MSK Imaging_4.Imaging of muscle china_by Dr. Jim Wu

Imaging of MuscleImaging of Muscle

Jim Wu, MDJim Wu, MDBeth Israel Deaconess Medical CenterBeth Israel Deaconess Medical Center

Harvard Medical SchoolHarvard Medical School

DisclosuresDisclosures

Kaneka Corp - research funding supportKaneka Corp - research funding support Boehringer Ingelheim - research funding Boehringer Ingelheim - research funding

supportsupport PharmaMar - imaging consultantPharmaMar - imaging consultant

Learning ObjectivesLearning Objectives

Understand skeletal muscle anatomy and Understand skeletal muscle anatomy and physiologyphysiology

Be able to recognize the imaging Be able to recognize the imaging appearance of various muscle injuriesappearance of various muscle injuries

Learn advanced imaging techniques to Learn advanced imaging techniques to study muscle study muscle

Skeletal MuscleSkeletal Muscle

((Garrett & Best. Ortho Basic Science AAOS 1994: 89-126)Garrett & Best. Ortho Basic Science AAOS 1994: 89-126)

More than 400 muscles in More than 400 muscles in the human bodythe human body

Constitutes 40-45% of Constitutes 40-45% of total body weighttotal body weight

Muscle injury is a leading Muscle injury is a leading cause of loss time from cause of loss time from workwork

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Skeletal Muscle AnatomySkeletal Muscle Anatomy

Muscle fiber is basic unit of Muscle fiber is basic unit of skeletal muscleskeletal muscle Capable only of contractingCapable only of contracting

Single nerve axon controls Single nerve axon controls one or more muscle fibers one or more muscle fibers to form motor unitto form motor unit

Site of connection between Site of connection between muscle fiber and tendon is muscle fiber and tendon is the myotendinous junctionthe myotendinous junction Weakest part of muscleWeakest part of muscle

Muscle fiber

Huard et al JBJS[Am] 2002; 84-A: 822

Types of Muscle ContractionTypes of Muscle Contraction ConcentricConcentric

Muscle force > resisting load Muscle force > resisting load Muscle shortens (contracts)Muscle shortens (contracts) Ex: biceps curlsEx: biceps curls

IsometricIsometric Muscle force = resisting loadMuscle force = resisting load Muscle length does not changeMuscle length does not change Ex: trying to lift a huge rockEx: trying to lift a huge rock

EccentricEccentric Muscle force < resisting loadMuscle force < resisting load Muscle lengthensMuscle lengthens Ex: jumping from a heightEx: jumping from a height

Types of Muscle ContractionTypes of Muscle Contraction

Movement is combination of concentric, Movement is combination of concentric, isometric, and eccentric muscle contractionisometric, and eccentric muscle contraction

More tension generated during eccentric More tension generated during eccentric contraction rendering the muscle more contraction rendering the muscle more susceptible to injurysusceptible to injury

Muscle tears occur during powerful Muscle tears occur during powerful eccentric contractioneccentric contraction

Garrett. Med Sci Sports Exerc 1990; 22: 436-443

Imaging of Muscle InjuryImaging of Muscle Injury

MRI is the best imaging testMRI is the best imaging test Allows for localization and Allows for localization and

characterization of injurycharacterization of injury ProtocolProtocol

T1 to assess for hemorrhage T1 to assess for hemorrhage and fatty atrophyand fatty atrophy

T2/STIR to assess for edemaT2/STIR to assess for edema Contrast not needed if tumor Contrast not needed if tumor

not suspectednot suspected

T1

STIR

Sites of Muscle InjurySites of Muscle Injury Tendon – boneTendon – bone

Apophyseal (growth plate)Apophyseal (growth plate) AvulsionAvulsion

Tendon Tendon TendinopathyTendinopathy Partial tearPartial tear Complete tearComplete tear

Myotendinous junctionMyotendinous junction Partial tear (strain)Partial tear (strain) RuptureRupture Delayed Onset Muscle Soreness Delayed Onset Muscle Soreness

(DOMS)(DOMS) Muscle bellyMuscle belly

Contusion/hematomaContusion/hematoma MyositisMyositis DenervationDenervation

Muscle Injury – Key pointsMuscle Injury – Key points Normal tendons do not ruptureNormal tendons do not rupture

