PMC8825373_01
Initial imaging findings: (A) Initial computed tomography (CT) images reveal a hyperdense structure confined to the right Sylvian fissure, leading to further investigation with magnetic resonance imaging (MRI). (B) T2-weighted MRI images do not confirm the suspected hemorrhage; instead, a fusiform aneurysm located in the distal M2-segment of the right middle cerebral artery (MCA) is delineated. (C) Cerebral angiogram illustrates a fusiform aneurysm, located in the inferior trunk of the right MCA. Furthermore, fusiform dilatation of a parieto-occipital branch arising from the right MCA is seen. The lesions are located adjacent to the right insula, in the depth of the Sylvian fissure. (D) Three-dimensional volume-rendering technique (VRT) of the aneurysm.
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Neuroradiologists suspected a traumatic subarachnoidal hemorrhage on computed tomography (CT) scans, confined to the Sylvian fissure (Figure 1A). Further imaging with magnetic resonance imaging (MRI) was recommended and showed a 10 x 6 x 5 mm fusiform aneurysm of the right middle cerebral artery (MCA), located in the distal M2-segment (Figure 1B). For exact depiction of the incidental aneurysm and assessment of treatment options, cerebral angiograms were acquired (Figures 1C,D).
Intra-interventional cerebral angiograms: (A) Lateral working projection during navigation of the microcatheter and microwire toward the aneurysm. (B) Directly after implantation of the flow diverter, contrast media stasis can be seen at the dome of the aneurysm as a gray, subtracted cap in the arterial phase. (C) In the venous phase, additional stasis in the majority of the aneurysm sack is depicted as a black band. (D) Postinterventional three-dimensional VRT showing the positioning of the flow diverter in relation to the aneurysm and marked stasis of contrast medium at the dome of the aneurysm.
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The procedure was performed by the end of August 2019 (Figure 2), and the patient recovered uneventfully.
Postinterventional imaging findings: (A) T1-weighted image 6 months after flow diverter implantation showing hyperintense thrombotic material around the flow diverter and near-complete occlusion of the aneurysm. The initial severe stasis at the dome (Figure 2B) is depicted as a hypointense cap. (B) Slow flow in the side branch originating from the aneurysm wall is documented 6 months post intervention after changing to monotherapy with aspirin. (C) Perfusion deficit of the affected territory is visible on mean transit time reconstructions of the MRI perfusion. (D) Small ischemic lesions, located in the right superior parietal lobule, are seen on DWI. (E) One month after detection of the slow flow in the side branch of the aneurysm-wall, T2-weighted images did not reveal an infarction in areas with delayed perfusion. (F) As 12 month-follow-up MRIs reveal, the aneurysm is completely filled with a hyperintense thrombotic material, which means that full occlusion of the aneurysm was achieved.
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Brain MRI indicated nearly complete thrombosis of the aneurysm (Figure 3A). Slow-flow was depicted in an MCA side branch (Figure 3B), originating from the aneurysm-wall, with a perfusion deficit of the respective territory (Figure 3C) and small embolic lesions on diffusion-weighted imaging (DWI, Figure 3D). The follow-up MRI scan showed no new cerebral infarction (Figure 3E) and normalization of the flow in the MCA side branch. Six-month follow-up MRI scan showed complete occlusion of the aneurysm (Figure 3F), regular flow in the side branch, and no cerebral infarction in the MCA territory or any hemorrhages.