ectatic ICA3-Arachnoid cyst 4-Epidermoid / Dermoid5-Rathke's cleft cyst6-Infundibular Non-Neoplastic
Masses :a) Sarcoidosisb) Langerhans cell histiocytosisc) Lymphocytic hypophysitis
a) Neoplastic :-The most common suprasellar lesion in a child is craniopharyngioma
while the most common suprasellar lesion in an adult is a pituitary macroadenoma that has extended superiorly
1-Pituitary Macroadenoma 2-Suprasellar Meningioma 3-Craniopharyngioma 4-Chiasmatic Glioma5-Infundibular Tumors6-Hypothalamic Hamartoma7-Suprasellar Germ Cell Tumors8-Suprasellar Lipoma
1-Pituitary Macroadenoma : (See intrasellar masses)
-Large tumors extend into the chiasmatic cistern (suprasellar cistern) where they can compress the
optic apparatus-Macroadenomas typically have a (cottage loaf or
figure of eight or snow man appearance )-Hemorrhage , cyst formation and midline origin is
suggestive of macroadenoma rather than meningioma
1-Suprasellar cistern2-Pituitary gland3-Pons4- 3rd ventricle 5-Corpus callosum
1-Suprasellar cistern2-Pituitary stalk3-Cerebral aqueduct4-Hippocampus
1-Suprasellar cistern2-ACA3-Lateral ventricle4-Caudate nucleus
2-Suprasellar Meningioma :a) Incidenceb) Radiographic Featuresc) Differential Diagnosis
a) Incidence :-Common in females (peak incidence 45 years of
age)-2nd most common tumor suprasellar tumor in adults-Arises from the anterior cranial fossa , sphenoid
wing or diaphragma sellae-Typically presents with visual loss due to optic
pathway involvement
An autopsy specimen with the brain removed showing a meningioma sitting on the diaphragma sellae
b) Radiographic Features :*CT :-Unenhanced CT shows a mass which is hyperdense
to underlying parenchyma , however , it may be iso or hypodense
-Contrast : Homogenous enhancement with dural tail
-Calcification in circular or radial pattern-Underlying parenchymal edema-Hyperostosis
CT without contrast
A: CT brain revealed a homogenous hyperdense globular mass at the suprasellar region
B: The mass enhanced homogenously with intravenous contrast agent
A: CT brain showing hyperostosis of the sphenoid bonyB: CT brain of showing normal sphenoid bone thickness
*MRI :-Isointense to grey matter on T1-Variable intensity on T2 ranging from iso to hyperintense-Enhancement is uniform-Dural tail-The pituitary gland should be identified separately (in
contrast to pituitary adenoma)-Parenchymal edema
c) Differential Diagnosis :-From pituitary macroadenoma (See before)
T1
T1
T2
T2
T1+C showed a nodular tumor with a tail of meningeal enhancement (arrow) extended onto the cribriform plate
T1+C
T1+C
3-Craniopharyngioma :a) Incidenceb) Clinical Picturec) Radiographic Findings
a) Incidence :-Benign tumor that arises from squamous epithelial
remnants along Rathke duct / pouch-Most common tumor of the suprasellar cistern of
childhood-Age: 1st to 2nd decade (>50%)-Location: Combined suprasellar / intrasellar ,
completely intrasellar is rare (it is almost always separate from the pituitary gland)
b) Clinical Picture :1-Growth retardation (compression of
hypothalamus)2-Diabetes insipidus (pituitary compression)3-Bitemporal hemianopsia (partial blindness
where vision is missing in the outer half of both visual fields)
4-Headaches (most common)5-Cranial nerve palsies (cavernous sinus
involvement)
c) Radiographic Findings :1-CT :-Midline cystic mass (90%) with mural nodule in suprasellar
location that extends superiorly and posteriorly -Calcification in 90% (children) , less common in adults (50%) ,
typically stippled and often peripheral in location-Enhancement of solid lesion rim , no enhancement of cystic
lesion (in contrast to Rathke’s cleft cyst , craniopharyngioma almost always enhances , is almost always calcified and is almost always separate from the pituitary
-Obstruction of foramen of Monro with hydrocephalus , 60%
Benign calcification Intermediate calcification
2-MRI :-Variable signal intensity by MRI depending on cyst
content : high protein content , blood , cholesterol
