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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 IntraMuscular 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 splaying around the lesion Nerve Nerve splaying around the lesion Nerve 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 Baker’s masses Achilles Tendon 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 Complete tear with hematoma filling gap Normal Long Axis Achilles Complete tear with hematoma filling gap Normal Short Axis Achilles 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. the SWEEP THROUGH THE MUSCLE! Long axis imaging of medial gastroc on the same patient › 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 Achilles masses 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 missdiagnosis. 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 tendon And medial to medial gastroc muscle Originate lateral to semimembranosus 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 noncompressible. 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 Nerve or Vein? Basilic Vein Brachial V Test Time… Brachial A Basilic Vein Median Nerve Brachial V Brachial A Look for the ‘ovary’, try scanning up and down the upper arm – no matter the venous configuration, Every person will have a median nerve