Greetings all!
Can anyone explain how the lumbar spine T-Scores are calculated? If one number between two disks exceeds -2.5 will that put someone in the osteoporosis category?
My radiologist explained that different facilities calculate T-Scores differently.
Also when someone has long standing degenerative disk disorder what type of scan should be used since the DXA findings states "Deg Disk Disorder may cause findings to look better than they actually are"?
I am very impressed that you actually got to speak to a radiologist. My T-score for spine was +2 through four DXAs, but that was two standard deviations better than the hips which was a little strange. A few weeks after my last DXA I had some spine xrays and they said "moderately severe osteopenia" and not the terrific +2 I had always been led to believe I had. So yes, arthritis and degenerative disk disorder can affect the accuracy of DXA.
Your diagnosis of osteoporosis or not should be based on an average lumbar t-score, not individual values.
Hello, ExArtillery Guy. The World Health Organization defines osteoporosis as a T-score lower than -2.5, but your physician will take other factors and lab results into account in making a diagnosis.
Here is some background on bone density testing and understanding your results.
The spine T-score is based on 4 vertebrae L1-L4. The individual values for each vertebra are calculated, and average is calculated.
This is what I've figured out based on looking at the data on a full report:
- the mass (g) and the area (cm2) of each vertebra is measured
- the BMD (bone mineral density) g/cm2 for each vertebra is calculated separately
- the total mass of all 4 vertebra is calculated
- the total mass is divided by the total area of all 4 vertebrae (g/cm2)
- those g/cm2 are then translated into your T-score (I don't pretend to understand that calculation, but it is a more complex one.)
The calculation differences between faciliites may be based on the equipment used. For example the values from a GE scan may be slightly different than those from a Hologic scan. A certified densitometrist can probably adjust for those minor differences.
The DXA is a 2-dimensional image which tries to portray the 3-dimensional reality. There are some other factors, such as arthritis, which can cloud th information. It's important to work with healthcare providers (densitometrists, radiologists, and other specialists) who have a deep understanding of the mechanisms.
What are the numbers of the individual vertebrae?
