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Large Study Finds CT With RT-PCR Effective in Diagnosing COVID-19

In a large study recently published in Radiology, researchers in France found that chest CT in combination with reverse transcriptase-polymerase chain reaction (RT-PCR) testing was effective as a diagnostic tool to assess COVID-19.

Key points of the study include the following:

• In a national survey of 26 hospitals (4,824 patients), chest CT sensitivity and specificity for diagnosing COVID-19 pneumonia were 90% and 91%, respectively.

• In 103 patients with an initial positive chest CT finding(s) for COVID-19 and a negative initial RT-PCR test, a repeat RT-PCR was positive in 90% (93/103).

• In patients with both negative chest CT and RT-PCR, the negative predictive value regarding final discharge diagnosis for COVID-19 was 99% (2,035/2,050 patients).

RT-PCR is the standard method for diagnosing CT. However, the test carries a wait time and a risk of false-negative results.

“In the context of this epidemic, the low sensitivity of RT-PCR implies that many patients with COVID-19 may not be identified and, consequently, may not be isolated from the healthy population,” the authors wrote.

“These individuals could continue to spread this disease,” according to the authors.

— Source: RSNA

CT Study Contrasts COVID-19, Influenza Virus Pneumonias

An open-access American Journal of Roentgenology article investigating the differences in CT findings between COVID-19 pneumonia and influenza virus pneumonia found that most lesions from COVID-19 were located in the peripheral zone and close to the pleura, whereas influenza virus was more prone to show mucoid impaction and pleural effusion.

“However,” cautions lead author Liaoyi Lin, MD, of China’s First Affiliated Hospital of Wenzhou Medical University, “differentiating between COVID-19 pneumonia and influenza virus pneumonia in clinical practice remains difficult.”

A total of 97 patients (49 women, 48 men) were enrolled in this study. Of them, 52 patients (29 men, 23 women; age range, 21 to 73 years) had COVID-19 pneumonia; 45 patients (26 women, 19 men; age range, 15 to 76 years) had influenza virus pneumonia (28, influenza A; 17, influenza B). All patients had positive nucleic acid testing results for the respective viruses, as well as complete clinical data and CT images.

According to Lin and colleagues, “Between the group of patients with COVID-19 pneumonia and the group of patients with influenza virus pneumonia, the largest lesion close to the pleura—ie, no pulmonary parenchyma between the lesion and the pleura—mucoid impaction, presence of pleural effusion, and axial distribution showed statistical difference (p<0.05).”

Meanwhile, the authors note that the properties of the largest lesion, presence of ground-glass opacities, consolidation, mosaic attenuation, bronchial wall thickening, centrilobular nodules, interlobular septal thickening, crazy paving pattern, air bronchogram, unilateral or bilateral distribution, and longitudinal distribution did not show significant differences (p>0.05). Additionally, no significant difference (p>0.05) in CT score, length of the largest lesion, mean density, volume, or mass of the lesions between the two groups was observed.

Because the CT manifestations of COVID-19 and influenza virus so often overlap, “even with the characteristics evaluated using AI software,” Lin and colleagues wrote, “no significant differences were detected.” Thus, the authors concluded that the more important role of CT during the present pandemic is in finding lesions and evaluating the effects of treatment.

— Source: American Roentgen Ray Society

Improving Lung Cancer CT Screening in Real-World Settings

An online-first manuscript published in the American Roentgen Ray Society’s American Journal of Roentgenology finds that focusing on lung cancer screening (LCS) subjects less likely to remain in the program—those with negative low-dose CT (LDCT) exams and those who still smoke—can improve that program’s cost-effectiveness and maximize its societal benefits. For people with a long history of smoking, LDCT LCS has been shown to decrease mortality; however, adherence to an LCS program remains significantly lower than in randomized controlled trials.

To assess real-world LDCT LCS performance and factors predictive of adherence to recommendations, three radiologists from the University of Pennsylvania’s Perelman School of Medicine retrospectively recorded patient demographics, smoking history and behavior changes, Lung-RADS category, positive predictive value (PPV) and negative predictive value (NPV), and adherence to screening recommendations for 260 subjects returning for follow-up LDCT from 2014 to 2019.

Forty-three subjects (16.5%) had positive scans, of which 28/260 (10.8%) were Lung-RADS category 3, 8/260 (3.1%) were 4A, 6/260 (2.3%) were 4B, and 2/260 (0.8%) were 4X. Four subjects were diagnosed with cancer: three lung cancers and one metastatic melanoma.

Meanwhile, 143/260 (55%) subjects were current smokers at baseline, and 121/260 (46.5%) were current smokers during the last round of LCS. Both LCS sensitivity and NPV were 100%, while specificity was 84.8% and PPV was 9.3%.

Overall adherence was 43%, though it increased progressively the higher the Lung-RADS category. Additionally, adherence was higher in former vs current smokers (50% vs 36.2%; p=0.002). Ultimately, there were only two significant independent predictors of adherence: having smoked previously and a positive (≥3) Lung-RADS category.

“Our study demonstrates that a real-world LCS can perform similar to randomized controlled trials in regard to important performance metrics,” concludes first author Eduardo J. Mortani Barbosa, Jr, MD.

Acknowledging that an economic incentive, such as an insurance premium reduction, could improve LCS adherence, Barbosa and colleagues add that multimodal communication (ie, face-to-face discussions with radiologists, letters from referring providers, and reminders via EHRs) should be investigated and incentivized.

“Such communications should emphasize that a negative LCS exam does not confer immunity to future lung cancer development,” the authors note, “and that continued participation in LCS, combined with smoking cessation, is essential to accrue the maximum benefits of mortality reduction amongst persons with substantial smoking history.”

