Photon-Counting Detector CT: Key Points Radiologists Should Know

Visualization of the middle meningeal artery on photon-counting detector CT: Comparison with energy-integrating detector CT

PURPOSE

The middle meningeal artery (MMA) is the target arteries for the treatment of intracranial diseases. The purpose of this study was to investigate the ability of photon-counting detector CT (PCD-CT) to improve the visualization of the MMA compared to energy-integrated detector CT (EID-CT).

METHODS

We retrospectively analyzed head CT angiography images from patients who underwent PCD-CT with ultra-high-resolution (UHR) mode between April 2023 and July 2024. We compared the images reconstructed with a slice thickness 0.2 mm and the matrix sizes 1024 × 1024 ('PCD-1024') and 512 × 512 ('PCD-512') with the same-patient images previously obtained by EID-CT with 0.75- or 1.0- mm slice thickness and the matrix size 512 × 512 ('EID-512'). Quantitatively, a region of interest (ROI) was placed on the maxillary artery near the origin of the MMA, and the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and contrast ratio (CR) were measured. Image sharpness was evaluated by measuring the full width at half maximum (FWHM) and the maximum intensity from the MMA vessel line profile. Qualitatively, the overall image quality, sharpness, and artifacts were evaluated using four-point Likert scales. The same evaluation was performed using PCD-CT with 0.2 mm ('0.2 mm') and virtual monoenergetic images (VMIs) ('45 keV', '55 keV', and '70 keV').

RESULTS

30 patients (19 males, 11 females; median age 65 years) were included. Quantitatively, the SNR (mean ± SD) for PCD-1024, PCD-512, and EID-512 were 16.9 ± 5.6, 20.3 ± 6.2, and 23.2 ± 7.8, respectively (P < 0.01 for PCD-1024 vs. EID-512). The CNR were 16.6 ± 4.5, 20.2 ± 5.5, and 44.4 ± 13.9. The CR were 0.74 ± 0.06, 0.74 ± 0.06, and 0.68 ± 0.08. The FWHM were 1.41 ± 0.17, 1.48 ± 0.15, and 1.77 ± 0.12, and the maximum intensity were 407.5 ± 71.7, 386.0 ± 72.5, and 218.2 ± 58.2 (P < 0.001 for PCD-1024 vs. EID-512 and PCD-512 vs. EID-512, respectively). Qualitatively, significant differences (P < 0.05) were identified among the PCD-1024, PCD-512, and EID-512 groups regarding the respective scores (median [IQR]) for overall image quality (4 [3-4], 3 [3-4], and 2 [2-3]), sharpness (4 [3-4], 3 [3-3], and 2 [2-3]), and artifacts (3 [3-3], 3 [2-3], and 2 [2-2]). In VMI analysis, quantitatively, 45 keV showed the highest values for SNR, CNR, CR, and maximum intensity; however, there were no differences in FWHM among the groups. Qualitatively, 0.2 mm was superior to the other groups in all evaluated aspects (P < 0.05).

CONCLUSION

PCD-1024 visualized the MMA better than both PCD-512 and EID-512. The 0.2 mm reconstruction was visually superior to the VMIs.

Radiomics-driven spectral profiling of six kidney stone types with monoenergetic CT reconstructions in photon-counting CT

OBJECTIVES

Urolithiasis, a common and painful urological condition, is influenced by factors such as lifestyle, genetics, and medication. Differentiating between different types of kidney stones is crucial for personalized therapy. The purpose of this study is to investigate the use of photon-counting computed tomography (PCCT) in combination with radiomics and machine learning to develop a method for automated and detailed characterization of kidney stones. This approach aims to enhance the accuracy and detail of stone classification beyond what is achievable with conventional computed tomography (CT) and dual-energy CT (DECT).

MATERIALS AND METHODS

In this ex vivo study, 135 kidney stones were first classified using infrared spectroscopy. All stones were then scanned in a PCCT embedded in a phantom. Various monoenergetic reconstructions were generated, and radiomics features were extracted. Statistical analysis was performed using Random Forest (RF) classifiers for both individual reconstructions and a combined model.

RESULTS

The combined model, using radiomics features from all monoenergetic reconstructions, significantly outperformed individual reconstructions and SPP parameters, with an AUC of 0.95 and test accuracy of 0.81 for differentiating all six stone types. Feature importance analysis identified key parameters, including NGTDM_Strength and wavelet-LLH_firstorder_Variance.

CONCLUSION

This ex vivo study demonstrates that radiomics-driven PCCT analysis can improve differentiation between kidney stone subtypes. The combined model outperformed individual monoenergetic levels, highlighting the potential of spectral profiling in PCCT to optimize treatment through image-based strategies.

KEY POINTS

Question How can photon-counting computed tomography (PCCT) combined with radiomics improve the differentiation of kidney stone types beyond conventional CT and dual-energy CT, enhancing personalized therapy? Findings Our ex vivo study demonstrates that a combined spectral-driven radiomics model achieved 95% AUC and 81% test accuracy in differentiating six kidney stone types. Clinical relevance Implementing PCCT-based spectral-driven radiomics allows for precise non-invasive differentiation of kidney stone types, leading to improved diagnostic accuracy and more personalized, effective treatment strategies, potentially reducing the need for invasive procedures and recurrence.

Dual-Contrast Agent with Nanoparticle and Molecular Components in Photon-Counting Computed Tomography: Assessing Articular Cartilage Health

PURPOSE

Photon-counting detectors (PCDs) are cutting-edge technology that enable spectral computed tomography (CT) imaging with a single scan. Spectral imaging is particularly effective in contrast-enhanced CT (CECT) imaging, especially when multiple contrast agents are utilized, as materials are distinguishable based on their unique X-ray absorption. One application of CECT is joint imaging, where it assesses the structure and composition of articular cartilage soft tissue. This evaluates articular cartilage and reveals compositional changes associated with early-stage osteoarthritis (OA) using a photon-counting detector CT (PCD-CT) technique combined with a dual-contrast agent method.

METHODS

A dual-contrast agent combination was used, consisting of proteoglycan-binding cationic tantalum oxide nanoparticles, developed in our lab, and a commercial non-ionic iodinated iodixanol agent. Ex vivo equine stifle joint cartilage samples (N = 30) were immersed in the contrast agent bath for 96 hours and imaged at multiple timepoints for analysis of proteoglycan, collagen, and water contents as well as collagen orientation, histological scoring, and biomechanical parameters.

RESULTS

By analyzing contrast agent concentrations, the technique provided a simultaneous assessment of the solid constituents and function of cartilage. Contrast agent diffusion depended on contrast agent composition and was significantly different between healthy and early-stage OA groups within 12 hours.

CONCLUSION

The present study shows the promising utility of the dual-contrast PCD-CT technique for articular cartilage assessment and early-stage OA detection.

Guidelines for the Selection of Scintillators for Indirect Photon-Counting X-ray Detectors

X-ray photon-counting detectors (PCDs) are a rapidly developing technology. Current PCDs used in medical imaging are based on CdTe, CZT, or Si semiconductor detectors, which directly convert X-ray photons into electrical pulses. An alternative approach is to combine ultrafast scintillators with silicon photomultipliers (SiPMs). Here, an overview is presented of different classes of scintillators, with the aim of assessing their potential application in scintillator-SiPM based indirect X-ray PCDs. To this end, three figures of merit (FOMs) are defined: the pulse intensity, the pulse duration, and the pulse quality. These FOMs quantify how characteristics such as light yield, pulse shape, and energy resolution affect the suitability of scintillators for application in indirect PCDs. These FOMs are based on emissive characteristics; a fourth FOM (ρZ eff 3.5) is used to also take stopping power into account. Other important properties for the selection process include low self-absorption, low after-glow, possibility to produce sub-mm pitch pixel arrays, and cost-effectiveness. It is shown that material classes with promising emission properties are Ce3+- or Pr3+-doped materials, near band gap exciton emitters, plastics, and core-valence materials. Possible shortcomings of each of these groups, e.g., suboptimal emission wavelength, nonproportionality, and density, are discussed. Additionally, the engineering approach of quenching the scintillator emission, resulting in a targeted shortening of the decay time, and the possibility of codoping are explored. When selecting and/or engineering a material, it is important to consider not only the characteristics of the scintillator but also relevant SiPM properties, such as recharge time and photodetection efficiency.

Photon-Counting CT Scan Phantom Study: Stability of Radiomics Features

Background/Objectives: To evaluate and optimize the reconstruction parameters of images acquired with a photon-counting CT scanner to achieve a stable radiomics signal. Methods: Radiomics is a quantitative imaging biomarker correlated to survival in oncology patients. Implementing radiomics in clinical routine remains challenging due to the feature's instability. Photon-counting CT scans use innovative technology directly converting photons into electrical signals resulting in higher-resolution images with reduced artifacts. This study used two organic phantoms: a natural wet sponge and a dry sausage. UHR images were acquired using a NAEOTOM Alpha photon-counting CT scan (Siemens) with a 0.4 mm slice thickness and 0.3 × 0.3 mm pixel size. Tube current and voltage were fixed at 112 mA and 120 KvP. A total of 24 reconstruction parameter sets were obtained by combining different values of kernel (Br), quantitative iterative reconstruction (QIR), spectral reconstruction (keV), and matrix size. Ten successive acquisitions were obtained on both phantoms. In total, 93 radiomic features were extracted on an ROI using the default parameters of Pyradiomic 3.0.1. Each feature's stability was evaluated using the coefficient of variation (CV) within each parameter set. Results: Of the 24 reconstruction parameter sets, 5 were selected based on best image quality by seven radiologists and three radiology technologists. Radiomics features were considered stable on a set when CV was less than 15%. Feature stability was impacted by reconstruction parameters and the phantom used. The most stable combination included 90 and 65 stable features of the 93 tested on the sausage and sponge respectively. It was configured with Br36, QIR 4, 60 keV, and a 1024 × 1024 matrix size. Conclusions: Images obtained on photon-counting CT scans offer promising radiomic feature stability with optimal parameter configurations that could be applied in a clinical setting.

