Bone fractures most commonly result from trauma, osteoporosis and overuse mechanisms. During adulthood, fracture rates for males increase gradually, while there is an exponential increase in females [1]. Regarding annual fractures in adults aged 35-55 years, rates in women and men are highest at the hip, spine, distal forearm, and humerus. Of these fractures, rates are some 3-4 times higher in women than men [2]. Sporting activities are the third most common cause of fractures and estimated at nearly 13% of overall annual fractures. Some 21% of sports-related fractures require surgical treatment due to injury complexity [3].
Effective initial and follow-up imaging should enable optimum clinical management by minimising 'missed' (occult/hidden) fractures, or most accurately determining the nature of complex fractures. Evaluation using general X-ray is the standard of care for initial and follow-up imaging to gauge healing progress, despite known limitations with this modality. In cases of uncertainty following X-ray evaluation, CT imaging is then typically performed; this relates to the ability of CT to obtain multiple slice 2D images reformatted in the three main body planes, along with 3D images. However, the drawback of CT imaging is higher radiation dose, in addition to metallic artefacts with internal or external fracture fixation hardware.
Overcoming the limitations of both X-ray and CT in the imaging diagnosis of a range of health problems is tomosynthesis. This new imaging technology aims to achieve the best of both worlds by combining the high resolution and very low radiation dose of X-ray with the multiple slice capability of CT imaging – hybrid X-ray/CT. Furthermore, tomosynthesis metal artefact reduction technology enables more accurate evaluation of the bone/metal interface in cases of suspected fixation hardware loosening.
While tomography itself is not new, having developed strongly in the computed-axial tomography (CT) field, the recent digitisation of X-ray has enabled computer ‘synthesis’ of X-ray imaging data – to create multiple slice layers through an anatomical region of interest. This helps overcome the challenge when interpreting X-rays, where anatomical structures are superimposed in a single flat image. Initial adoption of tomosynthesis has been with breast and chest imaging due to its multislice capability and very low radiation dose.
Tomosynthesis is now increasingly demonstrating its utility in skeletal imaging. For example, a recent study compared tomosynthesis, X-ray and CT in evaluation of wrist fracture healing after hardware fixation [4]. In this study, the researchers considered tomosynthesis to be superior to X-ray, with much less radiation than CT. The hardware was found to obscure the bony cortex less with CT than tomosynthesis, however this may relate to metal artefact reduction technology not being used with tomosynthesis in this study.
Case Example
Mr W, a 75 year old retiree was referred by his surgeon for a right wrist Tomosynthesis evaluation using metal artefact reduction technology, for follow-up imaging after internal fixation of a complex fracture.
Radiologist findings consisted of:
T-plate internal fixation of distal radial comminuted fracture. No periprosthetic lucency to suggest loosening. The fracture remains united. A 1.5mm dorsal radial articular surface gap is present. No significant step-off of the articular surface seen. Mildly displaced un-united ulnar styloid process fracture.
If we can be of assistance with Orthopaedic Tomosynthesis imaging, contact us on 03 9592 3319.
As an independent QIP Accredited Diagnostic Imaging Service, low dose CT, long view X-ray, spine/sports weight-bearing MRI and general X-ray are also available.
For more detailed information about Tomosynthesis, visit Shimadzu website: Tomosynthesis.
References
- Holloway K, et al. Age and sex related patterns of first fracture and fracture prevalence. Calcif Tissue Int 2015;96(1):38-44.
- Sanders K, et al. Age and gender specific rate of fractures in Australia: a population based study. Osteoporos Int 1999;10(3):240-247.
- Court-Brown C, et al. The epidemiology of acute sports-related fractures in adults. Injury 2008;39(12):1365-1372.
- Ha A, et al. Digital tomosynthesis to evaluate fracture healing: prospective comparison with radiography and CT. AJR 2015;205:136-141.
This is general health information designed for educational purposes only. It does not constitute individual health advice and should not replace thorough consultation with a registered health care practitioner.
