Tumors and tumors like

cysts intracranial

Dr Ahmed Esawy

ARACHNIOD VERSUS EPIDERMIOD

epidermiod Lower density than CSF

May show calcifications

invade structures

CT

LOWER THAN CSF MRI T1

HIGHER THAN CSF MRI T2

HIGH SIGNAL FLAIR

BRIGHT typical hyperintensity

T2 shine (restricted diffusion)

DIFFUSION

DARK lower than that of CSF and equal

to or higher than

that of brain parenchyma

ADC

Away from midlline CPA

, supra and parasellar region

middle cranial fossa and

cisterna magna

LOCATION

Dr Ahmed Esawy

T2

CT+no C CT+C

EPIDERMIOD AT CPA

Dr Ahmed Esawy

T2

T1+C

DIFFUSION

Epidermoid tumour

Dr Ahmed Esawy

Epidermoid, brain. CT+no C

, located in the middle cranial fossa with extension into the suprasellar cistern..

Dr Ahmed Esawy

Epidermoid, brain.

T2 T1+no C DIFFUSION

FLAIR

Dr Ahmed Esawy

epidermoid cysts

Dr Ahmed Esawy

EPIDERMOID

CYST

diffusion-shows markedly restricted diffusion (arrows .)

Dr Ahmed Esawy

T2WI T1WI

DWI ADC

End of images

EPIDERMOID

CYST

B 1000 ADC

Dr Ahmed Esawy

ARACHNIOD VERSUS EPIDERMIOD

epidermiod arachniod Lower density than CSF

May show calcifications

invade structures

CSF density

No calcification,no enhancment

displace structures

CT

LOWER THAN CSF Low signal like CSF MRI T1

HIGHER THAN CSF high signal like CSF

MRI T2

HIGH SIGNAL Low signal like CSF

FLAIR

BRIGHT typical hyperintensity

T2 shine (restricted diffusion)

DARK hypointensity

(free diffusion)

DIFFUSION

DARK lower than that of CSF and equal

to or higher than

that of brain parenchyma

BRIGHT marked

hyperintensity

like CSF

ADC

Away from midlline CPA

Retrocerebellar,CPA

Dr Ahmed Esawy

Differential Diagnosis

• arachnoid cyst. Arachnoid cysts are isointense to CSF at all

sequences, including FLAIR. They displace rather than invade structures such as the epidermoid. Finally, arachnoid cysts do not restrict on diffusion-weighted image .

• Dermoid cysts are typically located along the midline and resemble fat, not CSF .

• Cystic neoplasms often enhance and do not resemble CSF .

• Neurocysticercosis cysts often enhance and demonstrate surrounding edema or gliosis .

Dr Ahmed Esawy

Dermoid cyst

location Midline plane, posterior fossa, suprasellar area and Intraventricular

MRI: high signal in T1 [ fat ]

Dr Ahmed Esawy

CT: fat density ± calcification, no

enhancement

Dermoid cyst

Dr Ahmed Esawy

Dermoid tumor 26-Y M

cystic lesion is present in the right temporal lobe+

peripheral marginal calcification in the lesion

partial marginal

enhancement

T1+C

multiple small foci of hyperintense signal are present along the sulci of the right temporal lobe. These represent fat droplets in the subarachnoid space from the focal rupture of the dermoid tumor.

T1+C

T1+NO C

Dr Ahmed Esawy

Rupture intraventricular or subarachnoid → fat /fluid level

Dr Ahmed Esawy

Dermoid tumor. The high signal intensity areas in the

subarachnoid space of the Sylvian fissures and ambient cisterns

represent lipid material from the tumor that has contaminated the CSF

Dr Ahmed Esawy

Suprasellar rupture dermoid tumours

T1W

Fat globules, which have spilled into the

subarachnoid space, are seen as high

signal foci in the left Sylvian fissure Dr Ahmed Esawy

posterior fossa lesion with posterior mural nodule

Unusual Imaging Appearance of an Intracranial Dermoid Cyst

Dr Ahmed Esawy

Ruptured dermoid cyst

• mixed-signal-intensity lesion in the pineal region (straight arrow) with multiple hyperintense droplets scattered through the subarachnoid space (curved arrows). Moderate hydrocephalus is present ..

T1+no C

Dr Ahmed Esawy

Differential Diagnosis

• Epidermoid (typically resemble CSF (not fat), lack dermal

appendages, and are usually located off midline)

• Craniopharyngioma (suprasellar, with a midline location, and demonstrate nodular calcification. craniopharyngiomas are strikingly hyperintense on T2 enhance strongly.

• teratoma

• lipoma .

