final Flashcards
What provides a general direction for clinicians when deciding to take images or not?
Mercy guidelines.
What 2 questions should be asked before ordering imaging?
- Will it affect diagnositic certainty about a DDX (if so how much). 2. will it change my diagnostic thinking enough so that it will significantly affect my choice of treatment.
Name the things people can have that might be a high risk group for low back pain when radiographs have a high probability for positive findings?
Patients over 50, significant tauma, neuromotor deficits, unexplained weight loss, suspicion of ankylosing spondylitis, drug or alcohol abuse, history of cancer, corticosteroid use, fever over 100, DM/and or hypertension, lack of improvement, patients seeking compensation for back pain, dermopathy, cachexia, deformity and immobility, lymphadenopathy, elevated ESR, elevated acid or akaline phasphatase, positive Rheumatoid factor, positive HLA-B27, serum gammopathy.
CT scans are highly sensitive and specific for what?
degenerative spinal stenosis.
Why do we not take radiographs to screen for the clinically silent conditions?
A good history and physical should reveal red flags that place the person in the high risk groups so radiographs will then be taken.
Name 4 nonclinical reasons people take radiographs?
financial gain, force of habit, medicolegally advantageous, patient education.
low back pain that persists for how long should then be x-rayed?
7 weeks.
How much bone destruction is needed to be visualized on x-ray and bone scan?
x-ray- 30-50%, bone scan- 3-5%. So radiographs are very specific and less sensitive and bone scans are very sensitive and not specific.
Name 3 areas radiographs are used for biomechanica and posture?
scoliosis, spinogrpahic analysis, functional radiography.
Are full spine radiographs for scoliosis diagnosticly effective and have an acceptable risk/benefit ratio?
Yes.
Is spinographic analysis clinically justifiable?
No.
How clinically significant are functional radiographs (flexion/extension, lateral bending)?
New research shows they are probably not that good.
Should degenerative processes be monitored with radiographs?
No since it will not alter the treatment, besides with stenosis.
CT is particularly useful in evaluating what?
apophyseal joint degeneration, bone hypertorphy, spine fx/dislocations, infections, bone neoplasms, complex congenital anomalies, spinal stenosis, metabolic disease, post operative spines, HNP.
When is CT superior to MRI and when is MRI superior to CT?
CT is superior in evaluating bone changes and MRI is superior in evaluating soft tissue changes.
What are the indications for CT?
spinal stenosis, bone/joint/disc disease, complex anomalies, spinal trauma.
What are the indications for CT with myelography?
thecal sac, nerve root (if MRI is not available) MRI IS BETTER.
What are the indications for MRI?
direct visulaization of soft tissues, joint and disc diseases, sensitive to bone marrow pathologies.
What are the indications for MRI with gadolinium?
postoperative fibrosis (since scars will have increase in vascularization), recurrent HNP.
What are the indications for radionuclide studies?
to identify metabolic activity benign vs. aggressive, acute vs chronic, mets and infections.
What are the indications for diagnostic ultrasound?
indirect causes of back pain like: AAA, pelvic neoplasms, neonatal spinal evaluations.
What is the best test for herniated nucleus pulposus?
MRI.
What is the best test for spinal stenosis?
CT or CT with myelography.
What is the best test for spondylolisthesis?
plain film.
What is the best test for inflammatory arthropathies?
Plain film.
What is the best test for trauma?
CT.
What is the best test for infections?
MRI.
What is the best test for instability?
plain film.
What has replaced myelography?
MRI and CT.
What 2 things will MRI be really good at imaging?
Infection and neoplasms.
How can you distinguish between post operative fibrosis pain or pain from a recurrent disc herniation?
Use Gadolinium with the MRI. Fibrosis will take in the contrast within 15 minutes and disc herniations will only take in a little contrast after 30 minutes.
what is the main reason now days for using discography?
used as a provocative test.
What will hot spots on a bone scan mean?
Areas of increased blood flow due to increased metabolism.
What are SPECT bone scans used for?
Exact location of a lesion.
When should bone scans be used?
after less expensive imaging and with red flags.
When would you use ultrasound to image the spine?
Only with neonates.
Why would you take a Ct or an MRI of the brain?
CT- SAH, acute subdural. MRI- MS, recent infarct, tumors, aVM’s, cerebral aneurysms.
Why would you take a CT or an MRI of the orbits?
CT- graves, pseudotumors, foreign bodies, Fx. MRI- secondary evaluation of masses, tumors of optic nerve.
