BY : Dr . Sameeha Khan
(MDRD)
Part 1
 Understanding vascular anatomy is fundamental
to neuroimaging.
 About 18% of the total blood volume in the body circula...
 Part 1 –
 Aortic arch and great vessels
 Carotid arteries
 Circle of Willis
 Part 2 –
 Cerebral arteries
 Posterio...
1. Conventional intra-arterial angiography –
DSA system - techniques of image
acquisition
 Standard radiographic projecti...
2. Computed tomography angiography
3. Magnetic resonance angiography
I. Time of flight – inflow of unsaturated spin
II. Ph...
Starts from aortic arch :
Aortic arch
Innonimate
artery
Left
common
carotid
Left
subclavian
3 . Innonimate artery
10. Left subclavian
artery
15. Left common
carotid artery
 A.k.a Brachiocephalic trunk .
 1st vessel arising from the aortic arch .
Innonimate
artery
Right
subclavian
artery
Righ...
4. Right subclavian
artery
5. Right common
carotid artery
Right subclavian artery
Right
vertebral
artery
Internal
mammary artery
Thyrocervical
trunk
Costocervical
trunk
6. Right vertebral artery
9. Internal mammary
artery
16. Thyrocervical trunk
16
 Common arch anomaly
 0.5-1% of all cases
 Here it is the last
brachiocephalic vessel arising
from aortic arch -4th bra...
Barium studies – fixed narrowing
of esophagus at the level of arch
without mucosal deformity –
bayonet deformity
 1st Branch of right subclavian artery
 Right vertebral artery dominant -25%
 Anomalous origin – uncommon
 Arises from proximal IA
 Only cervical part as it arises caudally
 RCCA – directly from aortic arch ( when
right SCA is aberrant )
RCCA
RSCA
 2nd major branch from aortic arch
 Thoracic and cervical part –in thoracic it travels upwards throu
superior mediastinu...
LCCA- common
origin with IA
 LCCA – hypoplastic
or absent – here the
ECA and ICA arise
directly from aortic
arch
 Non bifurcating
carotid artery –
o...
 Last branch from aortic arch
 Major branches -
Left subclavian artery
Left vertebral
artery
Internal
mammary
Thyrocervi...
 First branch of left subclavian artery
 Dominant in 50-60%
 In 25% right and left VA are equal in size
11.Left vertebr...
 Left vertebral artery –directly from aortic arch
-5% ( nondominant )
RSCA
LSCA
Innominate
artery
LCCA
RCCA
RVA
LVA
 Course - Runs within a
fascial plane – the carotid
sheath –also contains IJV
and vagus nerve, vein
lateral to artery , n...
 Smaller of the 2 carotids.
 Origin anterior and medial to ICA.
 Supplies the extracranial structures.
 Branches –( Si...
External carotid artery
Anterior
Superior
thyroidal
Lingual
Facial
Posterior
Occipital
Posterior
auricular
Medial
Ascendin...
ECA – branches
Superior thyroid artery
Lingual artery
Facial artery
Occipital artery
Posterior auricular
artery
Ascending
pharyngeal arte...
Late arterial phase of CCA angiogram
Posterior auricular
artery
Occipital artery
Facial artery
Lingual artery
Superficial ...
 Internal maxillary artery-
 Runs forward deep to the
mandible.
 Branches – inferior
alveolar, middle meningeal,
deep t...
 On angiogram should be
differentiated from middle
meningeal artery –
characteristic hairpin turn
of STA over zygomatic
p...
Oblique view – MRA
Vertebral artery
Thyrocervical trunk
Facial artery
Lingual artery
Superficial
temporal artery
Occipital...
Straight AP view – MRA
Superficial
temporal artery
Hairpin turn of
STA
Maxillary artery
Facial artery
Lingual artery
Verte...
Late arterial phase – prominent vascular blushes in the
mucosa of sinuses , nose ,orbit , oropharynnx -
not to be confused...
Maxillary artery
• Middle meningeal
artery
• Foramen rotundum
artery
• Accessory meningeal
• Vidian artery
• Ant / mid dee...
