Lung Cancer CT Is Chance for 'Opportunistic' Osteoporosis Check

Nancy A. Melville

November 11, 2020

Low-dose chest CT for lung cancer screening provides the opportunity to simultaneously screen patients for osteoporosis, detecting notably higher rates of osteoporosis in men than the traditional tool of DXA, new research published in the Journal of Bone and Mineral Research shows.

"Our large-scale, multicenter study of bone density measured from routine low-dose CT scans demonstrated the great potential of using low-dose CT for the opportunistic screening of osteoporosis as an alternative to standard DXA scans," said senior author Wei Tian, MD, of the Chinese Academy of Engineering and the Peking University School of Medicine, in a press statement from the journal.

"Our study revealed the unexpectedly high prevalence of osteoporosis in men, which may impact on the management strategy of men in the future," Tian added.

Josephine Therkildsen, MD, Herning Hospital, Denmark, who has conducted similar research using cardiac CT scans, as reported by Medscape Medical News, said the findings add important new insights into the issue of opportunistic screening.

"The results are highly interesting, as they show that low-dose CT-based opportunistic screening could identify a substantial number of patients with low lumbar bone mineral density (BMD) with the future potential to diagnose osteoporosis and initiate relevant treatment before a fracture occurs," she told Medscape Medical News.

Perry J. Pickhardt, MD, chief of gastrointestinal imaging at the University of Wisconsin School of Medicine and Public Health in Madison, agrees. He told Medscape Medical News that CT scans of the chest and abdomen, commonly performed for a variety of clinical indications and widespread in most developed countries, can in fact be essential for the detection of a multitude of other concerns — yet are underused for those other purposes.

Use of CT in this way "would likely be very cost-effective and clinically efficacious," he said, adding: "We are seeing greatly increased interest in leveraging this extra information that is contained within every CT scan."

And, "Importantly, artificial intelligence advances now allow for automated approaches, which should allow for expanded use."

Lung Cancer CT Scans Shed Light on Osteoporosis Prevalence

In the study, led by Xiaoguang Cheng, MD, PhD, Department of Radiology, Beijing Jishuitan Hospital, China, researchers examined lung cancer CT screening data from the prospective China Biobank Project to determine the prevalence of osteoporosis in China.

This included the thoracic low-dose CT scans of 69,095 adults, including 40,733 men and 28,362 women, taken between 2018 and 2019.

To screen for osteoporosis, they used quantitative CT software to evaluate lumbar spine (L1-L2) trabecular volume BMD (vBMD) and diagnostic criteria from the American College of Radiology.

Using the vBMD measures from the CT imaging, they found the prevalence of osteoporosis among those over 50 years of age in the Chinese population to be 29% for women (49 million) and 13.5% for men (22.8 million).

Interestingly, the osteoporosis prevalence rate among women was comparable to estimates in the population derived from DXA (29.1%); however, the rate in men was twice that estimated from DXA scans (6.5%).

Decreases in trabecular vBMD with age were observed in both genders. However, declines were steeper among women, who had higher peak trabecular vBMD (185.4 mg/cm3) compared with men (176.6 mg/cm3) at age 30-34 years, but significantly lower measures (62.4 mg/cm3) than men (92.1 mg/cm3) at age 80 years.

The prevalence of osteoporosis in women increased from 2.8% at age 50-54 years to 79.8% at age 85 or older, while in men, the prevalence was 3.2% at age 50-54 years and 44.1% at age 85 or older.

"This is the first study to establish Chinese reference data for vBMD using opportunistic screening from low-dose chest CT in a large population cohort," the authors write.

"The opportunistic screening of osteoporosis using low-dose CT is clinically feasible and requires no additional exposure to ionizing radiation."

In addition, no additional equipment or patient time was required, suggesting that "this approach has potential for opportunistic screening for osteoporosis."

They note, however, that further cohort studies are needed to assess clinical utility of this method.

CT "Likely a More Accurate Measure" of Volumetric BMD

Pickhardt said the differences in osteoporosis prevalence observed between DXA and CT-derived measures in men likely reflect the greater accuracy of CT.

"DXA is a planar technique with a number of drawbacks," he told Medscape Medical News. "CT provides a more direct volumetric measure and is likely a more accurate method for BMD assessment."

He speculated that the greater differences between DXA versus CT seen in men than women "may relate to sex differences in cortical bone of vertebral bodies, which cannot be separated from the underlying trabecular bone with DXA (whereas CT directly measures the inner trabecular bone)." 

The authors note that although areal BMD (aBMD) derived from DXA is required for osteoporosis diagnosis according to World Health Organization criteria, "trabecular vBMD derived from CT can be also used for diagnosis based on thresholds published by the American College of Radiology of 120 mg/cm3 and 80 mg/cm3 to define osteopenia and osteoporosis, respectively, thresholds that were subsequently confirmed for the Chinese population."

Furthermore, vBMD has been shown in some studies to be more strongly related to fracture risk compared with DXA aBMD measures.

Importantly, in another recent study involving 9223 adults, Pickhardt and colleagues reported that bone and muscle biomarkers derived from CT were comparable to the Fracture Risk Assessment Tool score for the presymptomatic prediction of future osteoporotic fractures.

Pickhardt is an advisor to Bracco Imaging and Zebra Medical Vision. Therkildsen has reported no relevant financial relationships.

J Bone Miner Res. Published online November 4, 2020. Full text

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