The Radiology of Blood supply to the Brain and technique of demonstrating it

1. Radiologic Anatomy of the Blood
Supply to the Brain and MRI
Technique of Demonstrating it.
DR MUSA W. A.
Registrar
02/12/2022
1

2. Outline
• Introduction.
• Arterial Blood Supply.
• Relevant Gross Anatomy
• Radiologic Anatomy
• Venous Drainage.
• Relevant Gross Anatomy
• Radiologic Anatomy
• MRI technique of demonstrating the blood supply to the Brain.
• Conclusion.
• References.
2

3. Introduction
• The arterial supply of the CNS is derived from the internal carotid and
vertebral arteries referred to an anterior and posterior circulation
respectively.
• The anastomosis between the right and left internal carotid arteries,
their branches and the posterior cerebral arteries (of the
vertebrobasilar system) forms the circle of Willis
• All arteries entering the surface of the brain are end arteries.
3

4. Introduction
• The cerebral venous system do not follow the same courses as the
arteries that supply it.
• Generally, venous blood drains to the nearest venous sinus, except in
the case of that draining from the deepest structures, which drain to
deep veins which in turn drain to the venous sinuses
• The intracerebral veins are valveless, thin walled and without muscle.
4

5. Arterial Blood Supply to the Brain
5

6. Relevant Gross Anatomy
• The common carotid arteries arises from the aortic arch(left) and
brachiocephalic trunk (right), bifurcating between C3 to C5 to give internal
carotid arteries and external carotid arteries.
• The internal carotid artery (ICA) follows a tortuous course (6 bends) after
entering the carotid canal (petrous bone). Has 7 segments (Bouthillier
classification)
• C1: cervical segment
• C2: petrous (horizontal) segment
• C3: lacerum segment
• C4: cavernous segment
• C5: clinoid segment
• C6: ophthalmic (supraclinoid) segment
• C7: communicating (terminal) segment
6

7. 7

8. Relevant Gross Anatomy
• The internal carotid artery has
the following branches:
• C1: cervical segment, none
• C2: petrous (horizontal) segment
• Caroticotympanic artery
• Vidian artery (aka Pterygoid artery)
• C3: lacerum segment, none
• C4: cavernous segment
• Meningohypophyseal trunk
• Inferolateral trunk (cavernous a.)
• Capsular arteries (of McConnell)
(variable) – sellar region
8
• C5: clinoid segment, none
• C6: ophthalmic (supraclinoid)
segment
• Ophthalmic artery (1st large branch)
• Superior hypophyseal artery
• C7: communicating segment
• Posterior communicating
artery(PCOM)
• Anterior choroidal artery
• Anterior cerebral artery (ACA)
• Middle cerebral artery (MCA)

9. 9

10. Relevant Gross Anatomy
• The middle cerebral artery (MCA) is the larger of
the 2 terminal branches of the ICA.
• Course: passes laterally and ends as branches on
the insula, the overlying opercula and most of the
lateral surface of the cerebral hemisphere.
• Segments:
• M1: sphenoidal or horizontal segment
• M2: insular segment
• M3: opercular segment
• M4: cortical segment
• Branches: Medial and lateral striate (or
lenticulostriate) arteries; Cortical branches
(frontal, parietal, angular and superior temporal
branches).
10

11. Relevant Gross Anatomy
• The anterior cerebral artery is the smaller of the
2 terminal branches of the ICA.
• Course: passes anterosuperior to the optic
chiasm, winding around the posterosuperior
surface of the genu of the corpus callosum.
• Segments:
• A1: horizontal or pre-communicating segment
• A2: vertical, post-communicating or infracallosal
segment
• A3: precallosal segment
• A4: supracallosal segment
• A5: ​postcallosal segment
• Branches: Recurrent artery (of Heubner), ACOM,
Orbitofrontal a., Frontopolar a., Callosomarginal
a., Pericallosal a., Central branches.
11

12. Relevant Gross Anatomy
• The vertebral artery is a branch of the 1st part
of the subclavian artery. Lt > Rt in 80% of cases.
Lt may arise from aortic arch in 5%.
• Course: ascends posterior to the ICA in the
transverse foramina of C6 – C2 cervical
vertebrae. (Variant - C4, C5, C7).
• It has numerous small branches. Major:
Radicular/spinal branches (ant & post) and
posterior inferior cerebellar artery (PICA).
• Termination: combines with the contralateral
vertebral artery to form the basilar artery.
• Key relationships: posterior to the ICA; ascends
anterior to the roots of the hypoglossal nerve
(CN XII).
12

