REMS and DXA and QUS - comparison of technologies

We at the Bone Matrix accepted REMS technology early on - but not blindly and only after investigation and assessment of the available information. However, other providers may be slower in coming around to new technology for all of the above stated reasons. It goes back to knowing your provider, respecting their time, and understanding where they are coming from. However, your provider also has the responsibility of providing the best level of care that is available to you and so we recommend that you remain patient but be persistent and always, always respectful. Obviously, bone health is an important issue to all of you, so make sure that your provider understands that point and they should address it with you the same way that they address your weight or your blood pressure.

SHORT REMS LIST:

• REMS is equivalent to DXA in determining Bone Mass Density according to the World Health Organization standards
• REMS can be used to diagnose and to monitor osteoporosis
• REMS is radiation free - it is ultrasound-based
• REMS is done in a provider’s office and results are immediately available
• REMS is portable (significant public health value)
• REMS learning curve is not steep
• REMS is not prone to user error
• REMS is not prone to artifact error or patient positioning error
• REMS has a low LSC (0.5-1.0% - error rate) can be used to monitor bone over short periods of time
• REMS measures BMD and also provides a Fragility Score
• Fragility Score is a measure of BONE QUALITY
• FDA approved REMS in the US in 2018
• REMS is used in the European Union and multiple other countries: Italy, Belgium. France. United Kingdom, Poland, Australia, Japan, India, Brazil, Canada, Spain, United States.
• REMS was designated the Official method for bone densitometry in Italy in 2020.

Please feel free to copy this list!

Referenced DXA/REMS Fact Sheet - compiled by Andy Bush, MD, FAAOS, CWSP and Kim Zambito, MD, FAOA, FAAOS:

Other considerations and comparisons

Osteoporosis is diagnosed based on the WHO standard of measuring BMD at axial Regions of Interest (spine and hips) and then determining the T-score. A T-score of (-)2.5 or lower has been defined as threshold for the diagnosis of osteoporosis. (Tümay S, et al, An overview and management of osteoporosis, Eur J Rheumatol 2017; 4: 46-56).

Historical methods of performing densitometry:

DXA (Dual Energy X-ray Absorptiometry) has been historically the standard method to measure BMD at the appropriate Regions of Interest and it is the main method in the United States used to diagnose and monitor Osteoporosis per WHO standards. (Lewiecki, M, et al, Best Practices for Dual-Energy X-ray Absorptiometry Measurement and Reporting: International Society for Clinical Densitometry Guidance, Journal of Clinical Densitometry: Assessment & Management of Musculoskeletal Health, Volume 19, 2016, 127-140)

Error rates in DXA can be up to 90%! - that includes all errors.

The established error rate in BMD determination is 40-50%!

LSC for a calibrated DXA is 5%. - therefore, only if the change between two DXA bone BMD measurements is 5% or greater then should the results be considered clinically significant (Lecture #6, Can you Trust this DXA Report?, IOF/ISCD Clinician Course, US version December 2020).

Heel ultrasound (QUS) is another historical method to assess bone. QUS measurements were found to be predictive of fracture risk. However, because of technical issues, QUS could not provide axial BMD measurements; therefore, it could not be used to diagnose and/or monitor osteoporosis based on WHO standards. (Krieg D, Quantitative ultrasound in the management of osteoporosis: the 2007 ISCD, Official Positions, J Clinical Densit, 2008 Jan-Mar;11(1):163-87).

REMS (Radiofrequency Echographic Multi Spectrometry) is a novel sonographic (ultrasound) method of determining BMD. REMS is echogenic - it analyzes the soundwaves that have been reflected from the bone (the echo). Therefore, it is technically different from QUS which analyzes transmitted sound waves. Because of the technological improvements over QUS, REMS can be used for axial bone assessment. REMS has been determined to be a method that is equivalent to DXA in determining BMD at axial Regions of Interest (spine and hips). Therefore, REMS is a clinically acceptable method to diagnose and monitor Osteoporosis per WHO standards. It has been used for almost ten years in the European Union to determine BMD. (Cortet B, et al, Radiofrequency Echographic Multi Spectrometry (REMS) for the diagnosis of osteoporosis in a European multicenter clinical context, Bone, (2021) 143:115786).

