Bilateral internal carotid artery occlusion

This 77 year old male patient was admitted with a history of repeated cerebro-vascular accidents and recent deterioration of his neurological status.

Bilateral internal carotid artery occlusion, 1.5 T.
Fig.1 Axial T2-weighted fast spin-echo images. Multiple hyperintense lesions are identified within the basal ganglia and the periventricular deep cerebral white matter. Involvement of the corpus callosum is also conspicuous. A cortical-subcortical lesion is also present in the left prefrontal region.
Fig.2 Axial diffusion-weighted echo planar images (images in the left column represent diffusion weighting along the phase encoding axis, in the middle column along the frequency encoding axis and in the right column along the slice encoding axis). These images show the lesion areas more accurately and suggest that they correspond to acute infarctions (increased signal present on all types of the diffusion-weighted images usually signifies isotropically restricted water diffusion, most frequently seen in the case of cytotoxic edema).
Fig.3 Coronal (above) and axial (below) targeted MIP reconstruction from a non-enhanced multi-slab 3D TOF MRA acquisition data set. Only the distal segments of the internal carotid arteries are visualized. The left middle cerebral artery and its branches as well as both anterior cerebral arteries are poorly demonstrated suggesting slow flow (with resultant signal loss due to intravolume spin saturation). Good intravascular signal is seen within the posterior cerebral arteries. A well developed posterior communicating artery is seen between the right posterior cerebral artery and the right internal carotid artery siphon.

Video 1. Test bolus technique in Gd-3D-MRA (prolonged contrast travel time).
Test bolus injection before a Gadolinium-enhanced 3D MRA study of the cervical arteries. Sequential axial ultrafast gradient echo images over the common carotid arteries a few centimeters below the bifurcation (TR: 8.5 msec, TE: 4 msec, flip angle: 10 degrees, Tac: 1.11 sec). In this case the images were obtained at 1.3 sec intervals. 3 cc of Gadolinium was injected into the antecubital vein at a rate of 3 cc/sec. The contrast appears within the vertebral arteries on image 9 and within the common carotid arteries on image 10. The calculated contrast travel time was therefore 10 x 1.3 sec = 13 sec (in individuals with normal cardiac output the contrast travel time is usually less than 10 seconds). The internal jugular veins are fully visualized on image 19 (19 x 1.3 sec = 24.7 sec). This suggests an increased (approximately 12 seconds) cerebral circulation time. Injection to imaging delay was calculated as follows:
contrast travel time + theoretical perfusion time/2 [= actual injection time (24 ml at 3 cc/sec) + spread = 8 sec + 8 sec] - acquisition time/2 = 13 sec + 16/2 - 23/2 = 13 sec + 8 sec - 11.75 sec = 9.25 sec. For explanation of the equation see further in: Data acquisition time (Tac) and delay.

Fig.4 Coronal targeted MIP reconstruction from a Gd-enhanced 3D MRA acquisition data set (TR: 7 msec, TE: 2 msec, flip angle 45 degrees, Tac: 23 seconds). Occlusion of both internal carotid arteries is well demonstrated with residual stumps bilaterally. Note the signal intensity differences between the middle cerebral arteries, suggesting more severely impaired cerebral blood flow on the left than on the right side. Remember, that a well developed posterior communicating artery was demonstrated by a previous 3D TOF study of the intracranial vessels on the right side (Fig.4), most probably providing the bulk of the collateral flow from the posterior circulation towards the anterior circulation. Visualization of the terminal segments of the internal carotid arteries is either due to retrograde flow or collateral flow from the external carotid arteries via the ophthalmic arteries.
Fig.5 Coronal Gadolinium-enhanced 2D PC (left) and 3D MRA (right) images for comparison. At identical magnifications the somewhat poorer spatial and the higher contrast resolution (note the signal intensity differences between the two image types at the level of the common carotid arteries) of the Gd-enhanced 3D MRA technique is apparent. The 2D PC acquisition sec is much longer (Tac: 2 min 25) than the Gd-enhanced 3D MRA study (Tac: 23 seconds).
Fig.6 Sagittal targeted MIP reconstructions from a Gd-enhanced 3D MRA acquisition data set (TR: 5 msec, TE: 2 msec, flip angle 45 degrees, Tac: 23 seconds). Occlusion of both internal carotid arteries with residual stumps (possible sources of embolism, via external carotid artery collaterals).

Video 2. Bilateral internal carotid artery occlusion
Cine presentation of the Gd-enhanced 3D MRA acquisition data set in a case of bilateral internal carotid artery occlusion
Optimal visualization of the cervical arteries. Note the excellent visualization of the vertebral arteries along their entire course.

Fig.7 Axial Gadolinium-enhanced T1-weighted spin-echo images. Since the patient has already received intravenous contrast, Gadolinium-enhanced T1-weighted images were also obtained. They show contrast uptake (rupture of the blood-brain barrier) in many but in not all of the lesions areas demonstrated by the diffusion-weighted images (acute infarctions of different age?).

The ESNR CD-Rom Series