— Source: American Roentgen Ray Society

Updated USPSTF Lung Cancer Screening Guidelines Would Help Save Lives

Changes outlined in new draft US Preventive Services Task Force (USPSTF) lung cancer screening recommendations will greatly increase the number of Americans eligible for screening and help medical providers save thousands more lives each year.

The ACR strongly supports the USPSTF proposal to lower the starting age for screening from 55 to 50 and the smoking history requirements from 30 pack-years to 20 pack-years. The ACR encourages efforts to expand screening—particularly among minorities and women—and will provide further input to the USPSTF in the coming weeks.

Annual lung cancer screening with low-dose CT (LDCT) in high-risk patients significantly reduces lung cancer deaths. This screening can identify cancers at an early, treatable, and curable stage. Given that the American Cancer Society predicts 135,720 lung cancer deaths this year, more widespread screening could save 30,000 to 60,000 lives in the United States annually.

To save more lives from lung cancer, the ACR recommends the following:

• The USPSTF should lower the starting age for screening from age 55 to age 50 and the smoking history requirements from 30 pack-years to 20 pack-years.

• The USPSTF should extend the quit-smoking requirement from 15 years to 20 years.

• Medical providers must become familiar with lung cancer screening guidelines and prescribe these exams for high-risk patients. Today, only a fraction of the recommended population is screened.

“Lung cancer kills more people each year than breast, colon, and prostate cancers combined. Particularly with the new, more sensible pack-year threshold, if implemented nationwide, this cost-effective test would save more lives than any cancer screening test in history,” says Debra Dyer, MD, FACR, chair of the ACR Lung Cancer Screening 2.0 Committee. “Primary care providers and thoracic specialists should support the proposed lower starting age and more inclusive pack-year threshold and order these scans for their high-risk patients.”

“It's great to see the draft USPSTF proposal extending the reach of this massive lifesaving benefit to more people at risk. The threat to older current and former smokers from this disease means we must do all we can to ensure patients are appropriately referred and have widespread access to lung cancer screening CT. The lower starting age and broader pack-year threshold will help save more lives from the nation’s leading cancer killer,” says Ella Kazerooni, MD, MS, FACR, chair of the ACR Lung-RADS committee and Lung Cancer Screening Registry.

Additional CT lung cancer screening information is available at RadiologyInfo.org, NLCRT.org, and ACR Lung Cancer Screening Resources.

— Source: ACR

Cardiac CT Can Double as Osteoporosis Test

Cardiac CT exams performed to assess heart health also provide an effective way to screen for osteoporosis, potentially speeding treatment to the previously undiagnosed, according to a study recently published in Radiology. Osteoporosis causes the bones to weaken and become vulnerable to fracture. It affects an estimated 200 million people worldwide. Early detection and treatment are important, as several classes of drugs are effective at reducing the risk of fractures that exact a devasting toll on victims. A National Osteoporosis Foundation report last year found that nearly 20% of Medicare fee-for-service beneficiaries died within 12 months of a new osteoporotic fracture. Bone mineral density (BMD) tests can diagnose osteoporosis, but the number of people who get these tests is suboptimal.

“Osteoporosis is a prevalent, underdiagnosed, and treatable disease associated with increased morbidity and mortality,” says study lead author Josephine Therkildsen, MD, from Herning Hospital, Hospital Unit West, in Herning, Denmark. “Effective antiosteoporotic treatment exists and so, identifying individuals with greater fracture rate who may benefit from such treatment is imperative.”

Therkildsen and colleagues recently looked at cardiac CT, a test done to assess heart health, as an opportunistic way to screen for osteoporosis. Because the cardiac CT scan also visualizes the thoracic vertebrae, the bones that form the vertebral spine in the upper trunk, it is relatively easy to add a BMD test to the procedure. The study involved 1,487 participants who underwent cardiac CT for evaluation of heart disease. Participants also had BMD testing of three thoracic vertebrae using quantitative CT software.

Of the 1,487 people in the study, 179, or 12%, had very low BMD. During follow-up of just over three years on average, 80 of the participants, or 5.3%, were diagnosed with a fracture. The fracture was osteoporosis-related in 31 of the 80 people.

The association between a very low BMD and a higher rate of fracture strongly suggests that thoracic spine BMD may be used to guide osteoporosis preventive measures and treatment decisions, the study authors say. Adding BMD testing to cardiac CT is feasible and applicable in a clinical setting, according to Therkildsen. It does not add time to the exam and doesn’t expose the patient to any additional radiation. In fact, Therkildsen says, technological advances over time have reduced the radiation dose given at cardiac CT. BMD measurements can be made using existing nonenhanced CT images as long as a suitable calibration system is ensured, scanner stability is continuously monitored, and systematic imaging acquisition techniques are implemented.

“We believe that opportunistic BMD testing using routine CT scans can be done with little change to normal clinical practice and with the benefit of identifying individuals with a greater fracture rate,” Therkildsen says.

Although the researchers used cardiac CT images in the study, in theory, any CT images that include a view of relevant bone structures could be used for measuring BMD. The development of fully automated software for BMD measurements further enhances the adaptability and convenience of this approach. Additional research will help pin down the optimal BMD cut-off values for treatment, while providing more data on fracture risk based on gender and areas of the body. The impact of clinical risk factors in combination with BMD measured from CT scans for the assessment of fracture risk would also benefit from further study.

“Our research group is dedicated to extend the research in this field, as we believe it should be added to clinical practice,” Therkildsen says.

— Source: RSNA