Acute Chest Pain CXR AI

Patients who arrive at the ED with acute chest pain (ACP) syndrome end up receiving a series of often-negative tests, but a new MGB-led study suggests that CXR AI might make ACP triage more accurate and efficient.

The researchers trained three ACP triage models using data from 23k MGH patients to predict acute coronary syndrome, pulmonary embolism, aortic dissection, and all-cause mortality within 30 days. 

  • Model 1: Patient age and sex
  • Model 2: Patient age, sex, and troponin or D-dimer positivity
  • Model 3: CXR AI predictions plus Model 2

In internal testing with 5.7k MGH patients, Model 3 predicted which patients would experience any of the ACP outcomes far more accurately than Models 2 and 1 (AUCs: 0.85 vs. 0.76 vs. 0.62), while maintaining performance across patient demographic groups.

  • At a 99% sensitivity threshold, Model 3 would have allowed 14% of the patients to skip additional cardiovascular or pulmonary testing (vs. Model 2’s 2%).

In external validation with 22.8k Brigham and Women’s patients, poor AI generalizability caused Model 3’s performance to drop dramatically, while Models 2 and 1 maintained their performance (AUCs: 0.77 vs. 0.76 vs. 0.64). However, fine-tuning with BWH’s own images significantly improved the performance of the CXR AI model (from 0.67 to 0.74 AUCs) and Model 3 (from 0.77 to 0.81 AUCs).

  • At a 99% sensitivity threshold, the fine-tuned Model 3 would have allowed 8% of BWH patients to skip additional cardiovascular or pulmonary testing (vs. Model 2’s 2%).

The Takeaway

Acute chest pain is among the most common reasons for ED visits, but it’s also a major driver of wasted ED time and resources. Considering that most ACP patients undergo CXR exams early in the triage process, this proof-of-concept study suggests that adding CXR AI could improve ACP diagnosis and significantly reduce downstream testing.

Bayer Establishes AI Platform Leadership with Blackford Acquisition

Six months after becoming radiology’s newest AI platform vendor, Bayer accelerated its path towards AI leadership with its acquisition of Blackford Analysis.

The acquisition might prove to be among the most significant in imaging AI’s short history, combining Blackford’s many AI advantages (tech, expertise, relationships) with Bayer’s massive radiology presence and AI ambitions. 

After closing later this year, Blackford will operate independently through Bayer’s well-established “arm’s length” model, allowing Blackford to preserve its entrepreneurial culture, while leveraging Bayer’s “experience, infrastructure and reach” to drive further expansion.

Bayer’s Calantic platform and team will operate separately from Blackford, providing Bayer customers with two distinct AI platforms to choose from, while giving Bayer two ways to drive its AI business forward. 

Although few would have predicted this acquisition, it makes sense given Bayer and Blackford’s relatively long history together and their complementary situations. 

  • Blackford was part of Bayer’s 2019 G4A digital health accelerator class
  • The companies have been working together to develop Calantic since 2020
  • Bayer has big AI goals, but its AI customer base and reputation were unestablished
  • Blackford’s AI customer base and reputation are solid, but it needed a new way to scale and a positive exit for its shareholders

Even fewer would have predicted that imaging contrast vendors would be the driving force behind AI’s next consolidation wave, noting that Guerbet invested in Intrasense just last week. However, imaging contrast and imaging AI could serve increasingly interrelated (or alternative) roles in the diagnostic process, and there’s surely advantages to being a leader in both areas for Bayer and Guerbet.

Speaking of AI consolidation, it appears that all those 2023 AI consolidation forecasts are proving to be correct, while bringing some of radiology’s largest companies into an AI segment that’s historically been dominated by startups. It wouldn’t be surprising if that trend continued.

The Takeaway

Bayer and Blackford have been working on their AI strategies for years, and this acquisition appears to give both companies a much better chance of achieving long-term AI leadership. Considering that AI is still in its infancy and could eventually play a dominant role in radiology (and across healthcare), AI leadership might be a far more significant market position in the future than many can imagine today.

CXR AI’s Screening Generalizability Gap

A new European Radiology study detailed a commercial CXR AI tool’s challenges when used for screening patients with low disease prevalence, bringing more attention to the mismatch between how some AI tools are trained and how they’re applied in the real world.