Injuries often occur in muscles that cross 2 Injuries often occur in muscles that cross 2 jointsjoints Increase stress on muscleIncrease stress on muscle Rectus femoris, biceps, gastrocnemius, Rectus femoris, biceps, gastrocnemius,

hamstringshamstrings

Tendon-Bone Injury Tendon-Bone Injury

Common in kidsCommon in kids ClassificationClassification

AcuteAcute – violent muscle – violent muscle contraction contraction

ChronicChronic – repetitive – repetitive microtrauma (overuse)microtrauma (overuse)

Pelvic muscle insertions Pelvic muscle insertions most commonly injuredmost commonly injured

Can have aggressive Can have aggressive appearance mimicking appearance mimicking tumortumor

Tendon-Bone Injury (bony avulsion)Tendon-Bone Injury (bony avulsion)

Extensor tendon avulsion Peroneus brevis avulsion

Tendon-Bone Injury (bony avulsion):Tendon-Bone Injury (bony avulsion): Biceps femorisBiceps femoris

PD

Tendon-Bone Injury (apophyseal): Tendon-Bone Injury (apophyseal): Osgood SchlattersOsgood Schlatters

PD

Tendon-Bone Injury: Tendon-Bone Injury: Quadriceps tendon avulsionQuadriceps tendon avulsion

Normal PD T2 fat sat

Tendon-Bone Injury: Tendon-Bone Injury: Hamstrings avulsionHamstrings avulsion

STIR STIR

Tendon-Bone Injury: Tendon-Bone Injury: Pectoralis major tendon avulsionPectoralis major tendon avulsion

STIR T2 fat sat

Tendon-Bone Injury: Tendon-Bone Injury: Biceps tendon avulsionBiceps tendon avulsion

STIR STIR

Types of Muscle InjuryTypes of Muscle Injury Tendon – boneTendon – bone






Tendon InjuryTendon Injury

Tendons are relatively avascular structures Tendons are relatively avascular structures which attach muscles to bonewhich attach muscles to bone

Made of dense collagen fibers which Made of dense collagen fibers which interdigitate to form extremely tight bondsinterdigitate to form extremely tight bonds

Dark on all sequences due to few mobile protonsDark on all sequences due to few mobile protons

Normal tendons do not tear!Normal tendons do not tear!

Several conditions can weaken and predispose Several conditions can weaken and predispose tendons to injurytendons to injury

Tendon InjuryTendon Injury

Predisposing conditions:Predisposing conditions: Chronic repetitive stresses (microtears)Chronic repetitive stresses (microtears) Tendon degeneration (age-related)Tendon degeneration (age-related) Inflammatory processesInflammatory processes

Rheumatoid arthritisRheumatoid arthritis SLESLE

InfectionInfection DiabetesDiabetes Drugs (steroids, ciprofloxacin)Drugs (steroids, ciprofloxacin)

Tendon Injury (tendinosis):Tendon Injury (tendinosis):Achilles tendonAchilles tendon

PD STIR

Tendon Injury (partial tear):Tendon Injury (partial tear):AchillesAchilles

T2 fat satPD

Tendon Injury (complete rupture):Tendon Injury (complete rupture):AchillesAchilles

T2 fat satPD

Tendon Injury (complete rupture):Tendon Injury (complete rupture):SupraspinatusSupraspinatus

Normal T1 fat sat







Myotendinous Junction InjuryMyotendinous Junction Injury

Highly folded membrane at muscle-tendon Highly folded membrane at muscle-tendon interfaceinterface

Increases muscle-tendon contact by 15-20 timesIncreases muscle-tendon contact by 15-20 times

Majority of partial tears (strains) occur hereMajority of partial tears (strains) occur here

Due to eccentric contractionDue to eccentric contraction

Typically in muscles crossing 2 joints: Typically in muscles crossing 2 joints: biceps femoris, rectus femoris, gastrocnemiusbiceps femoris, rectus femoris, gastrocnemius Type II muscle fibersType II muscle fibers

(Garrett & Best. Ortho Basic Science AAOS 1994: 89-126Noonan & Garrett. Clin Sports Med 1992; 11:783-806)

