The skull and the brain

Introduction and Imaging methods

1) Text

a) Superior demonstration of anatomy and pathology by MRI

b) Skull radiography for skull fractures

c) MRI better than CT in the 3 orthoganal planes (axial, coronal and sagittal)

d) Middle and posterior fossa on MRI don’t have streak artefacts of CT

e) MRI based on difference on proton density. T1W Grey matter is darker, White Matter is lighter. T2W reversed.

f) CT white matter is darker than Grey Matter

g) Myelinated tracts with MRI

i) Fornix and Anterior Commissure, Heavily myelinated fiber tracts, hypointense appearance on T2W

ii) Corticospinal tract in the Internal Capsule, lower weighted myelin density,

h) Globus Pallidus, Substantia Nigra, and Red Nucleus are hypointense on T1W and T2W because of iron deposition

i) IV Iodinated contrast on CT enhances blood in the cranial arteries, veins and dural sinuses. Also the vascular choroidal plexus and the pituitary gland and the infundibulum

j) Gadolinium DTPA is used on MRI enhancement

i) Arteries fast flowing and are signal void

ii) Sluggish veins are hyperintense

iii) Pituitary, Infundibulum, cavernous sinus and dura enhance with gadolinium

k) Angiography

i) MR Angiography is non-invasive

ii) CT needs contrast

iii) Catheter Angiography allows visualisation of bone and vasculature in isolation. Mainly from the femoral artery (also the brachial artery).

2) Axial MRI hypointensity of substantia nigra and red nucleus is due to iron deposition

The Skull

Osteology of the skull

1) Text

1) Skull base

a) Occipital, sphenoid and temporal bones

2) Frontal and Temporal plus 3 bones of the base = 5 bones

3) Sutures fuse in adolescence, and raised Intracranial Pressure presents with head enlargement

4) Fontanelle

a) Anterior or Bregma, 2^nd Year

b) Lambda, 2^nd Month

c) Pterion, 3-4 Months

5) Extradural and Subdural hematomas cross sutures

6) SCALP – subcutaneous fat is high signal on MRI

7) Emissary veins, transverse the skull vault

a) Rich craniocerebral anastomosis – spread of infection

b) Collateral pathway if there is venous sinus occlusion

8) Venous Lacunae of Parietal bone

a) Receive arachnoid (pacchonian) granulations – reabsorb CSF

b) Lacunae cause thinning of the parietal bone

9) Two halves of the frontal bone fuse at 5 years, Metopic suture

10) Sphenoid Bone, body and greater and lesser wings and peterygoid plates

a) Sphenoid air sinuses, paired and asymmetrical

b) Pituitary fossa and the posterior clinoid process

c) Anterior Clinoid process

d) Tuberculum Sellae between b and c

e) Foramina

i) Ovale

(1) CN V3 – Mandibular Division of the trigeminal nerve and

(2) Accessory meningeal artery

ii) Spinosum

(1) Middle Meningeal Artery and Vein

iii) Rotundum

(1) CN V2 – Maxillary division of the trigeminal nerve

iv) Other foramina

(1) Vidian or pterygoid canal (medial to Foramen Rotundum)

(a) Artery of the pterygoid canal

(2) Versalius (Median to Foramen Ovale)