Why would you take a CT or an MRI of the head and neck?
CT- tumors and adenopathy. MRI- parathyroid tumors, problem solving after CT.
Why would you take a CT or an MRI of the chest?
CT- CXR abnormalities, CA, fibrosis, PE. MRI- problem solving after CT.
Why would you take a CT or an MRI of the abdomen?
CT- liver diseases/tumor, lymphoma, pancreatic CA, renal colic. MRI- problem solving after CT.
Why would you take a CT or an MRI of the pelvis?
CT- appendicitis and diverticulitis. MRI- uterine problem solving after US and prostate cancer staging.
Why would you take a CT or an MRI of the bones?
CT- Fx. MRI- tumors, osteomyelitis, AVN, stress Fx, Marrow changes.
Why would you take a CT or an MRI of the joints?
CT- loose bodies, post-arthrogram studies. MRI- most problems of the shoulder, hip, knee ankle and wrist.
Why would you take a CT or an MRI of the spine?
CT- degenerative stenosis. MRI- disc disease, bony metastasis, any cord pathology.
What are the 3 advantages of plain film radiography?
cost effective, minimal radiation, widely available.
Contrast resolution of CT is how much better than plain film radiopgraphy?
100 times better.
Will CT have a film based receptor?
No. Only numerical data is collected by a photon detector cell that is placed around the patient has the x-ray part rotates around the patient.
CT slices can be what sizes?
0.5m-10mm thick.
How much can the CT machine be angled?
15-30 degrees.
Typically what type of images are produced with CT?
axial images. Other types will have a decreased detail.
CT image is made up of a _____ and each part of this is known as ______.
matrix , voxel.
What are the 3 dimesions of a voxel?
length, width, depth.
what is a pixel?
a two dimensional representation of a voxel which is length and width.
What are the different types of units assigned to each voxel?
Hounsfield units from -1000 to 1000.
What will bone and air be in hounsfield units?
bone- 1000. Air- -1,000
What are the 2 types of contast or windows used with CT?
- Bone window- better to see fine detail of bone (cortex and medullary bone are distinctly different). 2. soft tissue window- better for soft tissue (cortex and medullary bone have similar densities.
What are the contraindications of CT?
metallic objects near by can create artifacts. Radiation, claustrophobia and sensitivity to iodine contrast.
When would CT be better than MRI for infections?
with cortical involvment, but MRI is better with medullary and soft tissue invovlement.
Why is CT better for chest and abdomen than MRI?
faster and less motion artifacts.
Would you use MRI or CT for sinuses?
CT.
What will a CT myelogram look like?
like a soft tissue density with white contrast around the cord.
What has better soft tissue contrast CT or plain film radiography?
CT.
How do you control contrast with CT?
electronic manipulation of the digital info like using different windows.
What are the disadvantages of CT?
relatively high radiation dosage, high cost, reformatted images not as good as original.
What is the cage used to sheild extraneous radiofrequencies from MRI machines?
Faraday cage.
The greater the ____ the better the image with MRI?
magnetic strength.
What do you need to do with an MRI magnet to maintain its magnetism and create a homogenous field?
Keep it cooled.
What will the radiofrequency do for MRI?
knock the neclei out of alignment so they can re-align.
What is the spin density?
The number of hydrogen protons in tissues being imaged.
How can you tell the difference between T1 and T2 MRI’s?
T1- fat will be white. T2- water will appear bright.
What will ligaments and tendons look like on T1 and T2 images?
both will be dark gray or black.
What will cortical bone look like with T1 and T2 MRI images?
black.
What is a high signal with MRI and what is a low signal?
White is high black is low.
T1 is used to better visualize what?
fat, precise anatomy, medullary bone, spinal cord, low signal bone, CSF intermediate.
T2 is used to better visualize what?
water, discs,
What has better detail T1 or T2?
T1.
What will the CSF look like with a proton density MRI?
Same as cord.
Gadolinium is only used with what type of MRI?
T1 images before and after.
What are the contraindications for MRI?
during first trimester of pregnancy, over 300 lbs, ferromagnetic artifacts, surgical clips, pacemakers, cochlear implants.
What are the limitations of MRI?
claustrophobia, have to hold still for 30 min to 1 hour, loud tapping noises.
Myelography is not used as much with plain film radiography anymore, but when is it used?
With CT to visualize indirectly a lesion in the spinal canal.