*T1 :-Hypointense (however , may be high signal on
T1W)-The T1 hyperintensity observed in the cystic
components of craniopharyngioma is attributable to the presence of protein , cholesterol granules and methemoglobin
*T2 :-Hyperintense*T1+C :-Rim like enhancement (avid enhancement of the solid
element and *MRA :-May demonstrate displacement of the A1 segment of
the anterior cerebral artery*Angiography :-Usually avascular
-In over 50% of cases craniopharyngiomas have a pathognomonic appearance -On these unenhanced and enhanced T1-weighted sagittal , coronal & axial images , a compressed pituitary gland can be identified-There is a large intrasellar and suprasellar mass with cystic and enhancing components as well as calcifications -These findings in a child are virtually pathognomonic for craniopharyngioma (perhaps with only a dermoid in the differential diagnosis)
T1
-Craniopharyngioma in a 2 year old boy -Sagittal T1 shows a large mass (*) that contains multiple high signal intensity components (arrows)
T2
T1+C
T1
T2
T1+C
The yellow arrows point to the cyst , the red to the solid part of the tumor and the blue to a dilated lateral ventricle (hydrocephalus)
The yellow arrow points to the small solid part , the red to the large cystic part
-N.B. :-A suprasellar mass in a child or adolescent is considered a
craniopharyngioma until proven otherwise-The majority of craniopharyngiomas have cystic
components ; purely solid tumors are rare-Clinical presentations of pediatric suprasellar region
lesions :1-Diabetes insipidus most common with eosinophilic
granuloma of stalk2-Precocious puberty most common with hypothalamic
hamartoma3-Growth delay most common with craniopharyngioma
4-Optic Pathway Glioma :-An astrocytoma involving the visual pathway (optic
nerve , optic chiasm and optic tract) is the 2nd most common suprasellar mass in children (craniopharyngioma is the most common)
-Minority of patients with optic pathway glioma have NF-1
-Tumors are isointense on T1 , hyperintense on T2 and usually enhances
Optic pathway glioma , (a) T1 , (b) T1+C show a suprasellar mass that is slightly hypointense relative to grey matter (yellow arrows) with diffuse enlargement of the adjacent optic chiasm (red arrow) , the mass demonstrates avid slightly heterogenous enhancement
T1 (a) , FLAIR (b) shows the lesion is hypointense on T1 and hyperintense on FLAIR image , optic chiasma and left optic nerve are involved
5-Hypothalamic (Tuber Cinereum) Hamartoma:a) Originb) Clinical Picturec) Radiographic Findings
a) Origin :-Sessile or pedunculated tumor lying between
the pituitary stalk and mamillary bodies-Not a true neoplasm
-Left: Normal infundibular recess of the third ventricle (blue arrow) , mamillary bodies (red arrow)-Right: Tuber cinereum hamartoma (curved arrow)
1-Tuber cinerum2-Corpus callosum3-Fornix4-Third ventricle 5-Cerebellum6-Fourth ventricle7-Pons
1-Tuber cinerum2-Cerebral peduncle3-Cerebral aqueduct4-Superior colliculus
1-Tuber cinerum2-Column of fornix3-Septum pellucidum4-Third ventricle
b) Clinical Picture :-Patients present with either : 1-Precocious puberty 2-Gelastic seizures (paroxysms of inappropriate
emotional outbursts , usually laughing)
c) Radiographic Findings :*CT: -Isodense-No enhancement (in contrast with
hypothalamic gliomas)
Axial (a) and sagittal (b) post-contrast CT demonstrate a tiny well-defined nonenhancing rounded suprasellar mass arising from hypothalamus (arrow) , note , the lesion is isodense to normal brain parenchyma
-CT images of a hamartoma suspended from the floor of the third ventricle-It does not enhance after the administration of intravenous contrast
-MR images of a similar small nodule suspended from the floor of the third ventricle
-Note the enhancement of the hypothalamic glioma-A : Unenhanced axial CT scan reveals a hyperdense mass (arrow) that enhances uniformly in the suprasellar region-B : CT+C reveals a hyperdense mass that enhances uniformly (arrow) in the suprasellar region