13. Relevant Gross Anatomy
• The basilar artery is formed by the confluence of the 2 vertebral arteries.
• Course: ventral to pons in the pontine cistern.
• Branches: numerous to cerebellum and pons.
• Anterior inferior cerebellar artery (AICA)
• Labyrinthine artery (variable origin; more commonly a branch of AICA)
• Pontine arteries
• Superior cerebellar artery (SCA)
• Termination: division into the two posterior cerebral arteries (PCAs).
• Variants: basilar artery fenestration; persistent carotid-basilar artery
anastomoses.
13

14. Relevant Gross Anatomy
• The posterior cerebral arteries (PCAs) are the 2
terminal branches of the basilar artery.
• Course: from basilar towards occiput.
• Segments:
• P1: pre-communicating segment
• P2: post-communicating segment
• P3: quadrigeminal segment
• P4: cortical segment
• Branches: Small branches to cerebral peduncle,
the posterior thalamus, the medial geniculate
body and the quadrigeminal plate;
Thalamostriate arteries; Medial and lateral
posterior choroidal arteries; Cortical branches –
posterior temporal branch and internal occipital
branch (calcarine a. & parieto-occipital a.)
14

15. Relevant Gross Anatomy
• The circle of Willis is an arterial polygon (heptagon) formed by the
anastomosis of the branches of the internal carotid and vertebral
arterial systems
• Seen around the optic chiasm, infundibulum of the pituitary stalk and
in the suprasellar and interpeduncular cisterns
• Comprises of
• Anterior circulation: Rt and Lt ICA, Rt and Lt ACA and ACOM
• Posterior circulation: PCOM, PCA and basilar artery.
• MCA not part of circle of Willis.
15

16. 16

17. 17

18. 18

19. 19

20. Radiologic Anatomy
• Radiological anatomy of the arterial blood supply to the brain can
best be described using the following imaging modalities
• Angiography
• MRA
• CTA
• Conventional (including DSA)
• Ultrasound
• Nuclear studies (radionuclide angiography).
• Plain radiograph
20

21. Radiologic Anatomy –
Conventional Angiography
• Gold standard for evaluating arterial blood supply.
• Contrast is injected into the target artery (e.g. ICA ) via a catheter
placed in situ through Seldinger technique.
• The vessels appear as contrast filled (radio-opaque) tubular branching
structures seen extending from the neck through the base of the skull
to the peripheries of the cerebral hemispheres.
• The vessels taper peripherally.
• DSA: vessel appear “dark” with radiopaque structures (e.g. bones)
digitally removed.
• Draw back: invasive
21

22. Radiologic Anatomy –
Conventional Angiography
• On the lateral view of the internal carotid angiogram, the sharp
angulation of the branches of the MCA at the upper and lower
borders of the insula approximately form a triangle, which is called
the sylvian triangle
• The uppermost point of these vessels as seen on AP views is called
the sylvian point. The sylvian vessels and the sylvian points should
appear symmetrical on both sides.
22

23. 23
(A) Internal Carotid Angiogram
(AP view)
1. Internal carotid artery in the
neck 2. Petrous part of the
internal carotid artery (carotid
canal) 3. Cavernous part of the
internal carotid artery 4.
Carotid siphon 5. Intracranial
part of the internal carotid
artery 6. Ophthalmic artery 7.
A1 segment of the anterior
cerebral artery 8. Pericallosal
artery 9. Callosomarginal
artery 10. Middle cerebral
artery 11. Anterior choroidal
artery 12. Lenticulostriate
arteries: medial and lateral 13.
Sylvian point 14. Posterior
parietal artery15. Angular
artery 16. Posterior temporal
artery
(B)Internal Carotid Angiogram (Lateral view)
1. Internal carotid artery in the neck 2. Internal carotid artery in the petrous bone 3. Internal carotid artery in the cavernous
sinus 4. Carotid siphon 5. Intracranial part of the internal carotid artery 6. Ophthalmic artery 7. Anterior cerebral artery 8.
Middle cerebral artery 9. Anterior choroidal branches 10. Callosomarginal artery 11. Pericallosal artery