• Occipital
• Ascending
pharyngeal artery
• Ascending
pharyngeal artery
• Facial artery
• Posterior auricular
artery
• Ver...
Intima – white endoluminal line
Media – darker line underneath
Adventitia –thick peripheral white line
• Laminar flow in l...
Left CCA
Right CCA
Internal carotid-
carotid bulb
ECA
3-D CTA
• Origin -Lateral to
ECA.
• Can be divided into
number of se...
Cervical
Intraosseous
/ petrous
Lacerum
Cavernous
Intracranial /
supraclinoid
Opthalmic
Communicating
ICA
Carotid bulb
Petrous
Cavernous
Supraclinoid
Cervical
Oblique DSALateral DSA
 Distal 2-4 cm of CCA
 Bulbous dilatation of ICA
origin
 Complex flow –
 flow distal to bulb is laminar
 Flow reversa...
 No narrowing
 No dilatation
 No branches
 No tapering
Course – crosses
behind and
medial to ECA
ICA
ICA
ECA
 10%- ICA
originates
medial to ECA
 Anomalous ECA
branches arises
from cervical
ICA
 Persistent
embryonic vesels
may an...
Vertical
•2 subsegments joined at genu
•Short vertical segment – anterior to IJV
•Genu – petrous ICA turns anteromedially ...
Axial NECT inferior to superior ( bone window )
Petrous segment of ICA
• Branches supply middle earIntrapetrous
• Inconstant
• Throu Foramen lacerum and vidian
canal
• An...
Foramen lacerumVidian canal
Aberrant course
•Posterolateral course thro temporal bone
•ICA parallel jugular bulb
•Inferior aspect of cochlear promonto...
ICA courses adjacent to jugular bulb ICA traverses the hypotympanum
Bony plate along tympanic portion of ICA absent
Axial ...
Rare- 0.48%
Intrapetrous embryonic vascular
channel stapedio-hyoid artery
Origin – petrous ICA/abICA
Course – passes t...
Small segment that extends from petrous apex above foramen lacerum curving
upwards towards and lies extradurally until it...
Carotid angiogram
C4 segments
1. Ascending (posterior vertical )
2. Posterior genu
3. Horizontal
4. Anterior genu
5. Anterior vertical
Branc...
Carotid
angiogram
Axial CT
Posterior genu as it
courses anteromedially
into the cavernous sinus
ICA courses along the
bony grooves of caroti...
C4 within cavernous sinus
Menigohypophyseal artery
•Posterior trunk
•Arises at junction of c4 and
c5
•Supplies –
•pituitary gland
•tentorium (artery...
•Between proximal , distal dural rings of
cavernous sinus
•Ends as ICA enters subarachnoid space
near anterior clinoid pro...
Extends from distal
dural ring at superior
clinoid to just below
posterior
communicating artery
(PCoA) origin
Branches –
•...
Origin –
• Intradural
•Antero-superior ICA
• Medial to anterior clinoid process
Course –
Anterior throu optic canal
Below ...
Mid arterial phase DSA
Lateral view MRA
Lateral DSA
Arises from posteromedial aspect of
supraclinoid ICA
Course – across the ventral surface of
optic chaisma
Terminates- pitu...
Unruptured
superior
hypophyseal
aneurysm
Normally SHA
not easily seen
•Extends from below PCoA to
terminal ICA bifurcation.
•Passes between optic and
occulumotor nerve.
C7 segment branches
Pos...
•Arises – posterior aspect
of intradural ICA just
below anterior choroidal
artery
•Course – posterolaterally
above the occ...
1. Hypoplasia – 1/3 rd cases
2. Persistence of embryonic
configuaration ( fetal origin of
posterior cerebral artery ) 20 –...
• PCoM is larger than P1 segment of PCA
and supplies the bulk of PCA . PCA
therefore is a part of anterior circulation
• N...
•Infundibular dilatation of
PCoA at origin from ICA- 5-
15%
•Should be 2 mm or less
•Funnel shaped , conical
•PCoA arises ...
