Individual muscle measurement. In the palm of your hand.

mScan uses electrical impedance myography (EIM) to measure a muscle’s electrical properties through the skin. Researchers use these measurements to study differences between muscles and changes over time.

For academic researchers, clinical study teams, and pharmaceutical companies.

Explore mScan ↓

Download the research overview (PDF)

The glossy black mScan device held in one hand, its green status light on

Meet mScan

A portable handheld instrument for fast, localized muscle measurement, in clinic or at home.

Investigational device — available for use in IRB-approved clinical research.

Measurement at rest: No muscle contraction required — readings don’t depend on participant effort.
Multi-frequency scan: Captures the muscle’s electrical response across a broad frequency range.
Guided research software: Supports muscle selection, scanning, and quantitative data review.

How EIM works

mScan rests on the skin over a muscle and sends a weak, painless current through it. How the muscle resists and stores that current reflects its composition and structure.

1
Send current. A low, imperceptible current passes through the skin into the muscle.
2
Measure. Electrodes record the voltage at 41 frequencies.
3
Calculate impedance. Resistance, reactance and phase per frequency. Changes in muscle structure and composition can alter EIM measurements

clear-black-mscan-on-thigh-diagram — The outer electrodes pass a weak current through the muscle. The inner electrodes record the voltage it produces.

Three core readouts from one scan

At each frequency, mScan records the muscle’s impedance, summarized as resistance, reactance, and phase.

Resistance Ω: How much the tissue opposes electrical current. Varies with tissue geometry, fluid content, and composition.
Reactance Ω: The electrical effect of cell membranes and other tissue interfaces. Sensitive to changes in muscle structure.
Phase angle °: A value calculated from resistance and reactance, summarizing their relationship at each frequency.

Healthy 10.5° at 100 kHz

HealthyEarly diseaseAdvanced disease

An illustrative example of how a muscle’s phase sweep can change as health declines.

Following muscle changes over time

Monthly averages from two participants in the same ALS study. The panels decline at different rates because progression varies from person to person and muscle to muscle.

Tibialis anterior Monthly averages · 8.2 months

Monthly averages from one participant’s tibialis anterior (quality-passing scans, phase at 100 kHz).

Wrist extensors −0.76° per month

Monthly averages from a second participant’s wrist extensors (quality-passing scans, phase at 100 kHz).

Why individual muscles matter

Disease and treatment can affect one muscle differently from another. Current tools leave gaps when a study needs to follow a specific muscle over time.

Whole-body tools

DXA and BIA measure the whole body and do not directly characterize individual muscles.

Performance tests

Strength and function tests depend on effort and cooperation, and are not possible in every population.

Imaging

MRI and CT are detailed but costly, not always accessible, and difficult to repeat frequently.

{{ photoName }}mScan placement from the app. Select a muscle on the map to see its site.

The mScan workflow

From muscle selection to measurement in three steps.

1
Select a muscle
The app guides placement on the chosen muscle site.
2
Collect a scan
Hold mScan on the skin while it runs a multi-frequency sweep in seconds.
3
Review measurements
Resistance, reactance, and phase are displayed across frequency for each scan.

Research applications

Across all of these, mScan supports repeated, effort-independent measurement of the same muscles over time — in clinic or at home.

Neuromuscular disease

Studied in ALS, muscular dystrophies, and other neuromuscular conditions, tracking disease-related change in the muscles each condition affects.

Aging

Used to study age-related differences in muscle properties and how they relate to function, such as strength.

GLP-1 and weight loss Exploratory

Early work on whether site-specific EIM can help characterize muscle changes during GLP-1–associated weight loss.

Evidence

EIM was pioneered by Myolex founder Seward Rutkove, MD , at Beth Israel Deaconess Medical Center and Harvard Medical School.

Seward B. Rutkove, MD

Founder, Myolex

Founder of Myolex, Dr. Rutkove is the Nancy Lurie Marks Chair of the Department of Neurology at Beth Israel Deaconess Medical Center and Professor of Neurology at Harvard Medical School. He received his medical degree from Columbia University’s College of Physicians and Surgeons, and his bachelor’s degree, magna cum laude, from Cornell University, College of Arts and Sciences.

Dr. Rutkove’s research focuses on the application of innovative techniques for the assessment of neuromuscular disease with an emphasis on electrical impedance and ultrasound methodologies. His work has been supported by numerous grants from the National Institutes of Health, NASA, and multiple foundations and has resulted in well over 170 peer-reviewed publications.

In 2011, he was awarded the Biomarker Challenge Prize from the non-profit foundation Prize4Life, Inc for his work demonstrating that electrical impedance measurements of muscle could speed clinical therapeutic studies in amyotrophic lateral sclerosis.

FSHD

Detects progression over 12 to 24 months

In 157 adults with facioscapulohumeral muscular dystrophy across 8 sites, EIM phase showed excellent test–retest reliability, correlated strongly with clinical function, and declined measurably by 12 months. Annals of Neurology, 2026. Read paper ↗

Screening

Disease classification in a research cohort

Using mScan on nine muscles in 119 adults and 111 children, machine learning-enhanced EIM identified neuromuscular disease with 84% accuracy in adults and 93% in children. Annals of Biomedical Engineering, 2026. Read paper ↗

Aging

Grip-strength estimation using EIM

In adults with and without sarcopenia, multi-frequency forearm EIM combined with machine learning explained 48% of the variance in hand grip strength. Muscle & Nerve, 2025. Read paper ↗

View all publications →

Frequently asked questions

What does mScan measure?

mScan measures the electrical impedance of an individual muscle through the skin: resistance, reactance, and phase, across a range of frequencies. These values reflect the muscle’s composition and structure.

Which muscles can be assessed?

The guided app includes placement sites for muscles of the arms, trunk, and legs, including the deltoid, biceps, triceps, wrist flexors and extensors, rectus abdominis, trapezius, lumbar paraspinals, gluteus, quadriceps, hamstrings, tibialis anterior, gastrocnemius, and soleus.

What does a scanning session involve?

The operator selects a muscle in the app, places mScan on the skin at the guided site, and holds it in place while the multi-frequency scan runs in seconds. No needles or muscle contraction are required, and sessions can be run in clinic or at home.

How do we get our data?

Myolex provides guidance on working with exported data, and technical support is available for the duration of your study.

How can we discuss using it in a study?

Use the form below or email info@myolex.com. Tell us about your population, muscles of interest, and timeline, and our team will follow up.

Bring individual muscle measurement into your study.

mScan is available for investigational use in clinical research.

Email: info@myolex.com
Phone: 888.382.8824
Office: 1309 Beacon St, Suite 300
Brookline, MA 02446

Regulatory status

The Myolex mScan system is pending FDA clearance. It is available for use in IRB-approved clinical research. It is not currently cleared for diagnostic use, and nothing on this page should be read as a diagnostic claim.

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