24. 24

25. 25
(A) DSA of the left vertebral
artery
1. Left vertebral artery 2. Right
vertebral artery (reflux of
contrast) 3. Posterior inferior
cerebellar artery 4. Anterior
inferior cerebellar artery 5.
Basilar artery 6. Superior
cerebellar artery 7. Posterior
cerebral artery 8.
Thalamoperforate branches 9.
Internal occipital artery 10.
Posterior temporal artery 11.
Calcarine branch of the internal
occipital artery 12. Parieto-
occipital branch of the internal
occipital artery
(B) DSA of the left vertebral artery
1. Vertebral artery 2. Posterior inferior cerebellar artery (PICA) – anterior medullary
segment3. Lateral medullary segment of PICA 4. Posterior medullary segment of PICA 5. Inferior tonsillar loop of PICA 6. Supratonsillar loop of PICA 7. Retrotonsillar segment of PICA 8. Vermis
branch of PICA 9. Tonsillohemispheric branch of PICA 10. Hemispheric branch 11. Superior cerebellar artery 12. Posterior cerebral artery 13. Posterior communicating artery 14. Thalamoperforate
branches of posterior cerebral artery 15. Medial posterior choroidal branches 16. Lateral posterior choroidal branches (arise distal to 15 ) 17. Superior vermian branches of 11
18. Internal occipital branch of 12
19. Parieto-occipital artery 20. Calcarine artery

26. Radiologic Anatomy - MRA
• Arterial vessels usually appear as signal void structures on T1W and
T2W MRI images.
• MRA sequences: Dark blood vs Bright blood
• Bright Blood: contrast vs non-contrast( TOF, Phased contrast)
• Arterial vessels show as branching tubular (3D T0F plane), linear, curvilinear or oval (axial
plane) hyperintense structures extending from the neck through the base of skull to the
peripheries of the cerebral and cerebellar hemispheres, tapering towards the periphery.
• Dark Blood: FSE, IR, SWI
• Same but hypointense.
26

27. Radiologic Anatomy - MRA
Axial scans
• At level of the Pons:
• basilar artery is visible as oval hyperintense structure in the pontine cistern between
the clivus and the pons,
• It may deviate from the midline away from the side of the dominant vertebral artery.
• At the level of the suprasellar cistern:
• some of the vessels of the circle of Willis, particularly the PCAs is seen as a
curvilinear hyperintense structure(s) as they wind around the midbrain.
• The ACAs and its branches may be seen in the interhemispheric fissure
while branches of the MCA may be identified in the sylvian fissure – linear
hyperintense structures.
27

28. 28
MR TOF angiographic images of the brain in axial plane at the level of the pons and midbrain

29. 29
MR TOF 3D VR
angiographic image of the
cerebral circulation(viewed
from above) showing the
circle of Willis.

30. 30
Low-dose contrast enhanced TOF MR
angiography. A small dose of intravenously
administered gadolinium (0.5 ml) improves
the visualization of the distal intracranial
arterial branches. (Limited venous
enhancement through the basal veins is
visible).

31. Radiologic Anatomy - MRA
• Variant of Circle of Willis
• In 90% complete, however in 60% has variation of at least one vessel, enough
to affect its role as a collateral route.
• The commonest variants are:
1. Hypoplasia of one or both posterior communicating artery (PCOM)
2. Large posterior communicating artery with origin of PCA from the ICA with
absent/hypoplastic P1 segment = ‘ fetal ’ PCOM
3. Hypoplastic proximal segment of the anterior cerebral artery.
4. Hypoplastic anterior communicating artery
5. Anterior cerebral artery may be fused as a single trunk, an azygos anterior
cerebral artery
31

32. 32

33. 33

34. Radiologic Anatomy – CT Angiography
• With IV contrast medium and appropriate timing, exquisite (axial,
coronal/sagittal reformatted and 3D VR) images can be obtained of
blood vessels during any particular vascular phase.
• The vessels appear as contrast filled (hyperdense) linear or curvilinear
branching structures on axial and coronal/sagittal reformatted
images.
• On 3D VR: tubular branching hyperdense structures
34

35. 35
Serial
Axial CT
angiogra
phic
images
of the
brain.

36. 36
Serial Coronal reformatted CT
angiographic images of the brain.
Intracranial circulation is
unremarkable with no vascular
malformation, aneurysm or
stenosis. No branch occlusion.
Dominant left vertebral artery.
Hypoplastic / absent right A1.

37. 37
CT 3D VR Angiogram of the common carotid
and the vertebral arteries.

