radiology lectures 2-4 Flashcards
when to use MRI (4) vs CT (1)
CT- good for boney fragments & spatial resolution (fractures)
MRI soft tissue tears/injury occult fxs not picked up on xray/CT edema/fluid structural abnormalities
MRI sequences… how do we see fat and fluid in
T1 vs. T2 vs. STIR
T1- fat bright, fluid dark
T2- fat bright, fluid bright, can do fat saturation
STIR- fat dark, fluid bright
T2 & STIR are fluid sensitive => good for seeing edema
standard views for: long bones joints shoulder pelvis & hips
long bones: 2 orthogonal view; 90 degrees from eachother
AP/laterl (for arm, forearm, thigh, leg)
joints: 3 views; AP, lateral, oblique
shoulder: 3 views; AP, y-scap & axillary
AP in IR and ER
pelvis & hips: 2 AP & frog-leg lateral
how to read an x-ray (8)
- identify normal bones
- look for cortical continuity
- look at alignment
- look for any extra densities or lucencies w/i or outside bone
- look at soft tissue for swelling or joint effusion
- look at adjacent joints
- compare with prior studies
- if still concerned get CT or MRI
3 hand arcs
arc I = proximal surface of: scaphoid, lunate, triquetrium
arc II = distal surface of: scaphoid, lunate, triquetrium
arc III = proximal surface of: capitate & hamate
alignment of wrist/ hand in lateral view
radius, lunate, capitate & 3rd MC line up
various ways fx show up on x-ray (6)
- cortical discontinuity or deformity
- radiolucent fx lines
- abnormally white or dense areas = overlapping fragments
- extra or unexplained bone fragments
- soft tissue swelling or jt effusion
- callus formation in healing fxs
gamekeepers thumb
a.k.a.
what is it
complication
a.k.a. skiers thumb
diruption of UCL at 1st MCP joint (falling on outstretched hand with aBducted thumb
stener lesion-displacement; UCL can’t heal properly because aponeurosis blocks insertion
posterior fat pad sign
normal anatomy on radiograph (2)
sign (1)
normal anatomy:
- anterior fat pad is normally a faint line more radiolucent than adjacent muscles & runs parallel to distal humerus
- posterior fat pad is normally pressed deep into olecranon fossa by tricep tendons and is invisible
posterior fat pad sign:
elevated anterior lucency and/or visible posterior lucency at true lat radiograph of elbow flexed at 90 deg
hill scahs lesion
what is it/ when do we see it?
how do we best view it
bankart lesion
what is it/ when do we see it?
hill sachs
- flattening of supero-lateral (posteriolateral) aspect of humeral head seen after forceful anterior shoulder dislocation
- best seen on AP IR plain film
bankart
inferior/ anterior aspect of glenoid injured during anterior dislocation
these two are commonly seen together
posterior shoulder dislocation
biomechanics (2)
cause
dx
- humerus forced posteriorly and IR
- anterior humeral head isimpacting posterior glenoid
- usually caused by convulsions, rarely by trauma
- difficult to dx by radiograph and often mis-dx as frozen shoulder or adhesive capsulitis * get CT or MR
shoulder dislocation rates
anterior
posterior
luxatio
anterior- 95-97%
posterior- 2-4%
luxatio (inferior) - 0.5%
clinical findings for RC tears
signs (3)
symptoms (2)
dx
signs
- supraspinatus weakness
- ER weakness
- impingement
symptoms
- over >60 yo
- night pain
if all 3 signs are positive or 2/3 and pt > 60; chance of tear is 98%
RC cuff tears most commonly affected where they begin full length extend to... subscap affects...
