3/20/2017. Disclosures. Ultrasound Fundamentals. Ultrasound Fundamentals. Bone Anatomy. Tissue Characteristics

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1 Disclosures Images of ultrasound equipment in this presentation are not an endorsement Fundamentals of Musculoskeletal Ultrasound Physics and Knobology Shane A. Shapiro, M.D. Assistant Professor Orthopedic Surgery Mayo Clinic College of Medicine Mayo Center for Regenerative Medicine slide-1 2 Ultrasound Fundamentals US transducer emits and receives sound waves Electrical current is applied to an array of piezoelectric crystals inside transducer Vibrational energy is created (ultrasound waves) Transducer is coupled to the body by ultrasound gel Waves move through body and are attenuated, reflected, and/or scattered Electrical signal from reflected waves are received back by transducer and processed by machine to generate an image on the screen. Ultrasound Fundamentals Depending on sound waves received, anatomy takes on different appearance (echoes) High water content appears dark (few reflections/echoes) = anechoic/hypoechoic Bone and tendon (heavy signal reflection) = hyperechoic appearance (bright) Medium density structures (organs) look grey slide-3 slide-4 Tissue Characteristics Bone Adipose Muscle Tendon Ligament Vasculature Nerves Cartilage Bone Anatomy Hyperechoic MSK Signature or Homebase slide-5 slide-6 1

2 Tissue Characteristics Muscle Sonography Adipose Tissue Cartilage Largely hypoechoic with Fibro-adipose septa slide- 7 slide-8 Tendon Sonographic Appearance Long Axis = Fascicular structure - multiple closely spaced lines in parallel Short Axis = multiple echogenic dots, starry night appearance Ligament Sonographic Appearance Striated Hyper/Hypoechoic anisotropy Uniform Compact slide-9 slide-10 Peripheral Nerve Anatomy Axons are cellular extensions Groups of axons surrounded by perineurium is a fasicle. Perineurium not visible but fat outside perineureum gives the nerve honeycomb appearance Epineurium surrounds perineurium Contains variable quantities of fat Peripheral Nerve Ultrasound Peripheral nerves 2-10mm Nerves may be Hypo- or Hyperechoic Numbers of fasicles Quantity of fat Surrounding tissues slide-11 2

3 Transducers Linear transducer Compact transducer Curved transducer Transducer Selection 8-13 MHz linear array probe Swiss Army Knife Good for most MSK 7-15 MHz hockey stick probe Smaller linear footprint Easier for gel standoff 4-9 MHz curved array probe Deeper structures Wider field of view slide-13 slide-14 System Presets Unique to individual machines, software General (MSK, Small parts, nerve) Specific joints: Shoulder, knee, elbow, wrist, hip, etc. Manufacture presets, or custom settings Standardize Vocabulary Probe Translation Probe Rotation Toggling Heel Toe Ultrasound Artifacts Anisotropy Variation in appearance of structure based on angle of ultrasound beam Reverberation smooth flat object Increased through Transmission (posterior acoustic enhancement) sound waves through fluid Acoustic shadowing Anechoic area extending deep to a structure caused by absorption or reflection of sound waves Anisotropy Angle of insonation Subtle changes alter the picture Diffraction and Scattering slide-17 slide-18 3

4 Anisotropy Heel-Toe Maneuver Peroneal Tubercle Peroneal Tubercle slide-19 slide-20 Wag Tail / Toggle Reverberation slide Acoustic Shadowing Increased through Transmission

5 Image Optimization Knobology Frequency Brightness (Gain) Contrast (Dynamic Range) Depth Focal Zone Power Doppler slide-25 slide-26 Frequency Frequency 13 mhz 10 mhz Depth Image Depth 29 slide-30 5

6 Focal Zones Selected by Target Depth Power Doppler Frequency Brightness (Gain) Contrast (Dynamic Range) Depth Focal Zone Power Doppler Depth = 2.5cm slide-31 slide-32 Miscellaneous Concepts Needle Movement Heel-toe Wag tail / Toggle Needle movement Tissue harmonics Power Doppler / color flow B-Steer Virtual convex Gel standoff Extended Field of View slide-33 slide-34 B-Steer Virtual Convex Simulates curved probe Gives wider field of view Eliminates keyhole effect May lose crossbeam/detail slide-35 slide-36 6

7 Virtual Convex Gel Standoff Allows for change in needle approach Obtain better visibility with needle parallel to probe Deactivates cross-beam technology Loses the improved detail of cross beam harmonics slide-38 Gel Standoff Extended Field of View slide-39 slide-40 Normal vs. Pathology Sonopalpation Lateral Facet slide-41 slide- 42 7

8 Dynamic Examination Measurements Digital Calipers Tissue Thickness Mass Size Circumferential Area Peripheral nerve slide Image Storage Diagnostic Billing CPT code Ultrasound, extremity, nonvascular, real-time with image documentation; complete CPT code Ultrasound, extremity, nonvascular, real-time with image documentation; limited All diagnostic ultrasound examinations require permanently recorded images in the patient record. Images do not need to be submitted with the claim. Images can be stored as printed images, on a tape or electronic medium. Documentation of the study must be available to the insurer upon request. A written report of all ultrasound studies should be maintained in the patient's record Diagnostic US Documentation Injection Billing - CHANGES 1/1/15 Standard Joint, Bursa, Tendon Injections do not accompany CPT 76942, US Guidance for Needle Placement when billing Medicare as of January 2015 (20600, and now have the language without ultrasound guidance) Ganglion, Tendon or Nerve procedure injection codes may still be used with needle guidance CPT US Guidance for Needle Placement in Small, Medium, Large Joints - CPT 20604, 20606, Requires documented indication Requires description of procedure Requires permanently stored image of target localization and needle May be used in combo with Diagnostic Codes if justified and appropriately documented 47 slide-48 8

9 Injection Documentation Conclusion Procedure: Joint Aspiration / Injection Procedure Indication: Symptomatic relief, glenohumeral osteoarthritis. Informed Consent: Prior to starting the procedure, the patient s identity was verified, pertinent available records were reviewed, the nature of the procedure was explained along with risks, benefits and alternatives. Consent was signed. The appropriate sites of the procedure were confirmed directly with the patient, verified, and marked. A pre-procedure pause was performed for final verification of all the above. Location: Right shoulder. Preparation and Technique: Skin prep ChoraPrep, sterile preparation of site (in usual fashion). Local anesthesia with lidocaine (1 ml, 1% strength, without epinephrine). An initial pre-injection ultrasound evaluation was performed to survey the relevant anatomy. Approach (lateral, posterior, under continuous ultrasound guidance using a 4S curved array probe at a frequency of 5 mhz, in plane approach, per the protocol originally published by Zwar, et. al. in the American Journal of Roentgenology, July 2004 Vol. 183.). Sterile needle used (size #22 gauge, length 2.5 inch). Joint injected with Kenalog 40mg 4ml 1% Lidocaine without epinephrine. Procedure tolerated well. No Complications. Patient Instructions: Ice shoulder tonight, gradually resume use as pain permits. Practice, but don't practice on patients slide-49 slide-50 9