Tag: PET

Next-Generation Brain PET

Posted on by Brian Casey

A new paper in JNM includes the first human images acquired with a next-generation dedicated brain PET/CT scanner that could create a new standard for neurological research. United Imaging’s NeuroEXPLORER scanner has sensitivity and spatial resolution “an order of magnitude” better than existing technology. 

In addition to its value as a clinical tool, PET has carved out a research role for investigating some of the most fundamental questions about brain function and pathology. 

  • Commercial whole-body scanners can be used for research, but dedicated brain systems like the High Resolution Research Tomograph (HRRT) offer even higher resolution for imaging tiny structures in the brain. 

NeuroEXPLORER was developed by a consortium that includes United Imaging, UC Davis, and Yale University to adapt for dedicated brain imaging the long-axis PET technology found in United’s uEXPLORER total-body PET/CT system. 

  • NeuroEXPLORER was a highlight at the recent SNMMI 2024 conference, and images acquired with the system won the show’s coveted Image of the Year honors.

In the new study, researchers go into more detail about NeuroEXPLORER’s specifications, which include … 

  • An extended axial field of view (FOV) of 49.5cm for higher sensitivity
  • Transverse spatial resolution ranging from 1.64-2.51mm at full-width half-maximum
  • Average time-of-flight resolution of 236 picoseconds
  • NEMA sensitivities of 46.0 and 47.6 kcps/MBq at center and 10cm offset, and absolute sensitivity of 11.8% at the center of the FOV

Such high sensitivity and spatial resolution enables tasks “previously considered difficult or impossible,” like imaging focal tracer uptake of small subcortical regions or low-density binding sites like cortical dopamine receptors. 

  • What’s more, NeuroEXPLORER’s long axial length enables high-quality imaging of the spinal cord and carotid arteries.

Now for the disclaimer: United Imaging notes that NeuroEXPLORER has not been submitted to the FDA for clearance and at present is only for research use; the company’s uEXPLORER scanner does have clearance and is in operation at several commercial sites. 

The Takeaway

Publication in a journal of the first human images from NeuroEXPLORER are an exciting development and underscore the potential of dedicated brain PET to advance research into neurological function and pathology. Whether the scanner develops into a clinical tool remains to be seen.

PET’s Milestone Moment

Posted on by Brian Casey

In a milestone moment for PET, CMS has ended its policy of only paying for PET scans of dementia patients if they are enrolled in a clinical trial. The move paves the way for broader use of PET for conditions like Alzheimer’s disease as new diagnostic and therapeutic agents become available. 

CMS said it was rescinding its coverage with evidence development (CED) requirement for PET payments within Medicare and Medicaid. 

  • Advocates for PET have chafed at the policy since it was established in 2013, claiming that it restricted use of PET to detect buildup of amyloid and tau in the brain – widely considered to be precursors to Alzheimer’s disease. The policy limits PET payments to one scan per lifetime for patients enrolled in clinical trials. 

But the landscape began changing with the arrival of new Alzheimer’s treatments like Leqembi, approved in January 2023. CMS telegraphed its changing position in July, when it announced a review of the CED policy, and followed through with the change on October 13. The new policy…

  • Eliminates the requirement that patients be enrolled in clinical trials
  • Ends the limit of one PET scan per Alzheimer’s patient per lifetime
  • Allows Medicare Administrative Contractors (MACs) to make coverage decisions on Alzheimer’s PET
  • Rejects requests to have the policy applied retroactively, such as to when Leqembi was approved

CMS specifically cited the introduction of new anti-amyloid treatments as one of the reasons behind its change in policy. 

  • The lifetime limit is “outdated” and “not clinically appropriate” given the need for PET for both patient selection and to potentially discontinue treatment if it’s ineffective or if it’s worked to clear amyloid from the brain – a key need for such expensive therapies. 

The news was quickly applauded by groups like SNMMI and MITA, which have long advocated for looser reimbursement rules.

The Takeaway

The CMS decision is great news for the PET community as well as for patients facing a diagnosis of Alzheimer’s disease. The question remains as to what sort of reimbursement rates providers will see from the various MACs around the US, and whether commercial payers will follow suit.

