A rapidly emerging sub-specialty

Requires dedicated training and consistent

exposure to become proficient

That being said…

› We as general sonographers often encounter

MSK in our day-to-day exams

› This lecture will cover a few generalist exam

scenarios where some basic MSK knowledge

can go a long way in understanding the clinical

picture.

Superficial masses

Achilles Tendon

Baker’s cyst

Peripheral nerves

Our lumps and bumps exams

Keys to assessment:

› Patient history

› Location

› Morphology

Size

Vascularity

Patient History: › Clinical questions:

How long have you had it?

Was there an injury?

Has it changed in size? (bigger or smaller)

It is painful?

The answers to these questions plus the imaging characteristics give the radiologist an index of suspicion about a given mass and which recommendations to make as to follow up.

Location:

› Tissue Layers

Skin: made up of epidermis and dermis

Subcutaneous tissue aka hypodermis or fat

layer

Muscle

Skin

› Thin and hyperechoic

› Lesions involving the skin layer often need

imaging with a standoff pad to optimize focal

zone and appreciate

outward mass effect

› Warts, calluses,

hemangiomas

Fat layer

› Variable in thickness

› Made up of ‘fat islands’, connective tissue,

blood vessels and lymphatic channels

› Common location

for lipomas, abcesses,

hematomas, bursitis

and ganglions.

Muscle layer › Generally hypoechoic with echogenic fascial

lines though muscle; can become echogenic with disuse and atrophy.

› Exhibits a striated pattern in long axis and well formed muscle fibers are capable of demonstrating anisotropy (change in echogenicity based on angle of insonation)

› Masses can form a mass effect upon the adjacent muscle or can directly invade/arise from the muscle

Side-to-side comparison most beneficial

Be aware of tissue/fascial planes

Morphology: › Sonographers are already well equipped to

describe the characteristics of any lesion they find

Cystic vs solid

Ill-defined vs well circumscribed,

Heterogenous vs homogenous

Presence of any vascularity

Size

What can be improved upon is describing the location of these superficial masses › Subcutaneous vs intra-muscular

› Any invasion into surrounding tissue?

› Lipomas

Variable in size and echogenicity (echogenic –

isoechoic)

Most frequently subcutaneous but can also be

intra-muscular in origin

Note should be made of lipomas that are

growing, painful and/or exhibit internal

vascularity – may need follow up

Subcutaneous

lipoma

Intra-

Muscular

Lipoma

› Focal fluid

Abcess

Hematoma

Bursitis

Inflammation of a bursal sac of synovial fluid

Ganglions/Synovial cysts

Caused by leakage of fluid from a joint or tendon sheath

into the surrounding tissue

Very similar imaging characteristics › Often an irregular subcutaneous fluid collection

Abscess – simple fluid or debris filled, may contain air or exhibit increased peripheral vascularity

Hematoma – variety of appearances depending on stage, can look simple or solid or combined

Patient history key › Abscess – red, inflamed skin, possible open

wound and discharge

› Hematoma – history of trauma, likely bruising and pain over site

Subcutaneous

Hematoma

(history of injury)

Bursal sacs lie through out the body offering

cushion and protection against friction.

Inflammation of this sac leads to excess

synovial fluid = fluid collection

Patient history

› Pain

› Possible swelling

› Often chronic, variable in severity

Painful swelling around

the knee

- No hx of trauma

- Not a hematoma

- Not assoc w/ the joint

- Not a ganglion

Bursitis

- Most often associated with tendons/joints of the

hands and feet

- Predominately cystic, may have a thickened

rim/septations which may have increased vascularity

- Demonstrate the origin if

possible

- Often change in size

- Can be painful

› Nerve tumors

Painful, results in numbness or tingling

Probe pressure reproduces symptoms

Can often be seen to directly arise from an

adjacent nerve

Has a ‘tail’ or trumpeted ends

Nerve

Nerve splaying around

the lesion

Nerve

Nerve splaying around

the lesion

Only in long axis

can you determine

that this lesion is

arising from the

nerve

› Mysterious masses

Asymmetric tissue layers Often fat but no focal lipoma

Compare side to side to appreciate layer differences

Muscle hernia Often due to a weakness or defect in the fascia

Dynamic scanning a must

Nothing Patients often palpate ‘lumps’ where there is no

corresponding abnormality – often palpating normal muscle anatomy, etc

Compare side to side

Patient complaint:

