Saving Contrast Media in Coronary CT Angiography with Photon-Counting Detector CT

Trading off Iodine and Radiation Dose in Coronary Computed Tomography

Coronary CT angiography (CCTA) has seen steady progress since its inception, becoming a key player in the non-invasive assessment of coronary artery disease (CAD). Advancements in CT technology, including iterative and deep-learning-based reconstruction, wide-area detectors, and dual-source systems, have helped mitigate early limitations, such as high radiation doses, motion artifacts, high iodine load, and non-diagnostic image quality. However, the adjustments between ionizing radiation and iodinated contrast material (CM) volumes remain a critical concern, especially due to the increasing use of CCTA in various indications. This review explores the balance between radiation and CM volumes, emphasizing patient-specific protocol optimization to improve diagnostic accuracy while minimizing risks. Radiation dose reduction strategies, such as low tube voltage protocols, prospective ECG-gating, and modern reconstruction algorithms, have significantly decreased radiation exposure, with some studies achieving sub-millisievert doses. Similarly, CM volume optimization, including adjustments in strategies for calculating CM volume, iodine concentration, and flow protocols, plays a role in managing risks such as contrast-associated acute kidney injury, particularly in patients with renal impairment. Emerging technologies, such as photon-counting CT and deep-learning reconstruction, promise further improvements in dose efficiency and image quality. This review summarizes current evidence, highlights the benefits and limitations of dose control approaches, and provides practical recommendations for practitioners. By tailoring protocols to patient characteristics, such as age, renal function, and body habitus, clinicians can achieve an optimal trade-off between diagnostic accuracy and patient safety, ensuring optimal operation of CT systems in clinical practice.

Current and future applications of photon-counting computed tomography in cardiovascular medicine

Photon-counting CT (PCCT) represents a transformative advancement in cardiac imaging, addressing key limitations of conventional CT. This review synthesises current evidence to demonstrate how PCCT's superior spatial resolution, enhanced tissue characterisation and multienergy capabilities broaden the diagnostic potential of cardiac CT. Applications include the precise detection and quantification of coronary artery calcifications, evaluation of coronary plaque burden and composition, improved assessment of coronary stents, and comprehensive myocardial tissue characterisation and perfusion analysis. By offering high-quality spectral information and detailed tissue characterisation, PCCT provides a non-invasive alternative for assessing coronary artery disease and myocardial pathology, reducing the need for invasive coronary angiography and cardiac MRI. Despite ongoing challenges in technology and clinical implementation, PCCT has the potential to revolutionise cardiovascular diagnostics, optimise diagnostic workflows and enhance patient care through more accurate, streamlined and comprehensive assessments.

[Photon-Counting Detector CT: Advances and Clinical Applications in Cardiovascular Imaging]

Since the approval of the first dual-source photon-counting detector CT (PCD-CT) in the fall of 2021, significant insights have been gained in its application for cardiovascular imaging. This review aims to provide a comprehensive overview of the current state of knowledge and the growing body of research literature, illustrating innovative applications and perspectives through case examples.We conducted a structured literature review, identifying relevant studies via Google Scholar and PubMed, using the keywords "photon-counting detector", "cardiovascular CT", "cardiac CT", and "ultra-high-resolution CT". We analyzed studies published since January 2015. Additionally, we integrated our own clinical experiences and case examples.In addition to the well-known benefit of increased temporal resolution offered by dual-source scanners, dual-source PCD-CT provides three key advantages: 1) Optimized geometric dose efficiency with an improved contrast-to-noise ratio, 2) intrinsic spectral sensitivity, and 3) the ability for ultrahigh-resolution CT. This technology enables improved image quality or radiation dose reduction in established cardiovascular protocols. Its use in non-invasive cardiac diagnostics for obese patients, those with a high plaque burden, or after stent implantation appears technically feasible, potentially expanding the scope of CT. The spectral sensitivity also allows tailored image acquisition, reducing metallic artifacts and contrast agent doses in patients with renal impairment. Early studies and clinical experience support these potential applications of PCD-CT in cardiovascular diagnostics, suggesting workflow optimization and improved patient management.However, challenges remain, including high costs, large data volumes, somewhat longer reconstruction times, and technical difficulties in combining spectral sensitivity with ultra-high resolution. Prospective randomized studies with clinical endpoints are lacking to confirm the clear advantage over conventional scanners. Future research should focus on endpoint-based studies and robust cost-benefit analyses to evaluate the potential of this technology and facilitate its evidence-based integration in clinical practice. · Photon-counting detector CT represents a technological advancement in computed tomography.. · Spectral sensitivity enhances iodine signal and minimizes artifacts.. · Ultra-high-resolution CT allows precise imaging, even in stents and advanced sclerosis.. · This technology must be validated through endpoint-based, randomized studies.. · Hagar MT, Schlett CL, Oechsner T et al. Photon-Counting Detector CT: Advances and Clinical Applications in Cardiovascular Imaging. Rofo 2025; 197: 509-516.

