NeuroImaging Flashcards
Transmission Imaging
Radiation sent through body + detected on other side (e.g. X-Ray, CT, Fluoroscopy, Mammography)
Reflection Imaging
Radiation passes partially into body and reflected back (e,g, Ultrasound, OCT)
Emission Imaging
Generate radiation inside body and detect as it leaves the body (e.g. MRI, nuclear)
Direction: rostral —> caudal
Coronal
Direction: dorsal —> ventral
Sagittal
Direction: medial —> lateral
Axial
T1 Weighting makes Vitreous and CSF ____ (white/dark)
Dark
T2 Weighting makes Vitreous and CSF ____ (white/dark)
White
CT scan is best to scan what parts of the body?
Bone, Blood, Muscle
CT scans can vary in cut size from __ mm to ___ mm
1 - 10
CT scan is a series of ___ scans
A-scans
Indications for CT
- Orbital/sinus pathology or trauma (except ON)
- Acute cerebral or subarachnoid hemorrhage
- Metallic foreign body
Disadvantages of CT Scans
- High cost
- Restricted to axial and coronal (no sagittal)
- Ionizing radiation
- CI in pregnancy, children
- Iodine contrast CI’d in kidney dz, allergy
TRUE/FALSE: Diabetic patients cannot get a CT scan
FALSE, but the patient must stop metformin 48 hours prior to scan
What gives rise to a MRI signal?
Change of quantum states of proton spin, against strong magnetic field (10,000x stronger than earth’s) — with radio frequency specific to Hydrogen
Note: uses the hydrogen in our water molecules
MRA
MRI Angiography — allows non-invasive imaging of BV w/o radiation or contrast
In MRI, signal intensity is determine by:
- Proton density
- T1 relaxation time
- T2 relaxation time
Proton density
Concentration of protons in tissue
In a cerebral tumor, which ‘weight’ is used to view anatomy? Which one is used to view lesion?
Anatomy — T1
Lesion — T2
FLAIR
Fluid Attenuated Inversion Recovery
Technique used to suppress certain anatomy tissue
Good for detecting demyelination; order w/ optic neuritis
Disadvantages of MRI
- Cost
- Poor images of lungs
- Inability to show calcification
- Fresh blood not well visualized
- Difficult to tolerate exam time
CI for MRI
- Pacemakers
- Cochlear implants
- Metallic FB
- Arterial aneurysmal clips
- Stents
What to order: blunt oculofacial trauma
X-ray, CT
What to order: orbital cellulitis
CT now
MRI later
What to order: orbital tumor
MRI
What to order: Aneurysm, AVM
MRI/MRA, cerebral angiography (invasive)
What to order: HTN, amaurosis fugax
Echocardiography, Carotid Doppler
What to order: histoplasmosis
X-ray, CT
What to order: Crohn’s, UC
Barium X-ray, CT
What to order: Sarcoidosis, TB
Chest X-ray, CT
What to order: Thymoma
Chest X-ray, CT
What to order: Thyroid Disease
Thyroid scan, Iodine uptake
What to order: Primary tumor or Mets
Mammography, CT, MRI
