neuro_module_part_2.pdf interpretation d'un ct scan
- 1. NEURORADIOLOGY DIL part 2 An approach to head CT interpretation K. Agyem MD, G. Hall MD, D. Palathinkal MD, Alexandre Menard March/April 2015
- 2. OVERVIEW • Introduction to Neuroimaging - DIL part 1 • Basic Brain Anatomy - DIL part 1 • Standardized Approach to Image Interpretation - DIL part 2 • Common Pathology • Bleeds (Hemorrhages) - DIL part 3 • Strokes (Infarcts) DIL part 4 • Masses (Tumors) part 5
- 3. APPROACH TO CT • The most important thing is to use the same approach every time! We will go through an example approach. • Use different window settings (ie brain vs bone windows). • Use different planes (axials, coronals and sagittals).
- 4. EXAMPLE APPROACH • Extra-axial space • Intra-axial space • Bones
- 5. EXTRA-AXIAL Axial Do the gyri abut the skull? If not, is there something in that space that shouldn't be there (ie a bleed or a mass)?
- 6. EXTRA-AXIAL Do the gyri abut the skull? If not, is there something in that space that shouldn't be there (ie a bleed or a mass)? Here, the gyri nicely abut the skull. There is nothing abnormal in the extra-axial space. Axial
- 7. EXTRA-AXIAL • Compare this CT to the prior one you just looked at. • We will cover this topic later on, but this is an example of an acute epidural hemorrhage. • This a bleed in the extra-axial space. Axial
- 8. EXTRA-AXIAL • Compare this CT to the prior one you just looked at. • We will cover this topic later on, but this is an example of an acute epidural hemorrhage. • This a bleed in the extra-axial space. Axial
- 9. EXTRA-AXIAL • Ventricles: • Are they symmetric? • Are they enlarged/dilated? This can suggest hydrocephalus. • Is there bright white material in the ventricles? This can represent intraventricular hemorrhage. Axial
- 10. EXTRA-AXIAL Notice in this example that the ventricles are symmetric and nondilated. Axial • Ventricles: • Are they symmetric? • Are they enlarged/dilated? This can suggest hydrocephalus. • Is there bright white material in the ventricles? This can represent intraventricular hemorrhage.
- 11. EXTRA-AXIAL • What do you think about the ventricles in this example? • How do they compare in size compared to the normal you just looked at? Axial
- 12. EXTRA-AXIAL This is an example of acute hydrocephalus. The bilateral lateral ventricles are markedly dilated. This case was due to an obstructing mass in the third ventricle (not shown). • What do you think about the ventricles in this example? • How do they compare in size compared to the normal you just looked at? Axial
- 13. EXTRA-AXIAL Axial • Vessels • Follow the course of the major intracranial arteries, looking for increased vessel density. • A "hyperdense vessel" suggests possible thrombus in the vessel.
- 14. EXTRA-AXIAL • Vessels • Follow the course of the major intracranial arteries, looking for increased vessel density. • A "hyperdense vessel" suggests possible thrombus in the vessel. • In this example, the course of the bilateral MCA's can be seen, and there is no hyperdense vessel. Axial
- 15. EXTRA-AXIAL • Follow the vessels in this example. • Do you see anything that looks hyperdense to suggest a thrombus? Axial
- 16. EXTRA-AXIAL • Follow the vessels in this example. • Do you see anything that looks hyperdense to suggest a thrombus? This is an example of a hyperdense left middle cerebral artery. This patient had an acute thrombus and resultant cerebral infarct (stroke). Axial
- 17. INTRA-AXIAL • Are the midline structures present and normal appearing? • Are there any masses? • Is there mass effect? • Is there "effacement" of cortical sulci? • Is there any brain herniation? We will cover this in a minute. • Are the basal ganglia present and symmetric?
- 18. INTRA-AXIAL • Is there any loss of "grey-white differentiation?" • Recall your anatomy of grey and white matter. • Usually the grey matter and white matter are different densities and can be distiguished from each other. • If there is loss of this distinction, it can be an early indication of acute cortical ischemia in strokes. Axial
- 19. INTRA-AXIAL • The grey-white differentiaion is preserved in this image. • Note the nice cortical ribbon of grey matter. • The deep grey matter structures are also preseverd in density. Axial
- 20. INTRA-AXIAL • This is an example of an acute cortical infarct. • Notice the loss of grey-white differentiation. Axial
- 21. INTRA-AXIAL • This is an example of an acute cortical infarct. • Notice the loss of grey-white differentiation. Axial
- 22. HERNIATION • The volume of the intracranial space is fixed. It contains brain tissue, CSF and blood vessels. • In pathologic states, if there is an intracranial space occupying lesion (eg. bleed, tumor, edema), mass effect can result. This can displace brain tissue under/over/through fixed structures. This process is called herniation. • The following slide demonstrates some of the common herniation syndromes.
- 23. HERNIATION • 1. Uncal • 2. Descending Transtentorial • 3. Subfalcine (midline shift) • 4. Transcranial • 5. Ascending Transtentorial • 6. Cerebellar Tonsillar http://upload.wikimedia.org/wikipedia/commons/7/79/Brain_herniation_types-2.svg
- 24. HERNIATION Axial • Here is an example of a large left sided space occupying lesion that is causing mass effect. • There is: • left uncal • left descending transtentorial herniation
- 25. HERNIATION • Here is an example of a large left sided space occupying lesion that is causing mass effect. • There is: • left uncal • left descending transtentorial herniation Axial
- 26. HERNIATION • Sometimes it can be easier to appreciate herniation on coronal images. • This is the same case, demonstrating left descending transtentorial herniation.
- 27. HERNIATION • Sometimes it can be easier to appreciate herniation on coronal images. • This is the same case, demonstrating left descending transtentorial herniation. See the brain tissue squishing over the tentorium cerebelli.
- 28. BONES • Don't forget the bone windows! • Are there any acute fractures or destructive bone lesions? • If you see cortical disruption, look at the contralateral side to ensure it isn't a normal cranial suture. Axial
- 29. BONES • Don't forget the bone windows! • Are there any acute fractures or destructive bone lesions? • If you see cortical disruption, look at the contralateral side to ensure it isn't a normal cranial suture. These are the lambdoid sutures between the temporal and occipital bones. Notice the symmetry. Don't get fooled for fractures! Axial
- 30. BONES • Don't forget the bone windows! • Are there any acute fractures or destructive bone lesions? • If you see cortical disruption, look at the contralateral side to ensure it isn't a normal cranial suture. What about this case? Do you see any fractures? Axial
- 31. BONES • Don't forget the bone windows! • Are there any acute fractures or destructive bone lesions? • If you see cortical disruption, look at the contralateral side to ensure it isn't a normal cranial suture. Notice the multiple asymmetric skull fractures, one of which is depressed. There is also part of a ventricular drain depicted as this patient had intraventricular hemorrhage and hydrocephalus. Drain Axial
- 32. • Introduction to Neuroimaging - DIL part 1 • Basic Brain Anatomy - DIL part 1 • Standardized Approach to Image Interpretation - DIL part 2 • Common Pathology • Bleeds (Hemorrhages) - DIL part 3 • Strokes (Infarcts) DIL part 4 • Masses (Tumors) part 5 End of module 2