Within suprasellar cistern under optic tract
Posteromedially around temporal lobe uncus
Cisternal Course :
Intraventricula...
Supplies
Choroidal plexus of lateral ventricle (
temporal horn and atrium )
Optic tract and cerebral peduncle
Uncal and...
Terminal ICA
Anterior cerebral artery Middle cerebral artery
3D CTA
MCA
ACA
ICA
3D CTAMid arterial phase DSA
2ICAs
Horizontal segment
A1 of both ACAs
2 Posterior
communicating
arteries
Anterior
communicating artery
Horizontal segme...
Interconnected arterial
polygon
Location – surrounds
ventral surface of
diencephalon,
adjacent to optic nerve
and tracts...
3DVRT CTA MRA
CT MRA
1. A1
2. P1
3. PCoA
4. ACoA
Cerebral
angiography-
single injection
Contrast
enhanced CT –
maximum
intensity
projection
Invasive MRA- time of
flight se...
• Medial lenticulostriate arteries
• Recurrent artery of HeubnerACAs
• Perforating branches – hypothalamus , optic
chiasma...
 Complete COW –only 20
– 25%
 Posterior circle
anomalies – 50%
anatomy specimens
Common variants
•Hypoplasia of 1 or bot...
•Hypoplasia or absent A1
ACA segment.
•Absent , duplicate or
multichannel ACoA – 10-15%
•Rare – congenital absence of 1 or
both ICAs
•Common – if 1 ICA absent
intrasellar intercommunicating
arteries
•ICA agenes...
 ICAs develop from 3rd aortic arches ,
dorsal aortae
 Embryonic ICAs divide into cranial,caudal
 Cranial divisions –
▪ ...
 Represent persistent embryonic
circulatory patterns
 Channels between embryonic aorta
(caudal carotid artery) and paire...
•Most common carotid vertebro basilar anastomoses - 0.1- 0.6%
•In utero – embryonic trigeminal artery supplies basilar art...
•PCoA is absent
•Supply entire vertebrobasilar circulation distal to
anastomosis
Saltzmann type
Ι
• Fetal PCA and I/L P1 s...
 2nd most common- 0.027-
0.26%
 .
 Intracranial aneurysms
 If present – single artery
that supplies brain stem
and cer...
Red – PHA Blue – sigmoid sinus Pink – coil mass with basilar
tip aneurysm
 Origin – petrous ICA
 Course – medially thro internal
auditory meatus and joins caudal
basilar artery
 VA – hypoplasti...
•Proatlantal infact is occipital artery
•C1 segment connection is proatlantal
type 1
•C2 connection is proatlantal type 2
...
ICA
Proatlantal
intersergmental
PIA – suboccipital anastamosis between ECA / cervical ICA and vertebral artery
– typically...
radiology Arterial and venous supply of brain neuroimaging  part 1
radiology Arterial and venous supply of brain neuroimaging  part 1
radiology Arterial and venous supply of brain neuroimaging  part 1
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radiology Arterial and venous supply of brain neuroimaging part 1

  1. 1. BY : Dr . Sameeha Khan (MDRD) Part 1
  2. 2.  Understanding vascular anatomy is fundamental to neuroimaging.  About 18% of the total blood volume in the body circulates in the brain, which accounts for about 2% of the body weight.  The blood transports oxygen, nutrients, and other substances necessary for proper functioning of the brain tissues and carries away metabolites.  Loss of consciousness occurs in less than 15 seconds after blood flow to the brain has stopped, and irreparable damage to the brain tissue occurs within 5 minutes.  Cerebrovascular disease or stroke, occurs as a result of vascular compromise or haemorrhage and is one of the most frequent sources of neurologic disability.