The researchers used an unnamed commercial AI tool to detect abnormalities in 3k screening CXRs sourced from two healthcare centers (2.2% w/ clinically significant lesions), and had four radiology residents read the same CXRs with and without AI assistance, finding that the AI:

  • Produced a far lower AUROC than in its other studies (0.648 vs. 0.77–0.99)
  • Achieved 94.2% specificity, but just 35.3% sensitivity
  • Detected 12 of 41 pneumonia, 3 of 5 tuberculosis, and 9 of 22 tumors 
  • Only “modestly” improved the residents’ AUROCs (0.571–0.688 vs. 0.534–0.676)
  • Added 2.96 to 10.27 seconds to the residents’ average CXR reading times

The researchers attributed the AI tool’s “poorer than expected” performance to differences between the data used in its initial training and validation (high disease prevalence) and the study’s clinical setting (high-volume, low-prevalence, screening).

  • More notably, the authors pointed to these results as evidence that many commercial AI products “may not directly translate to real-world practice,” urging providers facing this kind of training mismatch to retrain their AI or change their thresholds, and calling for more rigorous AI testing and trials.

These results also inspired lively online discussions. Some commenters cited the study as proof of the problems caused by training AI with augmented datasets, while others contended that the AI tool’s AUROC still rivaled the residents and its “decent” specificity is promising for screening use.

The Takeaway

We cover plenty of studies about AI generalizability, but most have explored bias due to patient geography and demographics, rather than disease prevalence mismatches. Even if AI vendors and researchers are already aware of this issue, AI users and study authors might not be, placing more emphasis on how vendors position their AI products for different use cases (or how they train it).

Guerbet’s Big AI Investment

Guerbet took a big step towards advancing its AI strategy, acquiring a 39% stake in French imaging software company Intrasense, and revealing ambitious future plans for their combined technologies.

Through Intrasense, Guerbet gains access to a visualization and AI platform and a team of AI integration experts to help bring its algorithms into clinical use. The tie-up could also create future platform and algorithm development opportunities, and the expansion of their technologies across Guerbet’s global installed base.

The €8.8M investment (€0.44/share, a 34% premium) could turn into a €22.5M acquisition, as Guerbet plans to file a voluntary tender offer for all remaining shares.

Even though Guerbet is a €700M company and Intrasense is relatively small (~€3.8M 2022 revenue, 67 employees on LinkedIn), this seems like a significant move given and Guerbet’s increasing emphasis on AI:

What Guerbet was lacking before now (especially since ending its Merative/IBM alliance) was a future AI platform – and Intrasense should help fill that void. 

If Guerbet acquires Intrasense it would continue the recent AI consolidation wave, while adding contrast manufacturers to the growing list of previously-unexpected AI startup acquirers (joining imaging center networks, precision medicine analytics companies, and EHR analytics firms). 

However, contrast manufacturers could play a much larger role in imaging AI going forward, considering the high priority that Bayer is placing on its Calantic AI platform.

The Takeaway

Guerbet has been promoting its AI ambitions for several years, and this week’s Intrasense investment suggests that the French contrast giant is ready to transition from developing algorithms to broadly deploying them. That would take a lot more work, but Guerbet’s scale and imaging expertise makes it worth keeping an eye on if you’re in the AI space.

Federated Learning’s Glioblastoma Milestone

AI insiders celebrated a massive new study highlighting a federated learning AI model’s ability to delineate glioblastoma brain tumors with high accuracy and generalizability, while demonstrating FL’s potential value for rare diseases and underrepresented populations.

The UPenn-led research team went big, as the study’s 71 sites in 6 continents made it the largest FL project to-date, its 6,314 patients’ mpMRIs created the biggest glioblastoma (GBM) dataset ever, and its nearly 280 authors were the most we’ve seen in a published study. 

The researchers tested their final GBM FL consensus model twice – first using 20% of the “local” mpMRIs from each site that weren’t used in FL training, and second using 590 “out-of-sample” exams from 6 sites that didn’t participate in FL development.

These FL models achieved significant improvements compared to an AI model trained with public data for delineating the three main GBM tumor sub-compartments that are most relevant for treatment planning.

  • Surgically targetable tumor core: +33% w/ local, +27% w/ out-of-sample
  • Enhancing tumor: +27% w/ local, +15% w/ out-of-sample
  • Whole tumor: +16% w/ local, +16% w/ out-of-sample data

The Takeaway

Federated learning’s ability to improve AI’s performance in new settings/populations while maintaining patient data privacy has become well established in the last few years. However, this study takes FL’s resume to the next level given its unprecedented scope and the significant complexity associated with mpMRI glioblastoma exams, suggesting that FL will bring a “paradigm shift for multi-site collaborations.”