38. 38
Coronal reformatted CT angiographic
image of the brain

39. Radiologic Anatomy – Ultrasonography
• USS examination of the neonatal brain(transfontanelle) and adults
brain(80%, trans-temporal) can be done.
• Vessels appear as tubular branching structures with hypoechoic
lumen and echogenic walls (due to collagen sheath) that demonstrate
color flow on doppler.
• on real-time transfontanelle USS studies:
• Pulsation of the middle cerebral vessels can be seen in the insula.
• The ACA can be seen in the inter- hemispheric fissure on coronal scanning
• The pericallosal and callosomarginal arteries may be identifiable on
parasagittal scanning.
39

40. Radiologic Anatomy – Ultrasonography
Transcranial Doppler
• Referred to as the doctors stethoscope of the brain.
• Indications include: Detection of vasospasm, detection of right to left
shunt, monitoring flow velocities for prevention of stroke.
• The four commonly used acoustic windows in adults are
• Temporal ( MCA,ACA,PCA PCOM)
• Orbital(Ophthalmic artery and ICA)
• Suboccipital(VA and BA)
• Submandibular( Distal cervical ICA)
40

41. 41

42. 42
Sagittal grey scale transfontanelle USS image with doppler
interrogation.

43. 43
Coronal grey scale
transfontanelle USS
image with doppler
interrogation.

44. 44
Grey scale TCD USS
image obtained via
the temporal acoustic
window.

45. 45
Grey scale
TCD USS
image
obtained via
the sub-
occipital
acoustic
window.

46. Radiologic Anatomy – Ultrasonography
• Normal spectral waveform is seen as a sharp systolic upstroke and
stepwise deceleration with positive end-diastolic flow.

47. Radiologic Anatomy – Plain Radiography
• Arteries are not visible unless calcified.
• This appears as linear or curvilinear opacities of calcific densities in
the region of the vessel wall.
• This occurs most commonly in the carotid siphon near the pituitary
fossa.
47

48. 48
Lateral
Neck
radiograph

49. Radiologic Anatomy – Nuclear Studies
Radionuclide cerebral angiography
• Brain scans with diffusible tracers, outline vascular structures within
the cranium.
• During the arterial phase in the AP position, a five-pointed star
pattern is formed by the two carotid arteries, the two MCAs and the
two ACAs, which are superimposed upon each other
49

50. Venous Drainage of the Brain
50

51. Relevant Gross Anatomy
• The Cerebral venous system may be
divided into the following sections:
1. Dural venous sinuses
• Large low-pressure veins within the
folds of dura – between fibrous dura
and endosteum.
• Except the inferior sagittal and the
straight sinuses which are between
two layers of fibrous dura.
• They are valveless and run alone
• They receive blood from the brain and
the skull (diploic veins) and
communicate with veins of the scalp
and face (emissary veins)
51
• Unpaired
• Superior sagittal sinus
• Inferior sagittal sinus
• Straight sinus
• Occipital sinus
• Intercavernous sinus
• Paired
• Transverse sinus
• Sigmoid sinus
• Superior petrosal sinus
• Inferior petrosal sinus
• Cavernous sinus
• Sphenoparietal sinus
• Basilar venous plexus

52. Relevant Gross Anatomy
2. Cerebral veins (Superficial vs Deep)
a) Superficial veins
• They are very variable.
• They drain to the nearest dural sinus – the superolateral surface of the
hemisphere drains to the superior sagittal sinus and the posteroinferior drains
to the transverse sinus.
• Named veins are:
The superior anastomotic vein (of Trolard)
The inferior anastomotic vein (of Labbé)
The superficial middle cerebral vein
52

53. 53

54. Relevant Gross Anatomy
2. Cerebral veins (Superficial vs Deep)
b) Deep veins
• Several veins unites to form the internal cerebral vein on both side. The
largest are the choroid vein , the septal vein and the thalamostriate vein.
Point of union = venous angle
• Other deep veins are:
The great cerebral vein (of Galen) – single short thick vein behind splenium.
The basal vein (of Rosenthal) – union of 3 veins: the anterior cerebral vein,
the deep middle cerebral vein and the striate veins.
54

55. Relevant Gross Anatomy
Veins of the Posterior Fossa
• Anterior pontomesencephalic vein
• Posterior mesencephalic vein
• Precentral cerebellar vein
• Superior vermian vein
• Inferior vermian veins
• Pontine veins
• Inferior medullary veins
55

56. 56

57. Radiologic Anatomy
• Discussed under the following radiologic modality
• Angiography
• MR Venography
• Angiography (venous phase)
• CT and MRI
• Plain Radiography
57