Lump over scapula

on left

Lump was her

scapula – more

outwardly

prominent

Herniation of

muscle thru

fascial defect

Normal

Dynamic scanning shows mass change with muscle contraction

Patients who complained of a ‘fullness’ or asymmetry

to their back

Unable to palpate specific mass at time of exam,

panoramic reveals equal tissue planes

› Other….

Numerous superficial mass types (benign and

cancerous) – ultrasound alone cannot distinguish

(may need MRI and/or biopsy)

Ultrasound can start the analysis

Solid vs. cystic

Vascular?

Invasive?

When in doubt:

Measure, color, clip

and give rough location

Superficial masses

Achilles Tendon

Baker’s cyst

Peripheral nerves

In regards to emergent requests post trauma; Query Tear › Often come from emergency departments and

to a lesser extent GP’s offices

Where possible these patients are being sent to dedicated MSK centers as many radiologists prefer to have them performed/read by MSK specialized staff.

However, this is not always feasible – there is a finite surgical window to consider (7-10 days)

These patients can’t necessarily wait to be shuffled around and re-booked.

› Achilles used to be done under general

ultrasound before MSK became its own field

› Can and is being done under general if the

technologist is able and the radiologist is willing

› Following a few key points when evaluating the

Achilles eliminates many possible pitfalls and

results in more consistent results.

Anatomy: Attaches the gastroc

(medial and lateral heads) and soleus muscles to the calcaneus

Broad and thin proximally at its origin mid calf – overlying the soleus muscle

Thickens and becomes fully formed distally, inserting on the posterior calcaneus

Key exam features

› Is there a tear? Evaluate the Achilles tendon in long and short axis

Majority of traumatic tears occur between the distal soleus and the calcaneus

Therefore most helpful to start where its normal (the

calcaneus) and work your way up.

A torn tendon retracts causing thickening and

heterogeneity to the torn ends (often includes

shadowing)

Debris and hemorrhage fills the gap *will have no

normal linear strands

Normal

Achilles

Torn Achilles Tendenotic Achilles

Key exam features

› Where is the tear? Measure the distance of the tear from the

calcaneous

Key exam features › Complete or partial tear?

Sweep side to side in long axis through the tear to look for any residual fibers

Take long and short axis clips through the tear to demonstrate the changes more clearly

› Functional tests:

Squeezing the calf = moves the proximal stump while the distal stump remains motionless = complete tear

Plantar/dorsi-flex the foot = moves the distal stump while the proximal stump remains motionless = complete tear

Normal Long Axis Achilles

Complete tear with

hematoma filling gap

Normal Short Axis

Achilles

Complete tear with

hematoma filling gap

Partial tear of Achilles.

Could be mistaken

for a complete tear in

long axis.

Key exam features

› Measure the tear

Long axis most important surgically

Can gently plantar/dorsi-flex the foot to help

define the edges of the tear

Measure the gap in neutral and again with

plantar flexion

Some tears are treated with a boot instead of surgery

if the tendon ends are closely approximated with

plantar flexion

Short axis measure if tear is partial

Not everyone has one

Lies adjacent and medial to the achilles

Most easily identifiable in short axis by

scanning the achilles over the soleus

muscle and focusing on the medial border

› Appears as a small, separate oval structure in

the same fascial plane

PITFALL:

› An intact plantaris tendon can mimic intact

medial achilles fibers

Can be used surgically to help repair the

achilles

Check if the patient has one

› Does it bridge the tear?

