1. Imaging Patterns of Skull Base Encephaloceles WITH CT/MR FUSION
Mina L. Labib, M.D.
Bradley N. Delman, M.D.
Icahn School of Medicine at Mount Sinai
New York, NY
Session ID: Sub session ID: eP-2
Control #: Poster #: eP-133

2. Disclosures M. L. Labib, M.D. No disclosures B. N. Delman, M.D.
Bayer Healthcare
Consultancy
Advisory Board

3. Purpose

4. Skull-Based Defects
Skull-based defects are frequently encountered in the hospital setting.
These may develop as the result of
Trauma
Skull base surgery
Infections
Tumors
Congenital deformities.
Spontaneous development, especially in setting of idiopathic intracranial hypertension (IIH) or impaired CSF drainage
24 slide max.
Purpose, Materials and Methods, Results, Conclusions

5. Manifestation These skull-based defects can manifest as:
Encephaloceles
Meningoceles
Meningoencephaloceles
Cerebrospinal fluid (CSF) leak

6. Clinical Importance Complications of skull-based defects
A persistent CSF leak can lead to headache of varying, sometimes debilitating, intensity.
CSF leaks are associated with an increased risk of meningitis.
Skull-based defects that may become symptomatic or predispose to meningitis should be promptly diagnosed and corrected.
Determining the precise location of these defects is essential for surgical correction.
Understanding pattern and typical appearance of skull-based defects is of great import to the neuroradiology community

7. Materials and Methods

8. Materials and Methods
A retrospective review of patients evaluated for skull base CSF leaks at our institution over the past 6 years was performed.
Patients were evaluated with either
Routine MRI
MR/CT fusion

9. Mount Sinai MR/CT Fusion Protocol
CT Sinuses
Non-contrast Helical acquisition
Minimum collimation: mm with recon overlapof 30%
Coverage: Paranasal sinuses and mastoids through the vertex
MRI Sinuses
With and without contrast
3 Tesla magnet
Extended echo train T2 coronal at beginning of scan (early)
Extended echo train T2 coronal at conclusion of scan (after ~45 min)
THEN
Fusion on GE AW Server
3 Series are typically returned to PACS for analysis:
Fused CT/MR (T2 MR in color over grayscale CT)
Pure CT as grayscale
Pure T2 MR as grayscale

10. Imaging Features
The imaging features of 80 patients were evaluated with particular attention to characteristics that may aid in both diagnosis and localization.

11. Results

12. Meningocoele through cribriform defect
Fusion CT
MRI

13. Meningoencephalocele

14. Developing Encephalocele

15. CSF Leak without Encephalocele
Fusion CT
MRI

16. Pointed Sulcus Sign
The gathered sulci (thin orange arrow) aids in localizing the site of skull-based defect. In this case it “points” to the location of the defect. Beyond the defect, an encephalocele has formed within the frontal sinus (yellow arrow).

17. Spontaneous CSF Leak in IIH
These patients may develop spontaneous CSF leaks
Identification of associated imaging manifestations may aid in the diagnosis
These associated findings include:
Expanded empty sella
Enlarged Meckel’s cave
Enlarged arachnoid granulations
Arachnoid pitting
Dural ectasia
Optic sheath dilatation

18. Empty Sella
Note the small tuberculum meningioma (arrow)

19. Arachnoid Pitting

20. Optic Sheath Ectasia and Large Meckel’s Cave

21. Pitfalls
Use of a magnet with a lower field strength significantly limits accurate diagnosis
3.0T
1.5T

22. Conclusion

23. Skull-Based Defect Assessment
Clear gap/defect in osseous density in skull base, esp.:
Cribriform
Planum sphenoidale
Sellar floor
Petrous apex
Pterygoid recess of sphenoid
Meningocele, encephalocele, or meningoencephalocele can be seen
Although patient can have CSF leak in the absence of the above.
Fluid channeling through or in close proximity to defect, esp:
  Superior olfactory recess
  Ethmoid cells
  Sphenoid cells (including pterygoid recess)
  Petrous apex into mastoid complex
Change in fluid over time (between early and late scan)
Ancillary findings suggestive of IIH, such as
Arachnoid granulations
Empty sella

24. References
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