2 GoalsWhat types of MR studies are available for evaluation of the musculoskeletal system?Considerations when ordering a studyRemember one of the roles of the radiologist is as consultant to work with you in determining the best study for the patient’s needs (it’s in the job description)… talk to them!Most common pathologies for which MSK MRI is performed
3 Exam Types MRI without contrast MRI with contrast MR Arthrogram Most commonEvaluation of ligaments, tendons, occult fracture, cartilageMRI with contrastEvaluation of bone or soft tissue tumor, osteomyelitis, abscessMR ArthrogramEvaluation of labrum, intercarpal ligaments
4 Body PartWhen ordering any study must have a ddx in mind, particularly with MRI (not a screening tool)Cannot perform an MRI of a whole extremity (time, pt motion, protocol issues)Must identify part to be imaged – be specificA joint, a bone (prox, mid, distal), a muscle (origin, belly, insertion)Must have plain radiographFOV about 25cm.
5 Most Common Indications Occult fx or stress fxEarly osteonecrosis – in pt with risk factors & pain, known AVN of one hipOsteomyelitis – plain film is insensitive (30-50% loss of bone density) BUT necessary for MRI interpretation, nucs has poor resolutionOsteochondral lesion – evaluate stabilityLigament/tendon injury – knee, shoulder, ankle > other jtsBone tumor – MUST HAVE X-RAY 1st, imperative in providing ddx on MRI (dx on x-ray, determine extent on MR)Soft tissue mass/muscle injury
6 Considerations when ordering an MRI Joint replacement in joint of interest – don’t do itPacemaker – don’t do itClaustrophobia - sedationUnable to hold still/follow instructions – sedationMetal in area of interest (susceptibility artifact) – consult radiologist, may vary technique or recommend another studyMetal not in area of interest ie. orbits (motion, overheating)If you only remember one thing, remember this:cannot do a PE protocol chest CT without contrast
7 Metal ArtifactSmall metal foreign body results in large area of signal void.Metal or gas = black hole.
8 General Principles Fluid, edema, inflammation is bright on T2 Fat is bright on T1 & T2 (can have fat sat)Blood is often bright on T1Tendons & ligaments are black on all sequencesCartilage is bright on T2Muscle is intermediate in signalDo not order an MRI for necrotizing fasciitis.
9 Pelvis & Hip – Normal Anatomy Joints – sacroiliac, pubic symphysis, hipsTendons – iliopsoas, gluteal, hamstrings, rectus femorisBursa – trochanteric, iliopsoasBones – evaluate for bone marrow replacing process (MM, mets), AVN, occult or stress fxAcetabular labrum – need intra-articular gadolinium
10 Femoral Head Osteonecrosis Groin painMany predisposing factors: trauma (fem neck fx, dislocation), steroids, SLE, sickle cell dz, pancreatitis, alcohol abuse, Gaucher’s dzIncreased risk of contralateral AVN, must evaluate other side, most sensitive study is MRIMRI:Early – bone marrow edemaLater – geographic area of abnormal signal in the anterosuperior femoral head; double line sign on T2Even later – subchondral collapse, femoral head collapse, degenerative joint dzDouble line sign – indicates ischemic necrosis, inner line of high signal surrounded by a line of low signal, interface of dead and living bone, may be chemical shift artifact
15 Labral Tear Clicking, locking, pain with pivoting/twisting Traumatic (young), degenerative (older) or assoc. with femoroacetabular impingement (middle-aged)MRI:Anterosuperior or posterosuperiorLinear high T2 signalLoss of triangular morphologyParalabral cystMR arthrogram most sensitive study – contrast fills tearFemoroacetabular impingement – repetitive microtrauma from impingement of femoral head against acetabulum, associated with labral tears and cartilage defects, focal acetabular chondral lesions, focal underlying subchondral sclerosis, edema, cystic change
