What’s New in Photon Counting CT?

September 30, 2026 · 5 articles · 6 research themes · covering September 23, 2026 – September 30, 2026

Overview

This week’s studies highlight a clear momentum toward photon-counting CT (PCCT) as a platform for more quantitative, reproducible imaging—spanning both clinical workflow improvements and physics-driven optimization. In neurovascular imaging, ultrahigh-resolution PCCT angiography combined with 3D volume rendering improved consistent aneurysm visualization and size measurement for surgical planning. In abdominal quantitative imaging, PCCT virtual monochromatic imaging (VMI) identified practical settings that standardize hepatic fat fraction estimation across body sizes, improving robustness of fat quantification. For functional imaging, PCCT demonstrated favorable dose efficiency and/or image-quality metrics for 4D parathyroid localization compared with conventional energy-integrating CT.

Complementing these clinical advances, two papers emphasize the underlying spectral/physics methods that enable better quantification. A physics-in-medicine study used photon-counting multi-spectral CT with an empirical energy bin selection algorithm to noninvasively map the spatiotemporal diffusion of cryoprotectants in a tissue-mimicking hydrogel, providing a framework to validate diffusion models and support cryopreservation protocol development. Finally, a neurology-focused diagnostic pathway study evaluated repeat myelography after an initial negative/nonlocalizing exam in suspected spontaneous intracranial hypotension, offering evidence-based guidance on when repeat testing is likely to be positive—particularly relevant for identifying elusive causes such as CSF-venous fistulas.

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Photon-Counting CT for Vascular/Neurovascular Imaging

3D Volume Rendering of Ultrahigh-Resolution Photon-Counting Detector CT Angiography for Preoperative Assessment of Intracranial Aneurysms: Initial Experience.

This retrospective study evaluated whether combining ultrahigh-resolution photon-counting detector CT angiography (UHR PCD-CTA) with 3D volume rendering (3DVR) post-processing improves reliable morphologic assessment and reproducible aneurysm size measurements in 21 patients (32 intracranial aneurysms). Two neurosurgeons assessed 2D UHR and 3DVR datasets for image quality and aneurysm characterization, with the key finding being that the UHR PCD-CTA + 3DVR workflow enabled consistent aneurysm visualization and size measurement for preoperative planning. The results support photon-counting CT angiography with 3DVR as a potentially more precise, reproducible imaging approach for surgical assessment of intracranial aneurysms.

Tóth A, Silbergleit M, Al Kasab S et al. · AJNR. American journal of neuroradiology · (2026) · View on PubMed ↗

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Photon-Counting CT for Quantitative Tissue Composition (Fat Fraction)

Uniform quantification of hepatic fat fraction across body sizes using photon-counting CT.

This European Journal of Radiology study used photon-counting CT (PCCT) virtual monochromatic imaging (VMI) to determine common VMI settings that enable accurate hepatic fat fraction (FF) quantification across body sizes, using anthropomorphic liver phantoms with known FF lesions (5%–40%). Scans were performed on a PCCT system (NAEOTOM Alpha) at 120 and 140 kV, with CT numbers measured across 40–190 keV (1-keV increments) and FF estimated via linear regression to minimize relative root-mean-square error (rRMSE). The key finding was that specific VMI settings can standardize hepatic FF estimation across medium and large body habitus, improving robustness of fat quantification with PCCT.

Li X, Kallman C, Zhang D et al. · European journal of radiology · (2026) · View on PubMed ↗ · Free PDF ↗

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Photon-Counting CT for Functional/4D Organ Imaging (Parathyroid)

Quantitative Evaluation of Image Quality Improvement and Reduced Radiation Output with Photon-Counting CT in 4D Parathyroid Imaging.

This AJNR study compared photon-counting CT (PCCT) with conventional energy-integrating detector CT (EIDCT) for 4D parathyroid imaging in terms of radiation output (CTDIvol and DLP) and image quality (signal-to-noise ratio and contrast-to-noise ratio). The key finding was that PCCT achieved improved dose efficiency and/or image quality metrics while reducing scanner radiation output compared with EIDCT in the 4DCT setting. Clinically, this supports PCCT as a strategy to maintain diagnostic image quality for anatomically complex parathyroid localization while lowering radiation exposure.

Arizono E, Buch K, Kelly HR et al. · AJNR. American journal of neuroradiology · (2026) · View on PubMed ↗ · Free PDF ↗

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Quantitative Imaging of Biological Transport (Cryoprotectant Diffusion)

Photon counting multi-spectral x-ray computed tomography of multi-component cryoprotectant diffusion into tissue surrogate.

This Physics in Medicine and Biology study used photon-counting multi-spectral x-ray CT (MSCT) with an empirical photon-energy bin selection algorithm to quantify heterogeneous diffusion of a ternary cryoprotectant mixture—dimethyl sulfoxide (DMSO), glycerol, and water—into a hydrogel tissue surrogate mimicking human muscle diffusion. The key finding was that multi-spectral photon-counting CT with optimized energy binning can quantitatively map the spatiotemporal distribution of diffusing cryoprotectants within the phantom. This provides a noninvasive imaging framework for measuring cryoprotectant transport kinetics, which is relevant to improving cryopreservation protocols and validating diffusion models.

Ali AM, Parker JT, Consiglio AN et al. · Physics in medicine and biology · (2026) · View on PubMed ↗ · Free PDF ↗

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Diagnostic Imaging Pathways in Neurology (Intracranial Hypotension/Myelography)

Diagnostic Yield of Repeat Myelography After an Initial Negative Study in Patients With Suspected Spontaneous Intracranial Hypotension.

This AJNR retrospective single-center study assessed the diagnostic yield of repeat myelography after an initial negative or nonlocalizing myelogram in 71 patients with suspected spontaneous intracranial hypotension, with an additional subgroup of 13 patients whose earlier suspicious target remained unresolved after treatment. The key finding was the clinically supported positivity rate of repeat myelography and identification of imaging/clinical features associated with a higher likelihood of a positive repeat study. This informs decision-making on whether to pursue repeat myelography to detect underlying causes such as CSF-venous fistulas when the first study is negative.

Callen AL, Jenkins K, Bhaumik D et al. · AJNR. American journal of neuroradiology · (2026) · View on PubMed ↗

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Generated automatically on September 30, 2026. Covers PubMed articles published September 23, 2026 – September 30, 2026. Summaries are AI-generated; always consult the original publication for clinical or research decisions.