. 2025 Jan-Feb;39(1):280-291.

doi: 10.21873/invivo.13826.

Identification of a T2-hyperintense Perivascular Space in Brain Arteriovenous Malformations

Thomas Wälchli^#^{1

2

3

4}, Kartik Dev Bhatia^{5

6}, Will Guest⁵, Jeroen Bisschop^{7

2

3

4

8}, Leonardo Olijnyk⁷, Hans Kortman^{5

9}, Paul E Constanthin¹⁰, Patrick Nicholson^{5

11}, Philippe P Monnier⁸, Aristotelis Kalyvas^{12

13}, Ethan A Winkler^{14

15

16

17}, Moncef Berhouma¹⁸, Timo Krings^{5

19}, Ivan Radovanovic^#^{20

2

21

22}

Affiliations

¹ Group Brain Vasculature and Perivascular Niche, Division of Experimental and Translational Neuroscience, Krembil Brain Institute, Krembil Research Institute, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, ON, Canada; thomas.waelchli2@uzh.ch.
² Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, ON, Canada.
³ Group of CNS Angiogenesis and Neurovascular Link, Neuroscience Center Zürich, and Division of Neurosurgery, University and University Hospital Zürich, Zürich, Switzerland.
⁴ Division of Neurosurgery, University Hospital Zürich, Zürich, Switzerland.
⁵ Division of Neuroradiology, Joint Department of Medical Imaging, Toronto Western Hospital, Toronto, ON, Canada.
⁶ Department of Medical Imaging (K.D.B.), Sydney Children's Hospital Network, Westmead, NSW, Australia.
⁷ Group Brain Vasculature and Perivascular Niche, Division of Experimental and Translational Neuroscience, Krembil Brain Institute, Krembil Research Institute, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, ON, Canada.
⁸ Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.
⁹ Department of Radiology, Section Interventional Radiology, Elisabeth Tweesteden Ziekenhuis, Tilburg, the Netherlands.
¹⁰ Department of Neurosurgery, Hôpitaux Universitaires de Genève, Geneva, Switzerland.
¹¹ Department of Neuroradiology, Beaumont Hospital, Dublin, Ireland.
¹² Attikon Hospital, Department of Neurosurgery, National and Kapodistrian University of Athens, Athens, Greece.
¹³ Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, ON, Canada.
¹⁴ Department of Neurological Surgery, University of California, San Francisco, CA, USA.
¹⁵ Eli and Edythe Broad Center for Regeneration Medicine and Stem Cell Research, University of California, San Francisco, CA, U.S.A.
¹⁶ Weill Institute for Neurosciences, University of California, San Francisco, CA, U.S.A.
¹⁷ Department of Neurosurgery, Barrow Neurological Institute, Phoenix, AZ, U.S.A.
¹⁸ Department of Neurosurgery, University Hospital of Dijon, Bourgogne, France.
¹⁹ Lahey Hospital and Medical Center, TH Chan School of Medicine, University of Massachusetts, Boston, MA, U.S.A.
²⁰ Group Brain Vasculature and Perivascular Niche, Division of Experimental and Translational Neuroscience, Krembil Brain Institute, Krembil Research Institute, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, ON, Canada; ivan.radovanovic@uhn.ca.
²¹ Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.
²² Division of Neurosurgery, Sprott Department of Surgery, University of Toronto, Toronto, ON, Canada.

^# Contributed equally.

PMID: 39740916
PMCID: PMC11705134
DOI: 10.21873/invivo.13826

Identification of a T2-hyperintense Perivascular Space in Brain Arteriovenous Malformations

Thomas Wälchli et al. In Vivo. 2025 Jan-Feb.

. 2025 Jan-Feb;39(1):280-291.

doi: 10.21873/invivo.13826.