18 ACL TearSports injury, rapid stopping/starting/pivoting (skiing, soccor, football, basketball etc), anterior drawer sign on PEMRI:Disruption of fibers, high signal on T2Pivot-shift contusionsAnterior translation of tibia relative to femurAssociated with MCL and medial meniscus injury – O’Donahue’s unhappy triadAssociated with Segond fx (avulsion of mid third lateral capsular ligament from lateral tibial plateau)
23 Meniscal Tear Joint line tenderness, clicking, locking MRI: High T2 signal in the meniscus extending to the articular surfacelongitudinal, radial, flap (flipped), oblique, bucket-handleParameniscal cyst
29 Medial Collateral Ligament Tear Valgus stressComplete or partial tears affecting superficial and/or deep fibersMRI:Disruption of fibers with thickening & abnormal high signalAssociated with ACL & medial meniscal tearsPellegrini-Stieda lesion – ossification at origin of MCL indicative of old tearSuperficial fibers – medial collateral ligament properDeep fibers – meniscofemoral & meniscotibial attachemnts
30 Medial Collateral Ligament Tear Pellegrini-Stieda lesionIndicates old MCL tearOssification at origin of MCL from medial femoral condyle
32 Patellar Tendon Tear Partial or complete Most commonly in proximal third of tendon at inferior pole of patellaPlain film:patella altaMRI:Disruption of fibers, thickening & abn signalFluid-filled gap, hemorrage or granulation tissue
35 Jumper’s Knee (Patellar Tendinosis) Repetitive traumaMRI:Proximal third of patellar tendon (posterior fibers)Early – edema in peritenonLater - thickening & edema (inc T2)Even later – partial or complete tear+/- reactive osteitis in lower pole patella (edema)Reactive edema in adjacent fat pad
36 Jumper’s KneeSuprapatellar effusion. Normal lucency of Hoffa’s fat pad is obscured.
38 Osteochondral Lesion Young male, 50% have h/o trauma Lateral aspect of medial femoral condyle, talar dome, capitellumPlain film: area of sclerosis or bone/cartilage fragment in situ or defect with loose body in jointMRI necessary to determine stability and guide treatment (stable-heal spontaneously, unstable-surgery)MRI:Fragment composed of hyaline articular cartilage and underlying subchondral boneUnstable if fluid between fragment and donor site on T2
41 Ankle – Normal AnatomyJoints – tibiotalar, distal tibiofibular, subtalar (ant, middle, post), intertarsalTendons – flexor (tibialis posterior, digitorum longus, hallucis longus), extensor (tibialis anterior, hallucis longus, digitorum), peroneus (longus, brevis), AchillesLigaments – medial (deltoid), lateral (talofibular, talocalcaneal), syndesmotic, Lis-FrancMuscles, bones, plantar fasciaNormal Variants – plantaris, accessory soleusTom Dick & HarryTom Hates DickPlantaris muscle tendon runs along side the achilles in 90% of people, can be mistaken for achilles tendon tear.
42 Tarsal Coalition Lack of segmentation of two tarsal bones Most commonly calcaneonavicular or talocalcaneal (middle subtalar joint)20% bilateral; pain, flat footCartilaginous, fibrous, osseousPlain film: anteater sign, continuous C sign, talar beak, pes planusMRI:Cartilaginous, fibrous or bony bridge between 2 tarsal bonesFibrous/cartilaginous - JSN, irregularity, sclerosis, bone marrow edemaBony – continuity of bone marrow and cortex
49 Peroneus Brevis Split Tear Peroneus brevis is normally round and anterior to longusTear most commonly at level of lateral malleolusMRI:C-shaped tendonLongitudinal split, peroneus longus may be interposed between two subtendons+/- fluid in tendon sheath (tenosynovitis)
51 Stress Fracture 2 types of stress fractures: Fatigue fx – normal bone under abnormal stress (young marathon runner, military recruit etc…)Insufficiency fx – abnormal bone under normal stress (elderly osteopenic female, steroids etc…)Characteristic locations: 3rd metatarsal, tibial diaphysis, calcaneus, medial aspect femoral neck, sacrumPlain film:Cortical bone – periosteal rxn and/or endosteal thickeningCancellous bone - ill-defined sclerosisMRI:Low signal line on T1High signal bone marrow edema on T2Calcaneus – trabecular fractures perpendicular to long axis
52 Stress FractureHx: 28 yo female training for marathon. Pain with running, stopped with rest.Note normal residua of growth plate.
