Musculoskeletal Imaging Flashcards
What is conventional radiography used for in musculoskeletal imaging?
gas
foreign bodies
tissue calcification/ossification
In an x-ray how many views must be taken at a minimum?
2 views perpendicular to one another
What are the advantages of conventional radiography for musculoskeletal imaging?
widely available
reproducible - standard protocols are available
inexpensive
minimal ionizing
What are the limitations of using conventional radiography for musculoskeletal imaging?
fractures may be occult if not displaced
importance of more than 1 view
complex bones and superimposed structures may limit evaluation
soft tissues are poorly evaluated with x-ray
What is CT used for in musculoskeletal imaging?
excelent evaluation of bone detail and calcifications
used for more detailed evaluation of fractures
preoperative planning
assessment of healing
What are the advantages of CT in musculoskeletal imaging?
widely available - short imaging time
excellent spatial resolution - occult fracture detection
can be done with or without contrast
can reformat images
alternative if MRI is contraindicated
What are the limitations of CT in musculoskeletal imaging?
ionizing radiation
high cost
soft tissue evaluation is inferior to MRI
metal causes artifact
What are the advantages of using MIR for musculoskeletal imaging?
high contrast resolution for soft tissue and bone
shows pathophysiologic events earlier than seen on x-ray
no radiation
widely available
large variety of imaging techniques
What are the limitations of using MRI for musculoskeletal imaging?
expensive
not patient friendly - claustrophobia and time intensive
quality varies between institutions and individual magnets
metal causes artifact
several absolute contraindications
What are the absolute contraindications of MRIs?
pacemakers - cardiac and GI
electronic stimulators
metallic foreign objects in or around the orbit
weight limit
contrast allergy
What are the relative contraindications for MRIs?
aneurysm clips
retained bullet fragments and metallic objects
renal function
What is fluoroscopy used for in musculoskeletal imaging?
most commonly used by radiologists for procedures
can be used to evaluate joint motion/dynamic imaging
used frequently by orthopedic surgeons during hardware placement
What are the advantages of fluoroscopy in musculoskeletal imaging?
widely available
dynamic imaging
What are the limitations of fluoroscopy in musculoskeletal imaging?
ionizing radiation to the patient and the operator
What is the use of ultrasound in musculoskeletal imaging?
excelent for superficial soft tissue structures such as tendons and muscles
limited evaluation for the surface of bones but not the test of choice
What are the advantages of ultrasound in musculoskeletal imaging?
patient friendly - no radiation or contrast
reproducible
small to moderate expense
widely available equipment
dynamic imaging
What are the limiations of ultrasound in musculoskeletal imaging?
extremely user/operator dependent
cannot be transmitted through cortical bone
not the test of choice for medullary space
What are the two most common bone imaging studies used in nuclear medicine?
bone density studies and technetium bone scans
What is the most important determining factor of bone fragility?
bone mineral density (BMD)
expressed as grams of mineral per area or volume
What is bone density measurement used for?
used to identify individuals at risk for developing osteoporosis or fracture
compared to age-matched, ex-matched, and race-matched controls
Who gets bone density measurements?
all menopausal women 65 years or older
menopausal women with under 65 with risk factors
premenopausal women 65 years or older
premenopausal women with 1 or more low-trauma fractures, women being treated for osteoporosis and people receiving long-term glucocorticoid therapy
What is dual x-ray absorptiometry (DXA_
uses pulse photons at alternating energies
about 1/1000 radiation of a routine spine film
time of exam is short (2-5 minutes)
standard exam includes imaging of the lumbar spine and proximal femur
How are bone density measurements using DXA scored?
scoring of bone density using T-score and Z-score
Where is osteoporosis most pronounced
trabecular bone
What are osteoporotic fractures most commonly associated with?
areas of high trabecular content (vertebral body, femoral neck, distal radius)
What is the T-score in bone density measurements? How is it interpreted?
T-score is the difference between BMD of the patient and the mean MBD of a standard young adult population matched for sex and ethnicity
more useful than the z-score
osteopenia is defined as BMD between 1 and 2.4 standard deviations below reference mean
<2.5 is osteoporosis
severe osteoporosis is <2.5 and one or more low-trauma fractures
What is the Z-score in bone density measurements?
the difference between the patient BMD and the mean BMD of age and gender matched controls
What are the limitations of dual x-ray absorptiometry (DXA)?
severe degenerative disease of the spine
aortic calcifications
compression fracture of the spine
What is bone scintigraphy?
a photon emitting substance is tagged to a compound and injected intravenously
most common agent used is technetium labeled methylene diphosphonate
sensitive but not specific
What conditions are bone scintigraphy sensitive for?
conditions which result in bone turnover and increased blood flow, specifically fracture, infection, and blastic metastases (prostate, breast)
they provide physiologic rather than anatomic information
What contributes to increased uptake of the agent in bone scintigraphy?
increased blood flow
areas and rate of new bone formation
interruption of sympathetic supply
What are the limitations of bone scintigraphy?
ionizing radiation
time sensitivity - radioisotope is injected and imaging is performed after several hours (3-6 hours)
What are the invasive image guided procedures?
image-guided biopsy
arthography
myelography
What is arthrography?
technique used to introduce contrast into a joint
the contrast contains iodinated compound allowing visibility on radiographs, CT, and fluoroscopy
gadolinium injected for MRI imaging
What is arthrography best for?
evaluation of the joiints:
- labrum (shoulder and hip)
- cartilage
- rotator cuff tendons
- intrinsic ligaments of the wrist and elbow
What are the contraindications of arthrography?
contrast allergy
same as for MRI
What is myelography?
technique used to introduce contrast into the central canal
contrast contains iodinated compound allowing visibility on fluoroscopy and CT
What are the advantages of myelography?
can be used if MRI is contraindicated
better evaluation of bone and its effects on the neural foramen and central canal
dynamic imaging allows for evaluation of the canal with flexion and extension
What are the limitations of myelography?
ionizing radiation
contrast allergy
inferior sofy tissue evaluation compared to MRI
invasive
What are the uses of image guided biopsy?
multiple modality choices
safer alternative to surfical/open biopsy - outpatient procedure
used for lesions of unknown etiology
confirms diagnoses
staging of disease
What are the types of image-guided therapy?
corticosteroid injections
calcific tendinnitis lavage
vertebroplasy
thermal ablation
What is the plan of action for imaging of chronic back pain?
plain radiographs and then MRI in an adult
plain radiographs and then nuclear medicine exam or MRI in children
What is the imaging procedure for acute back pain?
plain radiograph
consider CT if related to direct trauma
MRI
What is the imaging procedure for neck pain?
plain radiograph series
if normal bit still significant pain/symptoms consider MRI
CT useful in acute setting/trauma patient
What is the imaging procedure in joint pain?
plain radiographs
consider MRI if looking for soft tissue injury of ligament, cartilage, tendon, or muscle
What is the imaging procedure for neoplasms?
plain radiograph
MRI with contrast - if osseous, just image “joint to joint” and evaluate for skip lesions
CT
nuclear medicine study - osseous metastasis
What is the imaging procedure for occult fractures?
plain radiographs
if x-ray normal - CT, MRI, or nuclear medicine study
What is the imaging procedure for osteomyelitis?
in a diabetic patient, use plain radiograph, MRI, or nuclear medicine study
in non-diabetic patients, use plain radiograph or MRI with contrast
