Article Figures & Data
Figures
- FIG 1.
Basilar fenestrations. I) Classification. Basilar fenestrations were classified as either window-, hourglass-, or funnel-shaped (upper row illustrations: printed with permission from Insil Choi, copyright 2020). Axial CTA images (A–C) and magnified axial CTA images focusing on the basilar artery fenestration (A1, B1, C1) and coronal 3D reconstructions of the posterior circulation (A2, B2, C2) in various patients depict different morphologies of basilar fenestration apertures. II) Fenestration with calcification. Associated calcification is evident in 3 of the basilar fenestration cases (3/59; 5.1%). Sequential axial CTA images in one of these patients demonstrate a fenestration (D, wide gray arrow) with a small nodular calcification along its superior aspect (E, thin white arrow), a finding better evident on coronal MIP (F) and 3D reconstruction (G) of the basilar artery (fenestration highlighted by a thick gray arrow, and the nodular calcification, by the thin white arrow).
- FIG 2.
Basilar septations. I) Lack of interval changes: a basilar septation (upper row illustration, printed with permission from Insil Choi, copyright 2020) is identified in 21 patients (0.6%). A typical basilar septation can be seen on sequential axial CTA images at initial presentation in case 1 (A–C). Note the clearly defined linear hypodensity without a visible window or clear evidence of puckering or indentation of the vessel wall (A–C, arrows). Sequential axial CTA images obtained 1 year later (D–F) clearly show the absence of interval changes. Of the small subset of patients with >1 CTA, there is no evidence of interval changes at any time point. II) Evident on CTA and MRA: axial CTA image in case 2 (G1) demonstrates a septation along the ventral aspect of the basilar artery (white arrow). Note that the septation is thick anteriorly but markedly thins posteriorly. This finding is corroborated on axial MRA images with the thin posterior aspect slightly more evident (G2, white arrows). Axial CTA image in a different patient (H1) demonstrates a markedly subtle septation perhaps best visualized along the central lumen of the basilar artery (H1 magnified insert, arrowheads). This finding is again corroborated and much better visualized on a high-quality axial MRA (H2, white arrowhead). Although MRA was available in only a small subset of the patients, the presence of a septation was corroborated on this technique. Of note, depending on the quality of the CTA or MRA acquisition, the septations were, at times, better defined on CTA instead.
- FIG 3.
Basilar septations with nodularity without and with calcification (upper row illustrations, printed with permission from Insil Choi, copyright 2020). I) Several basilar septation cases exhibited areas of nodularity. Three representative cases are shown above. Axial CTA in the first case (A) demonstrates subtle nodularity along the midpoint of the basilar septation (A magnified insert, white arrow). Axial CTA image in a different patient (B) shows calcification associated with central nodularity (B magnified insert, white arrow). Axial CTA in a third patient (C2) demonstrates a prominent but only partially calcified nodular septation. The calcification is clearly evident on an axial noncontrast CT image (C1, arrow). The partially calcified prominent nodularity associated with the septation is well-demarcated on axial CTA (C2a magnified insert, white arrow) and coronal MIP (C2b, white arrow) images. II) Calcified basilar septations: focal calcification associated with basilar septations is seen in 13 cases (13/21, 61.9%). Axial CTA images in 6 different patients (D–I) demonstrate different patterns of calcification with some exhibiting a more linear pattern (D–F, arrows) and others exhibiting a more nodular pattern of calcification (G–I, arrows). Note the prominent nodular calcification occupying a large portion of the basilar lumen in case I.
Tables
Summary of imaging findingsa
Morphology Fenestration (n = 59) Septation (n = 21) Location Inferior third (No.) (%) 53 (89.8%) 14 (66.7%) Middle third (No.) (%) 4 (6.8%) 5 (23.8%) Superior third (No.) (%) 2 (3.4%) 2 (9.5%) Associated findings Calcification (No.) (%) 3 (5.1%) 13 (61.9%) Cerebral infarction (No.) (%) 14 (23.7%) 2 (9.5%) Parenchymal hemorrhage (No.) (%) 5 (8.5%) 2 (9.5%) Coincident vascular abnormalities Vertebral dissection (No.) (%) 2 (3.4%) 1 (4.8%) Carotid dissection (No.) (%) 2 (3.4%) 1 (4.8%) Carotid web (No.) (%) 1 (1.7%) 0 Fibromuscular dysplasia (No.) (%) 5 (8.5%) 0 ↵a A total of 80 cases with basilar artery intraluminal findings were identified. The location and distribution along the course of the basilar artery were similar for fenestrations and septations. Rarely, arterial dissections were found in the extracranial segments of vertebral artery or internal carotid artery. No intracranial dissections were identified in any of the cases.