Myelography has been largely replaced by what?
MRI.
What are the indications for myelography?
When CT or MRI is not available and can be used with CT presurgically.
When is CT-myelography the gold standard?
pre-surgically for spinal stenosis.
what are the disadvantages of Myelography?
Pt needs to be monitored for 3 hours after, infection risk, invasive.
What do radionuclides do with nuclear medicine?
They emit gamma radiation as they undergo radioactive decay.
What is the most commonly used radionuclide used with nuclear medicine?
technetium-99.
What is scintigraphy?
a three phase scan commonly employed.
What are the 3 phases of scintigraphy?
first- flow phase, second- blood pool, third- delayed or bone scan phase.
What type of sensitivity and specificity will bone scans have?
high sensitivity and low specificity.
Bone scan will uptake radionuclides when?
tumors, infections, acute Fx, stress Fx.
What are the advantages of bone scans?
evaluate entire body, very sensitive, only need 3-5% bone destruction to been seen.
What is discography?
injection of radiopaque contrast agent into the IVD as a provocative test and may demostrate dessicated discs and herniated discs.
What is SPECT?
Like a bone scan, but offers multiple imaging planes like CT.
What are the benefits of SPECT?
better localization of a lesion.
What is PET?
positron emission tomography.
What is PET used for?
to find soft tissue tumors like in lymph nodes, good for tumor grading, and used to monitor treatment success.
PET has a greater resolution than what?
SPECT or scintigraphy.
What is the major disadvanatge of PET?
high cost and low availability.
What provides a general direction for clinicians when deciding to take images or not?
Mercy guidelines.
What 2 questions should be asked before ordering imaging?
- Will it affect diagnositic certainty about a DDX (if so how much). 2. will it change my diagnostic thinking enough so that it will significantly affect my choice of treatment.
Name the things people can have that might be a high risk group for low back pain when radiographs have a high probability for positive findings?
Patients over 50, significant tauma, neuromotor deficits, unexplained weight loss, suspicion of ankylosing spondylitis, drug or alcohol abuse, history of cancer, corticosteroid use, fever over 100, DM/and or hypertension, lack of improvement, patients seeking compensation for back pain, dermopathy, cachexia, deformity and immobility, lymphadenopathy, elevated ESR, elevated acid or akaline phasphatase, positive Rheumatoid factor, positive HLA-B27, serum gammopathy.
CT scans are highly sensitive and specific for what?
degenerative spinal stenosis.
Why do we not take radiographs to screen for the clinically silent conditions?
A good history and physical should reveal red flags that place the person in the high risk groups so radiographs will then be taken.
Name 4 nonclinical reasons people take radiographs?
financial gain, force of habit, medicolegally advantageous, patient education.
low back pain that persists for how long should then be x-rayed?
7 weeks.
How much bone destruction is needed to be visualized on x-ray and bone scan?
x-ray- 30-50%, bone scan- 3-5%. So radiographs are very specific and less sensitive and bone scans are very sensitive and not specific.
Name 3 areas radiographs are used for biomechanica and posture?
scoliosis, spinogrpahic analysis, functional radiography.
Are full spine radiographs for scoliosis diagnosticly effective and have an acceptable risk/benefit ratio?
Yes.
Is spinographic analysis clinically justifiable?
No.
How clinically significant are functional radiographs (flexion/extension, lateral bending)?
New research shows they are probably not that good.
Should degenerative processes be monitored with radiographs?
No since it will not alter the treatment, besides with stenosis.
CT is particularly useful in evaluating what?
apophyseal joint degeneration, bone hypertorphy, spine fx/dislocations, infections, bone neoplasms, complex congenital anomalies, spinal stenosis, metabolic disease, post operative spines, HNP.
When is CT superior to MRI and when is MRI superior to CT?
CT is superior in evaluating bone changes and MRI is superior in evaluating soft tissue changes.
What are the indications for CT?
spinal stenosis, bone/joint/disc disease, complex anomalies, spinal trauma.
What are the indications for CT with myelography?
thecal sac, nerve root (if MRI is not available) MRI IS BETTER.
What are the indications for MRI?
direct visulaization of soft tissues, joint and disc diseases, sensitive to bone marrow pathologies.
What are the indications for MRI with gadolinium?
postoperative fibrosis (since scars will have increase in vascularization), recurrent HNP.
What are the indications for radionuclide studies?
to identify metabolic activity benign vs. aggressive, acute vs chronic, mets and infections.
