Whitney J. Palmer

Even though CT scans have not been widely used to diagnose COVID-19 infection, new research shows that using spectral CT with electron density (ED) imaging can make it much easier to assess the extent of lung lesion in patients who have early-stage disease.

Using a small group of case studies, published Oct. 21 in the 

a team of clinicians from Antony’s Private Hospital in France showed that electron density (ED) imaging can improve ground-glass opacity (GGO) visualization compared to conventional CT studies.

“ED imaging may improve the detection of early-stage COVID-19, a stage for which conventional CT has shown limited sensitivity for detection,” said lead study author Beatrice Daoud, an associate radiologist at Antony's. “Spectral CT may also provide a better assessment of the extent of the lung lesions.”

Deep Learning Plus CT Produces Spectral Images Without Higher Radiation

Although GGOs do show up on conventional CT scans, the visualization is subtle, Daoud’s team said, revealing only very small increases in attenuation compared with normal lungs. Consequently, accurate identification can be difficult, particularly during early infection. This study marks the first time investigators have looked into whether spectral CT scans can improve providers’ abilities to assess lung lesion extent.

To make this determination, the team retrospectively examined data from spectral CT scans conducted in four patients who have had confirmed COVID-19 cases with an RT-PCR test, they said. They reconstructed the spectral CT images using the same standard soft kernel (filter B) and a similar iterative method that is used to capture conventional CT images. They, then, compared initial conventional CT images with the follow-up conventional CT scans.

Based on their analysis, all 45 GGOs identified in the four patients showed up better on the ED images than the conventional CT scans, and the follow-up conventional CT images confirmed their presence. In addition, the lesion extent, which they assessed with semi-quantitative reporting scale denoting surface area involvement for each lobe, was much easier to determine on ED images, the team said.

“We reviewed conventional chest CT images obtained with a parenchyma kernel and standard lung window setting, as is usually the case in everyday radiology practices,” Daoud said.

The team compared the ED images to conventional images obtained using a soft mediastinum kernel and standard lung window setting, as well as conventional images captured with a soft mediastinum kernel and narrow lung window setting, virtual low-monoenergy images, virtual high-monoenergy images, and electron density images.

Based on these comparisons, the team discovered ED images made a difference in evaluating each of the four patients:

 A 39-year-old man diagnosed via conventional CT with lesions in both the right upper and lower lobes was found – with ED imaging – to have lesions in the upper left lobe that were barely noticeable previously.

 A 41-year-old woman with GGOs in both lower lobes discovered with conventional CT had additional lesions identified in the upper right lobe with ED imaging.

 A 64-year-old man had a conventional CT that showed peripheral bilateral diffuse GGOs. ED imaging revealed the GGOs to be more extensive and conspicuous than initially believed.

 An 80-year-old man had barely noticeable peripheral GGOs in the left upper lobe. Follow-up ED imaging showed the extent of these GGOs.

Overall, these results show that ED imaging offers greater detail for early assessment of GGOs that can be overlooked with conventional CT. The results are most promising, they said, by enhancing the contrast of GGOs compared with the normal lung.

“Our results suggest that the better ground-glass opacity visualization obtained using electron density imaging may be chiefly related to the increased visual noise in the image with soft kernel reconstruction and narrow lung window setting compared with electron density imaging, for which narrowing the window does not impair image quality,” they said.

Still, they said, a more systematic analysis of the different available image reconstruction is needed.

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Spectral CT provides greater detail about the extent of ground-glass opacities than conventional CT scans.

Spectral CT Makes Detecting Early-Stage COVID-19 Easier

CT colonography (CTC) exams occur less often in patients over age 65, a new study has found, and this downward trend could affect racial and ethnic minority patients the most.

Journal of the American College of Radiology

 a team of investigators from Emory University School of Medicine, led by Courtney Moreno, M.D., associate professor of radiology and imaging sciences in the Winship Cancer Institute, revealed the impetus for this drop could be because Medicare does not cover the exam.

“We observed that the relative utilization of screening CTC in individuals typically eligible for Medicare coverage decreased after age 65, suggesting access barriers related to a more restrictive Medicare coverage policy,” the team said.

Despite being a preventable condition with appropriate screening, colorectal cancer remains the second leading cause of cancer death in the United States. CTC is designed to detect colorectal cancer, as well as other types of colon cancer, but the Center for Medicare & Medicaid Services (CMS) announced in 2009 that evidence on the efficacy of CTC was lacking.

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Given the agency’s position, Moreno’s team set out to determine whether this stance is detrimentally impacting the quality of care given to patients. To do so, they examined CTC use, pulling 12,648 screening exams from the American College of Radiology’s CTC registry. They looked at both the age of patients, as well as any association between use of the exam and Medicare-eligible patient race.

Based on their analysis, the team identified a significant uptick in colon cancer rates in patients over age 50 – an annual increase of 5.3 percent in individuals between ages 52 and 64. On the flip-side, though, CTC screening rates began a noticeable decline after age 65, falling off by 6.9 percent for each additional year of age.

In addition, they noticed a difference in the screening rates between white and African American patients. For white patients, the CTC screening rate was highest between ages 65 and 69, but the test was administered most often in African American patients between ages 55 and 59.

