FIG. 1.

Cavum septum pellucidum (CSP) grading diagrams and CSP grade and length for each patient. (A) The initial measurements that were taken in the midsagittal plane. The solid horizontal line depicts the longest intraventricular distance from genu to splenium of the corpus callosum (termed “septal length”). All images were then reformatted such that the coronal axis was perpendicular to this line to optimize coronal measurements along the septum. The dashed vertical line depicts the most anterior aspect of the columns of the fornix. This line was used to distinguish between the pre-fornix septum (where separations of the leaves of the septum pellucidum are termed CSP) and the post-fornix septum (where separations of the leaves of the septum pellucidum are termed “cavum vergae” [CV]). (B) A reformatted coronal MRI image for one patient that shows the greatest evidence of separation of the leaves of the septum pellucidum. This view was used to perform CSP grading for each patient. The dashed box depicts the region that is then enlarged to illustrate “Grade 2” in panel B. (C) Enlarged views of representative T1 coronal images for each CSP grade. Note that the Grade 0 septum appears crisp without any evidence of cyst (CSP absent). Grade 1 septum shows slight interior hypointensity that is not, however, clearly CSF signal intensity (septum unclear/CSP equivocal). Grades 2–4 show clear evidence of CSF signal between the separated leaves of the septum pellucidum. The degree of separation between the leaves of the septum pellucidum is then used to assign a grade of 2–4: Grade 2 CSP is not wider than the septum, Grade 3 CSP is wider than the septum but less than half the intraventricular width, and Grade 4 CSP is greater than half the intraventricular width. (D) CSP grade and length for each patient. Manual horizontal jitter was added to overlapping “grade” values in the graph to improve visibility.