DEXA – The key to diagnosing osteoporosis

6th June 2024, NIA Diagnostic Imaging

DEXA (Dual-Energy X-ray Absorptiometry), is a non-invasive, quick and simple medical imaging modality used to measure bone mineral density (BMD). It is highly effective in diagnosing osteoporosis or osteopenia, hence enabling managing clinicians to assess the extent of bone loss for their patients. It is considered the “gold standard” by the World Health Organisation (WHO) and is the most accurate and inexpensive test to diagnose osteoporosis. Additionally, results from the scan (T-score and Z-score) can provide vital information to assess fracture risk and optimise treatment outcomes for patients, thus increasing their quality of life. This is vital for high-risk individuals such as; the elderly population, postmenopausal women, those with family history and those who have predisposing medical conditions like rheumatoid arthritis or hyperthyroidism.

At NIA Diagnostic Imaging Ingleburn, DEXA is readily available and Bulk-billed for patients who meet Medicare eligibility. No appointment is necessary for patients, they are welcome to walk-in, with all referrals being accepted. Our machine is quick, simple and very powerful – being powered by Hologic® the global pioneer in bone heath densitometry technology.

How DEXA measures Bone Mineral Density (BMD):
DEXA uses low-dose X-rays to measure the amount of calcium and other minerals in bone, providing bone density information. During a DEXA scan, the patient lies supine on a padded table, with the X-ray tube passing over the body, emitting x-rays. The common sites for measurement are the lumbar spine, hip (femoral neck) and forearm. These regions are chosen for the scan because they are common sties of osteoporotic fractures.

The amount of X-ray energy that passes through the bone and soft tissue are detected by the DEXA machine and based on the differences in absorption between bone and soft tissues, the machine calculates the bone mineral density in the measured region.
DEXA scan results:

T-Score: A T-score compares the patient’s bone density to that of a healthy young adult of the same gender.

A T-score between +1 and -1 is considered normal.
A T-score between -1 and -2.5 indicates low bone density or osteopenia.
A T-score of -2.5 or lower indicates osteoporosis.

Z-Score: The Z-score compares the patient’s bone density to that of individuals of the same age, gender, and body size. A Z-score below -2 indicates that your bone density is lower than it should be for someone of your age.

Based on the T-score or Z-score results, osteoporosis diagnosis can be made, and the patient’s fracture risk can also be assessed. This crucial information is vital for healthcare providers to develop appropriate management plans for individuals at risk of osteoporosis or monitoring the effectiveness of treatment for those already diagnosed with the condition. DEXA scans are also a great screening tool for osteoporosis as they can detect early changes in bone density prior to the occurrence of symptoms, thus allowing for early intervention and implementation of early treatment measures.

Considering all of these factors, many individuals would greatly benefit from a DEXA scan because aging is a major risk factor for osteoporosis.
At NIA Diagnostic Imaging our highly trained staff members are committed and passionate in delivering premium care to our patients whilst being quick and efficient. We acknowledge the importance of early diagnosis of osteoporosis and aim to ensure improved quality of life for all our patients.

References:

Cleveland Clinic. (2020, December 12). DEXA (DXA) Scan: Bone Density Test. https://my.clevelandclinic.org/health/diagnostics/10683-dexa-dxa-scan-bone-density-test
Johns Hopkins Medicine. (2024). Bone Densitometry. https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/bone-densitometry#:~:text=For%20various%20reasons%2C%20the%20DEXA,to%20break%20or%20fracture%20easily.
RadiolofyInfo.org. (2024, March 11). Bone Density Scan (DEXA or DXA). https://www.radiologyinfo.org/en/info/dexa#:~:text=Bone%20density%20scanning%2C%20also%20called,diagnose%20and%20treat%20medical%20conditions.
Centers for Disease Control and Prevention. (2021, October 20). Radiation in Healthcare: Bone Density (DEXA Scan). https://www.cdc.gov/nceh/radiation/dexa-scan.html#:~:text=DEXA%20(dual%20x%2Dray%20absorptiometry,the%20hip%20and%20the%20spine.
NHS. (2022, October 5). How is it performed-Bone density scan (DEXA scan). https://www.nhs.uk/conditions/dexa-scan/what-happens/
NIA diagnostic imaging. (2022). DEXA (Bone Density Scan). https://niaimaging.com.au/dexa/
Hologic. (2022). The future of DXA. https://car-asm.ca/wp-content/uploads/2022/02/Brochure-Horizon-DXA-PB-00238-CAN-EN-Rev001.pdf

PFO Closure

Furlan AJ, Reisman M, Massaro J, et al. Closure or medical therapy for cryptogenic stroke with patent foramen ovale. N Engl J Med 2012; 366: 991–

A multicenter, randomized, open-label trial of closure with a percutaneous device, as compared with medical therapy alone, in patients between 18 and 60 years of age who presented with a cryptogenic stroke or transient ischemic attack (TIA) and had a patent foramen ovale. The primary end point was a composite of stroke or transient ischemic attack during 2 years of follow-up, death from any cause during the first 30 days, or death from neurologic causes between 31 days and 2 years.