The Mammography AI Generalizability Gap

The “radiologists with AI beat radiologists without AI” trend might have achieved mainstream status in Spring 2020, when the DM DREAM Challenge developed an ensemble of mammography AI solutions that allowed radiologists to outperform rads who weren’t using AI.

The DM DREAM Challenge had plenty of credibility. It was produced by a team of respected experts, combined eight top-performing AI models, and used massive training and validation datasets (144k & 166k exams) from geographically distant regions (Washington state, USA & Stockholm, Sweden).

However, a new external validation study highlighted one problem that many weren’t thinking about back then. Ethnic diversity can have a major impact on AI performance, and the majority of women in the two datasets were White.

The new study used an ensemble of 11 mammography AI models from the DREAM study (the Challenge Ensemble Model; CEM) to analyze 37k mammography exams from UCLA’s diverse screening program, finding that:

  • The CEM model’s UCLA performance declined from the previous Washington and Sweden validations (AUROCs: 0.85 vs. 0.90 & 0.92)
  • The CEM model improved when combined with UCLA radiologist assessments, but still fell short of the Sweden AI+rads validation (AUROCs: 0.935 vs. 0.942)
  • The CEM + radiologists model also achieved slightly lower sensitivity (0.813 vs. 0.826) and specificity (0.925 vs. 0.930) than UCLA rads without AI 
  • The CEM + radiologists method performed particularly poorly with Hispanic women and women with a history of breast cancer

The Takeaway

Although generalization challenges and the importance of data diversity are everyday AI topics in late 2022, this follow-up study highlights how big of a challenge they can be (regardless of training size, ensemble approach, or validation track record), and underscores the need for local validation and fine-tuning before clinical adoption. 

It also underscores how much we’ve learned in the last three years, as neither the 2020 DREAM study’s limitations statement nor critical follow-up editorials mentioned data diversity among the study’s potential challenges.

Annalise.ai Gets ‘Comprehensive’ with Enterprise CTB

Annalise.ai doubled-down on its comprehensive AI strategy with the launch of its Annalise Enterprise CTB solution, which identifies a whopping 130 different non-contrast brain CT findings. 

Initially available for clinical use in the UK, Australia, and New Zealand, Annalise Enterprise CTB analyzes brain CTs as they are acquired, prioritizes urgent cases, and provides radiologists with details on each finding (types, locations, likelihood).  

If this sounds familiar, it’s because Annalise.ai’s original Enterprise CXR solution identifies 124 different chest X-ray findings, with previous clinical studies showing that it improves radiologists’ detection accuracy, diagnostic decision making, and reporting speed

We’re also seeing a (less-extreme) push towards comprehensive AI from other vendors, as Qure.ai’s brain CT solution detects 11 findings and a growing field of chest X-ray AI vendors lead with their ability to detect multiple findings (also Lunit, Qure.ai, Oxipit, Vuno).

The Takeaway

Whether Annalise.ai’s 10x-larger list of findings results in a similar performance advantage will be decided in the clinic, but Annalise Enterprise CTB and CXR (and any future solutions) should go a long way towards supporting radiology teams who want to improve their detection performance without patching together multiple “narrow AI” solutions .

iCAD and Solis CVD Alliance

iCAD and major breast imaging center company Solis Mammography announced plans to develop and commercialize AI that quantifies breast arterial calcifications (BACs) in mammograms to identify women with high cardiovascular disease (CVD) risks.

Through the multi-year alliance, iCAD and Solis will expand upon iCAD’s flagship ProFound AI solution’s ability to detect and quantify BACs, with the goal of helping radiologists identify women with high CVD risks and guide them into care.

iCAD and Solis’ expansion into cardiovascular disease screening wasn’t exactly expected, but recent trends certainly suggest that commercial AI-based BAC detection could be on the way: 

  • There’s also mounting academic and commercial momentum behind using AI to “opportunistically” screen for incidental findings in scans that were performed for other reasons (e.g. analyzing CTs for CAC scores, osteoporosis, or lung nodules).
  • Despite being the leading cause of death in the US, it appears that we’re a long way from formal heart disease screening programs, making the already-established mammography screening pathway an unlikely alternative.
  • Volpara and Microsoft are also working on a mammography AI product that detects and quantifies BACs. In other words, three of the biggest companies in breast imaging (at least) and one of the biggest tech companies in the world are all currently developing AI-based BAC screening solutions.