Grading of Muscle StrainsGrading of Muscle Strains

Grade 1Grade 1: Edema in muscle and myotendinous : Edema in muscle and myotendinous junction without disruption of muscle fibers. No or junction without disruption of muscle fibers. No or minimal perifascial fluidminimal perifascial fluid

Grade 2Grade 2: Partial tear. Irregular fibers and associated : Partial tear. Irregular fibers and associated muscle edema. muscle edema. Hematoma (pathognomonic) Hematoma (pathognomonic) and and moderate perifascial fluidmoderate perifascial fluid

Low – less than 1/3 of area involvedLow – less than 1/3 of area involved Moderate – 1/3 to 2/3 Moderate – 1/3 to 2/3 High – greater than 2/3High – greater than 2/3

Grade 3Grade 3: Rupture of the myotendinous junction: Rupture of the myotendinous junction

Myotendinous Junction Injury: Myotendinous Junction Injury: Grade 1 muscle strainGrade 1 muscle strain

Key Point: Myotendinous junction is weakest part of skeletal muscle

Myotendinous Junction Myotendinous Junction Injury: Grade 2 (Partial tear)Injury: Grade 2 (Partial tear)

T1 STIR

STIR

Hemorrhage indicates at least a Grade 2 injury

Myotendinous Junction Myotendinous Junction Injury: Grade 2 (Partial tear)Injury: Grade 2 (Partial tear)

STIRT1

Myotendinous Junction Injury – Myotendinous Junction Injury – Grade 3 (Complete Tear)Grade 3 (Complete Tear)

STIR STIR

Myotendinous Junction Injury – Myotendinous Junction Injury – Grade 3 (Complete Tear)Grade 3 (Complete Tear)

STIR T2 fat sat

Delayed Onset Muscle Soreness Delayed Onset Muscle Soreness (DOMS)(DOMS)

Muscle pain and soreness following renewed or Muscle pain and soreness following renewed or unaccustomed exerciseunaccustomed exercise

Pain peaks after 12-48 hours following exercise eventPain peaks after 12-48 hours following exercise event

Symptoms depend on:Symptoms depend on: Exercise durationExercise duration Exercise intensityExercise intensity

Stretching prior to exercise has not been shown to Stretching prior to exercise has not been shown to reduce symptomsreduce symptoms

Stretching and massage does not shorten recovery timeStretching and massage does not shorten recovery time But feels GOOD!But feels GOOD!


Normal response by muscle which will lead to Normal response by muscle which will lead to increase muscle strength and staminaincrease muscle strength and stamina

Grade 1 muscle strain due to microscopic tears Grade 1 muscle strain due to microscopic tears at the myotendinous junctionat the myotendinous junction

Can be associated with increase in serum Can be associated with increase in serum creatine kinase levelscreatine kinase levels

Rhabdomyolysis in rare severe casesRhabdomyolysis in rare severe cases


CPK >7000 IU/L (nl range <150 IU/L)CPK >7000 IU/L (nl range <150 IU/L)

STIRSTIR

Delayed Onset Muscle Delayed Onset Muscle Soreness (DOMS)Soreness (DOMS)

STIR







Muscle Belly Injury - ContusionMuscle Belly Injury - Contusion

Result of blunt traumaResult of blunt trauma Edema and Edema and

hemorrhage seen as hemorrhage seen as high T2 signal in the high T2 signal in the musclemuscle

Hemorrhage as high Hemorrhage as high T1 signalT1 signal

Often adjacent to Often adjacent to bonebone

STIR


STIRT1


STIR

Muscle Belly Injury - MyositisMuscle Belly Injury - Myositis

Inflammation of skeletal muscleInflammation of skeletal muscle Many causesMany causes Associated with pain and muscle weaknessAssociated with pain and muscle weakness Elevated serum creatine kinase and other Elevated serum creatine kinase and other

markers of muscle damagemarkers of muscle damage Imaging findings are non-specificImaging findings are non-specific

High signal on edema-sensitive MR sequencesHigh signal on edema-sensitive MR sequences

Autoimmune diseaseAutoimmune disease PolymyositisPolymyositis DermatomyositisDermatomyositis Inclusion bodyInclusion body

