An X-ray of an inflamed joint looks normal, and palpation cannot tell one millimeter of synovial thickening from three. Power Doppler shows hyperemic blood flow in the synovial tissue - the finding that separates inflammatory arthritis needing treatment now from other causes of pain.
A female patient with one month of progressive pain and swelling in the hands and wrists, now waking her in the mornings. Repetitive hand use at work. Differential: inflammatory arthritis versus overuse tenosynovitis. Serologies were sent, and rather than wait for them, Dr. Erickson scanned the hands in the same visit.
Longitudinal view of the left dorsal third metacarpophalangeal joint, the middle-finger knuckle. The synovial tissues of the joint space were thickened and hypoechoic with edema. Comparable changes were noted in multiple MCP joints of both hands. This symmetric synovitis pattern is typical of autoimmune inflammatory arthritis.


Butterfly iQ3™ imaging plus serology gave Dr. Erickson enough confidence to treat new-onset lupus arthritis rather than temporize with NSAIDs. He sent the images with the referral, and the rheumatologist moved the consultation up from the usual 6-to-9-month wait to a few weeks.
Serology alone was inconclusive. Power Doppler showed the inflammation was active, which gave Dr. Erickson the confidence to treat rather than wait, and gave the rheumatologist a reason to see the patient in weeks instead of months.
Grayscale alone showed thickened synovium. Power Doppler on the iQ3 showed pulsations of flow inside that tissue: the hyperemia that marks inflammation as active rather than old. The serology was not conclusive by itself. ANA and ESR were elevated, but these tests are pretty non-specific. The rheumatoid factor and anti-CCP were normal. It was the combination of serology and iQ3 ultrasound imaging that produced a diagnosis: new-onset lupus arthritis. The imaging half of it took only minutes in the office.
In many areas, a patient may wait 6-9 months for a new patient consult with a rheumatologist. Non-metropolitan rheumatologist workforce adequacy stood at 17.5% in 2025 against 97.3% in metropolitan areas.1 Sustained synovial inflammation causes irreversible joint damage over months, so the wait is itself the clinical risk.
“All the time, I’m surprised by what I find. As a new MSK ultrasound user you’re apprehensive: not sure what you’re looking at, worried a specialist might laugh at you for trying this instead of just ordering an MRI. You get over that as your experience grows. Rather than ‘I have a patient with joint pain, can you take a look,’ I could say ‘see these findings.’ They said, yes, you’re right, I’ll see the patient in a few weeks.”
Compare the same joint on the opposite hand before calling it abnormal, and keep depth at one to two centimeters before enabling power Doppler. Deeper than that, the microvascular flow that matters here will not register.
POCUS in MSK serves two purposes: diagnosing at the bedside and guiding procedures in real time. Diagnostically, iQ3 evaluates tendon and ligament injuries, joint effusions, nerve entrapments, muscle tears, and soft tissue masses — delivering answers in the room. On the procedural side, it guides joint injections and aspirations, bursa injections, nerve blocks, PRP delivery, and abscess drainage with real-time needle visualization.
iQ3 delivers both capabilities in one pocket-sized device — no cart, no probe swap, no separate imaging suite.
iQ3 includes 4 MSK-specific presets:
MSK – Soft Tissue delivers high dynamic range for soft tissue detail, covering 1–12 cm depth. It transitions automatically from linear to curvilinear format, spanning superficial trigger finger assessment to deep hip joint interrogation.
Musculoskeletal emphasizes contrast resolution for crisp structure and needle borders. Preferred for interventions and tendon or ligament evaluation.
Nerve is optimized for peripheral nerve assessment — nerve swelling, fascicular detail, and surrounding vessels — for carpal and cubital tunnel evaluation and hydrodissection guidance.
Needle: Out-Of-Plane
The Needle: Out-of-Plane preset is designed to help you see the needle tip sooner—within 1mm from the point of entry—when performing short-axis (out-of-plane) insertions.
Correct preset selection also reduces anisotropy artifacts, which can make normal tendons appear hypoechoic and mimic pathology.
Yes. Procedural guidance is the fastest-growing MSK POCUS application, and iQ3 offers two features purpose-built for it.