Photon-Counting Detector CT Applications in Musculoskeletal Radiology

ABSTRACT

Photon-counting detectors (PCDs) have emerged as one of the most influential technical developments for medical imaging in recent memory. Surpassing conventional systems with energy-integrating detector technology in many aspects, PCD-CT scanners provide superior spatial resolution and dose efficiency for all radiological subspecialities. Demanding detailed display of trabecular microarchitecture and extensive anatomical coverage frequently within the same scan, musculoskeletal (MSK) imaging in particular can be a beneficiary of PCD-CT's remarkable performance. Since PCD-CT provides users with a plethora of customization options for both image acquisition and reconstruction, however, MSK radiologists need to be familiar with the scanner to unlock its full potential. From filter-based spectral shaping for artifact reduction over full field-of-view ultra-high-resolution scans to postprocessing of single- or dual-source multienergy data, almost every imaging task can be met with an optimized approach in PCD-CT. The objectives of this review were to give an overview of the most promising applications of PCD-CT in MSK imaging to date, to state current limitations, and to highlight directions for future research and developments.

Imaging in multiple myeloma

Multiple myeloma (MM) is the second most common adult hematologic malignancy, characterized by clonal proliferation of malignant plasma cells mostly in the bone marrow. The presence of destructive changes of the mineralized bone is a hallmark feature of the condition and a sign of end-organ damage. Due to this, imaging plays an integral role in the diagnosis, prognostication, and treatment monitoring of patients undergoing therapy for MM as well as surveillance of patients with early-stage disease. While conventional radiography has traditionally been the mainstay of initial evaluation of patients suspected of having MM, the advent of more sensitive imaging techniques such as computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) have taken its place in assessing patients. While either CT alone or as part of a PET/CT examination is the initial radiographic method of choice, MRI remains the gold-standard modality in assessing bone marrow involvement, especially in early disease stages. PET/CT also provides valuable information regarding assessment of response to therapy and extramedullary manifestations of the disease. There is however increasing evidence that functional MRI techniques, albeit limitedly available, might be superior to PET/CT for treatment monitoring. This review summarizes current knowledge on the use of different imaging techniques in monoclonal plasma cell disorders and discusses future developments in this area of research.

Trends in Clinical Cardiac Photon-Counting Detector CT Research: A Comprehensive Bibliometric Analysis

Photon-counting detector computed tomography (PCD-CT) represents a significant advancement in radiological imaging, offering substantial potential for cardiac applications that remain partially underexplored. This bibliometric analysis investigates the evolution and current clinical application of cardiac PCD-CT by examining research trends from 2019 to 2024. The analysis aims to understand the development of this technology, its clinical implications, and future directions. A comprehensive literature search was conducted using databases such as PubMed, EMBASE, Scopus, and Google Scholar, yielding 984 records. After removing duplicates and applying inclusion criteria, 81 studies were included in the final analysis. These studies primarily focused on coronary artery calcium scoring, coronary atherosclerotic plaque assessment, and coronary artery stenosis quantification. The findings indicate a significant upward trend in the number of publications, peaking in 2023. The bibliometric analysis revealed that the USA, Germany, and Switzerland are the leading contributors to PCD-CT research, with prominent institutions like the Mayo Clinic and the University of Zurich driving advancements in the field. The NAEOTOM Alpha by Siemens Healthineers, being the only commercially available PCD-CT model, highlights its central role in cardiac imaging studies. Funding for PCD-CT research came from various sources, including industry leaders like Siemens and Bayer, as well as governmental and academic institutions. The analysis also identified several challenges that PCD-CT research faces, including the need for larger patient cohorts and broader geographical representation. In conclusion, the rapid growth of cardiac PCD-CT research underscores its transformative potential in clinical practice. Continued investment, collaboration, and extensive research are essential to fully harness the benefits of PCD-CT.

Diagnostic Performance and Clinical Impact of Photon-Counting Detector Computed Tomography in Coronary Artery Disease

BACKGROUND

Photon-counting detector-computed tomography (PCD-CT) has emerged as a promising technology, offering improved spatial resolution.

OBJECTIVES

This study aimed to evaluate the clinical impact and diagnostic performance of PCD-CT vs conventional energy-integrating detector computed tomography (EID-CT) for obstructive coronary artery disease (CAD).

METHODS

From 2022 to 2023, we retrospectively identified 7,833 consecutive patients who underwent clinically indicated coronary computed tomography angiography (CCTA) at a single center, with either PCD-CT (n = 3,876; NAEOTOM Alpha [Siemens Healthineers]) or EID-CT (n = 3,957; Revolution Apex 256 [GE HealthCare] or Aquilion ONE ViSION 320 [Canon Medical Systems]) scanners. Subsequent invasive coronary angiography (ICA) and percutaneous or surgical revascularization were performed as part of routine clinical care. Among those referred for ICA after coronary CTA, the presence of obstructive CAD in each vessel was determined by coronary CTA (severe stenosis on visual assessment per the Coronary Artery Disease Reporting and Data System) and ICA (≥50% diameter stenosis on quantitative coronary angiography) in a blinded fashion. The diagnostic performance of EID-CT and PCD-CT was compared by using quantitative coronary angiography as the reference standard.

RESULTS

Patients who underwent PCD-CT were less frequently referred to subsequent ICA than those undergoing EID-CT (9.9% vs 13.1%; P < 0.001). Among those who underwent ICA, revascularization was more frequently performed in the PCD-CT group than in the EID-CT group (43.4% vs 35.5%; P = 0.02). In the vessel-level analysis (n = 1,686), specificity (98.0% vs 93.0%; P < 0.001), positive predictive value (83.3% vs 63.0%; P = 0.002), and diagnostic accuracy (97.2% vs 92.8%; P < 0.001) were improved by PCD-CT. Sensitivity (90.9% vs 90.7%; P = 0.95) and negative predictive value (98.9% vs 98.7%; P = 0.83) for obstructive CAD were similar between the PCD-CT and EID-CT groups, respectively.

CONCLUSIONS

PCD-CT exhibited excellent diagnostic performance for detecting obstructive CAD. Compared with patients undergoing conventional EID-CT, fewer patients were referred to ICA after PCD-CT, but those referred were more likely to undergo revascularization.

EANM position paper on challenges and opportunities of full-ring 360° CZT bone imaging: it's time to let go of planar whole-body bone imaging

The introduction of smaller footprint, more sensitive Cadmium-Zinc-Telluride (CZT)-based detectors with improved spatial and energy resolution has enabled the design of innovative full-ring 360° CZT SPECT/CT systems (e.g., VERITON® and StarGuide™). With this transformative technology now aiming to become mainstream in clinical practice, several critical questions need to be addressed. This EANM position paper provides practical recommendations on how to use these devices for routine bone SPECT/CT studies, facilitating the transition from traditional planar whole-body imaging and conventional SPECT/CT to these novel systems. In particular, initial guidance is provided on imaging acquisition and reporting workflows, image reconstruction, and CT acquisition parameters. Given the emerging nature of this technology, the available evidence base is still limited, and the proposed adaptations in workflows and scan protocols will likely evolve before being integrated into definitive guidelines. In the meantime, this EANM position paper serves as a comprehensive guide for integrating these advanced hybrid SPECT/CT imaging systems into clinical practice and outlining areas for further study.

Myocardial Characterization on CT: Late Iodine Enhancement and Extracellular Volume

Myocardial tissue characterization is fundamental in diagnosing, treating, and managing various cardiac diseases. In recent years, cardiac computed tomography (CCT) emerged as a valuable alternative to cardiac magnetic resonance (CMR) for myocardial tissue characterization, with the possibility to detect myocardial scar and quantify the extracellular volume fraction in a single CT study with the advantage of combined coronary arteries evaluation, shorter scanning time, and less susceptibility to device artifacts compared to CMR. However, CCT is typically affected by a lower contrast-to-noise ratio and potentially increased radiation exposure. Therefore, a deep understanding of the available technology and the strategies for acquisition optimization is of fundamental importance to improve image quality and accuracy, while minimizing radiation exposure. This review summarizes principles of myocardial characterization on CCT, acquisition protocols according to the different technologies available including the dual-energy CT and the innovative photon-counting detector CT, and setting of clinical utility.

Reduction of Streak Artifacts in the Superior Vena Cava for Better Visualization of Mediastinal Structures Through Virtual Monoenergetic Reconstructions Using a Photon-counting Detector Computed Tomography

PURPOSE

Computed tomography (CT) is crucial in oncologic imaging for precise diagnosis and staging. Beam-hardening artifacts from contrast media in the superior vena cava can degrade image quality and obscure adjacent structures, complicating lymph node assessment. This study examines the use of virtual monoenergetic reconstruction with photon-counting detector CT (photon-counting CT) to mitigate these artifacts.

MATERIALS AND METHODS

The retrospective study included 50 patients who underwent thoracoabdominal scans. Virtual monoenergetic reconstructions at nine keV levels (60 to 140 keV) were analyzed for Hounsfield Unit (HU) stability, image noise, and artifact index in various regions of interest (ROIs): mediastinal adipose tissue (ROI 1 to 3) and vascular stations (ROI 4 to 6) were compared with reference tissue (ROI 7 to 8). The diagnostic image quality of the keV levels was assessed using a 5-point Likert Scale.

RESULTS

Lower keV values (60 to 80) exhibited higher image noise and lower HU stability in mediastinal adipose tissue compared with higher energies, with optimal noise reduction observed at 130 keV (ROI 1 to 3). HU stability in vascular structures (ROI 4 to 6) significantly improved above 80 keV, with the best performance at 140 keV. Artifact levels decreased progressively from 60 to 140 keV. Visually, keV levels of 110 keV (96% Likert ≥4) and 120 keV (60% Likert 4) were rated most diagnostically valuable, consistent with technical findings.