  3. 3.  Part 1 –  Aortic arch and great vessels  Carotid arteries  Circle of Willis  Part 2 –  Cerebral arteries  Posterior fossa arteries – vertebrobasilar system
  4. 4. 1. Conventional intra-arterial angiography – DSA system - techniques of image acquisition  Standard radiographic projections  carotid angio- ▪ Lateral projection – centered on pituitary fossa ▪ AP view – with petrous ridge projected over the roof of orbit ▪ I/L anterior oblique – for aneurysms in SAH  Vertebral angio – ▪ lateral , half-axial ( Towne’s) and AP – petrous ridge superimposed on lower border of orbit
  5. 5. 2. Computed tomography angiography 3. Magnetic resonance angiography I. Time of flight – inflow of unsaturated spin II. Phase contrast – accumulation of phase shifts proportional to flow velocity III. Contrast enhanced MRA  Intracerebral vessels -3D TOF MRA is technique of choice  Circle of willis – single slab 3D TOF  Larger part of intracranial circulation – 3-4 multiple overlapping slabs ( MOTSA )  Phase contrast sensitive for slow flow – used for cerebral veins 4. Doppler ultrasound
  6. 6. Starts from aortic arch : Aortic arch Innonimate artery Left common carotid Left subclavian
  7. 7. 3 . Innonimate artery 10. Left subclavian artery 15. Left common carotid artery
  8. 8.  A.k.a Brachiocephalic trunk .  1st vessel arising from the aortic arch . Innonimate artery Right subclavian artery Right common carotid artery
  9. 9. 4. Right subclavian artery 5. Right common carotid artery
  10. 10. Right subclavian artery Right vertebral artery Internal mammary artery Thyrocervical trunk Costocervical trunk
  11. 11. 6. Right vertebral artery 9. Internal mammary artery 16. Thyrocervical trunk 16
  12. 12.  Common arch anomaly  0.5-1% of all cases  Here it is the last brachiocephalic vessel arising from aortic arch -4th branch  Often asymptomatic – 10 % of people can have dysphagia lusoria.  Right common carotid arises directly from arch – first branch
  13. 13. Barium studies – fixed narrowing of esophagus at the level of arch without mucosal deformity – bayonet deformity
  14. 14.  1st Branch of right subclavian artery  Right vertebral artery dominant -25%  Anomalous origin – uncommon
  15. 15.  Arises from proximal IA  Only cervical part as it arises caudally
  16. 16.  RCCA – directly from aortic arch ( when right SCA is aberrant ) RCCA RSCA
  17. 17.  2nd major branch from aortic arch  Thoracic and cervical part –in thoracic it travels upwards throu superior mediastinum to the level of left sternoclavicular joint and continues as cervical 15.Left common carotid CCA bifurcates into ICA and ECA at midcervical level C3- C6 level.
  18. 18. LCCA- common origin with IA
  19. 19.  LCCA – hypoplastic or absent – here the ECA and ICA arise directly from aortic arch  Non bifurcating carotid artery – origin to all the ECA branches
  20. 20.  Last branch from aortic arch  Major branches - Left subclavian artery Left vertebral artery Internal mammary Thyrocervical trunk Costocervical trunk
  21. 21.  First branch of left subclavian artery  Dominant in 50-60%  In 25% right and left VA are equal in size 11.Left vertebral artery 14.Left internal mammary
  22. 22.  Left vertebral artery –directly from aortic arch -5% ( nondominant )
  23. 23. RSCA LSCA Innominate artery LCCA RCCA RVA LVA
  24. 24.  Course - Runs within a fascial plane – the carotid sheath –also contains IJV and vagus nerve, vein lateral to artery , nerve between the two  Runs obliquely upwards from the level of sternoclavicular joint to the level of thyroid cartilage  Bifurcates at the level of C3- C5 into external and internal carotid artery  At bifurcation ICA usually lies posterior and lateral to the ECA
  25. 25.  Smaller of the 2 carotids.  Origin anterior and medial to ICA.  Supplies the extracranial structures.  Branches –( Sister Lucy’s Powdered Face Attracts SO Many Medicos ) Internal carotid artery External carotid artery Common carotid artery
  26. 26. External carotid artery Anterior Superior thyroidal Lingual Facial Posterior Occipital Posterior auricular Medial Ascending pharyngeal Terminal Maxillary Superficial temporal
  27. 27. ECA – branches
  28. 28. Superior thyroid artery Lingual artery Facial artery Occipital artery Posterior auricular artery Ascending pharyngeal artery Early arterial phase of CCA angiogram
  29. 29. Late arterial phase of CCA angiogram Posterior auricular artery Occipital artery Facial artery Lingual artery Superficial temporal artery Maxillary artery Transverse facial
  30. 30.  Internal maxillary artery-  Runs forward deep to the mandible.  Branches – inferior alveolar, middle meningeal, deep temporal , accessory meningeal , sphenopalatine , infraorbital , descending palatine, muscular branches.  Middle meningeal artery – runs superiorly crosses STA on lateral projection thro foramen spinosum.  Supplies – dura and inner table of skull.
