21a

14c. Neuroradiology

Modality	Features	Pros	Cons
Plain Film	Collapsed image	Portable Cheap	Poor soft tissue discrimination Ionizing radiation
Angiography		Highest resolution of vessels Gold standard	Local puncture morbidity Ionizing radiation Expensive
Myelography	Images long segments of spinal axis Images dural sac only		Complications: headache, puncture bleeding, infection
Ultrasound	(Limited neuro applications)	Non-invasive Portable Inexpensive No radiation
NM/SPECT	Physiologic information		Not portable Ionizing radiation Expensive Poor spatial resolution Time-consuming
PET	Increased physiologic information	Repeatable	Very expensive Ionizing radiation Poor spatial resolution
CT	brightness=density bone: white	High spatial resolution Rapid Good for fresh blood	Expensive Fixed Ionizing radiation
MRI	Brightness made up of: 1. T1 2. T2 3. PD 4. Motion 5. Magnet Suscept.	Good for meningeal disease Excellent for soft tissue Non-ionizing	Expensive Not portable Incompatible with pacemakers etc.

Extra-axial lesions

- if mass effect: normal brain displaced inwardly

1. Vascular lesions

2. CN lesions

3. Hemorrhage (SAH, SDH, EDH)

4. Meningeal diseases

5. Skull base lesions

Intra-axial lesions

- Located and arising from the CNS

- Displaces brain tissue circumferentially away from lesion

1. Masses

a. Intrinsic

b. Metastases

c. Hemorrhages

d. Abscesses

2. Congenital

3. Vascular

4. Inflammatory

5. Infectious

6. Degenerative

7. Metabolic

8. Traumatic/Iatrogenic

Contrast/Brightness Basics

1. Noncontrasted CT scan

2. Contrasted CT scan

- allows distinction between gray (brighter) and white matter

- blackàwhite: air, fat, fluid (CSF, water), brain, white matter, gray matter, bone

- allows illumination of “damaged” areas of the brain (contrast can pass through damaged BBB)

3. Noncontrasted T1 weighted MRI

4. Contrasted T1 weighted MRI

5. T2 weighted MRI