This difference, the team said, could be attributed to Medicare’s lack of CTC coverage for patients over age 65. The average out-of-pocket expense for CTC screening, according to Costhelper.com, is $2,400, they said. Consequently, by not covering the test, the agency is likely making it harder for patients who cannot afford to pay for the test without insurance to secure the screening.

The factors behind this disparity are largely social and structural in nature, the team concluded, and they equate to a reduced ability to afford effective screening services. Not only is the average annual income lower for African American patients than it is for white patients, but African American Medicare beneficiaries also have, on average, lower levels of savings.

Due to these factors, the team determined, Medicare should change its course and move to cover CTC.

“Medicare coverage of screening CTC is needed so that Medicare patients who cannot afford to pay for this test out of pocket can undergo screening CTC,” they said.

African American, as well as other racial and ethnic minority, patients likely have lower levels of CTC screening due to out-of-pocket costs.

Lack of Medicare Coverage Limits CT Colongraphy Use in Minority Patients

New York-based start-up Ezra, a company focused on early cancer screening with MRI, has secured 510(k) clearance for its artificial intelligence (AI) tool for prostate cancer screening.

As the first prostate AI algorithm to receive clearance from the U.S. Food & Drug Administration, Ezra Prostate AI is designed to help radiologists analyze and segment prostate MRI while simultaneously reducing time and cost associated with MRI-based prostate cancer screening.

“Over the past two years, our team has worked tirelessly on building Ezra’s Prostate AI, and I’m thrilled to bring it to our imaging partners across the U.S.,” said Emi Gal, chief executive officer and co-founder of Ezra. “We will continue to work towards making the interpretation of prostate MRI scans faster and more affordable, in order to support the millions of men who are at risk of prostate cancer.”

Overall, company officials said, the prostate AI tool offers three capabilities:

Automatic lesion quantification: This tool helps providers segment lesions and can display lesion size automatically.

Automatic 3D volume rendering: Via the segmentation capabilities, radiologists can automatically render prostate gland and lesions 3D volumes, improving workflow efficiency.

According to company representatives, Ezra Prostate AI requires no software installation – the Ezra Plexo, a cloud-based PACS, has also received FDA clearance, and works directly in a web browser.

Ezra launched its MRI-based prostate cancer screening service in January 2019 and its full-body MRI scan in May 2019. In response to this FDA clearance, the company is dropping the price of an Ezra scan by 15 percent to $575.

Algorithm cleared to help radiologists analyze and segment prostate MRI.

Industry-First Prostate AI Cleared by FDA

Pre-operative MRI can catch more breast lesions in women with dense breasts who have receive their initial breast cancer diagnosis via digital breast tomosynthesis (DBT).

Together, investigators from a multi-institutional team determined that pre-operative MRI does perform differently between women who undergo DBT and those who have digital mammography (DM). They shared their results in the Oct. 13 

“In our study, we found a trend of increasing detection by MR of additional sites of malignancies in patients with dense breasts compared to those with non-dense breasts, irrespective of initial imaging modality – DM versus DBT,” said the team led by Elizabeth McDonald, M.D., Ph.D., assistant professor of radiology at the Hospital of the University of Pennsylvania.

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Based on their results, McDonald’s team discovered MRI detected additional malignant lesions in 57 percent of all women with dense breasts included in their study. This finding can be potentially critical because approximately 43 percent of American women between the ages of 40 and 74 have dense breasts, and evidence continues to mount that they could benefit from supplemental screening.

DBT is known to have a higher cancer detection rate in women regardless of their breast density, but little is know about how it compares to MRI in this regard.

“To optimize the use of breast MR in pre-surgical planning, it is necessary to identify a subset of patients who will benefit most from this exam,” they said.

To determine the impact of pre-operative MRI in detecting more cancers, the team conducted a retrospective analysis of 388 consecutive breast MRIs captured for newly diagnosed breast cancers between Oct. 1, 2013, to July 31, 2015. The original diagnosis was made either by DM or DBT, and the team stratified identified disease by modality, breast density, and background enhancement.

According to their analysis, pre-operative MRI picked up 50 additional malignancies – 37 ipsilateral and 13 contralateral. While there was no difference in MRI detection of additional disease between women imaged with either modality, MRI did detect more cancers in women with dense breasts who underwent DBT.

“There were significantly higher discordant MR findings in patients with dense breasts (p=0.004) with a trend toward significance for true-positive exams (p=0.06),” the team said. “In patients imaged with DBT, those with non-dense breasts had significantly fewer additional cancers detected by MR.”

Overall, they said, 7 percent of women with non-dense breasts had additional cancers identified versus 18 percent of women with dense breasts. In addition, background parenchymal enhancement on MRI was also significantly higher in patients with mammographically dense breasts.

“These findings suggest that in women imaged with DBT, MR may have less value for determining extent of disease in women with non-dense breasts,” the team said. “Among patients with DBT imaging at cancer diagnosis, women with dense breasts appear to benefit more from pre-operative MR than non-dense women.”

MRI catches more malignant lesions in women with dense breasts who undergo digital breast tomosynthesis than those who have digital mammography alone.

Author | Whitney J. Palmer

Articles

Spectral CT Makes Detecting Early-Stage COVID-19 Easier

Lack of Medicare Coverage Limits CT Colongraphy Use in Minority Patients

Industry-First Prostate AI Cleared by FDA

Pre-Operative MRI Catches More Cancers in Women with Dense Breasts