InfectionInfection HIVHIV LymeLyme ParasitesParasites

Trauma Trauma MedicationsMedications

StatinsStatins AlcoholAlcohol SteroidsSteroids

IdiopathicIdiopathic

Muscle Belly Injury - CausesMuscle Belly Injury - Causes

PolymyositisPolymyositis

STIRSTIR

PolymyositisPolymyositis

STIRSTIR

Statin MyopathyStatin Myopathy

STIRSTIR

Muscle Belly Injury: DenervationMuscle Belly Injury: Denervation

Loss of stimulus to muscleLoss of stimulus to muscle Nerve/muscle interfaceNerve/muscle interface Secondary to myotendinous Secondary to myotendinous

unit ruptureunit rupture

Imaging findings in Imaging findings in denervationdenervation Early: normal signal, normal Early: normal signal, normal

bulkbulk Subacute: high signal on T2 Subacute: high signal on T2

(edema), normal/decrease (edema), normal/decrease bulkbulk

Chronic: high signal on T1 Chronic: high signal on T1 (fatty atrophy), decrease bulk(fatty atrophy), decrease bulk

Deltoid Muscle Denervation Following Deltoid Muscle Denervation Following Rotator Cuff RepairRotator Cuff Repair

PD STIR

Supraspinatus Muscle AtrophySupraspinatus Muscle Atrophy

T2 fat satNormal

Supraspinatus Muscle AtrophySupraspinatus Muscle Atrophy

Normal T2 FSE

Fatty Atrophy from PolioFatty Atrophy from Polio

T1 T1

Sites of Muscle InjurySites of Muscle Injury Tendon – boneTendon – bone






Imaging of Muscle disordersImaging of Muscle disorders

Imaging studies are often normal despite Imaging studies are often normal despite symptomssymptoms

When imaging findings are present, they can be When imaging findings are present, they can be non-specificnon-specific

CK typically normal unless severe disease CK typically normal unless severe disease despite clinical symptomsdespite clinical symptoms

Makes diagnosis of the muscle disease difficultMakes diagnosis of the muscle disease difficult Need for better imaging tests to assess muscle Need for better imaging tests to assess muscle

diseases!!diseases!!

Novel imaging techniques to Novel imaging techniques to evaluate muscle disordersevaluate muscle disorders

Advance MRI techniquesAdvance MRI techniques 3131P MR SpectroscopyP MR Spectroscopy

Quantitative ultrasound (QU)Quantitative ultrasound (QU) Muscle echointensity Muscle echointensity

Advanced MR technique – 31P MR Spectroscopy

Uses Uses 3131Phosphorus Phosphorus imaging instead of imaging instead of 11HH

Many muscle Many muscle metabolites contain metabolites contain phosphorusphosphorus

Concentration of muscle Concentration of muscle metabolites directly metabolites directly related to mitochondrial related to mitochondrial function and muscle function and muscle healthhealth

Advanced MR technique – 31P MR Spectroscopy

ATPATP – energy rich compound – energy rich compound needed for muscle contraction needed for muscle contraction

Phosphocreatine (PCr)Phosphocreatine (PCr) Crucial energy store in skeletal Crucial energy store in skeletal

musclemuscle decreases in exercisedecreases in exercise

Phophosdiesterase (PDE)Phophosdiesterase (PDE) Breakdown product of cell Breakdown product of cell

membranesmembranes increases with high cell turnoverincreases with high cell turnover

Inorganic phosphate (Pi)Inorganic phosphate (Pi) Byproduct of PCr during muscle Byproduct of PCr during muscle

contractioncontraction increases with exerciseincreases with exercise

RestingResting

Peak Peak ExerciseExercise

Time

Pipinos et al J Vasc Surg 2000;31:944-952

Statins are used to lower cholesterol, but associated Statins are used to lower cholesterol, but associated with calf pain in 5-10% of patientswith calf pain in 5-10% of patients

Cause is not fully understoodCause is not fully understood 10 patients given statins for 4 weeks10 patients given statins for 4 weeks Studied the effects of statins on mitochondrial function Studied the effects of statins on mitochondrial function

and phosphocreatine (PCr) recovery with and phosphocreatine (PCr) recovery with 3131P MR P MR spectroscopy (before and after statin use)spectroscopy (before and after statin use)

