An automated AI algorithm that analyzes CT scans for signs of hepatic steatosis could make it possible to perform opportunistic screening for liver disease. In a study in AJR, researchers described their tool and the optimal CT parameters it needs for highest accuracy.
Hepatic steatosis (fatty liver) is a common condition that can represent non-alcoholic fatty liver disease (NAFLD), also known as metabolic dysfunction-associated steatotic liver disease (MASLD). Imaging is the only noninvasive tool for detecting steatosis and quantifying liver fat, with CT having an advantage due to its widespread availability.
Furthermore, abdominal CT data acquired for other clinical indications could be analyzed for signs of fatty liver – the classic definition of opportunistic screening. Patients could then be moved into treatment or intervention.
But who would read all those CT scans? Not who, but what – an AI algorithm trained to identify hepatic steatosis. To that end, researchers from the US, UK, and Israel tested an algorithm from Nanox AI that was trained to detect moderate hepatic steatosis on either non-contrast or post-contrast CT images. (Nanox AI was formed when Israeli X-ray vendor Nanox bought AI developer Zebra Medical Vision in 2021.)
The group’s study population included 2,777 patients with portal venous phase CT images acquired for different indications. AI was used to analyze the scans, and researchers noted the algorithm’s performance for detecting moderate steatosis under a variety of circumstances, such as liver attenuation in Hounsfield units (HU).
- The AI algorithm’s performance was higher for post-contrast liver attenuation than post-contrast liver-spleen attenuation difference (AUC=0.938 vs. 0.832)
- Post-contrast liver attenuation at <80 HU had sensitivity for moderate steatosis of 77.8% and specificity of 93.2%
- High specificity could be key to opportunistic screening as it enables clinicians to rule out individuals who don’t have disease without requiring diagnostic work-up that might lead to false positives
The authors point out that opportunistic screening would make abdominal CT scans more cost-effective by using them to identify additional pathology at minimal additional cost to the healthcare system.
This study represents another step forward in showing how AI can make opportunistic screening a reality. AI algorithms can comb through CT scans acquired for a variety of reasons, identifying at-risk individuals and alerting radiologists that additional work-up is needed. The only question is what’s needed to put opportunistic screening into clinical practice.
In the early days of the COVID-19 pandemic in China, hospitals were performing so many lung scans of infected patients that CT scanners were crashing. That’s according to an article based on an interview with a Wuhan radiologist that provides a chilling first-hand account of radiology’s role in what’s become the biggest public health crisis of the 21st century.
The interview was originally published in 2022 by the Chinese-language investigative website Caixin and was translated and published this month by U.S. Right to Know, a public health advocacy organization.
In a sign of the information’s sensitivity, the original publication on Caixin’s website has been deleted, but U.S. Right to Know obtained the document from the US State Department under the Freedom of Information Act.
Radiologists at a Wuhan hospital noticed how COVID cases began doubling every 3-4 days in early January 2020, the article states, with many patients showing signs of ground-glass opacities on CT lung scans – a telltale sign of COVID infection. But Chinese authorities suppressed news about the rapid spread of the virus, and by January 11 the official estimate was that there were only 41 COVID cases in the entire country.
In reality, COVID cases were growing rapidly. CT machines began crashing in the fourth week of January due to overheating, said the radiologist, who estimated the number of cases in Wuhan at 10,000 by January 21. Hospitals were forced to turn infected patients away, and many people were so sick they were unable to climb onto X-ray tables for exams. Other details included:
- Chinese regulatory authorities denied that human-to-human transmission of the SARS CoV-2 virus was occurring even as healthcare workers began falling ill
- Many workers at Chinese hospitals were discouraged from wearing masks in the pandemic’s early days to maintain the charade that human-to-human contact was not possible – and many ended up contracting the virus
- Radiologists and other physicians lived in fear of retaliation if they spoke up about the virus’ rapid spread
The article provides a stunning behind-the-scenes look at the early days of a pandemic that would go on to reshape the world in 2020. What’s more, it demonstrates the vital role of radiology as a front-line service that’s key to the early identification and treatment of disease – even in the face of bureaucratic barriers to delivering quality care.
New data on CT lung cancer screening rates offer a good news/bad news story. The bad news is that only 21.2% of eligible individuals in four US states got screened, far lower than other exams like breast or colon screening.
The good news is that, as low as the rate was relative to other tests, 21.2% is still much higher than previous estimates. And the study itself found that the rate of CT lung screening has risen over 8 percentage points in 3 years.