CONCLUSION

Virtual monoenergetic reconstructions with photon-counting CT effectively reduce beam-hardening artifacts near the superior vena cava, enhancing the visualization of lymph nodes and adjacent structures. This technology advances oncologic imaging by improving diagnostic accuracy in areas previously affected by artifact-related image degradation.

Comparison of Radiation Dose and Image Quality in Pediatric Abdominopelvic Photon-Counting Versus Energy-Integrating Detector CT

OBJECTIVE

Adoption of abdominal photon counting detector CT (PCD-CT) into clinical pediatric CT practice requires evidence that it provides diagnostic images at acceptable radiation doses. Thus, this study aimed to compare radiation dose and image quality of PCD-CT and conventional energy-integrating detector CT (EID-CT) in pediatric abdominopelvic CT.

MATERIALS AND METHODS

This institutional review board-approved retrospective study included 147 children (median age 8.5 y; 80 boys, 67 girls) who underwent clinically indicated contrast-enhanced abdominopelvic PCD-CT between October 1, 2022 and April 30, 2023 and 147 children (median age 8.5 y; 74 boys, 73 girls) who underwent EID-CT between July 1, 2021 and January 1, 2022. Patients in the 2 groups were matched by age and effective diameter. Radiation dose parameters (CT dose index volume, CTDIvol; dose length product, DLP; size-specific dose estimate, SSDE) were recorded. In a subset of 25 matched pairs, subjective image quality was assessed on a scale of 1 to 4 (1=highest quality), and liver attenuation, dose-normalized noise, and contrast-to-noise ratio (CNR) were measured. Groups were compared using parametric and/or nonparametric testing.

RESULTS

Among the 147 matched pairs, there were no significant differences in sex (P=0.576), age (P=0.084), or diameter (P=0.668). PCD-CT showed significantly lower median CTDIvol, DLP, and SSDE (1.6 mGy, 63.8 mGy-cm, 3.1 mGy) compared with EID-CT (3.7 mGy, 155.3 mGy-cm, 6.0 mGy) (P<0.001). In the subset of 25 patients, PCD-CT and EID-CT showed no significant difference in overall image quality for reader 1 (1.0 vs. 1.0, P=0.781) or reader 2 (1.0 vs. 1.0, P=0.817), or artifacts for reader 1 (1.0 vs. 1.0, P=0.688) or reader 2 (1.0 vs. 1.0, P=0.219). After normalizing for radiation dose, image noise was significantly lower with PCD-CT (P<0.001), while CNR in the liver (P=0.244) and portal vein (P=0.079) were comparable to EID-CT.

CONCLUSION

Abdominopelvic PCD-CT in children significantly reduces radiation dose while maintaining subjective image quality, and accounting for dose levels, has the potential to lower image noise and achieve comparable CNR to EID-CT. These data expand understanding of the capabilities of PCD-CT and support its routine use in children.

Improved display and detection of small renal stones using photon-counting detector CT compared to conventional energy-integrating detector CT

PURPOSE

To compare same-day photon-counting detector CT (PCD-CT) to conventional energy-integrating detector CT (EID-CT) for detection of small renal stones (≤ 3 mm).

METHODS

Patients undergoing clinical dual-energy EID-CT for known or suspected stone disease underwent same-day research PCD-CT. Patients with greater than 10 stones and no visible stones under 3 mm were excluded. Three radiologists selected the optimal reconstruction configuration for each CT modality and created the reference standard for renal stone presence. Two other radiologists, blinded to imaging modality, independently reviewed anonymized images to detect renal stones, rating confidence in potential stones using a Likert scale (1 = Definitely present, 2 = Probably present, 3 = Questionably present, 4 = Not seen). Sensitivity and false positive detections for PCD and EID-CT were calculated.

RESULTS

Twenty-one patients underwent clinical EID-CT followed by same-day PCD-CT, with the reference standard identifying 121 renal stones (mean size 2.8 ± 2.6 mm). 0.4-mm PCD-CT images were more likely to display a stone as definitely present compared to 1- or 2-mm EID-CT images (p < 0.0001). Overall sensitivity for detection of all stones was greater at PCD-CT (0.75 vs. 0.55, p < 0.05). Pooled sensitivity of stones ≤ 3 mm was also significantly higher at PCD-CT (0.67 vs. 0.41, p < 0.05), with false positive detections differing between readers and modalities (PCD-CT vs. EID-CT: R1-7 v. 5; R2 - 7 v. 1).

CONCLUSION

Sensitivity for renal stones was significantly higher using high spatial resolution PCD-CT vs. EID-CT, especially for stones 3 mm or less in size, which may be important for at-risk patient populations. Prospective evaluation in larger patient populations that will benefit from detection of small stones is warranted.

Stereotactic arrhythmia radioablation for ventricular tachycardia: a review of clinical trials and emerging roles of imaging

Ventricular tachycardia (VT) is a severe arrhythmia commonly treated with implantable cardioverter defibrillators, antiarrhythmic drugs and catheter ablation (CA). Although CA is effective in reducing recurrent VT, its impact on survival remains uncertain, especially in patients with extensive scarring. Stereotactic arrhythmia radioablation (STAR) has emerged as a novel treatment for VT in patients unresponsive to CA, leveraging techniques from stereotactic body radiation therapy used in cancer treatments. Recent clinical trials and case series have demonstrated the short-term efficacy and safety of STAR, although long-term outcomes remain unclear. Imaging techniques, such as electroanatomical mapping, contrast-enhanced magnetic resonance imaging and nuclear imaging, play a crucial role in treatment planning by identifying VT substrates and guiding target delineation. However, challenges persist owing to the complex anatomy and variability in target volume definitions. Advances in imaging and artificial intelligence are expected to improve the precision and efficacy of STAR. The exact mechanisms underlying the antiarrhythmic effects of STAR, including potential fibrosis and improvement in cardiac conduction, are still being explored. Despite its potential, STAR should be cautiously applied in prospective clinical trials, with a focus on optimizing dose delivery and understanding long-term outcomes. Collaborative efforts are necessary to standardize treatment strategies and enhance the quality of life for patients with refractory VT.

Diagnostic performance of CT for extrarenal fat invasion in renal cell carcinoma: a meta-analysis and systematic review

OBJECTIVES

Renal cell carcinoma (RCC) with extrarenal fat (perinephric or renal sinus fat) invasion is the main evidence for the T3a stage. Currently, computed tomography (CT) is still the primary modality for staging RCC. This study aims to determine the diagnostic performance of CT in RCC patients with extrarenal fat invasion.

METHODS

The PubMed, Web of Science, Cochrane Library, and EMBASE databases were systematically searched up to October 11, 2023. Study quality was assessed by the QUADAS-2 tool. Standard methods recommended for meta-analyses of diagnostic evaluation were used. Heterogeneity was analyzed through meta-regression analysis.

RESULTS

Fifteen studies were included in this meta-analysis. Among them, six studies focused on perinephric fat invasion (PFI) only, four on renal sinus fat invasion (RSFI) only, and five on both. Pooled weighted estimates of sensitivity, specificity, area of SROC curve, PLR, and negative likelihood ratio (NLR) of CT for PFI were 0.69 (95% CI: 0.55-0.79), 0.82 (95% CI: 0.69-0.90), 0.81 (95% CI: 0.77-0.84), 3.85 (95% CI: 2.22-6.67), and 0.38 (95% CI: 0.27-0.55). Pooled weighted estimates of sensitivity, specificity, area of SROC curve, PLR, and NLR of CT for RSFI were 0.81 (95% CI: 0.76-0.85), 0.79 (95% CI: 0.66-0.88), 0.82 (95% CI: 0.78-0.85), 3.91 (95% CI: 2.26-6.77), and 0.24 (95% CI: 0.18-0.31).

CONCLUSION

CT has the ability to detect the PFI and RSFI in patients with RCC. However, the diagnostic performance of CT has suffered from the limitation of slightly lower accuracy, resulting from the low positive sample in the current studies. Additionally, the current PLR is low.

CRITICAL RELEVANCE STATEMENT

This study provides radiologists and urologists with a systematic and comprehensive summary of CT and CT-related morphological features in assessing extrarenal fat invasion in patients with RCC.

KEY POINTS

CT can detect extrarenal fat invasion in patients with RCC, but the diagnostic performance is inconsistent. The diagnostic performance of CT is acceptable, but primarily affected by the low positive rate of included patients. Further large-scale trials are necessary to determine the true diagnostic capabilities of CT for extrarenal fat invasion.

Improved visualization of the inferior tympanic and mastoid canaliculi with photon counting detector CT

PURPOSE

To compare the performance of the photon-counting detector (PCD)-CT versus a state-of-the-art energy-integrating detector (EID)-CT to identify segments of the inferior tympanic canaliculus (Jacobsons nerve) and the mastoid canaliculus (Arnolds nerve).

MATERIALS & METHODS

Patients were prospectively recruited to undergo temporal bone CT on both EID-CT (Siemens Somatom Force) and PCD-CT (Siemens NAEOTOM Alpha) scanners under an IRB-approved protocol. Three neuroradiologists reviewed cases by consensus comparing the ability to identify the proximal, mid, and distal segments of the inferior tympanic canaliculus/Jacobsons nerve and mastoid canaliculus/Arnolds nerve on each scanner using 5-point Likert scales (with 1 indicating EID is far superior to PCD, 3 indicating they are equivalent, and 5 indicating PCD is far superior to EID).