(a) Emissary Vein

v) Foramen Lacerum

(1) Small arteries and nerves

(2) Carotid artery crosses the cranial part

vi) Larger Basil Foramina

11) Temporal Bone

a) Squamous part

b) Zygomatic Part and Zygomatic Arch and Mandibular Condylar Fossa

c) Petromastoid portion

d) Curved Tympanic portion

i) External Auditory Canal

ii) Non-articular part of the mandibular fossa

iii) Styloid process and the

iv) stylomastoid fossa

(1) CN VII

12) Occipital Bone

13) Jugular Foramen lies between the temporal bone and the Occipital bone

1. The normal Skull radiograph

a. Text

i. Lucencies within the vault seen on skull radiography

1. Sutures

2. Vascular Impressions

3. Normal Thinning of the temporal squame, and parietal bone

4. Parietal foramina

5. Pacchionian depression

6. Pneumatisation

ii. Calcifications within vault seen on skull radiograph

1. Pineal gland

2. Habenular commissure

3. Choroid plexus

4. Petroclinoid and interclinoid ‘ligaments’

5. Dura

b. Frontal Skull Radiograph

i. Sagittal suture

ii. Dural Calcification

iii. Frontal Sinus

iv. Crista Galli

v. Cribriform plate

vi. Innomate Line

vii. Anterior Clinoid process

viii. Zygomatic bone

ix. Maxilla

x. Superior Orbital Fissure

xi. Greater Wind of the Sphenoid

xii. Lesser Wing of the Sphenoid

xiii. Lambdoid suture

c. Lateral Skull Radiograph

i. Anatomical Features Lateral Skull Radiograph

1. Frontal Sinus

2. Floor of the anterior cranial fossa

3. Orbital Roof

4. Cribiform Plate

5. Sphenoid sinus

6. Anterior Cliniod process

7. Lamina Dura of the Pituitary fossa

8. Dorsum Sella

9. Clivis (Basiocciput and basisphenoid)

10. Mandibular Condyle

11. Frontal, Parietal, Occipital and Temporal Bone

12. Pterion

13. Zygomatic recess of the maxillary antra

ii. Lateral skull radiograph showing multiple lucencies due to venous lakes and arachnoid granulations. Normal thinning of the parietal bone

iii. Metopic Suture on PA and Towne’s skull views

d. CT Skull Base

i. Axial images

1. Maxillary antrum

2. Pterygomaxillary fissure

3. Zygoma

4. Foramen lacerum

5. Foramen Ovale

6. Foramen Spinosum

7. Carotid Canal

8. Jugular Foramen

9. Mandibular Condyle

10. Sphenoid Sinus

11. Superior Orbital Fissure

12. Pterygotympanic tube

ii. Coronal Images

1. Anterior clinoid process

2. Foramen rotundum

3. Posterior Clinoid process

4. Videan or pterygoid canal

5. Foramen ovale

e. Skull radiograph, the basal or submentovertical projection

i. Nasal septum

ii. Lateral wall of the orbit

iii. Lateral wall of the antrum

iv. Foramen ovale

v. Foramen Spinosum

vi. Mandibular Condyle

vii. Internal auditory canal

viii. Anterior arch of atlas

ix. Odontoid process

f. Axial CT of the basisphenoid synchondrosis. The metopic suture is also identified.

g. The hypoglossal or anterior condylar canal

i. Axial CT – foramen magnum and the Hypoglossal canal

ii. T2W axial MRI showing the hypoglossal nerve and the vertebral arteries

h. Frontal and Lateral Skull Radiograph showing calcifications of the choroid plexus. Sphenobregmatic sinus is also indicated.

i. Frontal skull radiograph showing pneumatisation of the right anterior clinoid process

j. Lateral skull radiograph

i. Calcification of the petroclinoid ligament

1. Fromposterior clionoid process to the tentorial edge

2. Dural calcification

ii. Calcification of the interclinoid ligament

2. The cerebral envelope

a. Text

i. Dura mater has two layers that enclose the dural sinuses.

1. Outer layer is the periosteum of the inner table (endostium)

2. Inner Layer covers the brain gives rise to the tentorium and falx. The falx may calcify

3. Falx, from the christa Galli to the internal occipital protubarence where it joins the tentorium

4. Tentorium, another double layer of dura,

5. Tentorium Cerebelli, another double fold of dura,

a. Uncus of the hippocampus and the posterior cerebral artery lie above the free edge of the tentorium and are at risk for compression against the tentorial edge with raised Intracranial Pressure (Coning)

6. Falx cerebelli

a. Terminates above the foramen Magnum

b. The Cranial Dura

i. Falx Cerebri

ii. Superior sagittal sinus

iii. Inferior sagittal sinus

iv. Transverse Sinus

v. Straight sinus

vi. Great vein of Galen

vii. Superior Petrosal Sinus

viii. Inferior Petrosal Sinus

ix. Internal Carotid Artery

x. Optic Nerve

xi. Superior Orbital Vein

xii. Anterior Facial Vein

xiii. Petrosal Venous plexus

c. Cranial MRI. Midline T1W sagittal image showing hyperintense (yellow) marrow within an ossified region of the falx

d. Axial CT with intravenous contrast showing the enhancing tentorial margins. Note the dura continues anteriorly to form the cavernous sinus.

Meningeal blood supply and innervations

· Text

1. Middle Meningeal Artery (main) with the carvernous carotid, ophthalmic, and vertebral arteries. Also accessory meningeal artery through foramen ovale.

