Allyson Budiño
DSR SRR
Imaging services manager at Holly House and Highgate Hospitals, UK
Holly House Hospital is a private hospital situated on the borders of London, Essex and Hertfordshire. It is part of the Aspen Healthcare group that comprises four hospitals in the UK, offering a wide range of out patient clinics for most specialities, day case and inpatient surgery as well as a fully equipped diagnostic imaging centre.
The hospital has a comprehensive multi-modality imaging department, and upgrades equipment regularly in line with the latest technology. Our latest acquisition is full-field digital mammography (FFDM). Our quest to choose the FFDM system equipment began in 2008 when we were invited by Sectra Medical Systems to visit a breast-screening unit in Dublin, Ireland. We were impressed with the style, comfort and image quality of the equipment. In 2009, I attended the Symposium Mammographicum seminar in Lille, France, and was impressed by the lectures given with regard to the minimal dose advantage of the Sectra Medical Systems unit. On returning from the symposium, a business case was prepared for its purchase in conjunction with the Sectra RIS/PACS solution (radiology information system/picture archiving and communication system).
During the negotiations with the Sectra applications team, it became apparent that the Sectra MicroDose unit also had the unique added facility for measuring bone density, which can be performed with mammography in one examination, and this added advantage was the ‘icing on the cake’. The business case was successful and installation and applications training was completed in May of this year.
At the opening of the unit, Sectra Medical Systems representatives gave a comprehensive lecture on its capabilities to radiographers, radiologists, breast surgeons and rheumatologists. The lecture generated a great deal of interest and it became apparent that all those that attended were keen to develop this unique system.
Osteoporosis – an underdiagnosed disease
Osteoporosis is a debilitating disease that can be monitored and treated in its early stages with lifestyle changes. Raising awareness in men and women is therefore extremely important. It is estimated that more than 200m individuals suffer from osteoporosis today1 and it has estimated that 9m individuals suffered from new osteoporotic fractures in the year 2000.2
Furthermore, in the same year, the direct cost of osteoporotic fractures on health services was estimated to be €32bn within the EU. As we live in an ageing community, the number of patients with osteoporosis will inevitably grow. It is expected that, between 1990 and 2025, the number of patients with new hip fractures (the osteoporotic fracture associated with the highest cost) will increase from 1.7m to 2.6m.3
Sectra uses the unique digital X-ray radiogrammetry (DXR) technology, which can calculate bone mineral density (BMD) based on a single radiology image. It is highly correlated to other measurement methods but with highest precision available on the market.
Through advanced image analysis and clinical research, Sectra MicroDose is able to evaluate bone status and deliver a BMD value. Based on the World Health Organisation standards, the BMD value is then evaluated in relation to a reference group to diagnose osteoporosis.4
This method will not diminish the use of full-body Dexa (DXA) scanning, but can provide a solution for use in screening programmes and can easily be implemented together with mammography in a cost-effective and less time-consuming process.
Accurate predictions
DXR is an automated method for determining the peripheral BMD from a regular X-ray of the hand5 and it has been shown to predict future fractures to a high extent.6,7 DXR can either be used alone for finding patients with osteoporosis or for higher specificity and sensitivity as a triage model where a third of the patients are remeasured by a DXA for final diagnosis. Those with the highest and lowest BMD are considered as being healthy or osteoporotic, respectively.8
As the woman patient is already at the X-ray machine, the extra time for adding BMD measurement is less than one minute, since DXR analysis means taking five images instead of four images. The extra radiation dose caused by the fifth image is equivalent to less radiation than staying three minutes in normal environment. By using DXR together with mammography, one can utilise the already available workflow on an osteoporotic risk group and find patients early in the disease. This can increase the number of identified osteoporosis cases, which will enable treatment and prevention of future fractures, with decreased personal suffering as well as costs for society. Furthermore, by adding the possibility to measure BMD in association with mammography, attendance for mammography scans may increase, having a beneficial impact on breast cancer screening too.
A service to the referring physicians
DXR is an automated online method for measuring distal forearm BMD. From a standard-projection digital X-ray image of the non-dominant hand, an estimation of the distal forearm is calculated. The acquired image is automatically de-identified and sent through a secure virtual private network (VPN) tunnel to the DXR online laboratory. In the laboratory, trained and certified operators assure the quality of the images and the positioning of the hand.
A BMD report with an examination identifier and result is returned by regular email. The result is presented as g/cm2 and a T- and Z-score. While T-score is based on the young adult mean – i.e. the age when the BMD is the highest – the Z-score is adjusted to the age of the patient. Studies have shown that the DXR is equal to peripheral DXR in its ability to assess fracture risk.
The increased risk of fracture per standard deviation decrease in BMD is slightly lower for DXR compared to DXA,7 but DXR has the advantage that it can be more easily implemented, since a regular X-ray modality is used to capture the image.
Boonen and associates9 compared different peripheral BMD measurement devices and their ability to detect patients at risk of osteoporosis (defined as having a hip T-score of -2.5 as assessed by central DXA) and concluded that DXR was better than calcaneal quantative ultrasound for this purpose and equal to radiographic absorptiometry. DXR has received a CE quality assurance label from the EU and has approval from the US Food and Drug Administration for use as a medical device.
Holly House Hospital is the first hospital in the UK and among the first in Europe to use Sectra’s unique service for osteoporosis assessment in clinical practice. Based on a single standard X-ray image of the hand, taken in connection with the mammography examination and using the same equipment, the Sectra DXR online service calculates the BMD and finds patients in the risk zone of osteoporosis.
The scanning procedure
Patients are offered the service with their routine breast screening appointment. Patients accepting the invitation will be given the available patient information and will be asked to complete a frax questionnaire. This information is required for rheumatologist consideration and will meet a certain criteria.
Following completion of the examination, the image is sent via PACS to the assessment centre. A report is expected within 24 hours. The report is then checked and identified with full patient demographics by two members of clinical staff.
A ‘normal’ template is then assigned to the BMD report or, in the case of significantly low BMD, the graph is referred for a more comprehensive report to a rheumatologist. Copies of reports are then administered to the patient and their general practitioner. Patient details will then be stored on a recall database and utilised accordingly. So far, 50 patients have been scanned: 92% of patients have had BMD measurements within the normal range and 8% of patients have been referred for further assessment.
Conclusion
Osteoporosis-related fractures remain one of the major health threats for women. However, if women at risk of osteoporosis are identified at an early stage, there are now inexpensive and effective ways of preventing fractures through lifestyle changes and medication.
Early detection also saves major resources for the health services. Collectively, these are important reasons why breast-screening services should consider the possibility of combining mammography with BMD measurements.
References
- Cooper C. osteoporosis Int 1999;9 (Suppl 2);S2-8.
- Johnell O et al. Osteoporosis Int 2006;17(12):1726-33.
- Reginster J-Y et al. Bone 2006;38;S2-9.
- Nelson HD et al. Ann Intern Med 2010;153;99-111.
- Rosholm A et al. Osteoporosis Int 2001;12(11);961-9.
- Bouxsein ML et al. Osteoporosis Int 2002;13; 358-65.
- Bach-Mortensen P et al. Calcif tissue Int 2006;79(1);1-6.
- Dhainaut A et al., J Clin Densitom 2010;13(4); 418-25.
- Boonen S et al. Osteoporosis Int 2005;16(1); 93-100.