57 Brachial Plexopathy Pain in the shoulder radiating down arm Etiologies: radiation >60 Gy(breast, lung ca), metastatic disease (via axillary lymphatics), direct invasion by tumor (Pancoast’s, lymphoma), direct trauma, stretch injuryMRI:Thickened fascicles with obliteration of the intervening fat planesWell-defined massWith diffuse thickening of fascicles favor infiltrative neoplasm or radiation fibrosis. With well defined mass favor mets.
58 Radiation-induced Brachial Plexopathy Which side is abnormal?
59 Radiation-induced Brachial Plexopathy Which number corresponds to the brachial plexus?What are the other 2 structures?132Subclavian arterySubclavian vein
61 Brachial Plexus Metastasis MassSubclavian arteryVeinPre and post-contrast cor T1 with fat sat
62 Shoulder – Normal Anatomy Rotator cuffLong head of the biceps brachialis tendon – intertubercular and intracapsular portionsAC joint/impingementGlenoid labrum – triangular low signal on all sequences, serves to deepen glenoid fossa thereby stabilizing GH joint, attachment site of long head of bicepsMyxoid degeneration, labral tear (alphabet soup), Bankart lesionBest evaluated with MR arthrographyShoulder MRI most commonly ordered for the evaluation of these structures. Of course there are other things we see and look at.
63 Normal AnatomyNormal rotator cuff, intra-articular and intertubercular long head of biceps, biceps anchor point.No contrast in subacromial/subdeltoid bursa.Normal communication of biceps tendon sheath with joint.
64 Rotator Cuff TearSupraspinatus, infraspinatus, teres minor, subscapularisPts > 40 yo, insidious onset of painSpectrum: tendinopathy, partial and full thickness tearEtiology: degeneration (age, overuse, impingement), trauma, collagen vascular diseaseMRI:Tendinopathy – thickened tendon, increased signal on PD, intermed on T2Partial tear – increased signal on T2, defect does not extend through cuffComplete tear – increased signal defect on T2 extending through RC from articular surface to bursal surface; fluid in subacromial/subdeltoid bursaChronic tear – muscle atrophyImpingement – shape or configuration of acromion, AC joint DJD, mass etc…
67 Supraspinatus Tendinopathy Underlying degenerated tendon as evidenced by thickening and abnormal signal
68 Labral Tear Young pts <40 yo, pain, instability Best evaluated with MR arthrogramMRI:Linear high T2 signal within substance of labrumDiffuse high signal (crush injury)Absent or small labrumDetached labrumMimics:Undercutting of articular cartilage between labrum and glenoidInterposed synovial recess (sulcus)Sublabral foramen/hole (detached anterosuperior labrum)
70 Labral Tear? NO Undercutting of cartilage between labrum & glenoid Interposed synovial sulcusContrast follows contour of glenoid (points medially)
71 Hillsach’s and Bankart Lesions History of anterior shoulder dislocationHillsach’s – impaction fracture of posterior superior humeral headBankart – anterior inferior labral avulsion w/ rupture of periosteum, many variantsBony Bankart – fracture of anterior glenoidMRI:Impaction fracture of posterosuperior humeral head (not round on 1st three axial images)Anterior labral tear or variant (best evaluated with arthrography)Many Bankart variants… alphabet soup.
72 Hillsach’s and ALPSAALPSA – anterior labroligamentous periosteal sleeve avulsion, medial displacement of labrum with periosteal stripping (intact periosteum), medialized PerthesPerthes – normal position of labrum, periosteum stripped medially, but intact
73 Elbow – Normal AnatomyTendons – biceps, brachialis, triceps, common flexor and extensor originsLigaments – ulnar and radial collateralJoints – elbow, proximal radioulnarOlecranon bursa
74 Olecranon BursitisPainless mass following acute direct trauma or recurrent trauma; assoc with systemic dzDistension of olecranon bursa (synovial sac) with fluidMRI:In superficial soft tissues adjacent to olecranon process and triceps insertionmm – cm in sizeHigh signal on T2, possible rim enhancement+/- hemorrhagic debris
76 Lateral Epicondylitis Insidious onset of lateral elbow pain with activityOveruse syndrome – repetitive varus stressChronic tendinopathy at common extensor origin, predominantly involving the extensor carpi radialis brevis tendonPartial avulsion with scar formationPlain film: normal or spur at lateral epicondyleMRI:Thickening of tendon with increased signal on T1 & T2