Dr Ahmed Esawy

CT +no C

epidermiod tumour (inclusion cyst) of Quadrigeminal cistern

Quadrigeminal cistern cyst

Dr Ahmed Esawy

CT +C

epidermiod tumour (inclusion cyst) of Quadrigeminal cistern

displacment of choriod plexus and the body of lateral ventricle

Dr Ahmed Esawy

MRI T1+C

epidermiod tumour (inclusion cyst) of Quadrigeminal cistern

Compression of quadrigeminal plate and cereberal aqueduct

Dr Ahmed Esawy

MRI T2 Quadrigeminal cistern

Dr Ahmed Esawy

Differential Diagnosis

of Quadrigeminal cistern cyst

• Arachniod

• Teratoma

• Cystic pineal tumour

Dr Ahmed Esawy

craniopharyngioma

Dr Ahmed Esawy

CT+C large suprasellar cyst with several nodular calcifications of varying size (arrow) in the wall of the cyst

T1+C cystic intra-/suprasellar mass with strong contrast enhancement of the cyst wall (arrow). The cyst contents are isointense with gray matter, reflecting their high protein content.

T2-strongly hyperintense homogeneous cyst contents. The well circumscribed cyst (arrow) displaces the anterior cerebral arteries anteriorly and the middle cerebral arteries bilaterally

Craniopharyngioma in a child

Dr Ahmed Esawy

Craniopharyngioma in an adult T2

T1+C

Dr Ahmed Esawy

cystic astrocytoma

Dr Ahmed Esawy

hemangioblastoma

Dr Ahmed Esawy

postcontrast T1

facial schwannoma associated with large

arachnoid cyst )(open arrow .)

postcontrast T1

large pituitary macroadenoma with multiple

cysts (arrows) surrounding the suprasellar

component trapped PVSs

NEOPLASM-ASSOCIATED BENIGN

CYSTS

Dr Ahmed Esawy

cystic metastasis

NEOPLASM-ASSOCIATED BENIGN

CYSTS

Dr Ahmed Esawy

T1W post-contrast i dark DW bright on the ADC map

Cystic metastasis from CA breast

unrestricted diffusion in the center of the mass

Dr Ahmed Esawy

large right cerebellopontine angle tumour with a medial cystic component.

Cystic vestibular schawannoma T2W

Dr Ahmed Esawy

Cystic astrocytoma

Dr Ahmed Esawy

II- Magnetic resonance imaging:

• MRI emerged as the imaging

modality of choice for most

intracranial abnormalities. This is

especially true for lesions located in

the posterior fossa, where the

sensitivity of CT is limited by beam-

hardening artifacts from the petrous

bone.

Dr Ahmed Esawy

• If metastases are to be excluded,

heavily T1-weighted pre- and

post-contrast images can be

obtained. Intravenous contrast is

a routine for tumor and infection

investigation.

Dr Ahmed Esawy

• A potential drawback of SE images

is that they may not reliably show

the internal architecture or

morphology of cystic masses. If

the solid portion does not

enhances with contrast material, it

difficult to determine whether the

mass is simple cyst or a cyst with

solid component.

Dr Ahmed Esawy

• Fluid-attenuation inversion-recovery

(FLAIR) MRI belongs to a family of

inversion-recovery sequences, that

generates heavily T2-weighted

images with nulling/subtraction of

the CSF sign and enable improved

characterization of complex cystic

masses.

Dr Ahmed Esawy

Functional studies of cystic brain lesion

Dr Ahmed Esawy

N-acetylaspartate (NAA)

creatine-phosphocreatine(Cr)

choline (Cho).

amino acid, lactate, alanine, acetate,

pyruvate, and succinate

MR spectroscopy

Dr Ahmed Esawy

primary cystic neoplasm versus metastases

primary cystic neoplasm choline

Cystic metastases where no choline resonance

is seen

Dr Ahmed Esawy

necrotic or cystic neoplasms Pyogenic brain abscesses

Elevated choline , decrease

NAA

elevated peaks of amino acid,

lactate, alanine, acetate,

pyruvate, and succinate

absent signals of NAA,

creatine, and choline

MRS

facilitate diffusion

dark

restricted diffusion

bright

DW

Bright on ADC map

The walls of necrotic or cystic

tumors have a lower ADC

value than of an abscess

markedly reduced ADC maps. ADC

wall of necrotic or cystic

neoplasms tends to have higher

rTBV

capsule of an abscess tends to

have lower rTBV

MR PERFUSION

Dr Ahmed Esawy

CT and MR stereotactic biopsy:

Solid contrast enhancing areas are preferred for biopsy rather than cystic, necrotic, or hemorrhagic tumor regions.

Cystic brain lesion biopsy and treatment

Dr Ahmed Esawy

Image guided therapy:

CT and MRI have revolutionized the diagnosis and management of brain abscesses. If excisional neurosurgery is not immediately or otherwise indicated an attempt at abscess aspiration should be made usually guided by CT when the lesion is accessible. Also intraoperative imaging using MR allows for precise localization of the lesion and its relationship. Dr Ahmed Esawy

THANK YOU

Dr Ahmed Esawy

THANK YOU

Dr Ahmed Esawy