  31. 31.  On angiogram should be differentiated from middle meningeal artery – characteristic hairpin turn of STA over zygomatic process  Supplies –part of scalp and ear.  Branch – transverse facial artery  Variant – TFA may arise from ECA directly STA Middle meningeal artery hairpin turn of STA
  32. 32. Oblique view – MRA Vertebral artery Thyrocervical trunk Facial artery Lingual artery Superficial temporal artery Occipital artery Maxillary artery
  33. 33. Straight AP view – MRA Superficial temporal artery Hairpin turn of STA Maxillary artery Facial artery Lingual artery Vertebral artery Middle meningeal artery
  34. 34. Late arterial phase – prominent vascular blushes in the mucosa of sinuses , nose ,orbit , oropharynnx - not to be confused with vascular malformations Oropharynx mucosal blush High nasopharynx mucosal blush Orbital mucosal blush Nasal conchae septal blush Palatal mucosal blush
  35. 35. Maxillary artery • Middle meningeal artery • Foramen rotundum artery • Accessory meningeal • Vidian artery • Ant / mid deep temporal ICA • Ethmoidal br of opthalmic artery • Inferlolateral trunk of ICA • Inferolateral trunk • Intratemporal ICA • Opthalmic artery
  36. 36. • Occipital • Ascending pharyngeal artery • Ascending pharyngeal artery • Facial artery • Posterior auricular artery • Vertebral • Vertebral C3 level • ICA (petrous and cavernous ) • ICA (opthalmic artery) • ICA (stylomastoid artery)
  37. 37. Intima – white endoluminal line Media – darker line underneath Adventitia –thick peripheral white line • Laminar flow in lumen of proximal ICA • Velocity of flow increases towards the aorta ( 9 cm / sec for each cm of distance from the carotid bifurcation)
  38. 38. Left CCA Right CCA Internal carotid- carotid bulb ECA 3-D CTA • Origin -Lateral to ECA. • Can be divided into number of segments between the bulb and its bifurcation into MCA and ACA.
