NeuroImaging

CT

CT

-What is the primary modality for…..

• Emergent situations (Speed is needed)

• Head trauma

• Acute Hemorrhage

• Fractures*

• Calcified lesions

• Claustrophobic* or Obese (>300 lbs)

• Patients with a device containing ferrous metal or metallic fragments around the eye.

-Superior for viewing bony structures and acute hemorrhages without contrast.

MRI

What is the Primary modality for….

• Tumors

• Demyelination and White matter diseases

• Subtle infracts

• Old Hemorrhage

• When anatomical detail is needed.

-Superior to CT in everything else but has disadvantages of cost, time, and access.

Lighter gray

What color would these structures be on a CT?

• Cortex (grey matter)

• Thalamus (gray matter)

Darker gray

What color would these structures be on a CT?

• Internal capsule (white matter)

Black

What color would these structures be on a CT?

• Ventricles

White

What color would these structures be on a CT?

• Skull

• Choroid plexus

• Pineal gland

(Calcified)

Look for white densities (bleeding)

Look for mass effect (displacement of normal anatomy)

• Can be detected when ventricles are compressed, sulci are effaced, or structures appear shifted.

• A shift of midline structures is a medical emergency

Look for loss of normal tissue contrasts

• Loss of distinction between gray and white matter is a sign of severe brain edema and has poor prognosis.

What should you be evaluating on a Head CT in an emergency setting?

Epidural hematoma

-Takes significant blunt trauma and is usually associated with a skull fracture

-Bleeding pattern is a BICONVEX or LENS shaped mass.

Subdural Hematoma

-Can be caused by minor trauma in the elderly or MVA in younger patients

-Pattern of Bleeding is CONCAVE to the brain.

Subarachnoid hemorrhage

-Thunderclap headache

-Bright white wherever CSF would normally be.

-It can extend to the ventricles, causing

Intracerebral Hemorrhage.

-Bleeding is encased in the substance of the Brian, often confined to the area of a ruptured vessel

-Looks like a white plaque in the brain tissue.

Non-Contrast head CT

What is the standard imaging study for an early acute stroke evaluation at most centers?

Ischemic stroke

-May be normal looking for the first 6-12 hours

-Then infarcted portions may appear hypodense (color = darker)

Hemorrhagic stroke

-Fresh bleeding is visible immediately and is WHITE

-After about a week it becomes isodesnse, then 2-3 weeks becomes hypodense.

Gadolinium

What is the typical contrast used with MRI to enhance inflammation or neoplasms?

T1

-Is best for showing anatomy

• water is black

• Bone is bright

• Gray matter is gray

• White matter is white

T2

-Best for detecting pathologic changes

• Water is bright

• Gray matter is light gray

• White matter is dark gray.

True

T/F: MRI is the study of choice for most diseases of the spine.

• Compression fractures

• Spinal Stenosis

• OA

• (Bone stuff)

What are the indications for a X-ray of the spine?

False

T/F: MRI is superior in all areas when evaluating bony structures when compared to CT.

Severe or progressive neurologic deficits

Fever

History of cancer or unexplained weight loss

Minor trauma in patients with osteoporosis

Major trauma in all other patients.

What are the “red flags” of back pain?

90%

What percent of patients in primary care have non-specific low back pain that most of the time gets better with preservative care?

Compression Fractures

Location: usually middle-lower thoracic and upper lumbar

Imaging: Conventional radiographs

Finding: Compression of the anterior and superior aspects of the vertebral body

Herniated Disks

Location: Usually cervical or lower lumbar, leading to pain and radiculopathy

Imaging: MRI

Finding: Focal protrusion of disk to compress the spinal cord.

Spinal Stenosis

Location: Usually cervical or lumbar

Imaging: MRI (may start with x-rays)

Finding: Narrowed spinal canal due to bony or soft tissue abnormalities.

Burst Fracture

Location: any spinal level

Imaging: CT is best

Finding: Comminuted compression fracture of the vertebral body, with the posterior aspect impinging on the spinal canal & the anterior aspect displaced forward.

Jefferson Fracture

Location: Burst fracture of C1

Imaging: CT

Finding: Fractures of the anterior and posterior arches or C1

Hangman fracture

Location: C2

Imaging: CT

Finding: Fracture of the posterior elements of C2, separating the posterior aspect of the C2 vertebral body from the anterior aspect, allowing C2 to slip forward (sub lux) on C3.

• C2 is split in half and the back half is on top of C3

Chance’s Fracture

-Location: Upper lumbar or lower thoracic

Imaging: CT

Finding: Horizontal fracture through the entire vertebral body, pedicles, and spinous process.

Locked Facets

Location: Cervical

Imaging: CT

Finding: Inferior facets of one vertebral body slide over and in front of the superior facets of the next vertebral body

• they are “locked” into place & cannot return to normal position.