PMC3307237_01
(a) Occlusion of the left internal carotid artery (ICA) near its terminal end (arrow). (b) Diffusion-weighted imaging showed scattered areas of high intensity around the left Rolandic fissure (arrow). (c) Digital subtraction angiography showed occlusion of the left ICA distal to the ophthalmic artery (arrow). (d) Perfusion weighted imaging (PWI) showed severely elongated MTT of the distribution of the left ICA and right ACA. (e) Magnetic resonance angiography (MRA) showed excellent flow through the STA-MCA bypass (arrow). (f) PWI study at the same time as (e) showed much better perfusion than before the operation. (g) The STA-MCA bypass is not visible on MRA 1 year later
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F1
Magnetic resonance angiography (MRA) showed severely impaired blood flow in the left ICA [Figure 1] and scattered regions of high intensity around the left Rolandic fissure [Figure 1. Digital subtraction angiography (DSA) was immediately performed and revealed that the left ICA was occluded distal to the ophthalmic artery [Figure 1] and that collateral blood flow was coming from the left posterior communicating (p-com) artery. Perfusion weighted imaging (PWI) showed a severely prolonged mean transit time (MTT) in the distribution of the left ICA and right anterior cerebral artery (ACA), whose flow is also dependent on the left ICA [Figure 1]. Postoperative MRA showed excellent blood flow through the STA-MCA bypass; however, anterograde ICA blood flow became normal 2 weeks later [Figure 1]. PWI performed at the same time showed much better perfusion than before the operation and almost no laterality [Figure 1]. The STA branches used for the bypass were not visible on MRA 1 year later, and remained undetectable on repeat MRA [Figure 1].
(a) Left ICA terminal stenosis was severe again (arrow) when the patient re-presented for mild right hemiparesis. (b) Perfusion weighted imaging at the time of re-presentation showed no laterality. (c) Angiography demonstrated severe stenosis near the terminal end of the left ICA (arrow). (d) Flow through the superficial temporal artery to middle cerebral artery (STA-MCA) bypass was visualized when the left MCA became occluded (arrow). (e) DWI the day after angioplasty showed limited infarction. (f) Magnetic resonance angiography (MRA) showed the ICA stenosis was improved after the angioplasty and the bypass was no longer visible. (g) One week later, left ICA flow was reduced and the STA-MCA bypass was dominant source of blood flow (arrow)
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F2
MRA showed a recurrence of severe stenosis of the ICA [Figure 2]. At this time, the bypass graft was not visible and PWI showed no laterality of perfusion [Figure 2]. Immediate angiography confirmed the severity of the ICA stenosis [Figure 2]. Even though the patient had been treated with antithrombotics since she was first diagnosed with ICA stenosis, transient ischemia occurred repeatedly and she experienced a recurrence of severe stenosis [Figure 2]. Flow from the STA-MCA bypass appeared when MCA occlusion occurred [Figure 2]. Diffusion-weighted imaging (DWI) the next day showed limited cerebral infarction [Figure 2] and her consciousness and right hemiparesis gradually improved. MRA revealed that the ICA stenosis was reduced following the angioplasty and the bypass graft was no longer visible [Figure 2]. However, 1 week later, left ICA flow reduced and STA-MCA bypass flow again became dominant [Figure 2].