RESULTS

Forty temporal bones were analyzed. Average Likert scores for the ability to evaluate the proximal, mid, and distal aspects of inferior tympanic canaliculus/Jacobsons nerve on the PCD compared to EID scanner were 4.5 (SD = 0.6), 4.2 (0.4), and 4.1 (0.3). The scores for the mastoid canaliculus/Arnolds nerve were 4.0 (0.4), 4.1 (0.4), and 4.0 (0.4). Overall, the PCD scanner performed better than EID for image quality (Median = 4.2, 95 % CI = [4.1, 5.0], p-value < 0.001).

CONCLUSION

PCD-CT provides superior visualization of the proximal, mid, and distal aspects of the inferior tympanic canaliculus/Jacobsons nerve and mastoid canaliculus/Arnolds nerve compared to EID-CT examinations. The improved visualization of these nerves could be important for characterization of subtle pathology involving these structures, such as tympanic paraganglioma or nodular perineural spread.

Diagnostic performance of Photon-counting CT angiography in peripheral artery disease compared to DSA as gold standard

BACKGROUND

Photon-counting (PC) CT has the potential to improve diagnostic confidence and image quality of CT angiography (CTA) in patients with peripheral artery disease (PAD).

PURPOSE

To retrospectively evaluate the diagnostic performance of Photon-counting CT angiography for the assessment of stenotic disease in patients with PAD compared to digital subtraction angiography (DSA) as gold standard.

MATERIALS AND METHODS

All patients undergoing PC CTA followed by DSA between November 2021 and November 2023 were included in this institutional review board approved HIPAA compliant retrospective analysis. The arterial vasculature of the lower extremity was divided into 10 segments from the iliac vasculature to the calf arterial vasculature. The images were evaluated independently by two experienced readers. Inter-reader agreement was determined using Cohen's kappa coefficient (κ). Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) as well as accuracy were calculated for PC CTA and PC pure lumen reconstruction compared to DSA as gold standard.

RESULTS

109 patients (mean age 74.68 ± 11.10 years; 77 males, 32 females) were included in the retrospective analysis. PC pure lumen reconstructions was available for 91 patients (83 %). A total of 933 vascular segments for PC CTA and 780 vascular segments for PC pure lumen reconstruction were evaluated. Good to perfect inter-reader agreement was found for PC CTA (κ = 0.791) and for PC pure lumen reconstruction (κ = 0.829). Sensitivity, Specificity and accuracy for PC CTA were 91 %; 95 % and 93 %, respectively. Sensitivity, Specificity and accuracy for PC pure lumen reconstruction were 85 %, 89 % and 88 %, respectively.

CONCLUSION

Photon-counting CTA demonstrates high sensitivity and specificity for the detection and diagnosis of stenotic lesions in PAD. PC non-calcium reconstruction does not further increase the accuracy compared to PC CTA.

Investigating the Effects of Reconstruction Conditions on Image Quality and Radiomic Analysis in Photon-counting Computed Tomography

Introduction

Photon-counting computed tomography (CT) is equipped with an adaptive iterative reconstruction method called quantum iterative reconstruction (QIR), which allows the intensity to be changed during image reconstruction. It is known that the reconstruction conditions of CT images affect the analysis results when performing radiomic analysis. The aim of this study is to investigate the effect of QIR intensity on image quality and radiomic analysis of renal cell carcinoma (RCC).

Materials and Methods

The QIR intensities were selected as off, 2 and 4. The image quality evaluation items considered were task-based transfer function (TTF), noise power spectrum (NPS), and low-contrast object specific contrast-to-noise ratio (CNRLO). The influence on radiomic analysis was assessed using the discrimination accuracy of clear cell RCC.

Results

For image quality evaluation, TTF and NPS values were lower and CNRLO values were higher with increasing QIR intensity; for radiomic analysis, sensitivity, specificity, and accuracy were higher with increasing QIR intensity. Principal component analysis and receiver operating characteristics analysis also showed higher values with increasing QIR intensity.

Conclusion

It was confirmed that the intensity of the QIR intensity affects both the image quality and the radiomic analysis.

Quantitative multi-energy CT in oncology: State of the art and future directions

Multi-energy computed tomography (CT) involves acquisition of two or more CT measurements with distinct energy spectra. Using the differential attenuation of tissues and materials at different X-ray energies, multi-energy CT allows distinction of tissues and materials. Multi-energy technology encompasses different types of CT systems, such as dual-energy CT and photon-counting CT, that can use information from the energy and type of material present in acquired images to create multiple datasets. These scanners have overcome many of the limitations of conventional CT, making it possible to improve the diagnostic performance of CT and expand its use to new applications through better tissue characterization and multiple quantitative parameters. Quantitative imaging biomarkers based on multi-energy CT have enormous potential in oncologic imaging, from the diagnosis and characterization of tumor phenotypes to the evaluation of the response to treatment. Nevertheless, implementing these techniques in clinical practice remains challenging. This article reviews the basic principles underlying multi-energy CT and the most recent technical developments in these systems together with their advantages and limitations to establish the value of quantitative imaging derived from multi-energy CT in the field of oncology.

Low-dose Ultra-high-resolution Photon-Counting Detector CT for Visceral Artery CT Angiography: A Preliminary Study

RATIONALE AND OBJECTIVES

To validate the image quality of low-dose ultra-high-resolution (UHR) scanning mode of photon-counting detector CT (PCD-CT) for visceral artery computed tomography angiography (CTA).

MATERIAL AND METHODS

We prospectively enrolled 57 patients each in the full dose (FD) and low-dose (LD) protocols, respectively, to undergo abdominal CT scans using the UHR mode on a PCD-CT system (NAEOTOM Alpha), between April 2023 and September 2023. Both the FD data and LD data were then reconstructed into two series of images: (a) 0.2 mm slice thickness, reconstruction kernel Bv48, quantum iterative reconstruction (QIR) 4; (b)1 mm slice thickness, Bv40, QIR 3. The signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) of seven arteries were objectively measured. The image noise, vessel sharpness, overall quality, and visibility of nine arteries were subjectively assessed by three radiologists.

RESULTS

The SNRs and CNRs of 0.2 mm reconstruction set was inferior to that of 1 mm reconstruction set (p < 0.001 for all the arteries and noise), however, the image quality of 0.2 mm reconstruction set was higher than that of 1 mm reconstruction set in qualitative evaluation especially for tiny arteries in Volume-rendered (VR) image (p < 0.001). The SNRs and CNRs were not significantly higher for FD group than LD group on the same slice thickness except for SNRs of common hepatic artery, splenic artery and bilateral renal arteries in 0.2 mm reconstruction set. In the comparison on image quality between normal weight and overweight patients within the same reconstruction set, the results showed that low-dose scan did not significantly impact the image quality in overweight patients. The ratings of visibility of nine visceral arteries were not significantly different among FD and LD at the same thickness reconstruction set except for superior mesenteric artery (p = 0.002 and 0.007 for 0.2 mm and 1 mm reconstruction set in axial image; p = 0.002 and 0.007 for 0.2 mm and 1 mm reconstruction set in coronal image, respectively) and left gastric artery (p = 0.002 and p < 0.001 for 0.2 mm and 1 mm reconstruction set in VR image, respectively).

CONCLUSION

The low-dose UHR scanning mode of PCD-CT has proven to be adequate for the clinical evaluation of visceral arteries. Utilizing a reconstruction with a slice thickness of 0.2 mm could enhance arterial depiction, particularly for small vessels.

Photon counting CT clinical adoption, integration, and workflow

Photon counting CT was recently introduced into clinical practice [Rajendran K, Petersilka M, Henning A, Shanblatt ER, Schmidt B, Flohr TG, Ferrero A, Baffour F, Diehn FE, Yu L, Rajiah P, Fletcher JG, Leng S, McCollough CH. First Clinical Photon-counting Detector CT System: Technical Evaluation. Radiology 2022;303(1):130-138. doi: https://doi.org/10.1148/radiol.212579 ]. Photon counting detectors (PCD) afford better spatial resolution, radiation dose efficiency, and iodine contrast-to-noise than EID-CT [Leng S, Bruesewitz M, Tao S, Rajendran K, Halaweish AF, Campeau NG, Fletcher JG, McCollough CH. Photon-counting Detector CT: System Design and Clinical Applications of an Emerging Technology. Radiographics 2019;39(3):729-743. doi: https://doi.org/10.1148/rg.2019180115 ); (Leng S, Rajendran K, Gong H, Zhou W, Halaweish AF, Henning A, Kappler S, Baer M, Fletcher JG, McCollough CH. 150-mum Spatial Resolution Using Photon-Counting Detector Computed Tomography Technology: Technical Performance and First Patient Images. Invest Radiol 2018;53(11):655-662. doi: https://doi.org/10.1097/RLI.0000000000000488 )(Booij R, van der Werf NR, Dijkshoorn ML, van der Lugt A, van Straten M. Assessment of Iodine Contrast-To-Noise Ratio in Virtual Monoenergetic Images Reconstructed from Dual-Source Energy-Integrating CT and Photon-Counting CT Data. Diagnostics (Basel) 2022;12(6). doi: https://doi.org/10.3390/diagnostics12061467 ); (Sawall S, Klein L, Amato C, Wehrse E, Dorn S, Maier J, Heinze S, Schlemmer HP, Ziener CH, Uhrig M, Kachelriess M. Iodine contrast-to-noise ratio improvement at unit dose and contrast media volume reduction in whole-body photon-counting CT. Eur J Radiol 2020;126:108909. doi: https://doi.org/10.1016/j.ejrad.2020.108909 ] while also maintaining multienergy CT (MECT) capabilities[Flohr T, Petersilka M, Henning A, Ulzheimer S, Ferda J, Schmidt B. Photon-counting CT review. Phys Med 2020;79:126-136. doi: https://doi.org/10.1016/j.ejmp.2020.10.030 ]. This article will review the clinical adoption of PCD-CT including protocol development, clinical applications, clinical integration and workflow considerations. Protocol development is institution specific and involves collaborative decision-making among radiologists, physicists, and technologists. Key PCD clinical applications include radiation exposure reduction, intravenous contrast volume reduction, and improved lesion conspicuity. Patients who would most benefit from these improvements may preferentially be scanned with PCD CT. With numerous available reconstructions, radiologists should be strategic in the series sent to PACS for interpretation and routinely sending spectral series to PACS can facilitate integration with clinical workflow. The Society of Abdominal Radiology PCD Emerging Technology Commission endorsed this article.