Deep learning reconstruction algorithm and high-concentration contrast medium: feasibility of a double-low protocol in coronary computed tomography angiography

OBJECTIVE

To evaluate radiation dose and image quality of a double-low CCTA protocol reconstructed utilizing high-strength deep learning image reconstructions (DLIR-H) compared to standard adaptive statistical iterative reconstruction (ASiR-V) protocol in non-obese patients.

MATERIALS AND METHODS

From June to October 2022, consecutive patients, undergoing clinically indicated CCTA, with BMI < 30 kg/m2 were prospectively included and randomly assigned into three groups: group A (100 kVp, ASiR-V 50%, iodine delivery rate [IDR] = 1.8 g/s), group B (80 kVp, DLIR-H, IDR = 1.4 g/s), and group C (80 kVp, DLIR-H, IDR = 1.2 g/s). High-concentration contrast medium was administered. Image quality analysis was evaluated by two radiologists. Radiation and contrast dose, and objective and subjective image quality were compared across the three groups.

RESULTS

The final population consisted of 255 patients (64 ± 10 years, 161 men), 85 per group. Group B yielded 42% radiation dose reduction (2.36 ± 0.9 mSv) compared to group A (4.07 ± 1.2 mSv; p < 0.001) and achieved a higher signal-to-noise ratio (30.5 ± 11.5), contrast-to-noise-ratio (27.8 ± 11), and subjective image quality (Likert scale score: 4, interquartile range: 3-4) compared to group A and group C (all p ≤ 0.001). Contrast medium dose in group C (44.8 ± 4.4 mL) was lower than group A (57.7 ± 6.2 mL) and B (50.4 ± 4.3 mL), all the comparisons were statistically different (all p < 0.001).

CONCLUSION

DLIR-H combined with 80-kVp CCTA with an IDR 1.4 significantly reduces radiation and contrast medium exposure while improving image quality compared to conventional 100-kVp with 1.8 IDR protocol in non-obese patients.

CLINICAL RELEVANCE STATEMENT

Low radiation and low contrast medium dose coronary CT angiography protocol is feasible with high-strength deep learning reconstruction and high-concentration contrast medium without compromising image quality.

KEY POINTS

Minimizing the radiation and contrast medium dose while maintaining CT image quality is highly desirable. High-strength deep learning iterative reconstruction protocol yielded 42% radiation dose reduction compared to conventional protocol. "Double-low" coronary CTA is feasible with high-strength deep learning reconstruction without compromising image quality in non-obese patients.

Photon-counting versus energy-integrating CT of abdomen-pelvis: a phantom study on the potential for reducing iodine contrast media

BACKGROUND

To assess the potential of virtual monoenergetic images (VMIs) on a photon-counting computed tomography (PCCT) for reducing the amount of injected iodine contrast media compared to an energy-integrating CT (EICT).

METHODS

A multienergy phantom was scanned with a PCCT and EICT at 11 mGy with abdomen-pelvis examination parameters. VMIs were generated at 40 keV, 50 keV, 60 keV, and 70 keV. For all VMIs, the contrast-to-noise ratio (CNR) of iodine inserts with concentrations of 1 mg/mL, 2 mg/mL, 5 mg/mL, 10 mg/mL, and 15 mg/mL was calculated by dividing the signal difference between HU in iodine inserts versus solid water by the noise value assessed on solid water. The potential reduction in iodine media was calculated by the rate of reduction in iodine concentration with PCCT while maintaining the same CNR obtained with EICT for the reference concentration.