58. Radiologic Anatomy – Angiography
MR Angiography
• MR venography is the primary non-invasive method of demonstrating
the cerebral veins and the venous sinuses – branching and/or straight
hyperintense structures.
• A 2D TOF technique is used, which is most sensitive to flow
perpendicular to the imaging slice.
• Coronal scans are most useful for evaluation of the sagittal sinuses
and the internal cerebral veins
• Limited for evaluation of the vertical posterior part of the superior
sagittal sinuses and the sigmoid and petrous sinuses.
58

59. 59

60. 60

61. Radiologic Anatomy – Angiography
Angiography in Venous Phase
• Superficial veins fill before deep veins and frontal veins before posterior
veins
• Of the superficial veins the superior or inferior anastomotic vein is often
visualized, but both are seldom seen on one angiogram.
• The deep veins are more constant than the superficial veins and before the
widespread use of CT were used to visualize the ventricular system, with
the thalamostriate vein indicating the size of the lateral ventricle and the
internal cerebral veins indicating the position of the roof of the third
ventricle Similarly, a change in position of other deep veins may indicate
the presence of a mass lesion nearby
61

62. 62

63. Radiologic Anatomy – MRI and CT
• The tentorium and falx are seen as relatively hyperdense structures
on CT owing to the venous sinuses that they enclose.
• Venous sinuses may also be seen at the internal occipital
protuberance
• A high division of the superior sagittal sinus may occur as an unusual
normal variant and should not be mistaken for sinus thrombosis
• On axial imaging, at the level of the midbrain the posterior
mesencephalic vein may be seen winding around the upper midbrain
In higher slices, the posterior end of the internal cerebral veins and
the great cerebral vein may be seen in the quadrigeminal cistern
63

64. Radiologic Anatomy – Plain Radiography
• On skull radiography
• The course of the venous sinuses can be seen where they groove the
inner plate of bone
• The arachnoid granulations may also indent the skull and show as
lucencies on each side of the superior sagittal sinus on the skull
radiograph.
64

65. 65

66. MRI Technique of Demonstrating the
Blood Supply to the Brain – Magnetic
Resonance Angiography (MRA)
66

67. 67

68. Method
• MRA of brain is used to assess abnormalities in the blood supply system of
brain
• It encompasses several MRI based imaging techniques for studying the
arterial and venous systems.
• 3-dimensional (3D) time-of-flight (TOF) MRA is the most common
technique used to assess the arterial blood supply system of brain
• Benefits:
• Non-invasive
• Lacks ionizing radiation exposure
• A non-contrast examination
• Ability of high-resolution volumetric images (MIP)
• Higher signal-to-noise and shorter imaging times
68

69. Method
Time-of-flight (TOF)
• These techniques derive contrast between stationary tissues and flowing
blood by manipulating the magnitude of the magnetization.
• The magnitude of magnetization from the moving spins is very large
compared to the magnetization from the stationary spins which are
relatively small.
• This leads to a large signal from moving blood spins and a diminished signal
from stationary tissue spins.
• Time of flight (TOF) utilizes the longitudinal magnetization vector for
imaging.
• The 3D acquisition allows for thinner slices with smaller voxel size (0.6-
1mm).
69

70. Indication
• Aneurysm, Stroke, Vasospasm, Vasculitis
• Internal Carotid Artery Occlusion and Stenosis
• Cerebral Artery Occlusion and Stenosis
• Basilar Artery Occlusion and Stenosis
• Arteriovenous malformation (AVM)
• Atherosclerotic Disease
70

71. Contra-indication
• Any electrically, magnetically or mechanically activated implant (e.g.
cardiac pacemaker, insulin pump biostimulator, neurostimulator,
cochlear implant, and hearing aids)
• Intracranial aneurysm clips (unless made of titanium)
• Pregnancy (risk vs benefit ratio to be assessed)
• Ferromagnetic surgical clips or staples
• Metallic foreign body in the eye
• Metal shrapnel or bullet
71

72. Equipment
• MRI machine
• Contrast medium: not required for TOF
72

73. Patient Preparation
• A satisfactory written consent form must be taken from the patient
before entering the scanner room
• Ask the patient to remove all metal objects including keys, coins,
wallet, cards with magnetic strips, jewellery, hearing aid and hairpins
• If possible provide a chaperone for claustrophobic patients (e.g.
relative or staff )
• Offer earplugs or headphones, possibly with music for extra comfort
• Explain the procedure to the patient
• Instruct the patient to keep still
• Note the weight of the patient
73