- supraspin is primarily involved in most instances
- tears usually begin at site of insertion
- tears can extend posteriorly to infraspin & teres minor
- subscap tendon may have isolated tear & associated with dislocation of bicep tendon
what is subscap tendon tear associated with?
anatomy
which location
dislocation of bicep tendon (usually medially)
subscap tendon continues across bicipital groove as transverse humeral ligament which helps stabilize bicep tendon.
radiographic findings of RC tears (3)
look at slides
- high riding humerus
- faceting & sclerosis in inferolateral acromion & superior aspect of greater tuberosity
- secondary osteophytes in GH joint to maintain joint congruity
full thickness tears of supraspinatus (4)
- fully extend from bursal to articular surface
- nonvisualization of tendon
- fluid in expected location of tendon
- measure AP width
calcific tendinosis most common place what we see on radiograph symptoms radiograph we need to find it tx
- most comon in supraspin tendon
- tendon is thickened and heterogenous w/o discrete defects
- subclinical -> painful
- can be seen as low signal intensity on all MR sequences
- treated by saline lavage
infection looking for... laundry list when its the joint its called... when its the bone its called... how to look for it (radiologic testing)
looking for… soft tissue swelling, ulcers, subcutaneous air, skin thickening, cellulitis, abscess, fistulas
joint => septic arthritis
bone => osteomyelitis
MRI is most sensitive to edema or do nuclear bone scan
approach to arthritis (ABCDES)
a= alignment b= bone mineralization c= cartilage loss d= distribution e= erosions? s= soft tissue masses
classifications of arthritis (3)
- OA; primary or secondary
- RA
- crystal; gout
degenerative arthritis
aka
radiologic findings
where do we commonly see DJD? where do we rarely see DJD?
does if affect more prox or distal in hands?
aka- OA
radiologic findings
- loss of articular cartilage
- joint space narrowing
- osteophyte formation
- sclerosis
- subchondral cysts
occurs in WB joints (hips knees), rarely in hands or shoulders
generally more distal in hands (than RA which is proximal)
RA what is it characterized by... what type of inflammation does it affect prox or distal more?
- chronic autoimmune inflammatory disease
- characterized by joint swelling, pain and destruction
- synovial inflammation - synovium becomes thickened and causes erosion in bones
- affects hands more proximally (vs. OA which is distal)
criteria for being dx with RA (4)
score needed
- based on # of jts
- blood tests for rheumatoid factor
- acute phase reactants (CPR &ESR)
- duration of symptoms
score 6/10 => dx
RA radiographic findings (5)
- soft tissue swelling
- osteoporosis
- joint space narrowing
- marginal erosions
- in hands; bilateral, proximal process
GOUT radiolgraphic features (4)
- eccentric soft tissue swelling (TOPHI)
- erosions with overhanging edges (reactive bone around tophus)
- jt space preserved
- erosions can be far away from joint
bisphosphonate-related atypical femoral fx
pathophysiology (2)
radiologic signs (3)
- med that inhibits bone resorption by supressing osteoclasts => increased bone mineral density
- this suppresses bone turnover & remodeling & healing of microinjury
radiologic signs
- lateral cortical thickening (transverse fx)
- lack of comminution
- medial femoral spike; sharp medial cortical projection, typically arising from distal femoral fragment
muscle attachments on pelvis iliac crest ASIS (2) AIIS greater trochanter lesser trochanter ischial tuberosity body of pubis & inferior pubic ramus
iliac crest- abs ASIS (2)- sartorius & TFL AIIS - rec fem greater trochanter - ERs lesser trochanter - iliopsosas ischial tuberosity- hamstrings body of pubis & inferior pubic ramus- adductors, gracilis
stress fx class appearance 2 types
classic appearance = condensation of cancellous bone - perpendicular to long axis
2 types:
fatigue= normal bone, abnormal stress
insufficiency = abnormal bone, normal stress
femoral neck stress fx
who it affects most
why its important
imaging
- commonly occurs in runners and military trainees
- blood supply to femoral head runs thru femoral neck => AVN of head
- need MRI or bone scan
hip fx precautions
if there is a hx of trauma & high clinical concern for fx keep pt NWB until MRI (even if xray is negative)
GOUT what it is primary gout secondary acute chronic places it commonly affects
due to hyperuricemia =>deposition of monosodium urate crystals
primary gout = inborn error of metabolism
secondary gout = disorders affecting urate metabolism (eg alcoholism)
acute= swelling and pain mimicking septic arthritis
chronic = tophi erode into bone, resulting in bony changes
places it commonly affects= 1st MTP jt =90%
olecranon bursitis
