MUSCULOSKELETAL IMAGING FOR PHYSIOTHERAPISTS: Flashcards
why use imaging for MS conditions?
Make an accurate tissue diagnosis
… e.g. acute fracture … not always appropriate (e.g. low back pain, knee pain)
Rule out other pathology (red flags) - tumours
Determine prognosis or to track a disease - OA
Indications for surgical intervention - ACL rupture, end stage OA
5 principles for using imaging for MS conditions
- understand imaging results
- only order imaging that will influence management
- explain the imaging to the patient
- provide relevant clinical findings on the referral form
- work with radiographers & radiologists
XRAYS
tissues containing calcium - BONY INJURY IF CAN’T WEIGHT BEAR, grading of OA SEVERITY,
Bone – fractures, alignment, joint spacing, tumours, etc.
xray pros and cons
pros - cheap, fast, widely available
negs - uses ionising radiation (low to medium), can’t differentiate soft tissues, 2D image of a 3D structure
CAN’T IF PREGNANT OR BREASTFEEDING
CT SCANNING
INCREASED DETAIL OVER FOOT - SMALL BNES IN FOOT AND HAND, anatomically complex regions
CT PROS AND CONDS
PROS relatively cheap; fast; widely available higher resolution than x-ray defines bone detail & detects calcification better than MRI 3D data geometrically accurate CONS: uses ionising radiation (medium to high dose) lower soft tissue contrast (vs. MRI) often requires contrast - risks
PREGNANCY, BREAST FEDDING, CHILDREN
USE FOR COMPLEX FRACTURE
BONE SCAN
… binds to hydroxyapatite at sites of osteogenesis (active bone formation)
… 3D image (single photon emission CT
Bone – stress fractures,
[SPECT]) – detectors rotate around body
tumours, etc.
use in bony stress reaction
BONE SCAN P AND C
PS can be relatively combined with high CT – anatomy radiation - may detect earlier stages of bony injury C- relatively high radiation dose low resolution images (show uptake) reasonably expensive slow (long period to keep still)
CIs
- BF, preg
ultrasound
tissues imaged - ligs, tendons, muscle, nerves – not bone
pros and cons ultrasound
p:
cheap; fast; widely available; portable
able to image soft tissues; high resolution
can perform dynamic imaging (real-time)
can interact with patient to correlate symptoms & findings
safe (no ionising radiation)
cs:
unable to penetrate bone & air
image quality depends on skill of operator
small field of view; can get some image distortion
MRI
magnetic field - Different tissues have different times for proton realignment, and different amounts of energy release – appear different on MR image
ALL TISSUES sharp anatomical detail § shows bone marrow § good for meniscal pathology § lacks sensitivity to detect soft tissue injury
MRI - Proton density-weighted
§ good for menisci and ligaments
fat = bright / intermediate
water = intermediate
calcium, tendons, fibrocartilage = dark
MRI - T2-weighted
highly sensitive for most soft tissue injuries, especially tendons
§ Abnormal tendons have high signal intensity (bright) – contrasts with the black of normal tendon
MRI - STIR
highlights excess water which may occur due to bone stress, bone marrow oedema, joint fluid and soft tissue pathology
§ use for bone stress injuries or subtle fractures not detectable on x-ray
MRI PS AND CS
excellent soft tissue contrast;
geometrically accurate
non- invasive; no ionising radiation
Can scan in any plane; 3D image capability
CS
bone resolution not as clear as CT
expensive; slow (keep still); low availability
non-weight bearing images (at present)
CIS
any implanted metal - PACEMAKER
claustrophobia