Opportunity and Opportunism in Artificial Intelligence-Powered Data Extraction: A Value-Centered Approach

Radiologists' traditional role in the diagnostic process is to respond to specific clinical questions and reduce uncertainty enough to permit treatment decisions to be made. This charge is rapidly evolving due to forces such as artificial intelligence (AI), big data (opportunistic imaging, imaging prognostication), and advanced diagnostic technologies. A new modernistic paradigm is emerging whereby radiologists, in conjunction with computer algorithms, will be tasked with extracting as much information from imaging data as possible, often without a specific clinical question being posed and independent of any stated clinical need. In addition, AI algorithms are increasingly able to predict long-term outcomes using data from seemingly normal examinations, enabling AI-assisted prognostication. As these algorithms become a standard component of radiology practice, the sheer amount of information they demand will increase the need for streamlined workflows, communication, and data management techniques. In addition, the provision of such information raises reimbursement, liability, and access issues. Guidelines will be needed to ensure that all patients have access to the benefits of this new technology and guarantee that mined data do not inadvertently create harm. In this Review, we discuss the challenges and opportunities relevant to radiologists in this changing landscape, with an emphasis on ensuring that radiologists provide high-value care.

Dual-energy computed tomography: pediatric considerations

Multidetector computed tomography (CT) has revolutionized medicine and is now a fundamental aspect of modern radiology. Hardware and software advancements have significantly improved CT accessibility, image quality, and acquisition times. While considerable attention has been directed towards the potential risks of ionizing radiation from CT scans in children, recent concerns regarding the possible short- and long-term risks related to magnetic resonance imaging (MRI) conducted under general anesthesia have generated fresh interest in novel pediatric CT applications and techniques that allow imaging of awake patients at low radiation doses. Among these novel techniques, dual-energy CT (DECT) stands out for its ability to provide enhanced diagnostic information, reduce radiation doses further, and facilitate faster scans, making it a highly promising tool in pediatric radiology. This manuscript explores the current role of DECT in pediatric imaging, emphasizing its technical foundations, hardware configurations, and various reconstruction techniques. We discuss advanced post-processing techniques, such as material decomposition algorithms and virtual monoenergetic imaging, highlighting their clinical advantages in improving diagnostic accuracy and patient outcomes. Furthermore, the paper reviews the clinical applications of DECT in evaluating pulmonary perfusion, cardiovascular assessments, and oncologic imaging in pediatric patients.

Visibility of Intracranial Perforating Arteries Using Ultra-High-Resolution Photon-Counting Detector Computed Tomography (CT) Angiography

Background/Objectives: Photon-counting detector computed tomography (PCD-CT) offers energy-resolved CT data with enhanced resolution, reduced electronic noise, and improved tissue contrast. This study aimed to evaluate the visibility of intracranial perforating arteries on ultra-high-resolution (UHR) CT angiography (CTA) on PCD-CT. Methods: A retrospective analysis of intracranial UHR PCD-CTA was performed for 30 patients. The image quality from four UHR PCD-CTA reconstruction methods [kernel Hv40 and Hv72, with and without quantum iterative reconstruction (QIR)] was assessed for the lenticulostriate arteries (LSAs) and pontine arteries (PAs). A subjective evaluation included peripheral visibility, vessel sharpness, and image noise, while objective analysis focused on the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Results: Peripheral LSAs were well visualized across all reconstruction methods, with no significant differences between them. Vessel sharpness and image noise varied significantly (p < 0.0001); sharper LSAs and more noise were seen with kernel Hv72 compared to kernel Hv40 (p < 0.05). A similar pattern was observed for PAs, though peripheral visibility was lower than that for LSAs. The SNR and CNR were the highest in the presence of kernel Hv72 with QIR, and lowest with kernel Hv72 without QIR, compared to kernel Hv40 (p < 0.05). Conclusions: UHR PCD-CTA provided a good visualization of the intracranial perforating arteries, particularly LSAs. The vessel sharpness and image noise varied by reconstruction method, in which kernel Hv72 with QIR offered the optimal visualization.

An experimental study on the diagnostic advantage of dual-energy computed tomography over single-energy scan to evaluate the treatment effect following transcatheter arterial chemoembolization

OBJECTIVES

We assessed the diagnostic advantage of dual-energy computed tomography (DECT) over single-energy computed tomography (SECT) to evaluate lipiodol accumulation in target lesions following transcatheter arterial chemoembolization (TACE).

METHODS

TACE was performed in 10 rabbits in whom the VX2 tumor was implanted in their left liver lobes. The miriplatin-lipiodol mixture was injected into the common hepatic artery. All rabbits were sacrificed 2 days after TACE, and the liver was harvested. CT was performed using both single-energy and dual-energy scan modes. The specimen was stained with Oil Red O to evaluate lipiodol accumulation; this was considered the reference standard. Mutual information (MI) was used to evaluate the significance of radiological-pathological correlation. Estimated iodine content values on iodine material density images were compared with actual values obtained using mass spectroscopy.

RESULTS

Mean MI values were 0.69, 0.32, 0.83, 0.72, 0.65, and 0.58 for single-energy scan; iodine density images; and virtual monoenergetic images for energy levels of 40, 60, 80, and 100 keV, respectively. The MI value of the monochromatic image (40 keV) was the highest among all sequences. However, this was not significant compared with the single-energy scan (p = 0.81). A significant correlation was observed between the estimated and actual values of iodine content (Pearson's product moment coefficient = 0.70, p = 0.023).

CONCLUSION

More accurate and quantitative lipiodol evaluation in targeted tumors after TACE can be achieved by applying DECT rather than SECT.

Non-invasive physiological assessment of coronary artery obstruction on coronary computed tomography angiography

Computed tomography-derived fractional flow reserve (CT-FFR) enhances the specificity of coronary computed tomography angiography (CCTA) to that of the most specific non-invasive imaging techniques, while maintaining high sensitivity in stable coronary artery disease (CAD). As gatekeeper for invasive coronary angiography (ICA), use of CT-FFR results in a significant reduction of negative ICA procedures and associated costs and complications, without increasing cardiovascular events. It is expected that CT-FFR algorithms will continue to improve, regarding accuracy and generalisability, and that introduction of new features will allow further treatment guidance and reduced invasive diagnostic testing. Advancements in CCTA quality and artificial intelligence (AI) are starting to unfold the incremental diagnostic and prognostic capabilities of CCTA's attenuation-based images in CAD, with future perspectives promising additional CCTA parameters which will enable non-invasive assessment of myocardial ischaemia as well as CAD activity and future cardiovascular risk. This review discusses practical application, interpretation and impact of CT-FFR on patient care, and how this ties into the CCTA 'one stop shop' for coronary assessment and patient prognosis. In this light, selective adoption of the most promising, objective and reproducible techniques and algorithms will yield maximal diagnostic value of CCTA without overcomplicating patient management and guideline recommendations.

Improved Pulmonary Artery Evaluation Using High-Pitch Photon-Counting CT Compared to High-Pitch Conventional or Routine-Pitch Conventional Dual-Energy CT

OBJECTIVE

Pulmonary CT angiography (CTA) to detect pulmonary emboli can be performed using conventional dual-source CT with single-energy acquisition at high-pitch (high-pitch conventional CT), which minimizes motion artifacts, or routine-pitch, dual-energy acquisitions (routine-pitch conventional DECT), which maximize iodine signal. We compared iodine signal, radiation dose, and motion artifacts of pulmonary CTA between these conventional CT modalities and dual-source photon-counting detector CT with high-pitch, multienergy acquisitions (high-pitch photon-counting CT).

METHODS

Consecutive clinically indicated pulmonary CTA exams were collected. CT number/noise was measured from the main to right lower lobe segmental pulmonary arteries using 120 kV threshold low, 120 kV, and mixed kV (0.6 linear blend) images. Three radiologists reviewed anonymized, randomized exams, rating them using a 4- or 5-point Likert scale (1 = worst, and 4/5 = best) for contrast enhancement in pulmonary arteries, motion artifacts in aortic root to subsegmental pulmonary arteries, lung image quality; pulmonary blood volume (PBV) map image quality (for multienergy or dual-energy exams), and contribution to reader confidence.

RESULTS

One hundred fifty patients underwent high-pitch photon-counting CT (n = 50), high-pitch conventional CT (n = 50), and routine-pitch conventional DECT (n = 50). High-pitch photon-counting CT had lower radiation dose (CTDI vol : 8.1 ± 2.5 vs 9.6 ± 6.8 and 16.2 ± 8.5 mGy, respectively; P < 0.001), and routine-pitch conventional DECT had significantly less contrast ( P < 0.009). CT number and CNR measurements were significantly greater at high-pitch photon-counting CT ( P < 0.001). Across readers, high-pitch photon-counting CT demonstrated significantly higher subjective contrast enhancement in the pulmonary arteries compared to the other modalities (4.7 ± 0.6 vs 4.4 ± 0.7 vs 4.3 ± 0.7; P = 0.011) and lung image quality (3.4 ± 0.5 vs 3.1 ± 0.5 vs 3.1 ± 0.5; P = 0.013). High-pitch photon-counting CT and high-pitch conventional CT had fewer motion artifacts at all levels compared to DECT ( P < 0.001). High-pitch photon-counting CT PBV maps had superior image quality ( P < 0.001) and contribution to reader confidence ( P < 0.001) compared to routine-pitch conventional DECT.

