Identification and anatomic description of the anterior choroidal artery by use of 3D-TOF source and 3D-CISS MR imaging

Abstract

Background and purpose: The importance of the anterior choroidal artery (AChA) is related to its supply of crucial anatomic structures, such as the internal capsule. Angiographically, the AChA can be detected in 71% to 98% of patients, but as yet, its visibility on MR images has not been evaluated. Our goal was to assess the sensitivity of MR imaging in the identification of the AChA and its anatomic characteristics.

Methods: Twenty volunteers underwent MR imaging with a 3D time-of-flight (3D-TOF) sequence, 10 of them additionally with a 3D Fourier transformation constructive interference in steady state (3D-CISS) sequence. The MR angiographic source images and the 3D-CISS images were analyzed independently by two neuroradiologists, who evaluated the ability to identify the different segments of the AChA and the posterior communicating artery (PComA) according to a previously defined scoring system (0 = not identified, 1 = most probably identified, 2 = identified with certainty). Additionally, three patients were examined who had an arteriovenous malformation (AVM) supplied by the AChA.

Results: In the volunteers, the PComA was identified with certainty in 87.5% on 3D-TOF sequences and in 95% on 3D-CISS sequences; the AChA was identified with certainty in 92.5% on 3D-TOF sequences and in 90% on 3D-CISS sequences. 3D-CISS images showed additional anatomic information in six of 20 vessels. In the three patients, the enlarged AChA was identified with certainty on both imaging sequences.

Conclusion: The AChA can be reliably identified using both 3D-CISS sequences and the source images of the 3D-TOF sequence. MR imaging can be used to assess and follow-up AChA-related disorders, especially AVMs.

fig 1.

A–C, Axial MR angiographic source images through the midbrain of a 31-year-old male volunteer obtained using a 3D-TOF sequence (31/7/1) with 0.81 mm between images and displayed from caudal (A) to cranial (C). The AChA can be seen bilaterally. The left AChA (long arrow) is visible from its point of origin from the carotid artery (A) throughout its cisternal segment (A and B) and as it runs along the medial aspect of the uncus and curves laterally along the medial aspect of the temporal lobe (gyrus ambiens) before crossing the cisterna ambiens to enter the choroidal fissure (C). The AChA on the right side (short arrow) is visible at its origin (B) and along its cisternal course (C).

fig 2.

A and B, Axial MR source images through the midbrain of a 27-year-old male volunteer obtained using the 3D-CISS sequence (12.3/5.9/1) with a distance of 1.32 mm between slices and displayed from caudal (A) to cranial (B). The PComA and AChA can be identified bilaterally. The right AChA (B, straight arrow) is visible where it originates from the posterior wall of the internal carotid artery distal to the origin of the PComA (A, curved arrow). On the left side, the PComA and the cisternal segment of the AChA can be seen (straight arrow, A and B). The AChA is located lateral to the PComA and has a slightly smaller diameter

fig 3.

A and B, Lateral projections of left internal carotid artery in a 37-year-old male patient with headaches show the AVM supplied by an enlarged left AChA (arrow, A). C, Axial MR angiographic source image obtained using a 3D-TOF sequence (31/7/1) shows areas of the AVM with high blood flow (curved arrow), the origin of the patient's right AChA (large straight arrow), and enlargement of the left AChA (small straight arrow) that supplies the AVM. D, Reconstructed MR angiographic image oriented along the axis of the cisternal course of the left AChA shows the entire cisternal course of the left AChA (arrow).

fig 4.

Schematic drawing of an axial cut through the midbrain. The AChA (4) originates from the internal carotid artery (2), runs toward the medial aspect of the uncus (12), and then curves laterally along the medial aspect of the temporal lobe through the ambient cistern to the choroidal fissure (13). The uncal artery on the left has a common origin with the AChA. 1, optic nerve; 2, internal carotid artery; 3, PComA; 4, AChA; 5, uncal artery; 6, oculomotor nerve; 7, posterior cerebral artery; 8, tip of the basilar artery; 9, mesencephalon; 10, aqueduct of Sylvius; 11, cerebellum; 12, uncus of the temporal lobe; 13, choroidal fissure