Table of Contents

For carotid ultrasound please refer to the ultrasound section.


Evolution of Blood Products


Scrollable Lobar Anatomy

Vascular Anatomy

Dimmick SJ, Faulder KC. Normal variants of the cerebral circulation at multidetector CT angiography. Radiographics. 2009 Jul-Aug;29(4):1027-43. doi: 10.1148/rg.294085730. PMID: 19605654.

Vascular Territories

Scrollable Vascular Territories


Stroke Quick Reference

Source: Dr. Heit Twitter

ASPECTS (MCA stroke)

  • 1 point for each area involved
Source: Radiopaedia

CT Perfusion

Thrombectomy (simplified)

  • Core infarct < 70mL
  • Tissue at risk >15mL

Blunt Cerebrovascular Injury

Denver Criteria

When to screen for BCVI:

Biffle/Denver Grade of BCVI

Grade Iluminal irregularity or dissection with <25% luminal narrowing 
Grade IIdissection or intramural hematoma with ≥25% luminal narrowing, intramural thrombus, or raised intimal flap 
Grade IIIpseudoanuerysm 
Grade IVocclusion 
Grade Vtransection with free extravasation 
Source: Neuroimaging Clinics


Overview of Facial Trauma

Source: Hopper RA, Salemy S, Sze RW. Diagnosis of midface fractures with CT: what the surgeon needs to know. Radiographics. 2006 May-Jun;26(3):783-93. doi: 10.1148/rg.263045710. PMID: 16702454.

NOE Types

Source: Hopper RA, Salemy S, Sze RW. Diagnosis of midface fractures with CT: what the surgeon needs to know. Radiographics. 2006 May-Jun;26(3):783-93. doi: 10.1148/rg.263045710. PMID: 16702454.
Type ILarge bone fragment
Type IIComminution with fracture lines central to tendon
Type IIICentral comminution with fracture lines beneath insertion of the tendon

Mandibular Anatomy




AO Spinal Injury Classification

Three column concept of the spine (Denis)

Simplified. If ≥2 contiguous spinal columns are disrupted the fracture will be considered unstable. For the lumbar spine but can be extrapolated to the other segments

ALL – anterior longitudinal ligament; PLL – posterior longitudinal ligament; LF – ligamentum flavum; IL – interspinous ligament; SL – supraspinous ligament.

Cervical Spine

Normal Craniocervical Measurements in Adults

Source: UW Emergency Radiology
Basion-dens interval< 9.5mm
Powers ratio< 0.9mm
Atlanto-dental interval<3.0mm
Atlanto-occipital interval<1.4mm

Ligamentous Anatomy of the Cervical Spine

Source: Radiopaedia

Atlanto-Occipital Dissociation

  • Basion-Dens interval >9.5mm
    • Alar ligament injury, tectorial membrane disruption
  • Associated injuries
    • SAH at foramen magnum
    • Avulsion of the basion, tip of the dens, or occipital condyles

Occipital Condyle Fractures

Type 1Comminuted, impacted
Type 2Extension of skull fracture
Type 3Disruption of Alar ligament (unstable)

C1-C2 Injury

Atlantoaxial Rotary Fixation 

Type IIntact transverse and alar ligaments
Type IITransverse ligament disruption; 2-3mm anterior translation with rotation
Type IIIAlar and transverse ligaments disrupted; >5mm anterior translation with rotation
Type IVAlar and transverse ligaments disrupted; anterior displacement of C1 over C2 with deficient odontoid

Atlas Fractures

Riascos R, Bonfante E, Cotes C, Guirguis M, Hakimelahi R, West C. Imaging of Atlanto-Occipital and Atlantoaxial Traumatic Injuries: What the Radiologist Needs to Know. Radiographics. 2015 Nov-Dec;35(7):2121-34. doi: 10.1148/rg.2015150035. PMID: 26562241.