2. Middle Meningeal Artery

1. is extradural and groove the inner table of the skull with the Meningeal Veins.

2. Supplies the ganglia of the trigeminal and the Facial Nerve

3. The Occipital artery

1. Via the Jugular Foramen and the Condylar canal supply IX, X, XI, XII

4. Innervation of the dura

1. CN V and lower cranial nerves

· Normal development of the brain

1. Text

1. Cerebral Myelination

· MR IR T1W used to asses to progress of myelination in 1^st 6 months

o Optic radiation myelinates at 2 to 3 months

o Then from the Splenium (3/12) to the Genu of the Corpus Callosum (5/12)

o 4/12 Anterior Limb of the Internal Capsule begins

· MR IR T2W is used thereafter

o Myelination is complete at 6/12

o Splenium of the Corpus Callosum is myelinated between 6 and 8 months, Genu at 8 to 11 Months

o Myelination of the Anterior Limb of the Internal Capsule is complete at 11 to 14 months

o Frontal Lobe complete at 14 Months

o Temporal Lobe 14 to 18 Months

o Normal Adult MRI pattern at 2 years

i) External Carotid Angiogram, Lateral projection. There is faint opacification of the internal carotid artery

ii) Normal Term Neonate

(1) Axial IR (T1W) MRI

(2) Axial T2W MRI

iii) Normal Child of 4 years Old

(1) Axial IR (T1W) MRI

(2) Axial T2W MRI

iv) Brainstem

(1) Level of pyramids

(a) Central canal

(b) Pyramid

(d) Dorsum Columns

(2) Level at Foramen Megendie

(a) Vertebral arteries

(b) Preolivary sulcus

(d) Pyramid

(e) Olive

(f) Post-olivary sulcus

(g) Foramen Megendie

(3) Level of the Cerebellum and Forth ventricle

(a) Basilar artery

(b) Inferior cerebellar peduncle

(d) Floor of the Forth Ventricle

(e) Tonsil of the Cerebellum

(f) Nodulus of the Cerebellum

(4) Cerebellum

(a) Basilar Artery

(b) Inferior cerebellar peduncle

(d) Floor of the Forth Ventricle

(e) Nodulus

(f) Tonsil

(5) Cerebellum

(a) Basilar Artery

(b) Inferior cerebellar peduncle

(d) Floor of the Forth Ventricle

(e) Nodulus

(f) Tonsil

(6) Vestibulocochlear Nerve and semicircular canals

(a) Basilar Artery

(b) Cerebellopontine angle cistern

(d) Cochlea

(e) Lateral semicircular canal

(f) IVth Ventricle

(g) Middle Cerebellar peduncle

(7) Trigeminal Nerve and Midbrain

(a) Trigeminal Nerve

(b) Superior cerebellar peduncle

(8) Dorsum Sellae and globes

(a) Dorsum sellae

(b) Oculomotor nerve CNIII

(d) Vermis

(9) Lateral geniculate body

(a) Lateral geniculate body

(b) Ambient cistern

(d) Lateral mesencephalic sulcus

(10) Gyrus rectus

(a) Gyrus rectus

(b) Optic chiasm

(d) Mamillary bodies

(e) Middle cerebral artery in Sylvian fissure

The cerebral parenchyma

1) The brainstem and cranial nerves

a) Text

2) The pons

3) The midbrain

4) The Cerebellum

a) Cerebellum

i) Sagittal T2W Sa

(1) Tectum of the midbrain

(2) Lingula

(3) Central Lobule

(4) Culman

(5) Primary fissure

(6) Declive

(7) Superior Postal fissure

(8) Folium

(9) Horizontal fissure

(10)Tuber

(11)Prepyramidal fissure

(12)Pyramid

(13)Uvula

(14)Tonsil

(15)Nodule

(16)Fourth Ventricle

ii) Coronal

(1) T1W

(a) Colliculi

(b) Superior Cerebellar peduncle

(d) Pons

(e) Middle cerebellar peduncle

(f) Nodule

(2) T2W

(a) Superior posterior fissure

(b) Horizontal Fissure

iii) Inferior aspect of the cerebellum

(1) Tonsil

(2) Uvula

(3) Nodule

(4) Central lobe

(5) Flocculus

(6) Pyramid

5) The diencephalon

a) T1W sagittal section to show the diencephalon

i) Optic chiasm

ii) Lamina terminalis

iii) Rostrum of the Corpus Callosum

iv) Genu of the Corpus Callosum

v) Splenum of the corpus callosum

vi) Habenular Commissure

vii) Pineal Gland

viii) Posterior Commissure

ix) Tectum of the Midbrain