The Takeaway

Widespread adoption of mammography AI-based cardiovascular disease screening might seem like a longshot to many readers who often view incidentals as a burden and have grown weary of early-stage AI announcements… and they might be right. That said, there’s plenty of evidence suggesting that a solution like this would help detect more early-stage heart disease using scans that are already being performed.

Arterys and Tempus’ Precision Merger

Arterys was just acquired by precision medicine AI powerhouse Tempus Labs, marking perhaps the biggest acquisition in the history of imaging AI, and highlighting the segment’s continued shift beyond traditional radiology use cases. 

Arterys has become one of imaging’s AI platform and cardiac MRI 4D flow leaders, leveraging its 12 years of work and $70M in funding to build out a large team of imaging/AI experts, a solid customer base, and an attractive intellectual property portfolio (AI models, cloud viewer, and a unique multi-vendor platform).

Tempus Labs might not be a household name among Imaging Wire readers, but they’ve become a giant in the precision medicine AI space, using $1.1B in VC funding and the “largest library of clinical & molecular data” to develop a range of precision medicine and treatment discovery / development / personalization capabilities.

It appears that Arterys will continue to operate its core radiology AI business (with far more financial support), while supporting the imaging side of Tempus’s products and strategy.

This acquisition might not be as unprecedented as some think. We’ve seen imaging AI assume a central role within a number of next-generation drug discovery/development companies, including Owkin and nference (who recently acquired imaging AI startup Predible), while imaging AI companies like Quibim are targeting both clinical use and pharma/life sciences applications.

Of course, many will point out how this acquisition continues 2022’s AI shakeup, which brought at least five other AI acquisitions (Aidence & Quantib by RadNet; Nines by Sirona, MedoAI by Exo, Predible by nference) and two strategic pivots (MaxQ AI & Kheiron). Although these acquisitions weren’t positive signs for the AI segment, they revealed that imaging AI startups are attractive to a far more diverse range of companies than many could have imagined back in 2021 (including pharma and life sciences).

The Takeaway

Arterys just transitioned from being an independently-held leader of the (promising but challenged) diagnostic imaging AI segment to being a key part of one of the hottest companies in healthcare AI, all while managing to keep its radiology business intact. That might not be the exit that Arterys’ founders envisioned, but in many ways it’s an ideal second chapter.

Plaque AI’s First Reimbursement

The small list of cardiac imaging AI solutions to earn Medicare reimbursements just got bigger, following CMS’ move to add an OPPS code for AI-based coronary plaque assessments. That represents a major milestone for Cleerly, who filed for this code and leads the plaque AI segment, and it marks another sign of progress for the business of imaging AI.

With CMS’ October 1st OPPS update, Cleerly and other approved plaque AI solutions now qualify for $900 to $1,000 reimbursements when used with Medicare patients scanned in hospital outpatient settings. 

  • That achievement sets the stage for plaque AI’s next major reimbursement hurdle: gaining coverage from local Medicare Administrative Contractors (MACs) and major commercial payers.

Cleerly and its qualifying plaque AI competitors join a growing list of Medicare-reimbursed imaging AI solutions, headlined by HeartFlow’s FFRCT solution ($930-$950) and Perspectum’s LiverMultiScan MRI software ($850-$1,150), both of which have since expanded their reimbursements across MAC regions and major commercial payers. 

  • The last few years also brought temporary NTAP reimbursements for Viz.ai (LVO detection / coordination), Caption Health (echo AI guidance), and Optellum (lung cancer risk assessments), plus a growing number of imaging AI CPT III codes that might lead to future reimbursements.

The new reimbursement should also drive advancements within the CCTA plaque AI segment, giving providers more incentive to adopt this technology, and providing emerging plaque AI vendors (e.g. Elucid, Artrya) a clearer path towards commercialization and VC funding.

The Takeaway

CMS’ new plaque AI OPPS code marks a major milestone for Cleerly’s commercial and clinical expansion, and a solid step for the plaque AI segment. 

The reimbursement also adds momentum for the overall imaging AI industry, which finally seems to be gaining support from CMS. That’s good news for AI vendors, since it’s pretty much proven that reimbursements drive AI adoption and are often necessary to show ROI.

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-- The Imaging Wire team