Results:

Primary end point was 5.5% in the closure group as compared with 6.8% in the medical-therapy group (adjusted hazard ratio, 0.78; 95% confidence interval, 0.45 to 1.35; P = 0.37)

Conclusion:

“In patients with cryptogenic stroke or TIA who had a patent foramen ovale, closure

with a device did not offer a greater benefit than medical therapy alone for the

prevention of recurrent stroke or TIA”

2 Saver JL, Carroll JD, Thaler DE, et al. Long-term outcomes of patent foramen ovale closure or medical therapy after stroke. N Engl J Med 2017; 377: 1022–

A multicenter, randomised, open-label trial ,randomly assigned patients 18 to 60 years of age who had a patent foramen ovale (PFO) and had had a cryptogenic ischemic stroke to undergo closure of the PFO (PFO closure group) or to receive medical therapy alone (aspirin, warfarin, clopidogrel, or aspirin combined with extended-release dipyridamole; medical-therapy group). The primary efficacy end point was a composite of recurrent nonfatal ischemic stroke, fatal ischemic stroke, or early death after randomisation.

Results:

Recurrent ischemic stroke occurred in 18 patients in the PFO closure group and in 28 patients in the medical-therapy group, resulting in rates of 0.58 events per 100 patient-years and 1.07 events per 100 patient years, respectively (hazard ratio 0.55; 0.31 – 0.999; P = 0.046)

Conclusion:

“Among adults who had had a cryptogenic ischemic stroke, closure of a PFO was associated with a lower rate of recurrent ischemic strokes than medical therapy alone during extended follow-up.”

Meier B, Kalesan B, Mattle HP, et al. Percutaneous closure of patent foramen ovale in cryptogenic embolism. N Engl J Med 2013; 368: 1083–

A prospective, multicenter, randomised, event-driven trial, randomly assigned patients to medical therapy alone (anti-platelet or warfarin therapy) or closure of the patent foramen ovale.

Results:

9 patients in the closure group and 16 in the medical-therapy group had a recurrence of stroke (hazard ratio with closure, 0.49; 0.22 – 1.11; P = 0.08). The primary analysis of the intentionto- treat cohort showed a nominal 51% hazard rate reduction with closure, but the reduction did not reach significance.

Conclusions:

” …there was no significant benefit associated with closure of a patent foramen ovale in adults who had had a cryptogenic ischaemic stroke.”

Sondergaard L, Kasner SE, Rhodes JF, et al. Patent foramen ovale closure or antiplatelet therapy for cryptogenic stroke. N Engl J Med 2017; 377: 1033–

Multinational trial involving patients with a PFO who had had a cryptogenic stroke, randomly assigned patients to undergo PFO closure plus antiplatelet therapy or to receive antiplatelet therapy alone.

Results:

During a median follow-up of 3.2 years, clinical ischemic stroke occurred in 6 of 441 patients (1.4%) in the PFO closure group and in 12 of 223 patients (5.4%) in the antiplatelet-only group (hazard ratio, 0.23; 0.09 to 0.62; P=0.002).

Conclusions:

“Among patients with a PFO who had had a cryptogenic stroke, the risk of subsequent ischemic stroke was lower among those assigned to PFO closure combined with antiplatelet therapy than among those assigned to antiplatelet therapy alone; however, PFO closure was associated with higher rates of device complications and atrial fibrillation.”

Mas JL, Derumeaux G, Guillon B, et al. Patent foramen ovale closure or anticoagulation vs. antiplatelets after stroke. N Engl J Med 2017; 377: 1011–

In a multicenter, randomised, open-label trial patients 16-60 years of age who had had a recent stroke attributed to PFO, to transcatheter PFO closure plus long-term antiplatelet therapy, antiplatelet therapy alone or oral anticoagulation.

Results:

No stroke occurred among patients in the PFO closure group, whereas stroke occurred in 14 of the 235 patients in the antiplatelet- only group (hazard ratio, 0.03; 0 to 0.26; P<0.001). Large number of patients discontinued anti-coagulation in the anti-coagulant group and statistical significance was not analysed because the study was not adequately powered to compare outcomes.

Conclusion:

“Among patients who had had a recent cryptogenic stroke attributed to PFO with an associated atrial septal aneurysm or large interatrial shunt, the rate of stroke recurrence was lower among those assigned to PFO closure combined with antiplatelet therapy than among those assigned to antiplatelet therapy alone. PFO closure was associated with an increased risk of atrial fibrillation.”

Lee PH, Song J-K, Kim JS, et al. Cryptogenic stroke and high-risk patent foramen ovale: the DEFENSE-PFO Trial. J Am Coll Cardiol 2018; 71: 2335–

Patients with cryptogenic stroke and high-risk PFO were divided between a transcatheter PFO closure and a medication-only group.

Results:

No events occurred in the PFO closure group. 12.9% of patients in the medication group had an event (p= 0.023).

Conclusion:

“PFO closure in patients with high-risk PFO characteristics resulted in a lower rate of the primary endpoint as well as stroke recurrence”