x) Cerebral aqueduct

xi) Forth Ventricle

xii) Infundibulum

xiii) Pituitary gland

xiv) ‘bright’ posterior pituitary

xv) Hypothalamus

xvi) Mamillary body

6) The pituitary gland

a) The pituitary and perisellar region

i) Coronal

(1) Optic tract

(2) Pituitary gland

(3) Cavernous sinus

(4) Oculomotor nerve CN III

(5) Trochlear CN IV

(6) Trigeminal Nerve CN V

(7) Abducent Nerve CN VI

ii) Anterior Clinoid process

(1) Anterior Clinoid process

(2) Oculomotor Nerve CN III

iii) Optic Chiasm

(1) Optic Chiasm

(2) Internal Carotid Artery

(3) Anterior Cerebral Artery

(4) Pituitary stalk

(5) Merckles cave

iv) Sylvian fissure

(1) Internal carotid artery

(2) Sylvian fissure

(3) Sphenoid sinus

v) Oculomotor Nerve and Lateral ventricles

(1) Optic chiasm

(2) Infundibulum

(3) Pituitary gland

(4) Oculomotor Nerve CN III

(5) Branches of Trigeminal Nerve CN V

(6) Internal Carotid Artery

vi) Pituitary gland

(1) Pituitary gland

(2) Internal carotid artery

(3) Petrosal vein of Dandy

vii) Infundibulum

(1) Middle cerebral artery

(2) Suprasellar cistern

(3) Infundibulum

(4) Posterior cerebral Artery

b) Ectopic posterior pituitary gland within the pituitary salk – T1W Sagittal MRI Scan

7) The Basal Ganglia

a) Putamen

b) Globus Pallidus

c) Body of the caudate nucleus

d) Insula

e) Claustrum

f) Head of the caudate nucleus

g) Internal capsule (note the striate appearance)

h) Lentiform nucleus

i) Head and Body of the Caudate Nucleus

8) The motor pathways

9) The cerebral hemispheres

a) Medial Cortical Gyrus

i) Medial Frontal Gyrus

ii) Paracentral Lobe

iii) Precuneus

iv) Cuneus

v) Calcarine Sulcus

vi) Parahypocampal gyrus

vii) Medial occipitotemporal gyrus

viii) Lateral occipitotemporal gyrus

ix) Uncus

b) Lateral Cortical Gyrus

i) Frontal Gyrus

(1) Superior

(2) Middle

(3) Inferior

(4) Pars triangularis

ii) Central Sulcus

(1) Precentral gyrus

(2) Postcentral gyrus

iii) Parietal

(1) Superior parietal lobe

(2) Inferior Parietal lobe

iv) Parieto-occipital sulcus

v) Temporo-occipital incisures

vi) Temporal Gyrus

(1) Superior Temporal Gyrus

(2) Middle Temporal Gurus

(3) Inferior Temporal Gyrus

c) Insula

i) Parasagittal T1W MRI scan to show the triangular shaped insula

10) The Central sulcus

a) T1W Axial

i) Superior Central Sulcus

ii) Precentral Sulcus

iii) Central Sulcus

b) T1W midline sagittal image

i) Central Sulcus

ii) Marginal Sulcus

iii) Cingulate Gyrus

iv) Corpus Callosum

c) T2W parasagittal image through Sylvian fissure

i) Y-Shaped Sulcus

ii) Precentral Sulcus

iii) Central Sulcus

11) The Limbic System

a) Medial aspect of the cerebral hemisphere showing the limbic system

i) Cingulate gyrus and Cingulum

ii) Dorsal Fornix

iii) Indusium griseum

iv) Septum Pallucidum

v) Column of the fornix

vi) Isthmus

vii) Fimbria of fornix

viii) Hippocampus

ix) Dentate gyrus

x) Parahippocampal gyrus

xi) Uncus

xii) Amygdala nuclear complex

xiii) Uncus

xiv) Mamillary bodies

b) The hippocampus viewed from above

i) Anterior Commissure

ii) Fornix

iii) Fibria

iv) Hippocampus

v) Pes hippocampus arrowed

vi) Temporal horn and hippocampus

c) Limbic lobe

i) Temporal horn of the lateral ventricle

ii) Tail of the caudate nucleus

iii) Choroid plexus

iv) Ammons horn

v) Fibria of the fornix

vi) Dentate gyrus

vii) Subiculum

viii) Hippocampus

ix) Parahippocampus gyrus

x) Temporal horn of the lateral ventricle

xi) Alvius

d) The fornix on coronal MRI

e) Olfactory bulbs

i) Coronal section

ii) Olfactory pathways

The cerebral ventricles, subarachnoid cisterns and related structures

1. The third ventricle

a. Interventricular foramen (Monro)