CONCLUSION

High-pitch photon-counting pulmonary CTA demonstrated higher contrast in pulmonary arteries at lower radiation doses with improved lung image quality and fewer motion artifacts compared to high-pitch conventional CT and routine-pitch conventional dual-energy CT.

Severe metallosis following catastrophic failure of total shoulder arthroplasty - a case report

Metallosis is an unusual but consequential complication arising from orthopedic hardware implantation, characterized by the deposition of metallic particles in the periprosthetic soft tissues. The incidence of metallosis associated with shoulder arthroplasties is exceptionally rare since the shoulder is not a weight-bearing joint, making it less susceptible to mechanical wear and, consequently, to conditions like particle disease and metallosis. Nevertheless, anomalous metal-on-metal interactions can develop in total shoulder arthroplasties if the polyethylene component fails due to wear, fracture, or dissociation. If left unaddressed, metallosis can incite an adverse immune-mediated local tissue response, culminating in joint destruction and adjacent soft tissues and muscle necrosis. In this case report, the diagnosis of metallosis was made in a patient with an anatomic total shoulder arthroplasty using a state-of-the-art photon counting detector CT supplemented by post-processing metal artifact reduction algorithms. This advanced imaging approach was effective in discerning the source of implant failure and in identifying manifestations of severe metallosis including osteolysis and pseudotumor formation. Advanced imaging methods can accurately characterize the severity and extent of metallosis, thereby helping guide surgical planning to mitigate serious complications associated with this condition.

Improvement of coronary stent visualization using ultra-high-resolution photon-counting detector CT

OBJECTIVES

This study aimed to compare the image quality and diagnostic performance of standard-resolution (SR) and ultra-high-resolution (UHR) coronary CT angiography (CCTA) based on photon-counting detector CT (PCD-CT) of coronary stents and explore the best reconstruction kernel for stent imaging.

METHODS

From July 2023 to September 2023, patients were enrolled to undergo CCTA using a dual-source PCD-CT system after coronary angioplasty with stent placement. SR images with a slice thickness/increment of 0.6/0.4 mm were reconstructed using a vascular kernel (Bv48), while UHR images with a slice thickness/increment of 0.2/0.2 mm were reconstructed using vascular kernels of six sharpness levels (Bv48, Bv56, Bv60, Bv64, Bv72, and Bv76). The in-stent lumen diameters were evaluated. Subjective image quality was also evaluated by a 5-point Likert scale. Invasive coronary angiography was conducted in 12 patients (25 stents).

RESULTS

Sixty-nine patients (68.0 [61.0, 73.0] years, 46 males) with 131 stents were included. All UHR images had significantly larger in-stent lumen diameter than SR images (p < 0.001). Specifically, UHR-Bv72 and UHR-Bv76 for in-stent lumen diameter (2.17 [1.93, 2.63] mm versus 2.20 [1.93, 2.59] mm) ranked the two best kernels. The subjective analysis demonstrated that UHR-Bv72 images had the most pronounced effect on reducing blooming artifacts, showcasing in-stent lumen and stent demonstration, and diagnostic confidence (p < 0.001). Furthermore, SR and UHR-Bv72 images showed a diagnostic accuracy of 78.3% (95% confidence interval [CI]: 56.3%-92.5%) and 88.0% (95%CI: 68.8%-97.5%), respectively.

CONCLUSION

UHR CCTA by PCD-CT leads to significantly improved visualization and diagnostic performance of coronary stents, and Bv72 is the optimal reconstruction kernel showing the stent struts and in-stent lumen.

CLINICAL RELEVANCE STATEMENT

The significantly improved visualization of coronary stents using ultra-high resolution CCTA could increase the diagnostic accuracy for in-stent restenosis and avoid unnecessary invasive quantitative coronary angiography, thus changing the clinical management for patients after percutaneous coronary intervention.

KEY POINTS

Coronary stent imaging is challenging with energy-integrating detector CT due to "blooming artifacts." UHR images using a PCD-CT enhanced coronary stent visualization. UHR coronary stent imaging demonstrated improved diagnostic accuracy in clinical settings.

Imaging in Renal Cell Carcinoma Detection

INTRODUCTION

Imaging in renal cell carcinoma (RCC) is a constantly evolving landscape. The incidence of RCC has been rising over the years with the improvement in image quality and sensitivity in imaging modalities resulting in "incidentalomas" being detected. We aim to explore the latest advances in imaging for RCC.

METHODS

A literature search was conducted using Medline and Google Scholar, up to May 2024. For each subsection of the manuscript, a separate search was performed using a combination of the following key terms "renal cell carcinoma", "renal mass", "ultrasound", "computed tomography", "magnetic resonance imaging", "18F-Fluorodeoxyglucose PET/CT", "prostate-specific membrane antigen PET/CT", "technetium-99m sestamibi SPECT/CT", "carbonic anhydrase IX", "girentuximab", and "radiomics". Studies that were not in English were excluded. The reference lists of selected manuscripts were checked manually for eligible articles.

RESULTS

The main imaging modalities for RCC currently are ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI). Contrast-enhanced US (CEUS) has emerged as an alternative to CT or MRI for the characterisation of renal masses. Furthermore, there has been significant research in molecular imaging in recent years, including FDG PET, PSMA PET/CT, 99mTc-Sestamibi, and anti-carbonic anhydrase IX monoclonal antibodies/peptides. Radiomics and the use of AI in radiology is a growing area of interest.

CONCLUSIONS

There will be significant change in the field of imaging in RCC as molecular imaging becomes increasingly popular, which reflects a shift in management to a more conservative approach, especially for small renal masses (SRMs). There is the hope that the improvement in imaging will result in less unnecessary invasive surgeries or biopsies being performed for benign or indolent renal lesions.

Photon-Counting Computed Tomography Angiography of Carotid Arteries: A Topical Narrative Review with Case Examples

Photon counting computed tomography (PCCT) represents a paradigm shift from conventional CT imaging, propelled by a new generation of X-ray detectors capable of counting individual photons and measuring their energy. The first part of this narrative review is focused on the technical aspects of PCCT and describes its key advancements and benefits compared to conventional CT but also its limitations. By synthesizing the existing literature, the second part of the review seeks to elucidate the potential of PCCT as a valuable tool for assessing carotid artery disease. Thanks to the enhanced spatial resolution and image quality, PCCT allows for an accurate evaluation of carotid luminal stenosis. With its ability to finely discriminate between different tissue types, PCCT allows for detailed characterization of plaque morphology and composition, which is crucial for assessing plaque vulnerability and the risk of cerebrovascular events.

Comparison of Image Quality and Radiation Dose in Pediatric Temporal Bone CT Using Photon-Counting Detector CT and Energy-Integrating Detector CT

BACKGROUND AND PURPOSE

Currently, there is a lack of research directly comparing photon-counting detector CT (PCD-CT) and energy-integrating detector CT (EID-CT) in pediatric temporal bone CT imaging. The purpose of this study was to compare the image quality and radiation dose of temporal bone CT scans in pediatric patients acquired with PCD-CT and EID-CT.

MATERIALS AND METHODS

The retrospective study included a total of 110 pediatric temporal bone CT scans (PCD-CT, n = 52; EID-CT, n = 58). Two independent readers evaluated the spatial resolution of 4 anatomic structures (tympanic membrane, incudostapedial joint, stapedial crura, and cochlear modiolus) and overall image quality by using a 4-point scale. Interreader agreement was assessed. Dose-length product for each CT was compared, and subgroup analyses were performed based on age (younger than 3 years, 3-5 years, 6-11 years, and 12 years and above).

RESULTS

PCD-CT demonstrated statistically significantly higher scores than EID-CT for all items (tympanic membrane, 2.9 versus 2.4; incudostapedial joint, 3.6 versus 2.6; stapedial crura, 3.2 versus 2.4; cochlear modiolus, 3.4 versus 2.8; overall image quality, 3.6 versus 2.8; P < .05). Interreader agreement ranged from good to excellent (interclass correlation coefficients, 0.6-0.81). PCD-CT exhibited a 43% dose reduction compared with EID-CT, with a particularly substantial reduction of over 70% in the subgroups of children younger than 6 years.

CONCLUSIONS

PCD temporal bone CT achieves significantly superior imaging quality at a lower radiation dose compared with EID-CT.

Inter-reader agreement of pancreatic adenocarcinoma resectability assessment with photon counting versus energy integrating detector CT

PURPOSE

To compare the inter-reader agreement of pancreatic adenocarcinoma resectability assessment at pancreatic protocol photon-counting CT (PCCT) with conventional energy-integrating detector CT (EID-CT).

METHODS

A retrospective single institution database search identified all contrast-enhanced pancreatic mass protocol abdominal CT performed at an outpatient facility with both a PCCT and EID-CT from 4/11/2022 to 10/30/2022. Patients without pancreatic adenocarcinoma were excluded. Four fellowship-trained abdominal radiologists, blinded to CT type, independently assessed vascular tumor involvement (uninvolved, abuts ≤ 180°, encases > 180°; celiac, superior mesenteric artery (SMA), common hepatic artery (CHA), superior mesenteric vein (SMV), main portal vein), the presence/absence of metastases, overall tumor resectability (resectable, borderline resectable, locally advanced, metastatic), and diagnostic confidence. Fleiss's kappa was used to calculate inter-reader agreement. CTDIvol was recorded. Radiation dose metrics were compared with a two-sample t-test. A p < .05 indicated statistical significance.

RESULTS

145 patients (71 men, mean[SD] age: 66[9] years) were included. There was substantial inter-reader agreement, for celiac artery, SMA, and SMV involvement at PCCT (kappa = 0.61-0.69) versus moderate agreement at EID-CT (kappa = 0.56-0.59). CHA had substantial inter-reader agreement at both PCCT (kappa = 0.67) and EIDCT (kappa = 0.70). For metastasis identification, radiologists had substantial inter-reader agreement at PCCT (kappa = 0.78) versus moderate agreement at EID-CT (kappa = 0.56). CTDIvol for PCCT and EID-CT were 16.9[7.4]mGy and 29.8[26.6]mGy, respectively (p < .001).

