Defining the Normal Dorsal Contour of the Corpus Callosum with Time

Abstract

Background and purpose: Morphological changes of the corpus callosum have been associated with a large number of congenital neurocognitive and psychiatric disorders. Focal defects or notches of the dorsal surface of the corpus callosum have not been well characterized. Our purpose was the following; 1) to characterize the dorsal contour of the corpus callosum during the life span, 2) to characterize the relationship of contour deviations to neighboring vessels, and 3) to determine whether contour deviations are congenital or acquired.

Materials and methods: We retrospectively reviewed normal sagittal T1-weighted brain MR images. A "notch" was defined as a concavity in the dorsal surface at least 1 mm in depth. The corpus callosum was considered to be "undulating" if there were >2 notches, including an anterior and posterior notch. The presence of a pericallosal artery and its relationship to a notch were assessed.

Results: We reviewed 1639 MR imaging studies, spanning 0-89 years of age. A total of 1102 notches were identified in 823 studies; 344 (31%) were anterior, 660 (60%) were posterior, and 98 (9%), undulating. There was a positive correlation between the prevalence (P < .001) and depth (P = .028) of an anterior notch and age and a negative correlation between the prevalence of a posterior notch and age (P < .001). There was no difference between patient sex and corpus callosum notching (P = .884). Of the 823 studies with notches, 490 (60%) were associated with a pericallosal artery (P < .001).

Conclusions: The prevalence and depth of notches in the anterior corpus callosum increase significantly with age; this finding suggests that most notches are acquired. There is a significant positive association between the presence of a corpus callosum notch and adjacent pericallosal arteries, suggesting that this may play a role in notch formation.

Fig 1.

A, Midline sagittal T1-weighted image shows an example of a normal corpus callosum without evidence of anterior or posterior notching. B, A “notch” was defined as a depression in the dorsal surface whose depth was at least 1 mm from a tangential (dashed) line to the surface of the CC. The solid arrow line shows a 3-mm-deep anterior notch. C, Three areas of notching indicated by the white arrows correspond to an undulating configuration. D, Midline sagittal T1-weighted image shows that a 3-mm anterior notch (arrow) is present. The flow void from the pericallosal artery is visualized extending into the notch (arrowhead).

Fig 2.

Scatterplot of prevalence versus age in 5-year increments. The posterior notch prevalence (red squares and red line) decreases with time, R² = 0.29. The anterior notch prevalence (blue diamonds and blue line) increases with time, R² = 0.60. The undulating pattern prevalence (green triangles and green line) also increases with time, R² = 0.28.

Fig 3.

Scatterplot of notch depth (millimeters) versus age. No significant difference is seen in the depth of the posterior notch with increasing age (R² = 0.01). There is a significant increase in the depth of the anterior notch with increasing age (R² = 0.39).