PMC4533333_01
Periventricular anastomosis originating from the lenticulostriate artery (Case 1). a: Anterior-posterior view of conventional angiography of the left internal carotid artery showing the medullary arteries (arrowheads) branching from a lenticulostriate artery (arrows). b: The same view of a maximum-intensity projection image reconstructed with 3-dimensional rotation angiography. c: Flow-sensitive black-blood magnetic resonance angiography revealing an anastomosis (asterisk) between the medullary arteries (arrowheads) and the lenticulostriate artery (arrows) at the lateral corner of the frontal horn of the ventricle.
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F1
Left internal carotid artery angiography (Fig. 1a, b) revealed the medullary arteries derived from a lenticulostriate artery, suggesting an anastomosis between the lenticulostriate and medullary arteries around the periventricular area. FSBB-MRA more clearly revealed an anastomosis between these arteries at the lateral corner of the frontal horn of the ventricle with exact correspondence to angiography (Fig. 1c).
Periventricular anastomosis originating from the thalamotuberal artery (Case 2). a: Anterior-posterior view of left common carotid artery angiography showing a tortuous thalamotuberal artery (arrows) connecting to the medullary arteries (arrowheads). b: Flow-sensitive black-blood magnetic resonance angiography demonstrating the arteries more clearly. Anastomotic sites are supposed to be located both beneath the ependyma of the third ventricle (asterisk) and at the lateral corner of the lateral ventricle (double asterisk). The evidence of bleeding is observed at the first anastomotic site (double arrow).
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Meticulous reading of left carotid artery angiography might identify a tortuous perforating artery originating from the thalamotuberal artery and connecting to the medullary arteries, but numerous overlapping vessels obscure the view (Fig. 2a). FSBB-MRA more clearly revealed the thalamotuberal artery, which coursed around the periventricular area of the third ventricle and then abnormally extended laterally beyond the thalamus and connected to the medullary artery (Fig. 2b).
Periventricular anastomosis originating in the thalamogeniculate artery (Case 3). a: Anterior-posterior view of vertebral artery angiography showing the thalamogeniculate artery (arrows), which connects to the insular artery (arrowhead) and subsequently to the middle cerebral artery (double arrowhead), revealing a somewhat arbitrary spatial relationship. b: Flow-sensitive black-blood magnetic resonance angiography more clearly demonstrating the anastomosis (asterisk) between the thalamogeniculate artery (arrows) and the insular artery (arrowhead), which is located at the temporal stem. c: Susceptibility-weighted imaging revealing a microbleed at the exact site of the anastomosis (double arrow).
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Right vertebral artery angiography showed the probable thalamogeniculate artery connecting to the insular artery and subsequently to the middle cerebral artery, revealing a somewhat arbitrary spatial relationship (Fig. 3a). FSBB-MRA more clearly demonstrated the anastomosis between the thalamogeniculate artery and the insular artery, a type of medullary artery originally derived from the middle cerebral artery (Fig. 3b). SWI revealed a microbleed at the exact point of the anastomosis (Fig. 3c).
Periventricular anastomosis originating in the anterior choroidal artery (Case 4). a, b: Anterior-posterior (a) and lateral (b) views of left internal carotid artery angiography showing dilated anterior choroidal artery (arrows) connecting to the medullary artery (arrowhead). c: Flow-sensitive black-blood magnetic resonance angiography revealing anastomosis (asterisk) between the choroidal artery (arrows) and the medullary artery (arrowheads) located beneath the lateral wall of the atrium. d: Susceptibility-weighted imaging showing the microbleed (double arrow) coincident with periventricular anastomosis.
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Left internal carotid artery angiography showed an abnormal extension of the dilated choroidal artery (Fig. 4a, b). FSBB-MRA more clearly revealed anastomosis between the choroidal artery and the medullary artery beneath the lateral wall of the atrium of the lateral ventricle (Fig. 4c), with exact correspondence to the anterior-posterior view from the angiography. The evidence of a microbleed can be observed at the exact point of the anastomosis (Fig. 4c, d).