1. The document discusses different types of intracranial cystic lesions including epidermoid cysts, dermoid cysts, craniopharyngiomas, and cystic metastases. 2. MRI is generally the preferred imaging modality and can help characterize lesions based on signal intensity on T1-weighted, T2-weighted, FLAIR, and post-contrast sequences. Diffusion imaging and MR spectroscopy can also provide additional information. 3. Biopsy or aspiration of cystic lesions is sometimes needed for diagnosis and is usually guided by imaging such as CT or MRI.

1. Tumors and tumors like
cysts intracranial
Dr Ahmed Esawy

2. ARACHNIOD VERSUS EPIDERMIOD
epidermiod
Lower density than CSF
May show calcifications
invade structures
CT
LOWER THAN CSFMRI T1
HIGHER THAN CSFMRI T2
HIGH SIGNALFLAIR
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

3. T2
CT+no C CT+C
EPIDERMIOD AT CPA
Dr Ahmed Esawy

4. T2
T1+C
DIFFUSION
Epidermoid tumour
Dr Ahmed Esawy

5. Epidermoid, brain. CT+no C
, located in the middle cranial fossa with extension into the suprasellar cistern..
Dr Ahmed Esawy

6. Epidermoid, brain.
T2T1+no C
DIFFUSION
FLAIR
Dr Ahmed Esawy

7. epidermoid cysts
Dr Ahmed Esawy

8. EPIDERMOID
CYST
diffusion-shows markedly restricted diffusion (arrows.)
Dr Ahmed Esawy

9. T2WIT1WI
DWI ADC
End of images
EPIDERMOID
CYST
B 1000
ADC
Dr Ahmed Esawy

10. ARACHNIOD VERSUS EPIDERMIOD
epidermiodarachniod
Lower density than CSF
May show calcifications
invade structures
CSF density
No calcification,no enhancment
displace structures
CT
LOWER THAN CSFLow signal like CSFMRI T1
HIGHER THAN CSFhigh signal like CSFMRI T2
HIGH SIGNALLow signal like CSFFLAIR
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 CPARetrocerebellar,CPA
Dr Ahmed Esawy

11. 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

12. Dermoid cyst
location Midline plane, posterior fossa,
suprasellar area and Intraventricular
MRI: high signal in T1 [ fat ]
Dr Ahmed Esawy

13. CT: fat density ± calcification, no
enhancement
Dermoid cyst
Dr Ahmed Esawy

14. 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

15. Rupture intraventricular or
subarachnoid → fat /fluid level
Dr Ahmed Esawy

16. 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

17. 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

18. posterior fossa lesion with posterior mural nodule
Unusual Imaging Appearance of an Intracranial Dermoid Cyst
Dr Ahmed Esawy

19. 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

20. 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

21. CT +no C
epidermiod tumour (inclusion cyst) of Quadrigeminal cistern
Quadrigeminal cistern cyst
Dr Ahmed Esawy

22. CT +C
epidermiod tumour (inclusion cyst) of Quadrigeminal cistern
displacment of choriod plexus and the body of lateral ventricle
Dr Ahmed Esawy

23. MRI T1+C
epidermiod tumour (inclusion cyst) of Quadrigeminal cistern
Compression of quadrigeminal plate and cereberal aqueduct
Dr Ahmed Esawy

24. MRI T2 Quadrigeminal cistern
Dr Ahmed Esawy

25. Differential Diagnosis
of Quadrigeminal cistern cyst
• Arachniod
• Teratoma
• Cystic pineal tumour
Dr Ahmed Esawy

26. craniopharyngioma
Dr Ahmed Esawy

27. 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

28. Craniopharyngioma in an adult
T2
T1+C
Dr Ahmed Esawy

29. cystic astrocytoma
Dr Ahmed Esawy

30. hemangioblastoma
Dr Ahmed Esawy

31. 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

32. cystic metastasis
NEOPLASM-ASSOCIATED BENIGN
CYSTS
Dr Ahmed Esawy

33. 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

34. large right cerebellopontine angle tumour with a medial cystic component.
Cystic vestibular schawannoma T2W
Dr Ahmed Esawy

35. Cystic astrocytoma
Dr Ahmed Esawy

36. 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

37. • 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

38. • 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

39. • 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

40. Functional studies of cystic
brain lesion
Dr Ahmed Esawy

41. N-acetylaspartate (NAA)
creatine-phosphocreatine(Cr)
choline (Cho).
amino acid, lactate, alanine, acetate,
pyruvate, and succinate
MR spectroscopy
Dr Ahmed Esawy

42. primary cystic neoplasm versus metastases
primary cystic neoplasm choline
Cystic metastases where no choline resonance
is seen
Dr Ahmed Esawy

43. necrotic or cystic neoplasmsPyogenic 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

44. 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

45. 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

46. THANK YOU
Dr Ahmed Esawy

47. THANK YOU
Dr Ahmed Esawy