Can occur simultaneously with an

achilles tear or mimic an achilles tear by

presenting with similar symptoms

Medial gastrocnemius most commonly

torn

› Feels like a kick or shot to the calf

› Patient has focal pain over the medial calf

Distal soleus may also be partially torn

with a high achilles tear

Anatomy

› Muscle fibers like tendon fibers should be linear

› Musculo-tendinous junctions should be sharp and angular

› Muscles should

have thin fascial

planes separating

them

› Tears:

Bunching and curling of muscle fibers Often with hematoma formation in the acute phase

*Compare to opposite side for confirmation*

Medial gastroc

tears often involve a

fascial tear/separation

from the soleus with

hematoma tracking

up the calf between

the two muscles

› How to document:

Image the distal musculo-tendinous junctions of

medial/lateral gastroc and soleous in both planes

*Scan through the muscle*

Measure any hematoma formation in three planes

Document any suspected muscle tears with static

and clip imaging

Patient can always be rescanned at a dedicated

MSK facility if clarification is needed but finding the

problem is the first step.

Long axis imaging of

the medial gastroc on the

same patient

SWEEP THROUGH

THE MUSCLE!

› While non-surgical, these tears can cause

significant pain and weakness causing the

patient to require a course of rest and

sometimes physio to ensure proper healing

› Missing these tears results the patient in trying to

resume activity too soon on the basis of a

normal achilles exam.

Superficial masses

Achilles Tendon

Baker’s cyst

Peripheral nerves

Cause of posterior knee pain and swelling

Often found incidentally during the course of a DVT study

Occasionally cystic collections at the back of the leg are not Baker’s cysts, many are similarly benign synovial cysts of the knee joint but rarely they can be a sarcoma

Simple land marking of these posterior cysts can ensure that we don’t make that miss-diagnosis.

Posterior knee

anatomy

The neck of a

Baker’s cyst originates

from between the

medial gastroc muscle

and semimembanous

tendon at the medial

aspect of the post knee

Originate lateral to semimembranosus tendon

And medial to

medial gastroc muscle

Key exam features:

› Identify fluid collection

Can be simple or complex

Can be multi loculated

Can extend superiorly or inferiorly from the

knee joint or both

› Measure in three planes

› PUT ON COLOR

Key exam features:

› Verify location

Axial plane

Follow the medial border of the medial

gastroc up to the knee joint

The cyst should originate from between the medial

gastroc muscle and semimembranosus tendon

(hamstring).

› Cysts/masses in any other location must be

considered to not be Baker’s cysts

Looks like a Baker’s cyst in long axis…..short axis reveals that it doesn’t originate from the proper location synovial cyst of post knee

3yo with a Baker’s cyst

that was compressing

his popliteal vein with

leg extension

Superficial masses

Achilles Tendon

Baker’s cyst

Peripheral nerves

Neurovascular bundle:

› Consist of a nerve, artery, vein and lymphatics that travel together in the body.

› Example: brachial,

posterior tibial, etc.

Brachial neurovascular bundle

› Most problematic in terms of upper limb

venous ultrasounds to assess for clot.

› Many venous anatomical variations in the upper limb

Duplicated axillary vein

Variable origin of basilic vein

Single brachial vein

Brachial neurovascular bundle › The median nerve also courses alongside the

brachial artery and can easily be mistaken for a thrombosed brachial vein - especially in a case where only one brachial vein exists. (leading to a diagnosis of DVT where none exists)

› This can be avoided by learning to recognize peripheral nerves and their locations in the body.

Are most easily recognized in cross section

Have a ‘pediatric ovary’ appearance by being comprised of multiple small hypoechoic fascicles separated by echogenic fascia.

These fascicles can become dilated and therefore resemble a thrombosed vein as they are without flow and are non-compressible.

Normal neurovascular bundle

Long axis nerve

- can be difficult to differentiate from surrounding tissue

- can still appreciate echogenic fascia separating the fascicles – more uniform than a thrombosis

Thickened hypoechoic nerve (on the right) adj. to an artery (veins compressed in this view)

Nerve would not show flow – could be mistaken for a thrombosed vein

Test Time…

Basilic Vein

Brachial A Brachial V

Nerve or Vein?

Look for the ‘ovary’, try scanning up and down the

upper arm – no matter the venous configuration,

Every person will have a median nerve

Basilic Vein

Brachial A

Brachial V

Median Nerve