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Updated: May 1, 2026
Author Spotlight: A 3D Digital Model for the Diagnosis and Treatment of Pulmonary Nodules
Published on: May 19, 2023
Comparing the detectability of pulmonary nodules on two ultra-high resolution CT scanners: a preliminary phantom
Joël Greffier1, Cécile Salvat2, Maxime Pastor3
1IMAGINE UR UM 103, Montpellier University, Department of Medical Imaging, Nîmes University Hospital, Nîmes, France. joel.greffier@chu-nimes.fr.
Objectives:
To objectively and subjectively compare the detectability of pulmonary nodules on an ultra-high-resolution CT (UHR-CT) scanner equipped with energy-integrating detectors and a photon-counting CT (PCCT) in UHR mode.
Materials And Methods:
An image quality phantom and an anthropomorphic phantom were scanned on a UHR-CT and a PCCT in UHR mode at 7.5/2.5/0.4 mGy. The parameters typically used for UHR chest CT scans were selected. Noise power spectrum and task-based transfer function were computed to assess noise-magnitude, noise texture (fav), and spatial resolution (f50), respectively. Detectability indices (d') were computed to model the detection of three chest nodules. Five radiologists subjectively evaluated their confidence in detecting these nodules available on the anthropomorphic phantom.
Results:
For PCCT, noise magnitude increased, and fav values were similar as the dose decreased. For UHR-CT, noise-magnitude decreased, and fav values decreased as the dose decreased. For both inserts and CT systems, f50 values decreased as the dose decreased. For both inserts and at all dose levels, f50 values were higher with PCCT than with UHR-CT. d' values increased as the dose increased with PCCT, and the opposite was found with UHR-CT. Confidence in nodule detection was considered clinically sufficient at all dose levels for high-contrast solid nodules at 7.5 and 2.5 mGy for subsolid nodules, and only for PCCT at 7.5 mGy for low-contrast nodules.
Conclusion:
Under UHR conditions, pulmonary nodule detectability strongly depends on the dose level and reconstruction parameters. High-contrast nodule detection can be performed at all dose levels with both CT systems, but reconstruction strategies must be optimized for low-contrast nodule detection.
Key Points:
Do the performance of UHR-CT and PCCT scanners improve the detectability of pulmonary nodules? PCCT showed dose-invariant noise texture and higher effective spatial resolution, whereas UHR-CT relied on dose-dependent noise suppression, producing smoother images and reduced spatial frequency. High-contrast nodule detection can be performed at all dose levels with both CT systems, particularly at ultra-low dose levels, but reconstruction strategies must be optimized for low-contrast nodule detection.