CONCLUSION

There was substantial inter-reader agreement for involvement of 4/5 major peripancreatic vessels (celiac artery, SMA, CHA, and SMV) at PCCT compared with 2/5 for EID-CT. PCCT also afforded substantial inter-reader agreement for metastasis detection versus moderate agreement at EID-CT with statistically significant radiation dose reduction.

Technical principles, benefits, challenges, and applications of photon counting computed tomography in coronary imaging: a narrative review

Background and Objective

The introduction of photon-counting computed tomography (PCCT) represents the most recent groundbreaking advancement in clinical computed tomography (CT). PCCT has the potential to overcome the limitations of traditional CT and to provide new quantitative imaging information. This narrative review aims to summarize the technical principles, benefits, and challenges of PCCT and to provide a concise yet comprehensive summary of the applications of PCCT in the domain of coronary imaging.

Methods

A review of PubMed, Scopus, and Google Scholar was performed until October 2023 by using relevant keywords. Articles in English were considered.

Key Content and Findings

The main advantages of PCCT over traditional CT are enhanced spatial resolution, improved signal and contrast characteristics, diminished electronic noise and image artifacts, lower radiation exposure, and multi-energy capability with enhanced material discrimination. These key characteristics have made room for improved assessment of plaque volume and severity of stenosis, more precise assessment of coronary artery calcifications, also preserved in the case of a reduced radiation dose, improved assessment of plaque composition, possibility to provide details regarding the biological processes occurring within the plaque, enhanced quality and accuracy of coronary stent imaging, and improved radiomic analyses.

Conclusions

PCCT can significantly impact diagnostic and clinical pathways and improve the management of patients with coronary artery diseases (CADs).

Trends and hotspots of energy-based imaging in thoracic disease: a bibliometric analysis

OBJECTIVE

To conduct a bibliometric analysis of the prospects and obstacles associated with dual- and multi-energy CT in thoracic disease, emphasizing its current standing, advantages, and areas requiring attention.

METHODS

The Web of Science Core Collection was queried for relevant publications in dual- and multi-energy CT and thoracic applications without a limit on publication date or language. The Bibliometrix packages, VOSviewer, and CiteSpace were used for data analysis. Bibliometric techniques utilized were co-authorship analyses, trend topics, thematic map analyses, thematic evolution analyses, source's production over time, corresponding author's countries, and a treemap of authors' keywords.

RESULTS

A total of 1992 publications and 7200 authors from 313 different sources were examined in this study. The first available document was published in November 1982, and the most cited article was cited 1200 times. Siemens AG in Germany emerged as the most prominent author affiliation, with a total of 221 published articles. The most represented scientific journals were the "European Radiology" (181 articles, h-index = 46), followed by the "European Journal of Radiology" (148 articles, h-index = 34). Most of the papers were from Germany, the USA, or China. Both the keyword and topic analyses showed the history of dual- and multi-energy CT and the evolution of its application hotspots in the chest.

CONCLUSION

Our study illustrates the latest advances in dual- and multi-energy CT and its increasingly prominent applications in the chest, especially in lung parenchymal diseases and coronary artery diseases. Photon-counting CT and artificial intelligence will be the emerging hot technologies that continue to develop in the future.

CRITICAL RELEVANCE STATEMENT

This study aims to provide valuable insights into energy-based imaging in chest disease, validating the clinical application of multi-energy CT together with photon-counting CT and effectively increasing utilization in clinical practice.

KEY POINTS

Bibliometric analysis is fundamental to understanding the current and future state of dual- and multi-energy CT. Research trends and leading topics included coronary artery disease, pulmonary embolism, and radiation dose. All analyses indicate a growing interest in the use of energy-based imaging techniques for thoracic applications.

The Effect of Severe Coronary Calcification on Diagnostic Performance of Computed Tomography-Derived Fractional Flow Reserve Analyses in People with Coronary Artery Disease

BACKGROUND

Negative CCTA can effectively exclude significant CAD, eliminating the need for further noninvasive or invasive testing. However, in the presence of severe CAD, the accuracy declines, thus necessitating additional testing. The aim of our study was to evaluate the diagnostic performance of noninvasive cFFR derived from CCTA, compared to ICA in detecting hemodynamically significant stenoses in participants with high CAC scores (>400).

METHODS

This study included 37 participants suspected of having CAD who underwent CCTA and ICA. CAC was calculated and cFFR analyses were performed using an on-site machine learning-based algorithm. Diagnostic accuracy parameters of CCTA and cFFR were calculated on a per-vessel level.

RESULTS

The median total CAC score was 870, with an IQR of 642-1370. Regarding CCTA, sensitivity and specificity for RCA were 60% and 67% with an AUC of 0.639; a LAD of 87% and 50% with an AUC of 0.688; an LCX of 33% and 90% with an AUC of 0.617, respectively. Regarding cFFR, sensitivity and specificity for RCA were 60% and 61% with an AUC of 0.606; a LAD of 75% and 54% with an AUC of 0.647; an LCX of 50% and 77% with an AUC of 0.647. No significant differences between AUCs of coronary CTA and cFFR for each vessel were found.

CONCLUSIONS

Our results showed poor diagnostic accuracy of CCTA and cFFR in determining significant ischemia-related lesions in participants with high CAC scores when compared to ICA. Based on our results and study limitations we cannot exclude cFFR as a method for determining significant stenoses in people with high CAC. A key issue is accurate and detailed lumen segmentation based on good-quality CCTA images.

Photon-Counting CT in the Head and Neck: Current Applications and Future Prospects

Photon-counting detectors (PCDs) represent a major milestone in the evolution of CT imaging. CT scanners using PCD systems have already been shown to generate images with substantially greater spatial resolution, superior iodine contrast-to-noise ratio, and reduced artifact compared with conventional energy-integrating detector-based systems. These benefits can be achieved with considerably decreased radiation dose. Recent studies have focused on the advantages of PCD-CT scanners in numerous anatomic regions, particularly the coronary and cerebral vasculature, pulmonary structures, and musculoskeletal imaging. However, PCD-CT imaging is also anticipated to be a major advantage for head and neck imaging. In this paper, we review current clinical applications of PCD-CT in head and neck imaging, with a focus on the temporal bone, facial bones, and paranasal sinuses; minor arterial vasculature; and the spectral capabilities of PCD systems.

Photon-Counting Computed Tomography: Experience in Musculoskeletal Imaging

Since the emergence of the first photon-counting computed tomography (PCCT) system in late 2021, its advantages and a wide range of applications in all fields of radiology have been demonstrated. Compared to standard energy-integrating detector-CT, PCCT allows for superior geometric dose efficiency in every examination. While this aspect by itself is groundbreaking, the advantages do not stop there. PCCT facilitates an unprecedented combination of ultra-high-resolution imaging without dose penalty or field-of-view restrictions, detector-based elimination of electronic noise, and ubiquitous multi-energy spectral information. Considering the high demands of orthopedic imaging for the visualization of minuscule details while simultaneously covering large portions of skeletal and soft tissue anatomy, no subspecialty may benefit more from this novel detector technology than musculoskeletal radiology. Deeply rooted in experimental and clinical research, this review article aims to provide an introduction to the cosmos of PCCT, explain its technical basics, and highlight the most promising applications for patient care, while also mentioning current limitations that need to be overcome.

Performance of calcium quantifications on low-dose photon-counting detector CT with high-pitch: A phantom study

Purpose

To evaluate the performance of calcium quantification on photon-counting detector CT (PCD-CT) with high-pitch at low radiation doses compared to third-generation dual-source energy-integrating detector CT (EID-CT).

Materials and methods

The phantom with three calcium inserts (50, 100, and 300 mg of calcium per milliliter), with and without the elliptical outer layer, was evaluated using high-pitch (3.2) and standard pitch (0.8) on PCD-CT, and standard pitch on EID-CT. Scans were performed with different tube voltages (PCD-CT: 120 and 140 kilo-voltage peak [kVp]; EID-CT: 70/Sn150 and 100/Sn150 kVp) and four radiation doses (1, 3, 5, and, 10 milli-Gray [mGy]). Utilizing the true calcium concentrations (CCtrue) of the phantom as the gold standard references, regression equations for each kVp setting were formulated to convert CT attenuations (CaCT) into measured calcium concentrations (CCm). The correlation analysis between CaCT and CCtrue was performed. The percentage absolute bias (PAB) was calculated from the differences between CCm and CCtrue and used to analyze the effects of scanning parameters on calcium quantification accuracy.

Results

A strong correlation was found between CaCT and CCtrue on PCD-CT (r > 0.99) and EID-CT (r > 0.98). For high- and standard-pitch scans on PCD-CT, the accuracy of calcium quantification is comparable (p = 0.615): the median (interquartile range [IQR]) of PAB was 5.59% (2.79%-8.31%) and 4.87 % (2.62%-8.01%), respectively. The PAB median (IQR) was 7.43% (3.77%-11.75%) for EID-CT. The calcium quantification accuracy of PCD-CT is superior to EID-CT at the large phantom (5.46% [2.68%-9.55%] versus 9.01% [6.22%-12.74%]), and at the radiation dose of 1 mGy (4.43% [2.08%-8.59%] versus 13.89% [8.93%-23.09%]) and 3 mGy (4.61% [2.75%-6.51%] versus 9.97% [5.17%-14.41%]), all p < 0.001.

Conclusions

Calcium quantification using low-dose PCD-CT with high-pitch scanning is feasible and accurate, and superior to EID-CT.

Photon-counting detector computed tomography for metal artifact reduction: a comparative study of different artifact reduction techniques in patients with orthopedic implants

PURPOSE

Artifacts caused by metallic implants remain a challenge in computed tomography (CT). We investigated the impact of photon-counting detector computed tomography (PCD-CT) for artifact reduction in patients with orthopedic implants with respect to image quality and diagnostic confidence using different artifact reduction approaches.

