Photon-counting CT for Pancreatic Cancer: Advancing Precision Imaging and Virtual Surgical Navigation

Initial Clinical Images From a Second-Generation Prototype Silicon-Based Photon-Counting Computed Tomography System

The clinical availability of photon-counting computed tomography (PCCT) has ushered in a new era of CT imaging. Spectral imaging coupled with superior contrast resolution, and ultrahigh spatial resolution (200 μm) offered by PCCT has the potential to revolutionize value-driven imaging. The potential of multicolor PCCT has generated excitement, and renewed interest, in novel contrast agent development for comprehensive disease interrogation, prediction and monitoring of treatment outcomes. Nanoparticles provide a versatile and powerful platform for the development of next generation contrast agents for spectral PCCT. In this article, we review recent developments and use of nanoparticle contrast agents for PCCT. We also discuss future research and translational opportunities for nanoparticle-based CT contrast agents enabled by the advent of PCCT and describe key considerations for their clinical translation.

Photon-counting computed tomography (PCCT) introduces a new era in thoracic imaging by offering ultra-high spatial resolution, reduced noise, spectral imaging capabilities, and lower radiation dose compared to conventional CT. These features are particularly relevant in thoracic surgery, where precise anatomical and functional assessment is essential throughout the perioperative period. This narrative review outlines the clinical potential of PCCT in surgical planning, intra- and postoperative evaluation, and follow-up of both oncologic and non-oncologic thoracic conditions. PCCT enables accurate bronchovascular mapping and iodine-based perfusion imaging, supporting sublobar resection planning and risk stratification in patients with complex anatomy or reduced lung function. Postoperatively, it enhances detection of subtle complications-such as air leaks or hematomas-and improves image quality near metallic implants through advanced artifact reduction techniques. The ability to combine high-resolution imaging with functional data allows for comprehensive evaluation in a single scan and may aid in differentiating fibrosis from local recurrence. Despite its promises, PCCT adoption is currently limited by high cost, restricted availability, and the need for training and system integration. Furthermore, prospective clinical studies are still needed to determine its impact on surgical outcomes. As technological and infrastructural challenges are addressed, PCCT may become a valuable component of image-guided thoracic surgery, contributing to safer, more personalized care.

Feasibility of ultra-high-resolution abdominal CT angiography in PCCT in outperforming conventional EICT.

PurposeTo characterize invasion-associated CT features in pulmonary subsolid nodules using low-dose ultrahigh-resolution (UHR) photon-counting CT (PCCT) images and evaluate UHR’s diagnostic superiority over standard high-resolution (HR) images.MethodsPatients with subsolid lung adenocarcinoma were recruited for chest scan on PCCT to obtain UHR and standard HR images between November 2023 and May 2024. Nodule characteristics were visually assessed and histogram features were extracted from each nodule. Image quality and radiation dose at previous energy-integrating detector CT (EID-CT) of 30 patients were compared with those of PCCT. Differences between UHR and standard HR, PCCT and EID-CT were compared using paired McNemar-test or paired Wilcox-test.ResultsOne hundred and eighty-four patients with 203 subsolid nodules were collected including 77 precursors, 77 minimally invasive adenocarcinoma (MIA) and 49 IA. UHR significantly outperformed standard HR in revealing CT findings including larger nodular diameter and solid-component diameter, more frequency of heterogeneous attenuation, lobulation, bubble-like sign, air bronchogram, pleural indentation and vascular sign (all P < 0.05). Additionally, UHR images exhibited significantly greater value in histogram-derived parameters compared to standard HR images (all P < 0.05), except for “Median,” “Minimum.” Furthermore, the radiation dose in PCCT was half of that in EID-CT (effective dose: 1.32 ± 0.27 vs. 3.85 ± 1.65/mSv, P < 0.001. CDTIvol: 2.97 ± 0.53 vs. 6.90 ± 2.97/mGy, P < 0.001), with image quality significantly better in PCCT.ConclusionThe UHR protocol on PCCT provides a magnified perspective to reveal CT characteristics of invasive growth in subsolid LUAD, previously undetectable on standard HR images, achieving halved radiation dose and better image quality than EID-CT.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11547-025-02057-0.

