1. eEdE# 76

2. No Disclosures

3. Taleb Almansoori, Prasad Hanagandi, Agatha Stanek, Rafael Glikstein. The value of high resolution CT images in the evaluation of skull fractures The Ottawa Hospital, University of Ottawa, Canada

4. To demonstrate the reliability of high resolution CT images in detecting occult calvarial fractures not visualized but suspected on the standard 5 mm thickness brain CT images. Purpose:

5. In this pictorial, we intend to compare between the standard 5 mm thickness CT images and the reconstructed high resolution CT images of the calvarium to visualize occult fractures according to our clinical experience. Approach/Methods:

6. The reconstruction of high resolution CT images is based on the indirect radiological findings visualized on the standard 5 mm thickness images such as : - Soft tissue swelling - Unexplained pneumocephalus. - Subtle intracranial bleeds - Presence of fluid in the mastoid air cells

7. Findings/Discussion: Traumatic head injuries can result in serious morbidty and mortality. Cross sectional CT imaging is an important diagnostic tool in the assessment for head injuries including skull fractures. At our institution, all head examinations requested by emergency physicians are performed using GE Lightspeed 64 scanner and the routine unenhanced CT protocol includes 5mm axial images along with 3mm coronal and sagittal reformats in both soft tissue and bone windows.

8. Findings/Discussion: After reviewing the images and a suspected underlying fracture is anticipated, a reconstructed high resolution images of 0.625 mm thickness in all three planes was performed. High resolution CT images confirm the presence of undetectable fractures on the initial 5mm thickness images. A collection of cases comparing the standard and the high resolution images including the indirect traumatic radiological signs will be shown through this pictorial.

9. SOFT TISSUE SWELLING

10. CASE 1 Hx: 75 year old male patient who fell from height. Only soft tissue swelling was noted along the right temporal region in the 5mm images. No fracture line identified. Arrows pointing to Soft tissue swelling.

11. CASE 1 Subtle fracture line is detected in the right temporal bone underneath the soft tissue swelling. Arrows pointing to fracture line.

12. Cont, CASE 1 Only soft tissue swelling visualized on the 5 mm coronal view. Non displaced fracture line is detected in the right temporal bone. Arrow pointing to fracture line.

13. CASE 2 22 year old male patient who was hit by a car. Thick CT image of the skull showed a soft tissue swelling in the right frontal region (Green thick arrow) and a partially imaged hypodense line concerning for a fracture ( Black thin arrow).

14. Cont, CASE 2 The same patient with thin CT image of the skull showing clearly the fracture line in the right frontal bone. ( Black thin arrow).

15. Cont, CASE 2 No fracture on the 5 mm image. Oblique fracture on the 0.625 mm image.

16. Pneumocephalus

17. CASE 3 23 year old male patient suffered a direct injury to the left orbit while playing with a soft ball. The next couple of images show a 5 mm thickness image on the left side and a 0.625 mm thickeness image on the right. A small pneumocephalus was visualized in the left frontal region only in the 0.625 mm. This was not seen in the 5mm thickness image but no obvious fracture line detected.

18. CASE 3

19. Cont, CASE 3 On the next slide, a 5mm image on the left and a 0.625mm on the right. A subtle fracture line is visualized in the roof of the left orbit.

20. Cont, CASE 3

21. Case 4 Young patient fell off motorcycle and suffered head trauma in the temporal region. Axial 5 mm image of the brain revealed soft tissue swelling and a small pneumocephalus (Thick arrow) in the right temporal region but no fracture detected in the axial plane.

22. The same patient but with a thinner 0.625 mm thickness image of the skull showing the soft tissue swelling, pneumocephalus and the fracture line in the right temporal bone. P ST ST : Soft tissue swelling P: Pneumocephalus

23. Intracranial Bleed

24. CASE 5 67 year old male patient with history of fall. Unenhanced CT scan of the brain showing acute subarachnoid bleed in the right temporal region.

25. Cont, CASE 5 The 5mm bone window image of the same patient did not detect a fracture line in the suspected area.

26. Cont, CASE 5 Thin 0.625 mm image of the skull detected a small fracture involving the right temporal bone (Thick arrow).

27. Presence of fluid in the mastoid air cells

28. CASE 6 Young patient with history of fall. Axial 5 mm image of the brain detected partial opacification of the right mastoid air cells but no fracture visualized in the axial plane.

29. Cont, CASE 6 Thin 0.625 mm image of the skull detected a small fracture involving the right temporal bone (Thick arrow).

30. Summary/Conclusion: Based on our observations, the high resolution CT images made a difference in confirming the doubts of undetectable fractures on the initial 5mm thickness images. High resolution CT images should be obtained in traumatic brain injury based on the formerly described indirect radiological signs.