Because the technique is not based on a flow entrance effect but on a T1 lowering of the blood (Compared with the surrounding tissues) by prescribing slabs in the coronal plane, it was possible to cover the region from the aortic arch to the carotid siphon
. Turbo MR Angiography was a spoiled gradient-recalled echo sequence performed with a 1.5m sec TR, a 1.0m sec TE, a 30[degrees] flip angle, a 300 x 225 mm field of view, a 320 x 160 matrix, and 42 partitions each 2mm thick with zero filling in the z-axis, which resulted in an imaging time of 4 sec.
Caption: Right common carotid artery injection revealing severe vasospasm affecting the right carotid siphon
before transluminal angioplasty is shown next to its corresponding transcranial doppler-measured cerebral blood flow velocity.
The patient was imaged using carotid angiography, and segmental narrowing of the carotid siphon
Exact mechanism of formation of these fistulae has not been clearly understood however it is believed that direct injury at skull base results in torsion and or stretching of carotid siphon
. The other possible explanation is impingement of vessels upon nearby bony prominences.1 Complete disruption of the wall
The mass surrounded and partially compressed the carotid siphon
and petrous segment of the internal carotid artery.
With the transorbital window, the Doppler is placed directly over the eye, allowing the ophthalmic artery (OA) and carotid siphon
(which consists of three segments, the supraclinoid, genu and parasellar) to be insonated.