Photon-counting CT has a completely different detector mechanism than conventional energy-integrating CT. In the photon-counting detector, X-rays are directly converted into electrons and received as electrical signals. Photon-counting CT provides virtual monochromatic images with a high contrast-to-noise ratio for abdominal CT imaging and may improve the ability to visualize small or low-contrast lesions. In addition, photon-counting CT may offer the possibility of reducing radiation dose. This review provides an overview of the actual clinical operation of photon-counting CT and its diagnostic utility in abdominal imaging. We also describe the clinical implications of photon-counting CT including imaging of hepatocellular carcinoma, liver metastases, hepatic steatosis, pancreatic cancer, intraductal mucinous neoplasm of the pancreas, and thrombus.Graphical

The purpose of this study is to evaluate and compare the quantitative imaging performance of the dual-energy CT (DECT) and differential phase contrast CT (DPCT). The electron density (ρ_e) and the effective atomic number (Z_eff) are selected as the two comparison bases for the DECT and DPCT imaging. From the numerically simulated data, image domain based decomposition algorithms are used to extract the ρ_e and Zeff information for three different spatial resolution levels (0.3 mm, 0.1 mm, and 0.03 mm). The contrast-to-noise-ratio (CNR) and modeled human observer studies have been investigated to compare the DECT and DPCT quantitative imaging performance. At low spatial resolution (0.3 mm), the DECT shows better quantitative imaging performance than DPCT. As a contrary, the DPCT outperforms the DECT for ultra high spatial resolution (0.03 mm) imaging. With the 0.1 mm spatial resolution, the DECT and DPCT shows similar quantitative imaging performance. In conclusion, the DECT is more favored for low spatial resolution applications, such as the diagnostic imaging tasks. However, the DPCT would be recommended for ultra high spatial resolution imaging tasks, such as the micro-CT imaging tasks.

Image acquisition in ultra-high-resolution (UHR) scan mode does not impose a dose penalty in photon-counting CT (PCCT). This study aims to investigate the dose saving potential of using UHR instead of standard-resolution PCCT for lumbar spine imaging. Eight cadaveric specimens were examined with 7 dose levels (5-35 mGy) each in UHR (120 × 0.2 mm) and standard-resolution acquisition mode (144 × 0.4 mm) on a first-generation PCCT scanner. The UHR images were reconstructed with 3 dedicated bone kernels (Br68 [spatial frequency at 10% of the modulation transfer function 14.5 line pairs/cm], Br76 [21.0], and Br84 [27.9]), standard-resolution images with Br68 and Br76. Using automatic segmentation, contrast-to-noise ratios (CNRs) were established for lumbar vertebrae and psoas muscle tissue. In addition, image quality was assessed subjectively by 19 independent readers (15 radiologists, 4 surgeons) using a browser-based forced choice comparison tool totaling 16,974 performed pairwise tests. Pearson's correlation coefficient ( r ) was used to analyze the relationship between CNR and subjective image quality rankings, and Kendall W was calculated to assess interrater agreement. Irrespective of radiation exposure level, CNR was higher in UHR datasets than in standard-resolution images postprocessed with the same reconstruction parameters. The use of sharper convolution kernels entailed lower CNR but higher subjective image quality depending on radiation dose. Subjective assessment revealed high interrater agreement ( W = 0.86; P < 0.001) with UHR images being preferred by readers in the majority of comparisons on each dose level. Substantial correlation was ascertained between CNR and the subjective image quality ranking (all r 's ≥ 0.95; P < 0.001). In PCCT of the lumbar spine, UHR mode's smaller pixel size facilitates a considerable CNR increase over standard-resolution imaging, which can either be used for dose reduction or higher spatial resolution depending on the selected convolution kernel.

To compare lung parenchyma analysis on ultra-high resolution (UHR) images of a photon-counting CT (PCCT) scanner with that of high-resolution (HR) images of an energy-integrating detector CT (EID-CT). A total of 112 patients with stable interstitial lung disease (ILD) were investigated (a) at T0 with HRCT on a 3rd-generation dual-source CT scanner; (b) at T1 with UHR on a PCCT scanner; (c) with a comparison of 1-mm-thick lung images. Despite a higher level of objective noise at T1 (74.1 ± 14.1 UH vs 38.1 ± 8.7UH; p < 0.0001), higher qualitative scores were observed at T1 with (a) visualization of more distal bronchial divisions (median order; Q1-Q3) (T1: 10th division [9-10]; T0: 9th division [8-9]; p < 0.0001); (b) greater scores of sharpness of bronchial walls (p < 0.0001) and right major fissure (p < 0.0001). The scores of visualization of CT features of ILD were significantly superior at T1 (micronodules: p = 0.03; linear opacities, intralobular reticulation, bronchiectasis, bronchiolectasis, and honeycombing: p < 0.0001), leading to the reclassification of 4 patients with non-fibrotic ILD at T0, recognized with fibrotic ILD at T1. At T1, the mean (± SD) radiation dose (CTDI vol: 2.7 ± 0.5mGy; DLP: 88.5 ± 21mGy.cm) was significantly lower than that delivered at T0 (CTDI vol: 3.6 ± 0.9mGy; DLP: 129.8 ± 31.7mGy.cm) (p < 0.0001), corresponding to a mean reduction of 27% and 32% for the CTDIvol and DLP, respectively. The UHR scanning mode of PCCT allowed a more precise depiction of CT features of ILDs and reclassification of ILD patterns with significant radiation dose reduction. Evaluation of lung parenchymal structures with ultra-high-resolution makes subtle changes at the level of the secondary pulmonary lobules and lung microcirculation becoming visually accessible, opening new options for synergistic collaborations between highly-detailed morphology and artificial intelligence. • Photon-counting CT (PCCT) provides a more precise analysis of lung parenchymal structures and CT features of interstitial lung diseases (ILDs). • The UHR mode ensures a more precise delineation of fine fibrotic abnormalities with the potential of modifying the categorization of ILD patterns. • Better image quality at a lower radiation dose with PCCT opens new horizons for further dose reduction in noncontrast UHR examinations.

