CT and MRI Anatomy

Authors: Flaherty, Alice W.; Rost, Natalia S.

Title: Massachusetts General Hospital Handbook of Neurology, The, 2nd Edition

Copyright 2007 Lippincott Williams & Wilkins

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CT and MRI Anatomy

A. Opposite of neuropathological conventions

Radiological images are presented with their anatomic left on the right side of the picture. The brainstem on a horizontal scan is upside down compared with pathological or textbook images of the brainstem in coronal section.

B. Sections

• Axial (horizontal): Parallel to ground if pt. were standing. The standard section. In the spine, gives a cross-section.

• Coronal: In plane, not with a crown, but a coronet (or one of those preppy headband things). Good for pituitary, cavernous sinus, skull-base, orbital, and hippocampal lesions.

• Sagittal: In plane with the interhemispheric fissure. In the spine, gives a longitudinal section.

C. Finding landmarks

• Ventricles and cisterns: In horizontal section, the ventricles form a face, with lateral ventricles for eyes, third ventricle for a nose, and a

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  mouth whose sides are the perimesencephalic cisterns and whose base is the quadrigeminal cistern below the colliculi. It should be smiling; flattening of the quadrigeminal cistern suggests herniation.

• Central sulcus: In horizontal section, it is most easily seen in uppermost sections, where it has a characteristic sickle shape (look for omega sign, as in Greek letter omega, outlining the motor cortex). The superior frontal sulcus, running parallel to the falx, terminates in the precentral sulcus; the central sulcus is just posterior.

• Orbit: There is proptosis if more than half the eyeball sticks out past the line between the zygoma and the nose.

Figure 22. Normal cisterns make a happy face; herniation makes it sad.

D. Pediatric neuroimaging

see p. 131 for patterns of myelination.