The skull base angle (of Boogard) allows the diagnosis of platybasia and basilar kyphosis. Several different techniques may be used on sagittal images from MRI or CT.
Traditionally, basal angle measurements were based on plain skull images. With the advent and generalization of MR imaging, it has been supplanted and is rarely used.
MRI techniques produce lower basal angles than those reported by using traditional radiography. For this reason, Koenigsberg et al. described a new measurement method for MRI usage, which provides consistent and reproducible measurements 1.
For both historical and utility purposes, both plain skull films and MRI measurement techniques are described.
Standard technique
Angle formed by ref:
line joining the nasion with the center of the pituitary fossa
line joining the anterior border of the foramen magnum with the center of the pituitary fossa
normal: 125°-143°
platybasia: >143°
basilar kyphosis: <125°
Modified MRI technique
Angle formed by 1:
line extending across the anterior cranial fossa to the tip to the dorsum sellae
line drawn along the posterior margin of the clivus
children: 114° +/- 5°
adults: 117° +/- 6°
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