Authors

Affiliations

¹ Group Brain Vasculature and Perivascular Niche, Division of Experimental and Translational Neuroscience, Krembil Brain Institute, Krembil Research Institute, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, ON, Canada; thomas.waelchli2@uzh.ch.
² Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, ON, Canada.
³ Group of CNS Angiogenesis and Neurovascular Link, Neuroscience Center Zürich, and Division of Neurosurgery, University and University Hospital Zürich, Zürich, Switzerland.
⁴ Division of Neurosurgery, University Hospital Zürich, Zürich, Switzerland.
⁵ Division of Neuroradiology, Joint Department of Medical Imaging, Toronto Western Hospital, Toronto, ON, Canada.
⁶ Department of Medical Imaging (K.D.B.), Sydney Children's Hospital Network, Westmead, NSW, Australia.
⁷ Group Brain Vasculature and Perivascular Niche, Division of Experimental and Translational Neuroscience, Krembil Brain Institute, Krembil Research Institute, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, ON, Canada.
⁸ Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.
⁹ Department of Radiology, Section Interventional Radiology, Elisabeth Tweesteden Ziekenhuis, Tilburg, the Netherlands.
¹⁰ Department of Neurosurgery, Hôpitaux Universitaires de Genève, Geneva, Switzerland.
¹¹ Department of Neuroradiology, Beaumont Hospital, Dublin, Ireland.
¹² Attikon Hospital, Department of Neurosurgery, National and Kapodistrian University of Athens, Athens, Greece.
¹³ Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, ON, Canada.
¹⁴ Department of Neurological Surgery, University of California, San Francisco, CA, USA.
¹⁵ Eli and Edythe Broad Center for Regeneration Medicine and Stem Cell Research, University of California, San Francisco, CA, U.S.A.
¹⁶ Weill Institute for Neurosciences, University of California, San Francisco, CA, U.S.A.
¹⁷ Department of Neurosurgery, Barrow Neurological Institute, Phoenix, AZ, U.S.A.
¹⁸ Department of Neurosurgery, University Hospital of Dijon, Bourgogne, France.
¹⁹ Lahey Hospital and Medical Center, TH Chan School of Medicine, University of Massachusetts, Boston, MA, U.S.A.
²⁰ Group Brain Vasculature and Perivascular Niche, Division of Experimental and Translational Neuroscience, Krembil Brain Institute, Krembil Research Institute, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, ON, Canada; ivan.radovanovic@uhn.ca.
²¹ Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.
²² Division of Neurosurgery, Sprott Department of Surgery, University of Toronto, Toronto, ON, Canada.

^# Contributed equally.

PMID: 39740916
PMCID: PMC11705134
DOI: 10.21873/invivo.13826

Abstract

Background/aim: Brain arteriovenous malformations (AVMs) are vascular malformations characterized by dysmorphic, aberrant vasculature. During previous surgeries of compact nidus brain AVMs (representing the majority of cases), we have observed a "shiny" plane between nidal and perinidal AVM vessels and the surrounding grey and white matter and hypothesized that preoperative neuroimaging of brain AVMs may show a neuroradiological correlate of these intraoperative observations.

Patients and methods: We retrospectively reviewed and analyzed multiplanar and multisequence 3-Tesla magnetic resonance (3T MR) imaging in five consecutive brain AVMs with special attention on imaging characteristics of the brain-AVM interface, i.e., the perivascular and perinidal regions.

Results: In all five patients, we identified T2-hypertinense perivascular perinidal spaces, which were predominantly observed around the AVM nidus and less prominently around the feeding arteries or draining veins.

Conclusion: The identification of T2-hypertinense perivascular spaces surrounding brain AVMs on neuroradiological imaging may provide insights into the anatomico-radiological relationships of brain AVMs and the surrounding grey and white matter parenchyma. These findings could have future implications for our understanding of brain AVM biology and may influence neurosurgical approaches to these lesions.

Keywords: Brain AVMs; T2-hyperintense perivascular rim around AVM nidus; Virchow-Robin space; neuroradiological characterization; perivascular (perinidal) space.

PubMed Disclaimer

Conflict of interest statement

The Authors declare no competing financial interests in relation to this study.

