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REMS vs DEXA: How a Radiation-Free Bone Scan Compares
DEXA measures bone density with a low dose of X-rays and is the UK reference test for diagnosing osteoporosis. REMS looks at the same bones, the lumbar spine and hip, using ultrasound, so there is no radiation at all. This page sets the two side by side, explains when an NHS DEXA referral is the right route, and shows where you can book a radiation-free REMS assessment in the UK.
What are the key differences between REMS and DEXA?
Both scans answer the same question, how strong are the bones most at risk of fracture, but they use different physics and sit in different places in the UK care pathway.
| Feature | DEXA (DXA) | REMS (radiation-free) |
|---|---|---|
| How it works | Two low-energy X-ray beams pass through the bone; detectors measure how much is absorbed. | An ultrasound probe on the skin; software analyses the raw radio-frequency echoes from the bone. |
| Radiation | Low dose of ionising radiation (much lower than a standard X-ray). | None. Ultrasound is non-ionising. |
| Sites scanned | Lumbar spine and hip. | Lumbar spine and hip (the same axial sites). |
| Results reported | Bone mineral density, T-score and Z-score. | Estimated bone density, T-score and Z-score, plus a Fragility Score. |
| UK diagnostic status | The reference test for diagnosing osteoporosis (NOGG 2024). | Not recommended by NOGG 2024 for diagnosing osteoporosis. |
| How to access it | On the NHS via a GP referral, usually in a hospital; also sold privately. | Not routinely offered on the NHS; available privately, including Screen My Bones assessment days. |
| Equipment | Fixed scanner, usually in a hospital or imaging centre. | Portable, so it can be used at non-hospital venues. |
Sources: (NHS) (NOGG 2024) (Royal Osteoporosis Society) (Diagnostics, 2025)
How does a DEXA scan work?
DEXA stands for dual-energy X-ray absorptiometry. You lie on a padded table while an arm passes over you and sends two low-energy X-ray beams through your spine and hip. Detectors measure how much of the X-ray passes through the bone, and that is converted into a bone mineral density figure (NHS).
It has been the clinical standard for decades, and the 2024 UK guideline from the National Osteoporosis Guideline Group (NOGG) names DEXA at the femoral neck as the reference technology for diagnosis (NOGG 2024). If you want to know more about the machine itself, read how a DEXA scanner works.
How does a REMS scan work?
REMS stands for Radiofrequency Echographic Multi-Spectrometry. A handheld ultrasound probe is placed against the skin at the lumbar spine and hip. Instead of building a picture, the system analyses the raw radio-frequency signals that echo back from the bone and compares them with reference models to estimate density (Diagnostics, 2025).
Because the equipment is portable and needs no shielded X-ray room, REMS can be used outside hospitals. That is how Screen My Bones runs pop-up assessment days at partner venues. Our REMS technology page explains the method and what your report includes.
Does DEXA use radiation, and is REMS really radiation-free?
DEXA uses a low dose of ionising radiation. The NHS describes bone density scans as very safe, with a much lower level of radiation than standard X-rays (NHS). A single DEXA is nothing to worry about. Our guide is a DEXA scan safe? puts the dose in context.
REMS uses ultrasound, which is non-ionising, so there is no radiation. That matters most if you want to repeat a scan regularly, or if you would simply rather avoid X-rays. Proposed practice parameters also list situations such as pregnancy, younger people and spinal hardware where REMS may be considered (Bone & Joint Open, 2025). These are proposals, not an adopted UK standard.
Radiation-free describes the method. It does not, on its own, mean the result is more or less accurate.
What does each scan measure and report?
Both scans report on the lumbar spine and hip. A DEXA report gives your bone mineral density, a T-score (compared with a healthy young adult) and a Z-score (compared with people of your age and sex).
A Screen My Bones REMS assessment reports a T-score and Z-score for the hip and spine, plus a Fragility Score, an indicator of fracture risk derived from the REMS analysis. In one cohort study of nearly 2,000 people, the lumbar spine Fragility Score discriminated between women with and without a later fragility fracture with an AUC of 0.811, significantly higher than the DEXA T-score in the same group (Aging Clin Exp Res, 2023). That is one study, not settled consensus.
One practical point: the Royal Osteoporosis Society notes that REMS and DEXA results cannot be compared directly (Royal Osteoporosis Society). To track change over time, compare REMS with REMS, or DEXA with DEXA.
How closely does REMS agree with DEXA?
A 2025 systematic review of 17 studies covering 11,664 patients reported diagnostic concordance with DEXA of roughly 63.6% to 90%, sensitivity of 70% to 91.7% and specificity of 73.2% to 95.5%. The same review noted that agreement can be lower in people with chronic disorders (Diagnostics, 2025). A 2025 narrative review adds that correlation between REMS and DEXA values is frequently above 0.90 (Cureus, 2025).
The picture is not uniform. In one study, REMS and DEXA agreed on the diagnostic category in 63% of people with primary osteoporosis but only 13% of people with disuse-related osteoporosis (J Clin Med, 2022). So REMS tracks DEXA well in many people, but it is not interchangeable in every group, and its evidence base is younger than DEXA's.