Significant drop in PCr recovery after 4 weeksSignificant drop in PCr recovery after 4 weeks Conclusion – Statins weaken mitochondrial functionConclusion – Statins weaken mitochondrial function

PCR recovery after cessation of exercise

31P MR SpectroscopyDiabetic Myopathy

Normal patient – Rapid PCr recovery

31P MR SpectroscopyDiabetic Myopathy

Diabetic Myopathy – blunted PCr recovery

Quantitative UltrasoundQuantitative Ultrasound

Diseased muscle (especially in neuromuscular Diseased muscle (especially in neuromuscular disorders) is often echogenic due to fibrosis and disorders) is often echogenic due to fibrosis and fatty infiltrationfatty infiltration

Technique assesses muscle health by Technique assesses muscle health by measuring the echointensity of the musclemeasuring the echointensity of the muscle

Easy to use: painless, quick, no radiationEasy to use: painless, quick, no radiation

Neuromuscular disorders (NMD)Neuromuscular disorders (NMD)

Patients with have disruption of normal muscle architecture with infiltration of fat and connective tissue

Have decreased muscle thickness and increased subcutaneous fat thickness when compared to controls

Normal With NMD

Infiltration of fat and connective tissue into muscle increases the number of reflective interfaces

PathophysiologyPathophysiology

a. Normal subject b. Patient with spinal muscular atrophy

Subcutaneous Fat

Fascia

Muscle

Bone

Diseased muscleMore echogenic

TechniqueTechnique

Step 1Step 1Step 1Step 1

US images are obtained in a US images are obtained in a relaxed limb relaxed limb at the midpoint at the midpoint of the muscle belly of the muscle belly

Various muscles can be Various muscles can be studied including biceps studied including biceps brachii, quadriceps, and brachii, quadriceps, and tibialis anteriortibialis anterior

US images US images can be obtained can be obtained in the transverse or in the transverse or longitudinal positionslongitudinal positions

Gain, compression, and Gain, compression, and time gain compensation time gain compensation kept constantkept constant

TechniqueTechnique

Step 1 continuedStep 1 continuedStep 1 continuedStep 1 continued

Subcutaneous skin thickness measured using electronic calipers

TechniqueTechnique

Step 1 continuedStep 1 continued

Measurements taken from the interface between the dermis and superficial fascia

US images are transferred to photo analysis software program

TechniqueTechnique


TechniqueTechnique


1) Place regions of interest in the subcutaneous fat

2) Apply grayscale histogram function

3) Take median value = 32

Quantify tissue luminosity:

Normal subject

TechniqueTechnique


1) Repeat steps with muscle. Exclude placing region of interest over fascia and muscle tendon transitions.

2) Apply grayscale histogram function.

3) Take median value = 38


Normal subject

Calculate luminosity ratio (LR) :Divide muscle luminosity value (LV) by the overlying

subcutaneous fat luminosity value

TechniqueTechnique

Step 3Step 3

Normal subject

TechniqueTechnique

1) Place regions of interest in the subcutaneous fat


3) Take median value--36


Distance 1.50

Patient with spinal muscular atrophy

TechniqueTechnique

1) Place regions of interest in the muscle


3) Take median value--88


Distance 1.50

Patient with spinal muscular atrophy

TechniqueTechnique Patient with spinal muscular atrophy

Calculate luminosity ratio (LR) :Divide muscle luminosity value (LV) by the overlying

subcutaneous fat luminosity value

Evaluated 25 pts with SMA and 21 normal controls from the Evaluated 25 pts with SMA and 21 normal controls from the spinal muscular atrophy clinic at Children’s Hospital Bostonspinal muscular atrophy clinic at Children’s Hospital Boston

Luminosity ratio for 4 muscle groups (biceps, wrist extensors, Luminosity ratio for 4 muscle groups (biceps, wrist extensors, quadriceps, and tibialis anterior) had a significant correlation quadriceps, and tibialis anterior) had a significant correlation with worsening diseasewith worsening disease

Able to distinguish between SMA subtypes 3 (walkers) and 2 Able to distinguish between SMA subtypes 3 (walkers) and 2 (sitters) using the luminosity ratio(sitters) using the luminosity ratio

