MSK ULTRASOUND Ramon Ylanan, MD CAQSM Team Physician University of Arkansas Razorbacks Director Primary Care Sports Medicine Fellowship UAMS NW Assistant Professor Family and Preventative Medicine UAMS NW

Conflicts of Interest I have no conflicts of interest regarding this presentation, nor do I support one manufacturer over another

Objectives Recognize basic scanning techniques, probe placement and probe orientation Differentiate between common structures such as muscle, tendon, ligament and bone Outline appropriate uses for diagnostic ultrasound and terminology Identify common findings associated with tendinopathy

Outline Principles of Sound MSK US 101 Pathology under US Equipment Knobology Terminology Pathology under US Advantages and limitations to MSK US

Outline Principles of Sound MSK US 101 Pathology under US Equipment Knobology Terminology Pathology under US Advantages and limitations to MSK US

Principles of Sound It’s all about frequency <20Hz (lower frequency) Whales, elephants 20Hz -20kHz (audible sound) Humans >20kHZ (higher frequency) Dogs, dolphins, bats

Principles of Sound Why is sound important in MSK US Higher frequency sound Greater resolution Shorter depth of sound penetration Lower frequency sound Less resolution Greater depth of sound penetration

Principles of Sound How does it work in MSK US Transducer crystals produce sound waves Piezoelectricity conversion of electricity to sound Sound bounces off structures and returns to transducer crystals Picture is dependent on stiffness and/or density of acoustic interface (structure) Each body part type has a different acoustic signature Transducer converts sound waves into electricity which machine converts into a picture Reverse-piezoelectricity conversion of sound into electricity

Outline Principles of Sound MSK US 101 Pathology under US Equipment Knobology Terminology Pathology under US Advantages and limitations to MSK US

MSK 101: Equipment Console Transducers GE, Sonosite, Terason, Arthrex, etc Each have pros and cons Cost ranges $20,000-$100,000 Personal preference Transducers Linear array transducer Compact linear array transducer Curved linear array transducer

MSK 101: Equipment Transducers Linear array transducer Workhouse of MSK US High frequency Superficial structures Able to scan most parts Shoulder Knee Elbow High resolution

MSK 101: Equipment Transducers Compact linear array transducer “Hockeystick” Subspecialty Very high frequency Small joints Very superficial structures High resolution

MSK 101: Equipment Transducers Curved linear array transducer Lower frequency Deep structures Hip Abdomen Lower resolution

MSK 101: Knobology Each machine Modes Depth Gain different layout, same principles Modes B-mode is common MSK scanning mode Depth Control depth of field of view Can be modified for each transducer, but has limits Gain Volume or picture brightness Just like listening to music, operator dependent

MSK 101: Terminology Already got some Transducer, piezoelectricity, etc Long axis – longtitudinal picture of target Short axis – cross sectional picture of target Anisotropy – poor picture due to poor scanning technique Sound wave/transducer was not perpendicular to target

MSK 101: Terminology Anisotropy

MSK 101: Terminology Hyperechoic – brighter gradient, relatively more dense Bone, tendon, ligament Hypoechoic – darker gradient, relatively less dense More solid cysts Isoechoic – grey gradient, relatively equal density Muscle Anechoic – very dark gradient, Vessels or fluid pockets

MSK 101: Terminology

MSK 101: Terminology Procedure In plane vs out of plane

Outline Principles of Sound MSK US 101 Pathology under US Equipment Knobology Terminology Pathology under US Advantages and limitations to MSK US

MSK Pathology under US Muscle Tendon Ligament Vessles Nerves Bone

Muscle Long axis  feather-like, pennate Short axis  starry night appearance

Muscle Not this starry night!

Muscle

Muscle Hamstring tear

Tendon Achilles Tightly packed, fibers of a broom, fibrillar Normal Tendinosis/Degeneration

Tendon Patellar tendon  Normal long axis Proximal patellar tendinosis

Tendon Rotator Cuff

Ligament MCL Similar characteristics to tendon (broom, fibrillar)

Ligament Elbow UCL

Vessels Femoral triangle N - nerve A - artery V - vein E - empty L - lymphatics

Nerve Carpal Tunnel Honeycomb in short axis Fascicular in long axis (not as tighly packed as tendon)

Bone Hip

Outline Principles of Sound MSK US 101 Pathology under US Equipment Knobology Terminology Pathology under US Advantages and limitations to MSK US

MSK US: Advantages High resolution imaging of soft tissue Real-time imaging with dynamic evaluation Patient experience and education Not affected by hardware Just can’t scan deep to the hardware

MSK US: Advantages Guided injections Portable No radiation Inexpensive for patients

MSK US: Limitations Focal/limited field and depth of view MRI better for wider field of view Limited with eval of bone or intra-articular pathology Operator dependent Picture quality depends on sonographer skill

MSK US: Limitations Education is post-training Building into fellowships now Cost to provider for equipment Purchase vs rent Quality of image depends on multiple factors Patient position Machine Sonographer skill

Basic Principles of MSK US Know the question What do you want to answer? Is US the modality to properly eval? Keep patient comfortable If patient is uncomfortable, results will be limited Select appropriate transducer Know you anatomy, know transducer limitations

Basic Principles of MSK US Keep control of transducer If it’s not stable, poor picture quality Hard to hit a moving target Take your time Using a 2D slice to reconstruct a 3D structure Must use multiple planes to properly scan

Scanning Time

References Smith, J. Finnoff, JT. Diagnostic and Interventional Musculoskeletal Ultrasound: Part 1. Fundamentals. PM&R 2009;1:64-75. Smith, J. Finnoff, JT. Diagnostic and Interventional Musculoskeletal Ultrasound: Part 2. 6th ed. Philadelphia, PA. WB SaundClinical Applications. PM&R 2009;Vol 1:162-177. Kremkau F. Diagnostic Ultrasound: Principles and Instruments.ers; 2002:428 Nazarian L, McShane J, Ciccotti M, et al. Dynamic US of the anterior band of the ulnar collateral ligament of the elbow in asymptomatic major league baseball pitchers. Radiology 2003;227:149-154 O’Conner P, Grainger A. Ultrasound imaging of joint disease. Imaging 2002;14:188-201