Compliance has lagged with CT lung screening ever since Medicare approved payments for the exam in 2015. A recent JACR study found that screening rates were low for eligible people for both Medicare and commercial insurance (3.4% and 1.8%).
Why is screening compliance so low? Explanations have ranged from fatalism among people who smoke to reimbursement requirements for “shared decision-making,” which unlike other screening exams require patients and providers to discuss CT lung screening before an exam can be ordered.
In this new study in JAMA Network Open, researchers examined screening rates in four states – Maine, Michigan, New Jersey, and Rhode Island – from January 2021 to January 2022. The study drew data from the National Health Interview Survey and weighted it to reflect the population of the US of individuals eligible for CT lung screening, based on the criteria of ages 55-79, 30-pack-year smoking history, and having smoked or quit within the past 15 years. Major findings included:
- The rate for CT lung cancer screening was 21.2%, up from 12.8% in 2019
- People with a primary health professional (PHP) were nearly 6 times more likely to get screened (OR=5.62)
- The age sweet spot for screening was 65-77, with lower odds for those 55-64 (OR=0.43) and 78-79 (OR=0.17)
- Rates varied between states, with Rhode Island having the highest rate (30.3%) and New Jersey the lowest (17.5%).
- Of those who got screened, 27.7% were in poor health and 4.5% had no health insurance
The findings offer some hope for CT lung screening, as the compliance rate is among the highest we’ve seen among recent research studies. On the other hand, many of those screened were in such poor health they might not benefit from treatment. The high rate of compliance in people with PHPs indicates that promoting screening with these providers could pay off, especially given the requirement for shared decision-making.
Samsung’s NeuroLogica subsidiary announced the FDA 510(k) clearance of its photon counting-based OmniTom Elite PCD, significantly expanding the mobile head/neck CT system’s diagnostic potential and adding to photon counting technology’s recent momentum.
About the OEPCD – The OmniTom Elite with PCD is now available as an optional upgrade (including field upgrades), swapping the standard OmniTom Elite’s energy integrating detector (EID) for a single-source cadmium telluride-based photon counting detector. Beyond the OmniTom Elite with PCD’s imaging advantages (2x higher spatial resolution, spectral CT images at multiple energy levels), all other key features are shared between the two configurations (16 row, 40cm bore, 30cm FoV).
The Photon Counting Race – NeuroLogica’s photon counting CT launch comes about six months after Siemens Healthineers’ NAEOTOM Alpha became the first FDA-cleared PCCT. The OmniTom Elite with PCD’s launch also comes amid major R&D and M&A efforts from essentially all major OEMs, as they compete for photon counting CT leadership.
The Photon Counting Advantage – Those efforts seem warranted, as PCCTs produce far higher quality images and provide far more imaging data, while potentially allowing lower radiation exposure and contrast dosage. For the OmniTom Elite’s head and neck applications, that could mean improved visualization and segmentation of bones, blood clots, plaques, hemorrhages, and intracranial tumors.
NeuroLogica’s Next Steps – Even if photon counting’s advantages are widely agreed upon, its potential clinical applications are still being explored. Because of that, NeuroLogica’s announcement emphasized ongoing research efforts to evaluate the OmniTom Elite with PCD’s performance with certain patients (e.g. post-trauma and post-surgical patients) and its plans to develop the mobile PCCT’s “full potential.”
The OmniTom Elite PCD’s head/neck imaging design (vs. whole body) and use of a single-source detector (vs. dual) make it quite different from the other PCCTs being developed, but it’s launch is still a notable milestone for photon counting CT technology. It’s also a testament to Samsung/NeuroLogica’s R&D efforts, coming 4.5 years after showing the detector at RSNA 2017, and reaching the market before most of the biggest CT players released their own PCCTs.
GE Healthcare had another busy RSNA, highlighted by several major modality launches and an overarching focus on helping imaging teams be more productive.
Return to MR Hardware – After focusing on AIR Recon DL during the last two RSNAs, GE Healthcare’s MR team made sure to roll-out new hardware at this year’s show.
- GE’s MR section was headlined by its new SIGNA Hero 3T MR, which brings a wide range of improvements (image quality, workflows, productivity, comfort, reconstruction, helium & energy), and a major focus on operator efficiency.
- GE also unveiled the SIGNA Artist Evo, which allows health systems / imaging centers to upgrade their existing 1.5T 60cm-bore MRs with 70cm bore systems (w/ AIR Recon DL & AIR Coils), without the construction and downtime typically required when upgrading to a net new MR system.