Normal Type 2 SMAType 3 SMA

LR: 1.19 LR: 2.44 LR: 5.31

Spinal Muscular AtrophyQuadriceps muscle

Echointensity increases with worsening muscle disease

Duchenne Muscular DystrophyDuchenne Muscular DystrophyBiceps brachii muscleBiceps brachii muscle

Increased muscle Increased muscle echogenicityechogenicity

Becker Muscular DystrophyBecker Muscular Dystrophy

21 yrs21 yrs 17 yrs17 yrs 15 yrs15 yrs

Quadriceps muscleQuadriceps muscle

Three brothers with Becker Muscular Dystrophy and normal strengthThree brothers with Becker Muscular Dystrophy and normal strength

Amyotrophic Lateral SclerosisAmyotrophic Lateral Sclerosis

72 year-old with ALS72 year-old with ALS

Biceps brachii muscleBiceps brachii muscle

Subcutaneous fatSubcutaneous fat

SummarySummary Skeletal muscle is a unique and dynamic organSkeletal muscle is a unique and dynamic organ Injuries can be classified by their location in the Injuries can be classified by their location in the

muscle-tendon-bone unitmuscle-tendon-bone unit Tendon-bone (weakest in children)Tendon-bone (weakest in children) TendonTendon Myotendinous junction (weakest in adults)Myotendinous junction (weakest in adults) Muscle bellyMuscle belly

Injuries often occur in muscles that cross 2 jointsInjuries often occur in muscles that cross 2 joints MR is the best conventional imaging test to MR is the best conventional imaging test to

localize and characterize muscle injurieslocalize and characterize muscle injuries

SummarySummary

Findings on conventional imaging studies can be Findings on conventional imaging studies can be normal despite clinical symptomsnormal despite clinical symptoms

Advanced imaging techniques can better assess Advanced imaging techniques can better assess skeletal muscle disordersskeletal muscle disorders 31P-MR spectroscopy31P-MR spectroscopy Quantitative ultrasoundQuantitative ultrasound

ReferencesReferences Garrett & Best. Ortho Basic Science AAOS 1994: 89-126)Garrett & Best. Ortho Basic Science AAOS 1994: 89-126) Huard et al JBJS[Am] 2002; 84-A: 822Huard et al JBJS[Am] 2002; 84-A: 822 Zaraiskaya et al. JMRI 2006; 24:402–408 Zaraiskaya et al. JMRI 2006; 24:402–408 Elsayes et al. Curr Prob in Diag Radiol2006;35(5):206-212Elsayes et al. Curr Prob in Diag Radiol2006;35(5):206-212 Noonan & Garrett. Clin Sports Med 1992; 11:783-806)Noonan & Garrett. Clin Sports Med 1992; 11:783-806) Garrett. Med Sci Sports Exerc 1990; 22: 436-443Garrett. Med Sci Sports Exerc 1990; 22: 436-443 Subhawong et al. RadioGraphics 2014; 34:1163–1177Subhawong et al. RadioGraphics 2014; 34:1163–1177 Kuo and Carrino. Curr Opin Rheumatol 19:530–535Kuo and Carrino. Curr Opin Rheumatol 19:530–535 Budzik et al. RadioGraphics 2014; 34:E56–E72Budzik et al. RadioGraphics 2014; 34:E56–E72 Costa et al. Muscle Nerve 46: 465–481, 2012Costa et al. Muscle Nerve 46: 465–481, 2012 Kassarjian et al. European Journal of Radiology 81 (2012) 3763– 3771Kassarjian et al. European Journal of Radiology 81 (2012) 3763– 3771 Shelly et al. Magn Reson Imaging Clin N Am 17 (2009) 757–773Shelly et al. Magn Reson Imaging Clin N Am 17 (2009) 757–773 Olsen et al. Current Rheumatology Reports 2005, 7:106–114Olsen et al. Current Rheumatology Reports 2005, 7:106–114 Wu et al. Neurology. 2010; 75(6):526-31. Wu et al. Neurology. 2010; 75(6):526-31. Wu et al. Muscle and Nerve. 2011; 43:76-81.Wu et al. Muscle and Nerve. 2011; 43:76-81.

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MSK Imaging_4.Imaging of muscle china_by Dr. Jim Wu