*MRI :-T1W: similar signal intensity as GM-T2W: hyperintense-N.B. : The floor of the third ventricle should be smooth
from infundibulum to mamillary bodies , any nodularity should raise suspicion for a hamartoma in the right clinical setting
-The best images to see hamartoma on are enhanced sagittal T1-Here you can see the non-enhancing hamartoma attached to the tuber cinereum between the pituitary stalk and mamillary body -Hamartoma (red arrow) posterior to the enhancing pituitary gland and stalk
Sagittal T1+C of a hypothalamic hamartoma , this is seen as a pedunculated mass hanging from the undersurface of the hypothalamus , it does not enhance and has the same signal as the grey matter of the brain parenchyma
(a) T1 , (b) FLAIR show a T1 isointense , FLAIR hyperintense suprasellar mass (yellow arrows) projecting inferiorly from the hypothalamus , the optic chiasm (red arrow) , anterior pituitary (blue arrow) and posterior pituitary bright spot (green arrow) are normal
T1
T2
T1+C
T1
T2
T1+C
6-Lymhoma & Leukemia :a) Lymphoma :-May involve the pituitary gland , infundibulum
and hypothalamus-Isointense on T1W with strong uniform
enhancement-Coexistent disease may be visible in the
paranasal sinuses or orbit
b) Leukemia :-Pituitary stalk involvement and thickening has
been reported with leukemia (chronic myelogenous leukemia and acute myelogenous leukemia)
-Clinically these patients have DI
7-Suprasellar Germ Cell Tumors : -Germinoma & Dermoid , see (Pineal Region Masses)-The most common intracranial germ cell tumor is a
germinoma , of which 80 % arise in the pineal region and 20 % arise in the parasellar region
-Seen in children and adolescents-Imaging shows a homogenous intensely enhancing
midline mass , the mass is hypointense on T2 and dark on ADC due to hypercellularity
Suprasellar Germinoma , T1
Suprasellar Germinoma , T2
Suprasellar Germinoma , T1+C
Sagittal T1+C of a germinoma with both a suprasellar and pineal enhancing mass lesions
Coronal T2W FLAIR (a) and postcontrast T1W (b) images show a solid heterogeneous moderately enhancing suprasellar mass in hypothalamic / infundibular region , multiple nonenhancing hypointense intratumoral areas are present representing intratumoral hemorrhage or calcification , postsurgical biopsy proved suprasellar germinoma
Suprasellar germinoma , sagittal T2 shows a solid mass with a cystic area (arrow) , the tumor extends upward toward the infundibular recess
Suprasellar germinoma , sagittal T1+C with fat saturation shows a solid mass with marked enhancement , the pituitary gland is compressed and flattened along the sellar floor (arrows) , the tumor extends upward toward the infundibular recess
Suprasellar Dermoid , T1
Suprasellar Dermoid , T1
Suprasellar Dermoid , T2
Suprasellar Dermoid , T1+C
8-Suprasellar Lipoma :a) Incidenceb) Radiographic Features
a) Incidence :-Suprasellar cistern lipomas have an incidence of
approximately 0.4% account for approximately 15% of all intracranial lipomas, third in frequency after pericallosal lipomas and quadrigeminal cistern lipomas
b) Radiographic Features :1-CT2-MRI
1-CT :-Suprasellar lipomas appear as small fat density
regions in the suprasellar cistern with matching negative density measurements (-30 to -100 HU)
-No calcification is present2-MRI :-High signal intensity on T1
Sagittal T1 of a suprasellar lipoma , the high signal mass containing fat is seen lying on the undersurface of the hypothalamus in the interpeduncular cistern
T1
T1
9-Metastases :-Breast cancer is by far the most common lesion
to metastasize to the parasellar region
b) Non-Neoplastic :1-Aneurysm of ICA2-Ectatic ICA3-Arachnoid cyst 4-Epidermoid / Dermoid5-Rathke's cleft cyst6-Infundibular non-neoplastic masses :a) Sarcoidosisb) Langerhans cell histiocytosisc) Lymphocytic hypophysitis
1-Aneurysm of ICA : See Parasellar Masses-A saccular supraclinoid ICA aneurysm may mimic a suprasellar