  39. 39. Cervical Intraosseous / petrous Lacerum Cavernous Intracranial / supraclinoid Opthalmic Communicating
  40. 40. ICA Carotid bulb Petrous Cavernous Supraclinoid Cervical Oblique DSALateral DSA
  41. 41.  Distal 2-4 cm of CCA  Bulbous dilatation of ICA origin  Complex flow –  flow distal to bulb is laminar  Flow reversal within posterior bulb  Thinner media and thicker adventitia containing many receptor endings of glossopharyngeal nerve
  42. 42.  No narrowing  No dilatation  No branches  No tapering Course – crosses behind and medial to ECA ICA ICA ECA
  43. 43.  10%- ICA originates medial to ECA  Anomalous ECA branches arises from cervical ICA  Persistent embryonic vesels may anastomose with vertebrobasilar system ICA ECA
  44. 44. Vertical •2 subsegments joined at genu •Short vertical segment – anterior to IJV •Genu – petrous ICA turns anteromedially in front of cochlea •Longer horizontal segment ICA –intraosseous 1. enters carotid canal in petrous temporal bone. 2. Surrounded by sympathetic plexus 3. exit at petrous apex Horizontal Genu
  45. 45. Axial NECT inferior to superior ( bone window )
  46. 46. Petrous segment of ICA • Branches supply middle earIntrapetrous • Inconstant • Throu Foramen lacerum and vidian canal • Anastomose with branches of ECA (Recurrent br of greater palatine) Vidian artery (artery of Pterygoid canal ) • Important branch –tympanic cavity • Supplies middle and inner ear Corticotympanic artery
  47. 47. Foramen lacerumVidian canal
  48. 48. Aberrant course •Posterolateral course thro temporal bone •ICA parallel jugular bulb •Inferior aspect of cochlear promontory •Reduced diameter •Visible pulsatile mass in hypotympanum •Bony plate separating ICA from tympanic cavity absent •Vertical segment of carotid canal absent Normal course of ICA •Anteromedial course thro temporal bone •ICA anterior to IJV •In front of cochlea • 2 segments
  49. 49. ICA courses adjacent to jugular bulb ICA traverses the hypotympanum Bony plate along tympanic portion of ICA absent Axial multidetector CT images Aberrant ICA d/d glomus tympanicum paraganglionoma biopsy – disastrous
  50. 50. Rare- 0.48% Intrapetrous embryonic vascular channel stapedio-hyoid artery Origin – petrous ICA/abICA Course – passes throu the footplate of stapes. Enclosed within a bony canal near cochlear promontary Termination – as middle meningeal artery CT- absentI/Lforamenspinosum d/d – glomus tumor Recognised before surgery
  51. 51. Small segment that extends from petrous apex above foramen lacerum curving upwards towards and lies extradurally until it reaches petrolingual ligament after this it becomes the cavernous segment Covered by trigeminal ganglion No branches
  52. 52. Carotid angiogram
  53. 53. C4 segments 1. Ascending (posterior vertical ) 2. Posterior genu 3. Horizontal 4. Anterior genu 5. Anterior vertical Branches Meningohypophyseal artery Inferolateral trunk Small capsular branches 1 Starts from petrous apex Terminates at its entrance into intracranial subarchnoid space adjacent to anterior clinoid process. Covered by trigeminal ganglion posteriorly.
  54. 54. Carotid angiogram
  55. 55. Axial CT Posterior genu as it courses anteromedially into the cavernous sinus ICA courses along the bony grooves of carotid sulcus along the basisphenoid bone • Throu cavernous sinus proper turns superiorly • Form grooves under anterior clinoid process • Anterior genu of ICA . • Curve upwards towards dural ring • Enter subarchnoid space Posterior genu Carotid sulcus Anterior genu
  56. 56. C4 within cavernous sinus
  57. 57. Menigohypophyseal artery •Posterior trunk •Arises at junction of c4 and c5 •Supplies – •pituitary gland •tentorium (artery of Bernasconi and Cassinari ) •cavernous sinus • clival dura • cn3 n 4 •High quality D/FSA •Enlarges to supply dural vascular malformation / neoplasm Inferolateral trunk • Lateral mainstream artery • Arises – inferolaterally from c4 segment • Supplies – • CN 3,4,6 • gasserian ganglion CN5 • cavernous sinus dura • Anastomose with br of internal maxillary artery . Collaterals b/w ECA N ICA • DSA – lateral view • Enlarged – vascular neoplasm / malformation / collaterals to ECA