NeedleViz™ colorizes the needle in real time at any approach angle, directly addressing the most common procedural frustration: maintaining tip visibility throughout the approach.
Biplane imaging shows simultaneous in-plane and out-of-plane views on one screen, confirming needle shaft and tip in both planes without repositioning — a first for handheld ultrasound.
Together, they reduce failed first-pass injections, lower cognitive load, and support safer needle delivery across joint injections, nerve blocks, PRP, and abscess drainage.
NeedleViz is a visualization aid and does not replace clinical judgment during ultrasound-guided procedures.
Yes. iQ3 replaces three to four traditional transducers with a single whole-body probe. Its 1–12 MHz range covers superficial tendon and nerve imaging through deep joint and nerve block targets — no probe switch required.
In a typical encounter, a clinician can diagnose a rotator cuff abnormality and guide the injection — same probe, same device, same visit. The swappable USB-C/Lightning connector supports iOS and Android; the 8–10 hour battery covers a full clinic day.
From sidelines to clinics, the same device evaluates an acute injury and, when needed, supports aspiration or injection guidance.
POCUS and MRI are complementary tools. MRI remains the reference standard for comprehensive joint imaging and surgical planning. POCUS offers distinct bedside advantages:
Real-time and dynamic. Captures tendon movement, effusion dynamics, and nerve response during range of motion — none visible on MRI.
Immediate at the bedside. Provides answers in the room without scheduling or transport. POCUS often determines whether a finding warrants MRI at all.
Guidance capability. MRI cannot guide a needle; POCUS is the standard modality for real-time procedural guidance.
No contraindications related to implants or claustrophobia. Safe for patients with implants or claustrophobia.
For complete rotator cuff tears, POCUS can approach MRI accuracy in trained hands. Its practical role is to answer the immediate question — effusion, tendon integrity, nerve entrapment — and decide whether advanced imaging is needed.
Any specific accuracy comparisons to MRI to be reviewed and cleared by BN Regulatory.
Yes. iQ3 and its MSK presets are built for sports medicine environments. At under 300g, it fits in a lab coat or equipment bag and moves from sideline to clinic without a cart.
On the sideline, iQ3 assesses tendon and ligament injuries, fractures, effusions, and muscle tears in real time, informing return-to-play or transport decisions. The same device then supports guided procedures when the patient follows up in the clinic.
Dynamic imaging under load reveals tendon and ligament function that static imaging cannot. Retrospective Cine Capture saves the video loop automatically, even without pressing record at the right moment.
Documentation and billing uncertainty are among the most-cited barriers to MSK POCUS adoption. Compass AI™ is designed to address both.
At the point of care: images and clips are captured, annotated, and saved to Butterfly Cloud automatically — eliminating the manual upload step that practitioners cite as a primary friction.
For billing: ultrasound-guided procedures require documented permanent image storage for CPT billing. Compass AI provides the structured archiving and reporting that makes this straightforward.
For practices and programs: Compass AI connects to the EHR and gives administrators visibility into scan volume, QA, and provider activity across sites — supporting credentialing and enterprise-wide adoption.
For clinicians: scan, document, and share without leaving the patient’s side. For practice owners: billable in-office procedures are captured and coded without the manual steps that get skipped in a busy clinic.
Compass AI™ is not intended to provide information used to make decisions regarding diagnosis or therapeutic purposes.
MSK POCUS has a longer learning curve than cardiac or abdominal applications — dynamic scanning, anisotropy management, and simultaneous probe-and-needle control all add complexity. The curve is well documented and manageable with structured training.
Common applications — guided injections, aspirations, and basic tendon assessment — are typically achievable after a targeted CME course plus 25–50 supervised procedures per application.
Butterfly supports the learning process through: MSK-specific presets, in-app voice annotation, and a free introductory MSK course through Butterfly ScanLab education platform. Auto-optimization also reduces manual gain and depth adjustments for new users.
AI-assisted tools lower the expertise barrier, making MSK scanning accessible to trained NPs, PAs, and primary care physicians looking to expand their scope.
1. Silvestre J, et al. Arthritis Care Res. 2026. doi:10.1002/acr.80092