tumor-Although parasellar aneurysms are relatively uncommon , it is
essential never to biopsy a mass that may represent an aneurysm
-Pulsation artifact may be present on conventional MRI sequences , CTA or MRA would be diagnostic
2-Ectatic ICA :-See (Intrasellar masses)
(a) CT without contrast shows a large peripherally calcified mass in the suprasellar region , it is hyperdense , (b) CTA of the circle of Willis shows a giant peripherally calcified ACA/Acom aneurysm , it is mostly thrombosed with a central lumen much smaller than the outer sac
(a) T1 , (b) T2 & (c) T1+C shows In the suprasellar region , anterior to the pituitary is a 19 x 21 x 18mm rounded mass with heterogeneous lamellated internal signal (predominantly high T1 and very low T2) consistent with a thrombosed aneurysm , posterosuperiorly flow void is noted consistent with a patent aneurysm 8 x 6 x 6mm arising from the ACA / Acom complex
3-Arachnoid Cyst (Leptomeningeal Cyst) :-See (Brain Tumors)
CT axial view showing suprasellar arachnoid cyst with obstructive hydrocephalus with (Mickey-mouse) appearance
Suprasellar
T1
T2
Flair
DWI
ADC
4-Epidermoid / Dermoid :Epidermoid : See (CPA Masses)-Occur most commonly in middle-aged adults in
the CPA but can be seen less commonly in the paraellar region
Dermoid : See (Brain Tumors)
T1
T1
T2
T1+C
T1+C
DWI
5-Rathke Cleft cyst :-See (Intrasellar masses)
6-Infundibular Non-Neoplastic masses : (See Intrasellar Masses)
a) Sarcoidosisb) Langerhans Cell Histiocytosisc) Lymphocytic Hypophysitis
Cavernous Sinus / Parasellar Masses a) Neoplasticb) Non-Neoplastic
a) Neoplastic1-Schwannoma 2-Meningioma3-Pituitary adenoma 4-Metastasis 5-Lymphoma & Leukemia6-Invasion by skull base
tumor 7-Nasopharyngeal carcinoma 8-Juvenile Angiofibroma
b) Non-Neoplastic1-Aneurysm of ICA2-Ectatic ICA3-Cavernous sinus thrombosis 4-Carotid-cavernous fistula 5-Invasive sinusitis6-Dermoid /Epidermoid7-Tolosa-Hunt syndrome 8-Infundibular Non-Neoplastic
masses :a) Sarcoidosisb) Langerhans cell histiocytosisc) Lymphocytic hypophysitis
a) Neoplastic :1-Schwannoma 2-Meningioma3-Pituitary adenoma 4-Metastasis 5-Lymphoma & Leukemia6-Invasion by skull base tumor 7-Nasopharyngeal carcinoma 8-Juvenile Angiofibroma
1-Schwannoma :-See (Cerebellopontine angle masses)
2-Meningioma :-See (Cerebellopontine angle masses)
3-Pituitary Adenoma : -Direct local invasion from the sella-See (Intrasellar masses)
4-Metastasis :-Metastases to the CS can be hematogenous or
perineural in naturea) Hematogenous Spread :-Distant tumors with hematogenous spread to the CS
are generally renal , gastric , thyroid , lung and breast cancers
-MR imaging shows CS enlargement , outward bowing of its lateral wall and replacement of the Meckel cave with soft tissue that homogeneously enhances
Meckel’s cave (number 1)
-Axial T1+C shows an enhancing mass (from primary breast carcinoma) in the Meckel cave (arrowhead)-In the absence of primary tumor elsewhere , schwannoma needs to be considered in the differential diagnosis
Coronal T1+C shows a classic "winking Meckel cave sign“ , the normal (left) Meckel cave is CSF-filled , hypointense (blue arrow) , the right side is filled with an enhancing mass that fills and expands the Meckel cave (red arrow) , patient had a history of multiple brain metastases from a lung cell carcinoma
b) Perineural Spread : -Perineural tumor spread is commonly seen along
branches of cranial nerve V-Perineural spread is most commonly seen with adenoid
cystic or squamous cell carcinoma but may also be seen with lymphoma , melanoma , basal cell carcinoma , rhabdomyosarcoma , neurogenic tumors and juvenile angiofibroma
-MR imaging features of perineural tumor spread include nerve enlargement and enhancement and foraminal enlargement and destruction
Trigeminal nerve (Normal anatomy)
Trigeminal nerve (Normal anatomy)
