W9 Shoulder methodology Flashcards
RF coils?
Shoulder phased array or surface 5’ ring.
Positioning ?
Supine head first, affected shoulder in isocenter, humerus horizontal, coil cover humeral head, surface coil parallel to z-axis. Oblique pt to affected side to flatten shoulder (scapula flat on table) to avoid high degrees of obliquity.
Landmarking ?
Through shoulder joint.
Staple sequences?
T2 FS, PD, PD FS
Planes, weighting, seq?
Routine Loc Ax T1, T1 FS (3D), T2 FS, T2* FS (3D), PD, PD FS Obl Cor T1, T2 FS, PD, PD FS Obl Sag T1, T2 FS, PD, PD FS
Arthrogram protocol?
All 3 planes T1 (3D), T2 FS, PD, PD FS
Planning ax? Phase dir?
Ax: AC joint to glenoid SI, bicipital groove to distal supraspinatus RL. Phase AP + sat band over chest medially.
planning obl cor what to include? Direction? Phase?
Obl Cor: infra to supra AP, acromion to subscap (~1 cm below glenoid) SI, deltoid to distal third of supra RL. Parallel to supra tendon/ perpendicular to joint space. Phase RL + sat band over chest, or phase SI.
planning obl sag what to include? Direction? Phase?
Obl Sag: glenoid to bicipital groove RL, joint capsule to acromion SI. Perpendicular to supra tendon or parallel to joint space. Phase AP.
fov?
14-16 cm
slice thickness/ gap
3-4 mm skip 0-0.5
matrix
med to fine
rBW
med to low
NEX
2 or more
IO (3)
OS, FC freq or slice, sat band over chest medially.
Indications
shoulder pain, impingement, rotator cuff tear, recurrent dislocation, Hill Sachs, Bankart, Bennet, SLAP lesion.
Is gad routine? what is it for?
no. cyst vs solid, inflammation vs infection from abscesses, arthrography (intra-articular), perfusion (osteoid osteoma)
intra-articular use of gad to diagnose rotator cuff tears, glenoid labral disruption, bicipital tendon and chondral defects= ?
Athrography
how is arthrogram performed? (ie. gad dilution, injection site, guidance)
Diluted gad (gad in saline 1:100) injected to joint-capsule under fluoroscopic guidance, then MR
IV injection of gad by body weight (no fluoro, non-invasive)= ? when is it used?
indirect arthography.
o When direct not possible, not as common/effective
o Exercise to increase gad circulation
o Inflamed tissue enhance.
Aber (abduction external rotation shoulder arthrography)= ?
o Obl sag – angle to long axis of humerus
o Obl cor can also be requested
- For high degrees of obliquity, some systems swap phase and freq - aliasing, some alter orientation. what to do?
o Oblique pt to affected side to flatten shoulder.
what is magic angle?
tendons brighter than normal due to short TE and tendon 55° to Bo.
what does magic angle mimic?
o Normal tendons and ligaments are hypointense – high signal= tears
o Mimics pathology, reposition joint and inc TE (maintain weighting)
