Final 1 Flashcards
List 10 indicators for when to order diagnostic imaging.
- Trauma
- Unexplained weight loss
- Hx of malignancy
- Night pains
- Inflammation or arthritis
- Nero-motor problem
- Fever of unknown origin (FUO)
- Failure to respond to therapy
- Deformity
- Abnormal blood findings
- Medico-legal implications (must take imaging before surgery)
What is conventional tomography?
Is it used much?
NOT a CT;
It is a type of tomography that moving X-rays images around the body allows for focal clarity.
Not widely used
What is the difference in appearance between a plain x-ray and conventional tomography?
Plain X-ray does not show bone destruction on a small scale.
Conventional tomography can be seen in axial slices from the moving camera and film.
Which imaging plane is commonly used in computed tomography (CT)? Can more than one imaging plane be demonstrated with CT?
Axial
Yes; however the resolution is then decreased
What is the difference between CT soft tissue and bone window?
Soft Window better visualization of soft tissues.
Bone Window better visualization of the fine details of the osseous structures.
What is the appearance of bone in a soft tissue window?
Bone appears white or light grey
What is the appearance of bone in a bone window?
cortex being light/white and the medullary being semitransparent.
Does CT utilize the theory of attenuation (absorption of x-rays)?
Yes
Which is more sensitive in the differentiation of tissue densities, CT or plain X-ray?
CT, because it can image the soft tissues contrast.
What is the appearance of fat on CT vs. MRI?
CT fat is black, similar to air
MRI T1-> fat is white
MRI T-2-> fat is dark/grey
By what routes can CT contrast material be administered?
- Orally-> GI contrast (Barium)
- IV-> organs outside GI
- Rectally-> GI
- Myelographically in subarachnoid space-> spinal cord & brain (CNS)
- Intra-articular->Joint space
How does MRI acquire images?
hydrogen ions;
This released energy is what captures the image or difference in densities that portray an image that we see.
What does a T1 weighted MRI image look like compared to a T2 weighted image? What structures are high signal (white) vs. low signal (dark) on each weighting?
T1=> fat appears white bc=>fat sensitive weighted imaging.
*CNS fluid appears darker.
T2=> fluid appears light/white bc this is a water weighted imaging.
*Fat will appear darker/grey
Which modality would best demonstrate dehydration (desiccation) of the nucleus pulposis, CT or MRI?
MRI T2 imaging because it is a water weighted imaging.
If dehydration=> lack of water would appear dark.
Which modality would best demonstrate an intervertebral disc herniation, CT or MRI?
(MRI) T2 imaging, bc gelatinous fluid in disc is 80% water.
What is the contrast called that is sometimes used with MRI and why is it used?
Gadolinium=> Infections, tumors soft tissues and vasculature
Where is the contrast material placed in myelography?
subarachnoid space
What modality besides plain film radiography is myelography often used with?
CT=> b4 a surgery
When is myelography utilized?
Pre-surgery or when an MRI or CT is not available or contraindicated.
Also in examining lesions, disc herniation, tumors, osteophytes and inflammation.
What is a “hot spot” in bone scan?
Bone destruction, bright white spot or hot spot on the bone scan.
When might SPECT scan be useful?
For localizing a lesion and/or confirming a fracture in the pars interarticularis.
When might PET scan be useful?
Accessing treatment success or tumor localization,
When might discography be useful?
To document a specific disc lesion or pain and to access disc integrity
When might diagnostic ultrasound be useful?
- Thyroid gland
- Heart
- Gallbladder/gallstones
- Kidney/kidney stones
- Pregnancies/fetus
- Observe scrotum and prostate
- Evaluate blood flow
- Help Dx CA or infection
- Guide needles for aspirating tumor biopsy or for treatment
Which modality would be most appropriate to evaluate an intervertebral disc protrusion?
MRI because you can use T2 weighted
Which modality would be most appropriate to evaluate a stress fracture?
Bone scan
Which modality would be most appropriate to confirm or rule out an occult fracture or questionable fracture initially discovered on plain x-ray?
Normally a bone scan would be best; however, the X-ray is able to see the fracture so an MRI T1 weighted
Which modality would be most appropriate to evaluate avascular necrosis?
MRI T2-absence of blood (water)
If appears black => Necrosis.
Which modality would be most appropriate to evaluate most chest and abdomen pathologies?
CT because it is quick and the patient can hold their breath
What are the relative radiation doses for each imaging modality discussed?
- MRI has no ionizing radiation
- Ultrasound no ionizing radiation
- X-ray- less than what you get in air travel
- SPECT- similar to that which is experience in environment in 1 year time period.
- Bone Scan ionizing radiation that is highest in bladder
- PET scan ionizing radiation
- Pyelography small dose of ionizing radiation, but is also used with CT
- CT uses ionizing radiation, but is kept low
- Discography uses low dose fluoroscopy and used in conjunction with X-ray or CT
Know your imaging planes (i.e. axial, coronal, sagittal).
Axial-middle of the body (Top & Bottom)
Coronal- front from back
Sagittal- right from left
Which 2 modalities expose Pt’s to no radiation
MRI & Ultra Sound
Which of these have lower radiation rates?
X-ray or Nuclear Medicine (PET,SPECT, Bone Scan)
X-ray
Which modality has a relative radiation rate similar to which is experienced in environment in 1 yr?
SPECT
Which modality has a relative radiation rate similar to which is experienced in air travel?
X-ray
What is SPECT?
3-D pictures. SPECT scan produces images that show how your organs work.
Myelography is used with which 2 Modalities?
CT & X-rays
Myelography is used to examine what?
Pathologies of the Spinal Cord
- Spinal Cord injuries
- Cysts
- Tumors
- lesions
- disc herniation
- Inflammation
- osteophytes