(a) Coronal T1+C shows a thick enhancing third division (arrows) of the right trigeminal nerve in a patient with a small adenoid cystic carcinoma in the nasopharynx , (b) slightly posterior to (a) , the tumor has invaded the Gasserian ganglion and fills the Meckel cave (arrow)
5-Lymphoma & Leukemia :-As with metastases , lymphoma and leukemia
reach the CS by direct extension from a primary lesion or from hematogenous spread
-MR imaging may show infiltrative lesions of the skull base invading the CS without arterial narrowing
-Lymphoma and leukemia may also appear as diffuse enlargement and enhancement of the CS similar to the appearance of metastases
-Although they tend to be T2 hypointense , most have no specific MR imaging findings but the diagnosis may be suggested because of the clinical results
-Nowadays , most patients with known lymphoma/leukemia who have been treated will have clinical evidence of relapse by the time MR imaging depicts the new lesions
T1 shows a parasellar mass lesion which is isointense
T2 shows a parasellar mass lesion which is isointense to hypointense
T1+C shows a parasellar mass lesion which is inhomogeneously enhanced
6-Invasion by Skull Base Tumors :Chordoma and chondrosarcoma-See (Intrasellar Masses)
T2 shows a lobulated , hyperintense lesion (arrow heads) arising from the dorsum sellae and invading the Meckel's cave and the cavernous sinus on the right side
(a) Coronal T1+C shows a large inhomogeneous-appearing mass involving the left CS , sella , suprasellar region , ipsilateral middle cranial fossa & intratemporal region , the mass has a cystic lateral component , (b) Axial T2 shows that the solid portion of the mass is hyperintense , a finding that is typical of chondrosarcoma
7-Nasopharyngeal Carcinoma :-The most common primary malignant extracranial
neoplasm to invade the CS-Intracranial extension may occur directly via the
skull base erosion or by perineural spread along branches of the trigeminal nerve
-Tumor can extend through the petro-occipital synchondrosis and foramen lacerum into the inferior CS or via the carotid canal to gain access to the CS without destroying bone
-Once the CS is invaded , bulky masses are present in the nasopharynx
-The tumor is generally hypointense to iso-intense (relative to muscles) on T1-weighted images and T2 hypointense and shows moderate-to-intense contrast enhancement
-Axial T2-weighted image shows a relatively hypointense mass involving the left CS and sella , extending into the posterior ethmoid air cells-Invasive T2 hypointense masses are generally either neoplasias or fungal infections
8-Juvenile Angiofibroma :-Is a highly vascular tumor that affects mostly
adolescent boys-It can extend into the central skull base and to the
anterior part of the CS through the foramen rotundum , vidian canal or foramen lacerum
-The tumor can invade the CS directly by erosion of the pterygoid bone
-The characteristic signal intensity voids on MR imaging representing large vascular structures are typical of this tumor
-Axial postcontrast T1-weighted image shows a very large tumor involving both CSs and surrounding the ICAs (arrows)-The mass extends into the sella , paranasal sinuses , right middle cranial fossa and both orbits-Note flow voids (arrowheads) due to enlarged blood vessels
b) Non-Neoplastic : ICA & Cavernous Sinus1-Aneurysm of ICA2-Ectatic ICA3-Cavernous sinus thrombosis 4-Carotid-cavernous fistula 5-Invasive sinusitis6-Dermoid /Epidermoid7-Tolosa-Hunt syndrome 8-Infundibular Non-Neoplastic Masses :a) Sarcoidosisb) Langerhans cell histiocytosisc) Lymphocytic hypophysitis
1-Aneurysm of ICA :a) Incidence b) Clinical Picturec) Radiographic Features
a) Incidence :-Cavernous carotid aneurysms compose 5% of giant
aneurysms (>2.5 cm in diameter)
b) Clinical Picture :They may produce CS syndrome by virtue of mass
effect , inflammation or rupture into the CS with subsequent development of a CCF
-Most are idiopathic but they may occasionally be traumatic or mycotic in nature