74. Technique
PATIENT POSITIONING
• Head first supine
• Position the head in the head coil and immobilise with cushions
• Give cushions under the legs for extra comfort
• Centre the laser beam localiser over the glabella
74

75. 75

76. Technique
PROTOCOLS, PARAMETERS AND PLANNING
• Localiser
• A three plane localiser is taken in the beginning to localise and plan the
sequences.
• Localizers are normally less than 25sec T1 weighted low resolution scans.
76

77. 77

78. Technique
PROTOCOLS, PARAMETERS AND PLANNING
• T2 tse axial
• Plan the axial slices on the sagittal plane; angle the position block parallel to
the genu and splenium of the corpus callosum.
• Slices must be sufficient to cover the whole brain from the vertex up to the
line of the foramen magnum.
• Check the positioning block in the other two planes.
• An appropriate angle must be given in coronal plane on a tilted head
(perpendicular to the line of 3rd ventricle and brain stem).
78

79. 79

80. Technique
PROTOCOLS, PARAMETERS AND PLANNING
• 3D time-of-flight (TOF)
• Plan the axial 3D block on the sagittal plane; angle the position block parallel
to the genu and splenium of the corpus callosum.
• Slices must be sufficient to cover the whole Circle of Willis from the corpus
callosum up to the line of the foramen magnum.
• Check the positioning block in the other two planes. An appropriate angle
must be given in coronal plane on a tilted head (perpendicular to the line of
3rd ventricle and brain stem).
• Using saturation bands over the axial block will reduce the venous
contamination of the images.
80

81. 81

82. Technique
PROTOCOLS, PARAMETERS AND PLANNING
• Maximum intensity projection (MIP)
• MIP is the most commonly used post processing technique in MRI vascular
studies.
• MIP reconstructs a 2D projection image from 3D data by a ray tracing
algorithm, which produces an image of white pixels representing the highest
intensity signal in that location within the examined volume.
82

83. 83

84. Aftercare
• Usually no aftercare required.
• If sedative is used, avoid driving and operating heavy machine as well
as drinking alcohol for 24hrs.
84

85. Complication
• From MRI machine: None, if contraindication is ruled out.
• From use of contrast (Not required for TOF!)
• Local irritation from IV access
• Allergic reaction (mild to severe) – very rare
• Nephrogenic Systemic Fibrosis
85

86. Complication
• Other documented Complications
• Thermal: Skin reddening, blisters, warming, or heating sensation;
• Acoustic: Hearing loss and/or tinnitus;
• Image Quality: Lost exams, inadequate images, or images attributed to the incorrect
patient;
• Projectile: Objects were pulled into or attracted to the main static magnetic field;
• Mechanical: Falls, crush injuries, broken bones, cuts, or musculoskeletal injuries;
• Peripheral Nerve Stimulation: Nerve or muscle stimulation or patients experiencing
tingling, twitching, or involuntary movements;
• Miscellaneous: Adverse event that can not be classified in any of the other
categories;
• Unclear: Insufficient information was available to make conclusions regarding the
connection to the MRI exam.
86

87. Conclusion
• Good knowledge of the gross and radiologic anatomy of the blood
supply to the brain is essential for ruling out pathology of vascular
origin.
87

88. References
• Ryan Stephanie, et al, Anatomy for Diagnostic Imaging. 3rd edn, Saunders Elsevier 2011; pg 80 –90.
• Özsarlak, Özkan & Van Goethem, Johan & Maes, Menno & Parizel, Paul. (2005). MR angiography of the
intracranial vessels: Technical aspects and clinical applications. Neuroradiology. 46. 955-72. 10.1007/s00234-
004-1297-9.
https://www.researchgate.net/figure/Low-dose-contrast-enhanced-time-of-flight-MR-angiography-A-small-
dose-of-intravenously_fig1_8148360
• New Techniques in CT Angiography. Michael M. Lell, Katharina Anders, Michael Uder, Ernst Klotz, Hendrik
Ditt, Fernando Vega-Higuera, Tobias Boskamp, Werner A. Bautz, Bernd F. Tomandl
https://doi.org/10.1148/rg.26si065508
• De Leucio A, De Jesus O. MR Angiogram. [Updated 2022 Jul 25]. In: StatPearls [Internet]. Treasure Island (FL):
StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK558984/
• https://appliedradiology.com/articles/comparison-of-magnetic-resonance-angiography-and-computed-
tomographic-angiography
• Radiopedia
88

89. Thank you for Listening
89