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 A1 horizontal segment A2 vertical segment A3 callosal segment Lt ACA Infarct Bilateral ACA Infarct Middle Cerebral Artery MCA Variations M4 M3 M2 M1 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 P4 P3 P2 P1 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% 0% 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.