Last Updated on January 30, 2025
Digital X-ray radiogrammetry is an automated digital version of the traditional technique of radiogrammetry. Radiogrammetry is a technique that uses a conventional radiograph to assess bone status by using cortical width as a measure of bone strength. While radiogrammetery is done on a manual basis, in digital x-ray radiogrammetery, a digital x-ray of the hand is sent to computer that analyzes the cortical thickness and bone width of various metacarpals.
. A plain digital hand radiograph is sent to a computer. The system automatically locates measurement regions around the diaphyses of metacarpals two, three, and four respectively, Fig. 1. It determined the average cortical thickness (Ti) and bone width (Wi) individually for each metacarpal i, and the bone volume per projected area (VPAi) was computed assuming a cylindrically shaped bone:
Measuring bone mineral density forms the basis for the working definition of osteoporosis.
Osteoporosis is a systemic skeletal disease characterized by low bone mass and micro-architectural deterioration of bone tissue, consequent increase in bone fragility and susceptibility to fractures.
Fractures are the hallmark of osteoporosis. The risk of fracture in osteoporosis is determined by the risk of fall, the force of impact, and the strength of the bone. Reduced bone mineral density is an important component of fracture risk in osteoporosis.
The following methods are used for measuring bone mineral density
- Radiography
- Radiogrammetry
- Radiographic absorptiometry
- Single- (SXA) and dual X-ray absorptiometry (DXA)
- Spinal and peripheral quantitative computed tomography (QCT/ pQCT)
- Quantitative ultrasound (QUS)
- Magnetic resonance imaging.
In this article, we will discuss radiogrammetry and digital X-ray radiogrammetry.
Digital Xray Radiogrammetry
Digital x-ray radiogrammetry uses computerized radiogrammetric analysis and textural analysis of a digital radiograph of the hand. Information from the middle three metacarpals is used by the system to generate a BMD estimate.
A digital radiograph is sent to the computer. The initial computer processing identifies anatomical landmarks and automatically defines the ‘Regions of Interest’ (ROIs).
The system automatically locates measurement regions around the diaphyses of metacarpals two, three and four respectively. It determined the average cortical thickness (Ti) and bone width (Wi) individually for each metacarpal. Then it calculates the bone volume per projected area (VPAi) was computed assuming a cylindrically shaped bone
It also estimates three-dimensional porosity P, the fraction of the cortical bone that is not occupied by bone , and finally output DXR-BMD
The system computes the Digital x-ray radiogrammetry BMD [DXR-BMD] based on the cortical thickness of the ROIs. About one centimeter of both the cortices in ROI is studied. The cortical thickness is measured 118 times per vertical centimeter of the ROI in each cortex. Thus a total of 236 measurements per centimeter are made over the two cortices.
The resulting DXR-BMD estimate is presented as
- Absolute bone mineral density estimate in g/cm 2
- Graphic form, in a DXR-BMD versus age plot, together with a reference curve
- T score
- Z score.
Significance of Digital X-ray Radiogrammetry
Repeated studies have shown a high correlation of DXR -BMD [digital x-ray radiogrammetry bone marrow density] with DXA-BMD [digital x-ray absorptiometry bone mineral density]. It is said to be good in predicting fractures as well as discriminating between patients with and without fractures.
Moreover, DXR-BMD can also detect a change in bone density with time and anti-resorptive therapy.
There are four different ways in which bone mineral density should be used
- Help in the diagnosis of osteoporosis
- Able to detect changes in BMD with time or after treatment
- Can predict the occurrence of fragility fractures on osteoporosis
- Discriminate between patients with and without previous fragility fractures.
It must be noted that for all the above points, dual-energy x-ray absorptiometry [DXA-BMD]is the gold standard. Therefore, the comparison of radiogrammetry is made with that.
The studies have suggested that digital X-ray radiogrammetry
- has a high correlation with site-specific. So it can be used in the diagnosis of osteoporosis.
- Can detect changes similar to DXA BMD over time or after treatment
- Not as good in discrimination of between patients with or without fragility fractures but correlates well
Digital X-ray grammetry does present a simple and cost-effective alternative to conventional bone densitometry measurements by DXA.
References
- Ketan C Pande. Digital X-ray radiogrammetry: a new technique for bone mineral density estimation in osteoporosis. Indian Journal of Orthopaedics. April 2004 Volume 38 : Number 2 : P. 73-79
- A. Dhainaut, G.E. Rohde, U. Syversen, V. Johnsen, G. Haugeberg. The ability of hand digital X-ray radiogrammetry to identify middle-aged and elderly women with reduced bone density, as assessed by femoral neck dual-energy X-ray absorptiometry. J Clin Densitom, 13 (4) (Oct.-Dec. 2010), pp. 418-425
- M.L. Wilczek, J. Kälvesten, J. Algulin, O. Beiki, T.B. Brismar. Digital X-ray radiogrammetry of hand or wrist radiographs can predict hip fracture risk—a study in 5420 women and 2837 men
Eur. Radiol., 23 (5) (May 2013), pp. 1383-1391 [link]