For the full evidence review, including where REMS may help when DEXA readings are distorted by arthritis or implants, read our in-depth article REMS vs DEXA: accuracy, safety and monitoring.
When is a DEXA scan or NHS referral the right choice?
If you need a formal diagnosis, go the DEXA route. NOGG 2024 makes a strong recommendation that REMS is not used to diagnose osteoporosis (NOGG 2024), and the Royal Osteoporosis Society notes that REMS is not routinely offered on the NHS (Royal Osteoporosis Society). Talk to your GP about an NHS DEXA referral if:
- you are over 50 with risk factors for osteoporosis, or under 50 with risk factors such as smoking or a previous broken bone (NHS)
- you have been diagnosed with osteoporosis, or are on or starting bone medication, and your specialist monitors you with DEXA
- a REMS result suggests low bone density or raised fracture risk
Our guide to getting a bone density scan on the NHS explains the referral process. Screen My Bones does not offer DEXA scans.
Who might choose a radiation-free REMS assessment?
- People who want a baseline before symptoms and may not yet meet NHS referral criteria.
- People who want to re-check regularly, for example through menopause or while on weight-loss medication, without repeated X-rays.
- People who would rather avoid radiation.
- People who want a scan at a local venue rather than a hospital department.
A REMS result is a starting point. If it shows something worth acting on, take it to your GP. Read more in is there a radiation-free alternative to DEXA? and REMS scan explained.
How much do REMS and DEXA scans cost, and how do you access them?
An NHS DEXA is arranged through your GP when you meet the referral criteria. Private DEXA scans are sold by imaging clinics, and private REMS assessments are offered by providers such as Screen My Bones. Prices vary by provider and change over time, so we compare the options in our guide to bone density scan costs in the UK. Current Screen My Bones prices are shown when you book.
Where can you get a REMS scan in the UK?
Screen My Bones runs radiation-free REMS assessment days at partner venues. You book directly, with no GP referral needed. Choose your nearest city to see venues and upcoming dates, or view all locations.
REMS vs DEXA: frequently asked questions
What is the difference between REMS and DEXA?
DEXA measures bone mineral density with a low dose of X-rays. REMS assesses the same sites, the lumbar spine and hip, with ultrasound and uses no radiation. DEXA is the UK reference test for diagnosing osteoporosis; REMS is a radiation-free option used for screening and monitoring.
Is a REMS scan a good alternative to a DEXA scan?
It depends on what you need. If you want a radiation-free picture of your bone health, or you want to re-check over time without X-rays, REMS is a credible option that agrees well with DEXA in many studies. If you need a formal osteoporosis diagnosis or NHS treatment decisions, UK guidance points to DEXA.
Is REMS more accurate than DEXA?
The evidence does not support saying REMS is more accurate than DEXA overall. A 2025 systematic review found diagnostic concordance with DEXA of roughly 63.6% to 90%, and agreement was much lower in some groups. DEXA remains the UK diagnostic reference.
Does REMS use radiation?
No. REMS is an ultrasound technique, so there is no ionising radiation. DEXA uses a low dose of X-rays that the NHS describes as much lower than a standard X-ray.
Can I get a REMS scan on the NHS?
REMS is not routinely offered on the NHS. The usual NHS route is a DEXA scan arranged through your GP. REMS is available privately, including at Screen My Bones assessment days in London, Leeds, Bath and Huddersfield.
Do I need a GP referral for a REMS scan with Screen My Bones?
No GP referral is needed to book a Screen My Bones assessment day; you choose a venue and date on the booking page. If your result suggests low bone density or raised fracture risk, the next step is to discuss it with your GP, who may arrange a DEXA scan.
Can I compare my REMS T-score with an old DEXA T-score?
Not directly. The Royal Osteoporosis Society notes that REMS and DEXA results cannot simply be compared with each other. For tracking change over time, compare like with like: REMS with REMS, or DEXA with DEXA.
Sources
- Radiofrequency Echographic Multi Spectrometry: A Novel Tool in the Diagnosis of Osteoporosis and Prediction of Fragility Fractures: A Systematic Review. Diagnostics (Basel), 15(5):555.
- Fragility Score: a REMS-based indicator for the prediction of incident fragility fractures at 5 years. Aging Clinical and Experimental Research.
- Reproducibility and Accuracy of the Radiofrequency Echographic Multi-Spectrometry for Femoral Mineral Density Estimation and Discriminative Power of the Femoral Fragility Score in Patients with Primary and Disuse-Related Osteoporosis. Journal of Clinical Medicine.
- The 2024 UK clinical guideline for the prevention and treatment of osteoporosis (NOGG). Archives of Osteoporosis, 20(1):119.
- Proposed practice parameters for the performance of radiofrequency echographic multispectrometry (REMS) evaluations. Bone & Joint Open, 6(3):291-297.
- Axial Skeletal Assessment in Osteoporosis Using Radiofrequency Echographic Multi-spectrometry: Diagnostic Performance, Clinical Utility, and Future Directions. Cureus.
- Bone density scan (DEXA scan). NHS (nhs.uk).
- Other scans and tests. Royal Osteoporosis Society.
This page is general information, not medical advice. A REMS assessment is a screening tool and does not replace a clinical diagnosis. Speak to your GP about any concerns about your bone health.