  • Look for the bilateral displacement of the lateral masses on coronal views.
  • Burst and lateral mass fractures can be associated with tears of the transverse ligament, which are unstable.
    • Rule of Spence – separation of fracture fragments >5.4mm on CT = transverse ligament disruption and instability
  • Ruptures of the ligament can compromise the atlantodental relationship, causing dorsal displacement of the dens, and possibly resulting in compression of the thecal sac.
  • Jefferson Fracture = C1 burst fracture

Odontoid Fractures

Type IApical avulsion fracture (stable in isolation)
Type IITransverse fracture – most common and unstable. If >4mm displacement or comminuted risk nonunion
Type IIIExtends into the C2 body; unstable

Hanged Man Fracture

  • Hyperextension injury with fracture of both pars interarticularis or pedicles of C2
  • Atypical fracture – propegation into the vertebral body – get CTA
Type IBilateral pars fractures without translation or angulationStable; rigid collar
Type II>3mm anterior displacement or significant angulation
C2/3 disc disruption and PLL disruption
Most common
Unstable, reduction or surgery depending on the degree of displacement
Type IIaSignificant angulation without anterior displacement
Fracture line is more horizontal
Type IIIAnterior translation and angulation with facet subluxation or dislocationUnstable, surgery

Subaxial Spine

  • Injury is most common around C4/C5

Hyperflexion Injury

  • Progressive ligamentous injury from posterior to anterior
    • Interspinous process widening
    • Uncovering of facet joints
    • Widening of the posterior disc space – unstable
    • Focal kyphosis
    • Anterior subluxation
  • Hyperflexion sparain – isolated PLC disruption – stable
  • Anterior subluxation – disruption of the PLV and posterior annulus – unstable (2 column injury)
  • Interfacetal dislocation – unstable
    • Perched or jumped facets
    • Bilateral or unilateral
    • All should undergo MRI
  • Flexion teardrop – most severe hyperflexion injury
    • Anterior cord syndrome – qudriplegia with pain and temperature insensitvity, preserved vibratory and position sense

Hyperextension Injuries

  • Can be easy to miss
  • Hyperextension dislocation – disruption of all three columns and unstable
    • Anterior disc space widening
    • Facet widening
    • Extension teardrop fracture

Fused Spine Injury

  • Chalk stick type fractures – hairline fracture through a fused spine, can be easy to miss
    • Seen in hyperflexion and hyperextention injury
  • If seen – image the entire spine as noncontiguous fractures are common
Source: Radiopaedia

Thoracolumbar Spine

Injury pattern is based on AO Classification which uses the tension band concept

  • Anterior Tension Band – limits extension
  • Posterior Tension Band – limited flexion

AO Spine Classification for Thoracolumbar Injuries

Source: AO Spine

Compression Fracture (A1)

  • Failure of the anterior column
  • Isolated anterior compression fracture is considered stable

Pincer Fracture (A2)

  • Complete coronal split fracture with central collapse and herniation of disc material into the fracture
  • Unstable

Burst Fracture (A3 or A4)

  • Disruption of the posterior vertebral body cortex differentiates from compression fracture
    • If unclear, look for widening of the interpedicular distance on coronal
  • Evalute for retropulsed fragment that can cause cord compression
  • Incomplete burst – one endplate involved (A3)
  • Complete burst – both endplates invovled (A4)

Flexion Distraction Injuries (B1 or B2)

  • Transosseous Tension Band Disruption (B1) – Chance Fracture – extends through all through osseous spinal columns
    • High association with intraabdominal injuries
    • Can also have a pure ligamentous injury – look for distraction and widening of the interspinous space
  • Ligamentous disruption of the posterior tension band with an class A fracture (B2)

Hyperextension Injury (B3)

  • Anterior disc space widening
  • Can be seen within rigid spine (see Carrot stick fracture above)
  • Can be ligamentous or osseoligamentous

Fracture Dislocation (Type C)

  • Disruption of all three spinal columns with distraction, dislocation, or translation
  • If you see two vertebral bodies on the same axial image = fracture dislocation

Source: Radiopaedia

Programmable Shunt Settings

Deep Spaces of the Neck

CT Sinus Anatomy

Scrollable Temporal Bone