c) Radiographic Features :-A patent aneurysm shows signal intensity void on
spin-echo MR imaging sequences-Partially thrombosed giant aneurysms show mixed
signal intensities representing various stages of clot in their walls (due to chronic dissections) or within their lumen
-Flowing blood through the patent portion of the lumen appears as a signal intensity void on spin-echo images and high signal intensity on gradient techniques
(a) Axial T2 shows a left intracavernous ICA (A) aneurysm , note flow artifacts (arrow) confirming the pulsatile nature of the lesions
(b) Coronal post contrast maximum-intensity image from a CTA in the same patient shows the left intracavernous aneurysm
T2 shows a large aneurysm characterized by flow void is seen in the right cavernous sinus
2-Ectatic ICA :-See (Intrasellar masses)
3-Cavernous Sinus Thrombosis :a) Etiologyb) Radiographic features
a) Etiology :-Most commonly results from contiguous spread
of infection from the sinuses or middle third of the face or less commonly dental abscess or orbital cellulitis
-Staphylococcus aureus is the most common infectious microbe found in 50 - 60% of the cases
b) Radiographic features :-MR imaging signs of CS thrombosis include
changes in signal intensity and / or in the size and contour of the CS , MRI with contrast is the modality of choice
-Although subacute thrombus exhibits high signal intensity on all pulse sequences and is easy to recognize , acute thrombosis may be isointense and difficult to diagnose
-Enhancement of the peripheral margins of an enlarged CS may suggest a clot within it
-Indirect signs that help to suggest the diagnosis are dilation of the superior ophthalmic veins , exophthalmos and increased dural enhancement along the lateral border of CS and ipsilateral tentorium
-The presence of sinusitis and appropriate clinical symptoms confirm the diagnosis
T1+C shows meningeal enhancement consistent with meningitis (White arrow) , swollen non-enhancing cavernous sinus . i.e. cavernous sinus thrombosis (open arrows) , narrowed ICA (green arrows)
(a) Coronal T1+C shows an enlarged and inhomogeneous appearing right CS that contains areas of low signal intensity (arrow) compatible with clot
(b) Coronal T1+C in a different patient shows a large nonenhancing clot expanding the left CS , the ipsilateral ICA is slightly narrowed
4-Caroticocavernous fistula :a) Definitionb) Etiologyc) Clinical Pictured) Classificatione) Radiographic Features
a) Definition :-Represent abnormal communication between
the carotid circulation and the cavernous sinus
b) Etiology :-Direct CCFs are often secondary to trauma ,
most commonly seen in the young male patients , presentation is acute and symptoms develop rapidly
-In contrast , indirect CCFs have a predilection for the postmenopausal female patient and the onset of symptoms is often insidious
c) Clinical Picture :1-Pulsatile exophthalmos / proptosis : 75 % 2-Chemosis and subconjunctival haemorrhage3-Progressive visual loss : 25-32 % 4-Pulsatile tinnitus ( usually objective )5-Raised intracranial pressure6-subarachnoid haemorrhage, intracerebral
hemorrhage , otorrhagia, epistaxis : 2.5-8.5 %
d) Classification :-It can be broadly classified into two main types1-Direct : Direct communication between intra-
cavernous ICA and cavernous sinus 2-Indirect : Communication exists via branches
of the carotid circulation ( ICA or ECA )
-Another method is to classify according to four main types :
Type A : Direct connection between the intracavernous ICA and CS
Type B : Dural shunt between intracavernous branches of the ICA and CS
-Type C : Dural shunt between meningeal branches of the ECA and CS
-Type D : B + C
Direct : type A-A direct fistula is due to a direct communication
between the intracavernous ICA and the cavernous sinus
-There are a number of causes , however aneurysm rupture and trauma are by far the most common
Indirect : types B , C & D-Indirect fistulas are due to communication by