  58. 58. •Between proximal , distal dural rings of cavernous sinus •Ends as ICA enters subarachnoid space near anterior clinoid process •No important branches •Unless OA arises within CS
  59. 59. Extends from distal dural ring at superior clinoid to just below posterior communicating artery (PCoA) origin Branches – •Opthalmic artery •Superior hypophyseal artery CECT Anterior clinoid process C6
  60. 60. Origin – • Intradural •Antero-superior ICA • Medial to anterior clinoid process Course – Anterior throu optic canal Below optic nerve Crosses superomedially over the nerve Supply -globe Gives off ocular , lacrimal , muscular branches •Anastomose with ECA
  61. 61. Mid arterial phase DSA Lateral view MRA Lateral DSA
  62. 62. Arises from posteromedial aspect of supraclinoid ICA Course – across the ventral surface of optic chaisma Terminates- pituitary stalk and gland Supplies – anterior pituitary , Infundibulum , optic nerve and chaisma Anastomose - with hypophyseal branch from the contralateral ICA forms plexus – superior hypophyseal plexus DSA – usually not visualized if not enlarged
  63. 63. Unruptured superior hypophyseal aneurysm Normally SHA not easily seen
  64. 64. •Extends from below PCoA to terminal ICA bifurcation. •Passes between optic and occulumotor nerve. C7 segment branches Posterior communicating artery Anterior choroidal artery Lateral DSA AChA PCoA 3D CTA
  65. 65. •Arises – posterior aspect of intradural ICA just below anterior choroidal artery •Course – posterolaterally above the occulumotor nerve to join posterior cerebral artery •Branches – anterior thalamoperforating arteries •Supplies – optic chiasma, pituitary stalk , thalamus , hypothalamus. Lateral late arterial DSA MRA
  66. 66. 1. Hypoplasia – 1/3 rd cases 2. Persistence of embryonic configuaration ( fetal origin of posterior cerebral artery ) 20 – 25% 3. Junctional dilatation at PCoA origin ( infundibuli ) 6 % 4. PCoA duplication/ fenestraion – rare PCoA fenestration PCoA hypoplasia
  67. 67. • PCoM is larger than P1 segment of PCA and supplies the bulk of PCA . PCA therefore is a part of anterior circulation • Non fetal PCA , PCoM lies superomedial to CN3 • Fetal PCA, PCoM lies superior lateral to CN 3 •Hypoplastic / absent P1 segment •PCoA is same diameter as I/L PCA
  68. 68. •Infundibular dilatation of PCoA at origin from ICA- 5- 15% •Should be 2 mm or less •Funnel shaped , conical •PCoA arises from apex
  69. 69. Within suprasellar cistern under optic tract Posteromedially around temporal lobe uncus Cisternal Course : Intraventricular course: AChA angles sharply laterally Enters choroidal fissure of temporal bone Abrupt kink – plexal point AChA-origin few mms above PCoA Cisternal segment Intraventricular segment
  70. 70. Supplies Choroidal plexus of lateral ventricle ( temporal horn and atrium ) Optic tract and cerebral peduncle Uncal and parahippocampal gyri of temporal lobe . Thalamus and posterior limb of internal capsule. Anastamoses – with AChA segments and LPChA and MPChA Variants – uncommon Aplasia rare Hypoplasia – 3 % Hyperplasia – 2.3 % AP mid arterial DSA AP Late arterial DSAMRA lateral view Choriodal blush
  71. 71. Terminal ICA Anterior cerebral artery Middle cerebral artery 3D CTA MCA ACA ICA 3D CTAMid arterial phase DSA
  72. 72. 2ICAs Horizontal segment A1 of both ACAs 2 Posterior communicating arteries Anterior communicating artery Horizontal segment P1 of both PCA s Basilar artery
  73. 73. Interconnected arterial polygon Location – surrounds ventral surface of diencephalon, adjacent to optic nerve and tracts, inferolateral to hypothalamus Anterior circulation 2 B/L ICAs 2ACAs Unpaired ACoA anteriorly Posterior circulation Basilar bifurcation from merged VAs 2PCAs from BAs B/L PCoAs
  74. 74. 3DVRT CTA MRA CT MRA 1. A1 2. P1 3. PCoA 4. ACoA