MATERIAL AND METHODS

In this prospective study, consecutive patients with orthopedic implants underwent PCD-CT imaging of the implant area. Four series were reconstructed for each patient (clinical standard reconstruction [PCD-CTStd], monoenergetic images at 140 keV [PCD-CT140keV], iterative metal artifact reduction (iMAR) corrected [PCD-CTiMAR], combination of iMAR and 140 keV monoenergetic [PCD-CT140keV+iMAR]). Subsequently, three radiologists evaluated the reconstructions in a random and blinded manner for image quality, artifact severity, anatomy delineation (adjacent and distant), and diagnostic confidence using a 5-point Likert scale (5 = excellent). In addition, the coefficient of variation [CV] and the relative quantitative artifact reduction potential were obtained as objective measures.

RESULTS

We enrolled 39 patients with a mean age of 67.3 ± 13.2 years (51%; n = 20 male) and a mean BMI of 26.1 ± 4 kg/m2. All image quality measures and diagnostic confidence were significantly higher for the iMAR vs. non-iMAR reconstructions (all p < 0.001). No significant effect of the different artifact reduction approaches on CV was observed (p = 0.26). The quantitative analysis indicated the most effective artifact reduction for the iMAR reconstructions, which was higher than PCD-CT140keV (p < 0.001).

CONCLUSION

PCD-CT allows for effective metal artifact reduction in patients with orthopedic implants, resulting in superior image quality and diagnostic confidence with the potential to improve patient management and clinical decision making.

Impact of different metal artifact reduction techniques in photon-counting computed tomography head and neck scans in patients with dental hardware

OBJECTIVES

Metal artifacts remain a challenge in computed tomography. We investigated the potential of photon-counting computed tomography (PCD-CT) for metal artifact reduction using an iterative metal artifact reduction (iMAR) algorithm alone and in combination with high keV monoenergetic images (140 keV) in patients with dental hardware.

MATERIAL AND METHODS

Consecutive patients with dental implants were prospectively included in this study and received PCD-CT imaging of the craniofacial area. Four series were reconstructed (standard [PCD-CTstd], monoenergetic at 140 keV [PCD-CT140keV], iMAR corrected [PCD-CTiMAR], combination of iMAR and 140 keV monoenergetic [PCD-CTiMAR+140keV]). All reconstructions were assessed qualitatively by four radiologists (independent and blinded reading on a 5-point Likert scale [5 = excellent; no artifact]) regarding overall image quality, artifact severity, and delineation of adjacent and distant anatomy. To assess signal homogeneity and evaluate the magnitude of artifact reduction, we performed quantitative measures of coefficient of variation (CV) and a region of interest (ROI)-based relative change in artifact reduction [PCD-CT/PCD-CTstd].

RESULTS

We enrolled 48 patients (mean age 66.5 ± 11.2 years, 50% (n = 24) males; mean BMI 25.2 ± 4.7 kg/m2; mean CTDIvol 6.2 ± 6 mGy). We found improved overall image quality, reduced artifacts and superior delineation of both adjacent and distant anatomy for the iMAR vs. non-iMAR reconstructions (all p < 0.001). No significant effect of the different artifact reduction approaches on CV was observed (p = 0.42). The ROI-based analysis indicated the most effective artifact reduction for the iMAR reconstructions, which was significantly higher compared to PCD-CT140keV (p < 0.001).

CONCLUSION

PCD-CT offers highly effective approaches for metal artifact reduction with the potential to overcome current diagnostic challenges in patients with dental implants.

CLINICAL RELEVANCE STATEMENT

Metallic artifacts pose a significant challenge in CT imaging, potentially leading to missed findings. Our study shows that PCD-CT with iMAR post-processing reduces artifacts, improves image quality, and can possibly reveal pathologies previously obscured by artifacts, without additional dose application.

KEY POINTS

• Photon-counting detector CT (PCD-CT) offers highly effective approaches for metal artifact reduction in patients with dental fillings/implants. • Iterative metal artifact reduction (iMAR) is superior to high keV monoenergetic reconstructions at 140 keV for artifact reduction and provides higher image quality. • Signal homogeneity of the reconstructed images is not affected by the different artifact reduction techniques.

Photon-Counting Computed Tomography in Atherosclerotic Plaque Characterization

Atherosclerotic plaque buildup in the coronary and carotid arteries is pivotal in the onset of acute myocardial infarctions or cerebrovascular events, leading to heightened levels of illness and death. Atherosclerosis is a complex and multistep disease, beginning with the deposition of low-density lipoproteins in the arterial intima and culminating in plaque rupture. Modern technology favors non-invasive imaging techniques to assess atherosclerotic plaque and offer insights beyond mere artery stenosis. Among these, computed tomography stands out for its widespread clinical adoption and is prized for its speed and accessibility. Nonetheless, some limitations persist. The introduction of photon-counting computed tomography (PCCT), with its multi-energy capabilities, enhanced spatial resolution, and superior soft tissue contrast with minimal electronic noise, brings significant advantages to carotid and coronary artery imaging, enabling a more comprehensive examination of atherosclerotic plaque composition. This narrative review aims to provide a comprehensive overview of the main concepts related to PCCT. Additionally, we aim to explore the existing literature on the clinical application of PCCT in assessing atherosclerotic plaque. Finally, we will examine the advantages and limitations of this recently introduced technology.

Cranial Computer Tomography with Photon Counting and Energy-Integrated Detectors: Objective Comparison in the Same Patients

This study provides an objective comparison of cranial computed tomography (CT) imaging quality and radiation dose between photon counting detectors (PCCTs) and energy-integrated detectors (EIDs). We retrospectively analyzed 158 CT scans from 76 patients, employing both detector types on the same individuals to ensure a consistent comparison. Our analysis focused on the Computed Tomography Dose Index and the Dose-Length Product together with the contrast-to-noise ratio and the signal-to-noise ratio for brain gray and white matter. We utilized standardized imaging protocols and consistent patient positioning to minimize variables. PCCT showed a potential for higher image quality and lower radiation doses, as highlighted by this study, thus achieving diagnostic clarity with reduced radiation exposure, underlining its significance in patient care, particularly for patients requiring multiple scans. The results demonstrated that while both systems were effective, PCCT offered enhanced imaging and patient safety in neuroradiological evaluations.

High yield clinical applications for photon counting CT in neurovascular imaging

Photon-counting CT (PCCT) uses a novel X-ray detection mechanism that confers many advantages over that used in traditional energy integrating CT. As PCCT becomes more available, it is important to thoroughly understand its benefits and highest yield areas for improvements in diagnosis of various diseases. Based on our early experience, we have identified several areas of neurovascular imaging in which PCCT shows promise. Here, we describe the benefits in diagnosing arterial and venous diseases in the head, neck, and spine. Specifically, we focus on applications in head and neck CT angiography (CTA), spinal CT angiography, and CT myelography for detection of CSF-venous fistulas. Each of these applications highlights the technological advantages of PCCT in neurovascular imaging. Further understanding of these applications will not only benefit institutions incorporating PCCT into their practices but will also help guide future directions for implementation of PCCT for diagnosing other pathologies in neuroimaging.

Innovations in cardiac computed tomography: Imaging in coronary artery disease

Coronary computed tomography angiography (CCTA) has emerged as a pivotal tool in the non-invasive evaluation of coronary artery disease (CAD). Recent advancements in imaging techniques, quantitative plaque assessment methods, assessment of coronary physiology, and perivascular coronary inflammation have propelled CCTA to the forefront of CAD management, enabling precise risk stratification, disease monitoring, and evaluation of treatment response. However, challenges persist, including the need for cardiovascular outcomes data for therapy modifications based on CCTA findings and the lack of standardized quantitative plaque assessment techniques to establish universal guidelines for treatment strategies. This review explores the current utilization of CCTA in clinical practice, highlighting its clinical impact and discussing challenges and opportunities for future development. By addressing these nuances, CCTA holds promise for revolutionizing coronary imaging and improving CAD management in the years to come. Ultimately, the goal is to provide precise risk stratification, optimize medical therapy, and improve cardiovascular outcomes while ensuring cost-effectiveness for healthcare systems.

Multi-institutional Protocol Guidance for Pediatric Photon-counting CT

Performing CT in children comes with unique challenges such as greater degrees of patient motion, smaller and densely packed anatomy, and potential risks of radiation exposure. The technical advancements of photon-counting detector (PCD) CT enable decreased radiation dose and noise, as well as increased spatial and contrast resolution across all ages, compared with conventional energy-integrating detector CT. It is therefore valuable to review the relevant technical aspects and principles specific to protocol development on the new PCD CT platform to realize the potential benefits for this population. The purpose of this article, based on multi-institutional clinical and research experience from pediatric radiologists and medical physicists, is to provide protocol guidance for use of PCD CT in the imaging of pediatric patients.

Advanced Imaging of Shunt Valves in Cranial CT Scans with Photon-Counting Scanner

This brief report aimed to show the utility of photon-counting technology alongside standard cranial imaging protocols for visualizing shunt valves in a patient's cranial computed tomography scan. Photon-counting CT scans with cranial protocols were retrospectively surveyed and four types of shunt valves were encountered: proGAV 2.0®, M.blue®, Codman Certas®, and proSA®. These scans were compared with those obtained from non-photon-counting scanners at different time points for the same patients. The analysis of these findings demonstrated the usefulness of photon-counting technology for the clear and precise visualization of shunt valves without any additional radiation or special reconstruction patterns. The enhanced utility of photon-counting is highlighted by providing superior spatial resolution compared to other CT detectors. This technology facilitates a more accurate characterization of shunt valves and may support the detection of subtle abnormalities and a precise assessment of shunt valves.