GE’s Scalable CT Platform – GE unveiled the unique Revolution Apex platform, which offers the modularity and scalability to cover a wide range of current and future needs, and represents GE’s biggest CT launch since 2014.
- The FDA-cleared Revolution Apex CT is available with multiple detector coverage configurations (40mm, 80mm, 160mm, upgradable w/o replacing gantry) and is offered with GE’s new Smart Subscription service (allows software upgrades/downgrades, plus auto updates).
- True to GE’s productivity focus, the Revolution Apex also includes a range of features to improve technologist efficiency and/or expand clinical applications (e.g. “Effortless Workflow,” patient positioning camera, TrueFidelity DLIR, motion correction for cardiac).
Much More – GE Healthcare has been busy throughout 2021, so although the other products in its RSNA booth were still quite new, they’ve already been detailed in previous Imaging Wire issues. Some of these other highlights include its in-development Photon Counting CT, it’s now FDA-approved Endotracheal Tube X-ray AI tool, its StarGuide SPECT/CT scanner, and its recent alliance with Optellum.
Siemens Healthineers’ Shape 22 pre-RSNA event featured a pair of ambitious hardware announcements that stand to expand what can be done with CT exams and where MRIs can be performed.
NAEOTOM Alpha PCCT – Siemens Healthineers confirmed its pole position in the Photon-Counting CT race, officially launching its NAEOTOM Alpha scanner. Although the NAEOTOM Alpha already received a rare marketing head-start from the FDA, this week’s launch begins its official 2022 rollout, and provides new details about this milestone product:
- Far higher image quality than CT
- Provides much more imaging data and new levels of CT-based insights
- Expands CT to new cardiac, oncology, and pulmonology use cases
- Allows 50% lower radiation dosage, could shift exams to non-contrast
- Supports Siemens’ core solutions, including operability and AI-based diagnosis
- Cleared in US and Europe, 20 systems already installed, 8k patients scanned
- PCCT expected to become the main CT technology within 10 years
- Siemens is holding another NAEOTOM Alpha event today (Nov. 18)
- Siemens might be first, but we’re seeing more PCCT activity from GE Healthcare, and Canon and Philips aren’t far behind
MAGNETOM Free.Star MRI – One year after introducing the MRI-expanding MAGNETOM Free.Max, Siemens continued its MRI accessibility push, revealing the “disruptively simple” MAGNETOM Free.Star. The new Free.Star MRI will inherit much of the MAGNETOM Free.Max’s accessibility-friendly qualities (0.55T, small/light, low helium & installation requirements), and will have the ambitious goal of supporting the half of the world’s population that doesn’t have MRI access. The MAGNETOM Free.Star is still early-stage (it hasn’t begun the FDA process), but it’s massive healthcare ambitions make it worth keeping an eye on.
The Takeaway – The NAEOTOM Alpha is expected to be the start of a major shift towards Photon-Counting CT, while the new MAGNETOM Free.Max and Free.Star could expand where MRIs are used. That makes these extremely significant products.
The FDA announced the 510(k) clearance of Siemens Healthineers’ NAEOTOM Alpha photon-counting CT scanner, calling it “the first new major technological improvement for Computed Tomography (CT) imaging in nearly a decade.” Those are some big words from a federal agency not known for hyperbole, and it doesn’t appear they are exaggerating.
About Photon-Counting CTs – Photon-counting CTs (PCCTs) produce far higher quality images than traditional CTs, with lower radiation and contrast dosage. Unlike standard CTs that simultaneously measure the total energy from many X-rays (at the expense of image info, clarity, and contrast), photon-counting CT detectors directly convert each individual X-ray photon into digital electrical signals that are then “counted.”
The NAEOTOM Alpha – The NAEOTOM Alpha might be the first PCCT scanner, but the star of this announcement is its detector. The new photon-counting detector leverages a CdTe active detection layer to achieve PCCT’s targeted image/dosage/contrast advantages, and it could be the foundation of Siemens’ PCCT portfolio for years to come.
The PCCT Race – The other major OEMs seem to be doing everything they can to earn a spot among the PCCT leaders. GE Healthcare and Canon both acquired PCCT detector makers within the last year and are planning their own PCCT launches, while Philips appears to have ramped up its PCCT R&D.
The Takeaway – PCCT has been viewed as the “future” of CT technology for quite a while, and that future just became a lot closer with last week’s announcement. We’re going to see similar PCCT launches from the other major OEMs, but Siemens Healthineers will enjoy its role as the only player with an FDA-approved PCCT scanner until then.