b. Cerebral aqueduct

c. Third ventricle

d. Forth ventricle

e. Fornix

f. Tela choroidea of third ventricle

g. Thalamus

h. Thelamostriate veins

i. Choroid plexus

j. Basal vein of Rosenthal

k. Vein of Galen

l. Cistern of the velum interpositum

2. The fourth ventricle

3. The subarachnoid cisterns

a. MRI

i. Callosomarginal artery

ii. Pericallosal artery

b. Cisterns

i. Supraoptic recess of the 3^rd ventricle

ii. Callosal Cistern

iii. Cistern of the Velum interpositum

iv. Suprapineal recess

v. Pineal recess of the third ventricle

vi. Superior cerebellar Cistern

vii. Quadrigeminal plate cistern

viii. Cisterna magna

ix. Pontine Cistern

x. Interpeduncular Cistern

xi. Chiasmatic Cistern

The Intracranial Circulation

1) The Internal Carotid Artery

a) The arch aortogram

i) Subclavian Artery

(1) Common Carotid Artery

(a) External carotid Artery

(b) Internal Carotid Artery

(2) Vertebral Artery

(3) Subclavian Artery

b) Internal Carotid Angiogram, lateral projection showing the trigeminal artery, an embryonic variant

i) Anterior choroidal artery

ii) Basilar Artery

iii) Posterior Communicating artery

iv) Posterior Cerebral Artery

(1) Occipital branches

c) Digital subtraction angiogram

i) Posterior Communicating artery

ii) anterior cerebral artery

(1) Horizontal (A1) segment of the

(2) Anterior communicating artery

(3) Ophthalmic Artery

(4) Frontopolar artery

(5) Callosomarginal artery

(6) Pericallosal Artery

(7) Anterior choroidal artery

iii) Middle cerebral Artery

(1) Horizontal (M1) segment of the

(2) Genu of the Middle cerebral Artery

(3) Sylvian segment

(4) Top of the insula

(5) Posterior Medial Cerebral Artery (Parietal)

(6) Branches of the middle cerebral artery

2) The Circle of Willis

3) The anterior Cerebral Artery

a) Vascular territories of the brain arterial distribution

4) The middle cerebral Artery

5) The posterior cerebral artery

6) The supratentorial venous system

7) The vertebrobasilar arterial system

a) Vertebral Artery

b) Posterior Inferior Cerebellar Artery

i) Anterior medullary segment

ii) Lateral medullary segment

iii) Posterior medullary segment

iv) Supratonsilar segment (cranial loop)

c) Basilar Artery

d) Anterior inferior Cerebellar Artery

e) Superior Cerebellar Artery

f) Posterior Cerebral Artery

i) Thelamo perforating arteries

ii) Posterior Temporal Arteries

iii) Posterior Choroidal Arteries

(1) Lateral and Medial

iv) Posterior pericallosal Artery

8) The posterior cerebral artery

9) The veins of the posterior fossa

a) The dural venous sinuses

i) Superior Sagittal Sinus

ii) Transverse Sinus

iii) Sigmoid Sinus

iv) Straight sinus

v) Basosphenoid synchondrosis

b) Cavernous Nodule

c) Intercavernous fat deposits

d) DSA Cerebral veins

i) Vein of Galen

ii) Basal Vein of Rosenthal

iii) Vein of Labbe

iv) Internal Cerebral Vein

v) Thelamostriate vein

vi) Vein of Trolard

vii) Septal Vein

e) Veins of the posterior fossa

http://www.strokecenter.org/education/ais_images/ais49a-lg.jpg

Radiologist Human

Rabu, 16 Maret 2011

The skull and the brain

Introduction and Imaging methods

The Skull

Osteology of the skull

Meningeal blood supply and innervations

The cerebral parenchyma

The cerebral ventricles, subarachnoid cisterns and related structures

The Intracranial Circulation

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