Perforator flaps are crucial in plastic surgery, providing versatility in complex reconstructions. However, anatomical variations pose challenges in flap dissection and anastomosis. Conventional computed tomography angiography (CTA) is standard for preoperative planning but has limitations in evaluating small arteries. A novel technique, photon-counting computed tomography (PCCT), offers enhanced spatial resolution with lower radiation exposure. From December 2023 to September 2024, a pilot study was conducted at Peking Union Medical College Hospital in Beijing. Seven patients undergoing perforator flap reconstructions received preoperative PCCT angiography (experimental group). Five patients underwent conventional CTA scans (control group 1), and another five had flap reconstructions guided by traditional imaging methods (control group 2). Three flap types were analyzed: deep inferior epigastric perforator flap, anterolateral thigh perforator flap, and superficial circumflex iliac artery perforator flap. Imaging efficacy, radiation dose, and surgical outcomes were compared. PCCT identified significantly more perforators (14.5 ± 2.1 vs. 10.2 ± 1.8, p < 0.05) and smaller branch diameters (0.8 ± 0.1 mm vs. 1.2 ± 0.2 mm, p < 0.05) compared to conventional CTA. The radiation dose was lower with PCCT (6.3 ± 1.1 mSv vs. 8.1 ± 0.9 mSv, p < 0.05). The experimental group experienced shorter operation and flap harvesting times, with fewer complications than control group 2. PCCT angiography enhances preoperative assessment of perforator vessels by detecting more and smaller perforators while reducing radiation exposure, thereby improving surgical planning and outcomes in perforator flap reconstructions. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Digital phantoms are valuable tools for evaluating small animal imaging systems. They can help optimize imaging parameters before live studies, supporting efforts to reduce animal use and refine experimental protocols. Wistar rats are widely used in preclinical imaging research due to their well-characterized biology and relevance to human disease. This study develops a series of anatomically variable digital Wistar rat phantoms to support small animal imaging research. We constructed 10 computational Wistar rat phantoms (six males, four females) with weights ranging from 188 to 474g using high-resolution (200µm) co-registered micro-CT and MRI data to generate detailed 3D anatomical models. The segmented organs and bones, including 35 distinct anatomical tissues, were fitted with smooth polygon mesh surfaces, ensuring flexibility for modeling motion, anatomical variation, and seamless voxelization at any resolution. To demonstrate the utility of the phantoms, we conducted a photon-counting CT (PCCT) simulation using a 279g female model. The phantom was voxelized into material maps representing soft tissue, iodine contrast, and bone. Simulated PCCT projections were reconstructed using both analytical and iterative methods to compare image quality and accuracy of material decomposition. Measured body sizes and organ masses confirm that the computational phantoms capture inter-subject anatomical variation. Iterative reconstruction outperformed analytical reconstruction in the PCCT simulation, reducing noise and improving material decomposition accuracy. Root mean square error (RMSE) across the water, iodine, and calcium maps decreased from 0.17 g/mL, 2.07 mg/mL, and 11.49 mg/mL to 0.02, 0.21, and 1.98, respectively. The resulting anatomically variable digital phantoms will provide a valuable resource for preclinical imaging research, enabling the evaluation of imaging systems, optimization of imaging protocols, and validation of reconstruction algorithms across a representative range of anatomies. The demonstrated PCCT study highlights the potential of these phantoms for advancing virtual pre-clinical imaging trials.

Qualitative and quantitative image quality of coronary CT angiography using photon-counting computed tomography: Standard and Ultra-high resolution protocols

Photon counting CT improves coronary stent imaging and fat attenuation index assessment across reconstruction modes

Coronary stent imaging in photon counting computed Tomography: Optimization of reconstruction kernels in a phantom

Pancreatic cancer in photon-counting CT: Low keV virtual monoenergetic images improve tumor conspicuity