Figures

**Figure 1**
Imaging characteristics of a brain arteriovenous malformation (AVM) in patient 1. A left selective preoperative Internal carotid Artery (ICA) angiogram, shown in anteroposterior (A), lateral (B) projections, along with a 3D reconstruction (C), revealing a brain AVM in the left parietal region. The AVM is supplied by the left middle cerebral artery, and features cortical venous drainage, with a nidus measuring 2.5 cm at its major diameter. Axial (D-F) and coronal (G-I) T2 MRI images of the nidus show a thin high-signal space surrounding the periphery of the nidus, marked with white arrowheads. FLAIR sequence (J) showing mild peri-lesional edema. T1- (K) and GRE (L) sequences showing no evidence of acute or chronic hemorrhage. The Spetzler-Martin Grade is classified as II.

**Figure 2**
Imaging characteristics of a brain arteriovenous malformation (AVM) in patient 2. Right selective preoperative vertebral artery angiogram, in anteroposterior (A), lateral (B) projections, and 3D reconstruction (C), revealing a brain AVM in the right occipital region supplied by posterior cerebral arteries with deep venous drainage, with a nidus measuring 2.4 cm at its major diameter. Axial (D-F) and coronal (G-H) T2 MRI images of the nidus show a thing high-signal space surrounding the periphery of the nidus, marked with arrowheads. DWI sequence (I) showing no evidence of ischemia. FLAIR sequence (J) showing minimal peri-lesional edema. T1- (K) and GRE (L) sequences showing no evidence of acute or chronic hemorrhage. The Spetzler-Martin Grade is classified as II.

**Figure 3**
Imaging characteristics of a brain arteriovenous malformation (AVM) in patient 3. Right selective preoperative ICA angiogram, in anteroposterior (A), lateral (B) projections, and 3D reconstruction (C), revealing a brain AVM in the right parietal region supplied by the right middle cerebral artery and the lateral posterior choroidal artery with cortical venous drainage into the superior sagittal sinus, with a nidus measuring 4.5 cm at its major diameter. Axial (D-F) and coronal (G-H) T2 MRI images of the nidus show a thin high-signal space surrounding the periphery of the nidus, marked with arrowheads. DWI sequence (I) showing no evidence of ischemia. FLAIR sequence (J) showing minimal peri-lesional edema. T1- (K) and GRE (L) sequences showing no evidence of acute or chronic hemorrhage. The Spetzler-Martin Grade is classified as I.

**Figure 4**
Imaging characteristics of a brain arteriovenous malformation (AVM) in patient 4. Right selective preoperative ICA angiogram, in anteroposterior (A), lateral (B) projections, and 3D reconstruction (C), revealing a brain AVM in the right frontal region supplied by the right anterior cerebral artery, with cortical venous drainage into the superior sagittal sinus, with a nidus measuring 2.5 cm at its major diameter. Axial (D-E) T2 MRI images of the nidus showing a thing high-signal space surrounding the periphery of the nidus, marked with arrowheads. DWI sequence (F) showing no evidence of ischemia. FLAIR sequence (G) showing no peri-lesional edema. T1- (H) and GRE (I) sequences showing no evidence of acute or chronic hemorrhage. The Spetzler-Martin Grade is classified as I.

**Figure 5**
Imaging characteristics of a brain arteriovenous malformation (AVM) in patient 5. Left selective preoperative ICA angiogram, in anteroposterior (A), lateral (B) projections, and 3D reconstruction (C), revealing a brain AVM in the left frontal region supplied by the left anterior cerebral artery with superficial cortical venous drainage into the superior sagittal sinus, with a nidus measuring 2.5 cm at its major diameter. Axial (D-F) and coronal (G-I) T2 MRI images of the nidus show a thin high-signal space surrounding the periphery of the nidus, best defined on the lateral margin, marked with arrowheads. FLAIR sequence (J) showing minimal peri-lesional edema. T1- (K) and GRE (L) sequences show no evidence of acute or chronic hemorrhage. The Spetzler-Martin Grade is classified as I.

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Identification of a T2-hyperintense Perivascular Space in Brain Arteriovenous Malformations

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Identification of a T2-hyperintense Perivascular Space in Brain Arteriovenous Malformations

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