  75. 75. Cerebral angiography- single injection Contrast enhanced CT – maximum intensity projection Invasive MRA- time of flight sequence with multiple overlapping thin slab technique Transcranial Doppler ultrasound Non invasive
  76. 76. • Medial lenticulostriate arteries • Recurrent artery of HeubnerACAs • Perforating branches – hypothalamus , optic chiasma , cingulate gyrus , corpus callosum , fornix • Large vessel – median artery of corpus callosum arises from ACoA ACoA • Anterior thalamoperforating arteriesPCoA • Posterior thalamoperforating arteries • Thalamogeniculate arteries Basilar artery, PCAs Supplies- 1.Optic chiasma and tracts 2.Infundibulu m 3.Hypothala mus 4.Base of brain
  77. 77.  Complete COW –only 20 – 25%  Posterior circle anomalies – 50% anatomy specimens Common variants •Hypoplasia of 1 or both PCoA – 34% •Fetal origin of PCA from ICA
  78. 78. •Hypoplasia or absent A1 ACA segment. •Absent , duplicate or multichannel ACoA – 10-15%
  79. 79. •Rare – congenital absence of 1 or both ICAs •Common – if 1 ICA absent intrasellar intercommunicating arteries •ICA agenesis – intracranial aneurysm common •ACA- ACoA complex •Infraoptic origin of ACA •Single (azygous) ACA (holoprosencephalies ) •PCoA- PCA- BA complex •Persistent carotid basilar anastomosis Absent ICA
  80. 80.  ICAs develop from 3rd aortic arches , dorsal aortae  Embryonic ICAs divide into cranial,caudal  Cranial divisions – ▪ primitive olfactory , anterior / middle cerebral , anterior choroidal arteries ▪ Anterior communicating artery – forms from coalescence of a midline plexiform network ,it connects developing ACAs  Caudal divisions – ▪ becomes posterior communicating arteries ▪ Supply stems of posterior cerebral arteries.  Paired dorsal longitudinal neural arteries fuse – basilar artery  Developing vertebrobasilar circulation usually incorporates PCAs  Caudal ICA divisions regress forming PCoAs.
  81. 81.  Represent persistent embryonic circulatory patterns  Channels between embryonic aorta (caudal carotid artery) and paired longitudinal neural arteries (form basilar and vertebral arteries ) fail to regress. 1. Primitive persistent trigeminal artery 2. Primitive hypoglossal artery 3. Persistent otic artery 4. Proatlantal intersegmental artery PCoA PTA Otic Hypoglossal Proatlantal intersegmental
  82. 82. •Most common carotid vertebro basilar anastomoses - 0.1- 0.6% •In utero – embryonic trigeminal artery supplies basilar artery before the PCoA and vertebral artery develops •As these vessels enlarge – PTA normally disappears course – arise when ICA exists carotid canal and enters cavernous sinus Runs posterolaterally along trigeminal nerve 41% Crosses over / throu dorsum sella before joining basilar artery Connects ICA to vertebrobasilar system trident shape on lateral DSA
  83. 83. •PCoA is absent •Supply entire vertebrobasilar circulation distal to anastomosis Saltzmann type Ι • Fetal PCA and I/L P1 segment absent • Fill superior cerebral arteries (SCA) with posterior cerebral arteries (PCA ) fills via patent PCoA Saltzmann type ΙΙ •Increased incidence of intracranial aneurysms / malformations •Increased importance in transpenoidal surgery Hypoplastic basilar
  84. 84.  2nd most common- 0.027- 0.26%  .  Intracranial aneurysms  If present – single artery that supplies brain stem and cerebellum Courses thro hypoglossal canal Parallel to CN 12 Connects cervical ICA with basilar artery
  85. 85. Red – PHA Blue – sigmoid sinus Pink – coil mass with basilar tip aneurysm
  86. 86.  Origin – petrous ICA  Course – medially thro internal auditory meatus and joins caudal basilar artery  VA – hypoplastic / absent – POA is the sole arterial supply to basilar artery Basilar artery POA
  87. 87. •Proatlantal infact is occipital artery •C1 segment connection is proatlantal type 1 •C2 connection is proatlantal type 2 • vertebral artery proximal to proatlantal is hypoplastic
  88. 88. ICA Proatlantal intersergmental PIA – suboccipital anastamosis between ECA / cervical ICA and vertebral artery – typically courses between the arch of C1 and occiput

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