REMS is FDA approved for use in the US for the determination of osteoporosis and to monitor its treatment and to provide a FRAX-based fracture risk. (FDA 501(k) premarket notification of intent to market, October 19, 2018).

Sources of error in densitometry:

DXA accuracy is affected by arthritis or other artifacts including patient positioning all of which can affect and modify how x-rays penetrate tissues (attenuation differential) leading to inaccurate BMD determination.

REMS is not susceptible to the effects of artifacts or by patient positioning. In a REMS assessment, the sound waves will interact with the tissues (bone) that they insonify and the information about the properties of that tissue will be contained in the “echo”. The echographic waves are analyzed and only the waveforms that are determined to be quantitatively similar to bone will be used for BMD and Fragility Score determination. (Giovanni Adami, et al, Radiofrequency Echographic Multis Spectrometry for the prediction of incident fragility fractures: A 5-year follow-up study, Bone, (2020) 134:115297).

The reported LSC, Intra-operator and inter-operator repeatability for REMS are significantly less than DXA (0.5 - 1.05%). (Marco Di Paola, et al, Radiofrequency Echographic Multi Spectrometry compared with Dual X-ray Absorptiometry for osteoporosis diagnosis on lumbar spine and femoral neck, Osteoporosis International, (2019) 30(2):391-402).

DXA testing requires uniformity of testing methods to minimize error rates. When performing a series of tests with DXA it is imperative that all DXA scans are performed on the same machine preferably by the same examiner. The results of DXA tests performed on different machines and by different examiners should not be considered diagnostically useful. (Lecture #6, Can you Trust this DXA Report?, IOF/ISCD Clinician Course, US version December 2020).

REMS testing is echogenic and that is the reason why REMS is not susceptible to artifact error. The basic physics of insonified bone and how the reflected sound waves are analyzed eliminates the effects of arthritis, bone pathology and the presence of foreign material on the results of the REMS assessment. This is in significant contrast to DXA. (Marco Di Paola, et al, Radiofrequency Echographic Multi Spectrometry compared with dual X-ray absorptiometry for osteoporosis diagnosis on lumbar spine and femoral neck, Osteoporosis International, (2019) 30(2):391-402).

DXA-derived BMD is not a very accurate way to determine fracture risk:

DXA-derived BMD fracture risk determination is imperfect. The correlation of BMD to fracture risk can be best described as associative, and not determinative. Low BMD values are associated with an increase in fracture risk; however, it is estimated that approximately 50% of all fragility-type fractures occur in individuals with BMD values that are either normal or near-normal. It is now understood that the structural properties of bone other than just BMD, which are commonly referred to as the bone quality, factor into the determination of fracture risk. (Leslie W, et al, Why Does Rate of Bone Density Loss Not Predict Fracture Risk? J of Clin Endo & Metab, 2015, 100(2); 679–683).

REMS offers a novel way to determine fracture risk:

REMS provides the Fragility Score (FS). The FS is a value that is derived from the identification and analysis of a particular sound wave that contains information on structural properties of the bone. The analysis of this sound wave yields a measure of bone quality. Therefore, FS is a method to quantify fracture risk - this aspect of REMS is similar to the established capability of QUS. (Paola Pisani, et al, A quantitative ultrasound approach to estimate bone fragility: A first comparison with dual X-ray absorptiometry, Measurement (2017) 101: 243-249).

Hopefully, the information in this post will help at least some of you in your Bone Health journey. Remember that healthcare is a team effort and your provider is a member or YOUR team. They are there to give you advice and guidance but the person who makes the ultimate decision for your healthcare is YOU! Please feel free to copy and paste the above information into a Word Document of PDF and take it along to your appointment. Your provider may be willing to look at it and it may open the door to a REMS discussion with them.