CMS May Shake Up PET Payments

Posted on by Brian Casey

In a major victory for PET advocates, CMS this week said it was opening a review of its reimbursement policy on PET scans for Alzheimer’s disease. The review could lead to more generous Medicare and Medicaid payments for PET to detect amyloid buildup in the brain, long known as a link to the debilitating – and inevitably fatal – disease. 

Medicare’s current policy on PET for Alzheimer’s has been in place since 2013 and is based on its coverage with evidence (CED) framework; it restricts reimbursement to a single scan per lifetime for patients who must be participating in clinical trials. The CED policy reflects not only CMS’ cautious approach to new technology, but also the fact that for years there have been no effective treatments for Alzheimer’s disease. 

That’s all changed within the last year. A new class of drugs that target amyloid buildup in the brain has begun to receive FDA approval, the most recent being Leqembi from Esai/Biogen in January 2023. And this week, Eli Lilly reported positive results for its amyloid-targeting treatment donanemab (see below), with approval expected by the end of 2023. 

The new drugs have changed the game when it comes to diagnosis and treatment of Alzheimer’s disease: 

  • PET can now be used to identify eligible patients and monitor their treatment
  • Thanks to PET, patients won’t continue to be given expensive drugs after amyloid buildup has been eliminated
  • Expanded PET reimbursement could boost the use of PET diagnostic tracers for identifying amyloid buildup 

CMS is taking comments on its proposal through August 16. If the agency eliminates the CED policy in favor of a national coverage decision, then decisions on PET reimbursement will be made by local Medicare Administrative Contractors (MACs). 

This week’s news could be a Pyrrhic victory if PET reimbursement levels are set too low. One positive sign is that CMS has said it also plans to review its policy that bundles radiotracer payments together with scan payments, which tends to depress reimbursement.

The Takeaway

The nuclear medicine and molecular imaging community has chafed for years under CMS’ restrictive policies on PET for Alzheimer’s disease, with groups like SNMMI lobbying for the change. This week’s news should have wide-ranging benefits not only for the PET business sector, but also for patients who are facing the scourge of Alzheimer’s disease.

SubtlePET Validations

Posted on by Jake Fishman

Two new studies out of France added to the growing field of evidence supporting Subtle Medical’s SubtlePET solution, with each confirming that it allows shorter-duration PET exams without affecting image quality. 

The first study, published in EJNMMI Physics, proclaimed SubtlePET “ready to be used in clinical practice for half-time or half-dose acquisitions” after it restored 18F-FDG PET/CT exams from three different scanners without impacting diagnostic confidence.

The researchers performed 18F-FDG PET/CT exams on 110 patients, producing full-acquisition, 50%-reduced, and 66%-reduced images (PET100, PET50, and PET33). They then denoised the images with SubtlePET and had two senior nuclear physicians evaluate them, finding that SubtlePET improved:

  • PET33 image quality from 16.7% to 86.7% “interpretable” & 0% to 26.7% “good”
  • PET50 image quality from 83.6% to 100% “interpretable” & 1.8% to 84.5% “good”
  • High-BMI patients’ PET100 exams from 60% to 80% “good” image quality (both were 100% interpretable)

The second study out of France’s Baclesse Cancer Center further confirmed that SubtlePET preserves 18F-FDG PET image quality with half-duration exams. 

The researchers performed 90-second and 45-second 18F-FDG PET/CT exams on 195 patients (PET90 & PET45), and then used SubtlePET to denoise the 45-second images, finding that:  

  • PET45 exams produced mediocre image quality (8% poor, 68% moderate) and achieved an 88.7% lesion concordance rate with PET90
  • After SubtlePET enhancement, PET45’s image quality matched PET90 (both 92% good, 8% moderate) and achieved a 97.7% lesion concordance rate with PET90
  • 7 of the discordant lesions (0.8%) were only detected with PET90 and 13 (1.5%) were exclusively detected with SubtlePET-enhanced PET45 images

The Takeaway
May was a particularly big research month, but SubtlePET has been on an academic hot streak for over a year, including at least three previous studies validating its performance with lower radiotracer dosage and faster acquisition times.

Subtle Medical’s marketing currently appears to focus on SubtlePET’s support for shorter scans, but it’s easy to see how patients and clinicians would welcome both shorter scans and lower radiotracer dosage, and the research increasingly seems to validate both use cases.

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