multiple branches between the ICA / ECA and CS-The are most frequent are type C , with meningeal
branches of the ECA forming the fistula-They are postulated to occur secondary to
cavernous sinus thrombosis with revascularization
-Other predisposing factors appear to be pregnancy , surgical procedures in the region , sinusitis
e) Radiographic Features :1-CT2-MRI3-Catheter Angiography
1-CT :-Proptosis-Enlargement of cavernous sinus , enlarged
superior ophthalmic veins -Extra ocular muscles may be enlarged-Orbital edema-May show SAH / ICH from ruptured cortical
vein
2-MRI :-Findings of CCFs include a dilated CS with multiple
signal intensity void structures that are associated with proptosis and an enlarged superior ophthalmic vein
-On gradient-echo images , these flow voids shows high signal intensity , the presence of flow-related enhancement in the CS on MR angiography suggests the diagnosis in the right clinical setting
-Other supporting findings are a dirty appearance of the retro-orbital fat and enlargement of the extraocular muscles , due to the presence of intracavernous communications , very high-flow fistulas may result in enlargement of both CSs
3-Catheter Angiography :-Rapid shunting from ICA to CS-Enlarged draining veins-Retrograde flow from CS , most commonly into the
ophthalmic veins
ICA to a CS fistula , axial source image from an MRA shows flow-related enhancement in the medial (arrow) left CS from a direct-type fistula
MRA shows an enlarged superior ophthalmic vein (arrow)
MRA shows a right carotid cavernous fistula (arrow)
5-Invasive Sinusitis :-Invasive aspergillosis may affect the sphenoid sinus
in immunocompromised patients and may extend intracranially with invasion of the CS
-This infection shows low signal intensity on both T1 and T2 which is attributed to the presence of ferromagnetic elements and calcium in the fungal and mucous concretions
-It exhibits intense inhomogeneous contrast enhancement
(a) Coronal T1+C shows involvement by aspergillosis of the mucosa in the left sphenoid sinus (white arrow) which extends laterally and has resulted in thrombosis of the adjacent CS (black arrow) , the intracavernous ICA (arrowhead) is narrowed and its walls are significantly thickened
(b) In a different patient , an axial T1+C shows enhancing mucosa in the right sphenoid sinus with enhancing soft tissues in the ipsilateral CS (including the Meckel cave) , with narrowing of the ICA and significant thickening of its walls
6-Epidermoid / Dermoid :-See Suprasellar Masses
(a) Axial T1+C shows a large mass (E) epidermoid cyst inside the right the Meckel cave , the mass does not enhance and is nearly isointense to CSF
(b) Axial T2 shows that the mass (E) is nearly as bright as CSF
(a) T1 shows a heterogenous T1 hyperintense lesion (arrows) in Meckel’s cave and the cavernous sinus , note the presence of T1 hyperintense droplets (arrow heads) on the cerebellar folia , (b) Axial fat saturated T1+C shows the signal of the mass is suppressed and no enhancement is seen (arrows) , ruptured dermoid cyst
7-Tolosa-Hunt syndrome :-Is a term applied to a retro-orbital pseudotumor
extending to the CS-Its clinical triad includes unilateral
ophthalmoplegia (pain) , cranial nerve palsies and a dramatic response to systemic corticosteroids
-The process is usually unilateral but may be bilateral (5%)
-MR imaging findings include an enlarged CS containing abnormal soft tissues that are isointense to muscle on T1-weighted images and dark or bright on T2-weighted images and display contrast enhancement with focal narrowing of the ICA
(a) Axial T2 shows hypointense soft tissue throughout the right CS and extending into the superior orbital fissure
(b) Coronal T1+C shows that the abnormal soft tissue enhances prominently and diffusely and involves the Meckel cave
8-Infundibular Non-Neoplastic Masses :a) Sarcoidosisb) Langerhans cell histiocytosisc) Lymphocytic hypophysitis-See (Intrasellar masses)
