Anatomy of Intracranial Vessels and Vascular Territories

Outline

Anatomy of Intracranial Vessels and Intracranial ICA and its branches Vascular Territories Circle of Willis and variants ECNR 2018 Cortical territories (ACA, MCA, PCA) Perforating vessels arising form Circle of Willis Vetebro-basilar system UCL Institute of Neurology Queen Square, London

Bouthillier classification of ICA Bouthillier classification of ICA

1. cervical segment 2. petrous (horizontal) segment 1. cervical segment 3. lacerum segment 2. petrous (horizontal) segment 4. cavernous segment 3. lacerum segment 4. cavernous segment 5. clinoid segment 5. clinoid segment 6. ophthalmic (supraclinoid) segment 6. ophthalmic (supraclinoid) segment 7. communicating (terminal) segment 7. communicating (terminal) segment

1 cervical 2 ascending intra-petrous 3 horizontal intra-petrous 4 ascending foramen lacerum 5 horizonantal intracavernous 6 clinoid 7 termination

Proximal Branches ICA

MHT

ILT PCOM Infundibulum and PCOM Aneurysm Enlarged Meningohypohyseal Trunk Meningioma

MHT branches: 1. marginal tentorial a. (Bernasconi-Casanari artery) 2. clival branches 3. inferior hypophyseal a.

Enlarged Meningohypohyseal Trunk: AVM Anterior Choroidal Artery

DWI ADC FA

3D TOF MRA MPR

Circle of Willis Thomas Willis (1621-1675)

It is not a circle but a nonagon!

Cerebri Anatome cui Accessit Nervorum Descriptivo et Usus (1664) Common Variations of Circle of Willis Common Variations of Circle of Willis

20% 10% 10%

Foetal PCA Bilateral Foetal PCA Absent A1

Variations of Circle of Willis Absent left A1 , Foetal origin PCA

Complete circle 42% of general Western population (1) 90% of Japanese population (2) 27% in Chinese population (3)

(1) Krabbe Hartkamp 1998; (2) Tanaka 2006; (3) Qi Li 2011

Basilar Artery In Presence of R Foetal PCA Cortical Territories Cortical Territories Anterior Cerebral Artery

Anterior Cerebral Artery Anterior Cerebral Artery

A3 A3

A2 A 2

A1 horizontal segment A2 vertical segment A3 callosal segment

Lt ACA Infarct Bilateral ACA Infarct Middle Cerebral Artery MCA Variations

M1 Horizontal segment M3 Opercular segment M2 Insular segment M4 Cortical segment

MCA Variants Left MCA Infarct

Fenestration of M1segment Duplication of MCA

Left MCA Infarct Posterior Cerebral Artery

P1 pre-communicating segment P3 Quadrigeminal segment P2 brainstem segment P4 Cortical segment Posterior Cerebral Artery Infarct PCA Infarct

T2 FSE DWI

PCA- Splenium of Corpus Callosum Borderzone Territories

Mangla Radiographics 2011

ACA/ MCA Borderzone

15 volunteers

Hendrikse et al Radiology 2007 Right Borderzone Infarcts Variations in Perfusion Territories

Van der Zwan & Billen, Stroke, 1991;22:1078-1084 Van der Zwan et al., J Neurosurg, 1992;77:927-940

Territorial Arterial Spin Labeling Normal Population: Non-variant Type COW

68 subjects

100%

Hendrikse et al. Stroke 35 (2004) Van Laar et al. Neuroimage 29:136 144 (2006)

Normal Population Normal Population

Unilateral foetal type PCA (right) Missing A1 segment (right) 8 subjects 19 subjects

100% 100% Left Left ICA ICA

Right Right ICA ICA

VBA VBA 0% 0%

Van Laar et al. Neuroimage 29:136 144 (2006) Van Laar et al. Neuroimage 29:136 144 (2006) Perforating Arteries of Circle of Willis Textbook Perfusion Territories of the BG

Medial Perforators (incl Heubner) Lateral Perforators Thalamoperforators Thalamogeniculate

Images from The Radiology Assistant , http://www.radiologyassistant.nl/en/484b8328c b6b2

Lenticular and Perforating Arteries Lenticulostriate Arteries

Images from The Radiology Assistant , http://www.radiologyassistant.nl/en/484b8328c b6b2

Lenticulostriate Territory Infarct Recurrent Artery of Heubner

Otto Heubner 1848-1926 Thalamoperforators Artery of Percheron Aneurysm and Infarct

AOP- artery of Percheron

G. Percheron. 1973 Hopital de la , Paris.

Lazzaro AJNR 2010 31: 1283-1289

Perfusion Territories of the BG Vertebrobasilar Sytem

Non-variant Circle of Willis

Perforators SCA AICA Hypoplastic L A1 Foetal R PCA PICA Ant Spin A.

Hendrikse et al. Radiology 254(3):867-875 (2010)

Vertebrobasilar Sytem Lateral View Haemodynamic Balance between AICA and PICA AICA/PICA Haemodynamic Balance

PICA dominant AICA dominant R AICA dominant L PICA dominant Duplication of R SCA

L PICA Infarct

Brainstem Perforators : Medulla Brainstem Perforators Territories

Lateral = PICA Medial = Vertebral