Osteoporosis CT: Difference between revisions
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==Overview== | ==Overview== | ||
Revision as of 22:26, 14 August 2017
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Osteoporosis Microchapters |
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Osteoporosis CT On the Web |
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American Roentgen Ray Society Images of Osteoporosis CT |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Eiman Ghaffarpasand, M.D. [2]
Overview
Despite that bone mineral density (BMD) measurement may provide so much information about osteoporosis and also osteoporotic fracture risk, but some researchers suggest that it has a limited role in bone strength description. In order to describe the bone strength more precisely, it seems necessary to do quantitative assays such as dual energy X-ray absorbtiometery (DXA) and CT scan (especially volumetric quantitative CT (vQCT)). Modalities for assessing osteoporotic fracture risk, without any destruction or invasion, include high resolution CT (hrCT) and micro CT (μCT). The only tests that is possible in vivo are hrCT and vQCT.
CT scan
- Despite that bone mineral density (BMD) measurement may provide so much information about osteoporosis and also osteoporotic fracture risk, but some researchers suggest that it has a limited role in bone strength description. In order to describe the bone strength more precisely, it seems necessary to do quantitative assays such as dual energy X-ray absorbtiometery (DXA) and CT scan (especially volumetric quantitative CT (vQCT)).
- Modalities for assessing osteoporotic fracture risk, without any destruction or invasion, include high resolution CT (hrCT) and micro CT (μCT).
- The only tests that is possible in vivo are hrCT and vQCT.[1]
Volumetric quantitative CT scan (vQCT)
Volumetric quantitative CT scan (vQCT) is a kind of CT scan, presenting precise trabecular BMD in single transverse CT slices. It is totally used for lumbar spine and mid forearm.[2]
Advantages
- Very high precision; 1-2% of fault for BMD in radius, hip, and spine
- Very instant availability; seconds to minutes
- High accessibility throughout the world
- Least operator dependence (vs. ultrasonography)
Disadvantage
Comparing to DXA method, vQCT is much more better in recognizing treatment success and estimating fracture risk; especially in hip. The exact reason is that trabecular and cortical bones (especially in vertebrae) are metabolically more active, can serve as first indicator of response to medical therapy; whereas, vQCT main method is to measure these bones' BMD, separately.[3]
High resolution CT scan (hrCT)
While current CT scanners have isotropic spatial resolution of about half a millimeter (for axial skeleton measurements), the high resolution CT scanners (hrCTs) provide higher precise and also thinner slices; which allow to better distinguishing trabecular and cortical bones. This may lead to better estimation of fragility fractures. Trabecular bone density measurement also is done indirectly through some other descriptors, such as texture or statistics.[1]
In distinguishing fractured from non-fractured vertebrae, it seems that trabecular bone measurement using hrCT is more effective than BMD measurement using DXA.[4]
Micro CT scan (μCT)
The microCT (μCT) has resolution of 1-100μm, using synchrotron radiation. It helps to replace the need for multiple staining and histomorphometric analyses. Because of simplicity of X-ray usage, the synchrotron-based μCTs were substituted with X-ray tubed ones, soon.[5]
As it would be too difficult to take human bone biopsy for screening or diagnosing osteoporosis, therefore the μCT is more used in laboratory animals for research purposes.
The comparison between three different modalities[1]
| vQCT | hrCT | μCT | |
|---|---|---|---|
| Site of study | vertebrae, hip, forearm, and tibia | vertebrae and forearm | Human biopsies: iliac crest
Animals and specimen: various |
| Samples | Human in vivo | Human in vivo/human biopsies/bone specimen | Laboratory animals in vivo and in vitro/ bone specimen |
| Applications | BMD/bone macrostructure/FEM | Bone macrostructure/trabecular microstructure | Trabecular and cortical microstructure/μFEM |
References
- ↑ 1.0 1.1 1.2 1.3 Genant HK, Engelke K, Prevrhal S (2008). "Advanced CT bone imaging in osteoporosis". Rheumatology (Oxford). 47 Suppl 4: iv9–16. doi:10.1093/rheumatology/ken180. PMC 2427166. PMID 18556648.
- ↑ Lang TF, Guglielmi G, van Kuijk C, De Serio A, Cammisa M, Genant HK (2002). "Measurement of bone mineral density at the spine and proximal femur by volumetric quantitative computed tomography and dual-energy X-ray absorptiometry in elderly women with and without vertebral fractures". Bone. 30 (1): 247–50. PMID 11792593.
- ↑ Bousson V, Le Bras A, Roqueplan F, Kang Y, Mitton D, Kolta S, Bergot C, Skalli W, Vicaut E, Kalender W, Engelke K, Laredo JD (2006). "Volumetric quantitative computed tomography of the proximal femur: relationships linking geometric and densitometric variables to bone strength. Role for compact bone". Osteoporos Int. 17 (6): 855–64. doi:10.1007/s00198-006-0074-5. PMID 16547689.
- ↑ Ito M, Ikeda K, Nishiguchi M, Shindo H, Uetani M, Hosoi T, Orimo H (2005). "Multi-detector row CT imaging of vertebral microstructure for evaluation of fracture risk". J. Bone Miner. Res. 20 (10): 1828–36. doi:10.1359/JBMR.050610. PMID 16160740.
- ↑ Ebashi, Setsurō (1991). Handbook on synchrotron radiation, volume 4. Amsterdam New York New York, NY, USA: North-Holland Sole distributors for the USA and Canada, Elsevier Science Pub. Co. ISBN 0444874232.