RESULTS

Significantly higher CNR values were found with PCCT at all VMI energy levels for iodine concentrations above 1 mg/mL. The highest reduction was observed at 40 keV, with a value of 48.9 ± 1.6% (mean ± standard deviation). It decreased as the energy level increased, by 38.5 ± 0.5%, and 30.8 ± 0.8% for 50 and 60 keV, respectively. For 70 keV, the potential reduction of 24.4 ± 1.1% was found for iodine concentrations above 1 mg/mL. This reduction reached 57 ± 2.3% at 40 keV with PCCT compared to 60 keV with EICT.

CONCLUSION

For abdomen-pelvis protocols, the use of VMIs with PCCT significantly improved the CNR of iodine, offering the potential to reduce the required contrast medium.

RELEVANCE STATEMENT

The use of VMIs with PCCT may reduce the quantity of iodine contrast medium to be injected compared with EICT, limiting costs, the risk of adverse effects, and the amount of contrast agent released into the wastewater.

KEY POINTS

PCCT improves the image quality of VMIs. PCCT offers the potential for reducing the amount of injected contrast medium. PCCT potential for reducing the injected contrast medium depends on energy level.

Multienergy cardiovascular CT imaging: current state and future

Multienergy cardiovascular CT imaging can be defined as data acquisition at 2 (dual-energy) or multiple X-ray energies. Multienergy cardiovascular CT imaging provides additional qualitative and quantitative information such as material maps or virtual monoenergetic images, which are supposed to further improve the quality and diagnostic yield of CT. Recently introduced photon-counting detector CT scanners further address some of the challenges and limitations of previous, conventional CT machines, hereby enhancing and extending the applications of CT for cardiovascular imaging. This review summarizes the technical principles of multienergy cardiovascular CT imaging and addresses the optimization of image quality and discusses the various dual-energy-based applications for coronary, valvular, and myocardial imaging. New developments in regard to k-edge imaging and new contrast media for multienergy cardiovascular CT imaging are being also discussed.

Potential of photon-counting detector CT technology for contrast medium reduction in portal venous phase thoracoabdominal CT

OBJECTIVES

To compare image quality and iodine attenuation intra-individually in portal venous phase photon-counting detector CT (PCD-CT) scans using protocols with different contrast medium (CM) volume.

MATERIALS AND METHODS

A prospectively acquired patient cohort between 04/2021 and 11/2023 was retrospectively screened if patients had the following combination of portal venous phase thoracoabdominal CT scans: (a) PCD-CT with 120 mL CM volume (PCD-CT120 mL), (b) PCD-CT with 100 mL CM volume (PCD-CT100 mL), and (c) prior energy-integrating detector CT (EID-CT) with 120 mL CM volume. On PCD-CT, virtual monoenergetic image (VMI) reconstructions at 70 keV were applied for both groups as well as additional VMI at 60 keV for PCD‑CT100 mL. Quantitative analyses including signal-to-noise (SNR) and contrast-to-noise ratios (CNR) and qualitative analyses were performed using a mixed linear effects model.

RESULTS

The final study cohort comprised 49 patients (mean age 67 [31-86] years, 12 female). Comparison to EID-CT was available in 33 patients. In standard 70 keV VMI reconstructions, PCD-CT100 mL was non-inferior to PCD-CT120 mL as well as to EID-CT120 mL for CNR in abdominal organs (all p > 0.050). The mixed linear effects model revealed significant differences between contrast volume groups for both contrast enhancement and image quality ratings. PCD-CT100 mL/70 keV demonstrated the smallest deviation from optimal contrast enhancement (-0.306, p < 0.001).

CONCLUSION

In portal venous phase thoracoabdominal PCD-CT, a nearly 17% reduction in CM was achievable while maintaining subjective and objective image quality compared to prior higher CM volume PCD-CT scans within the same patients and still surpassing image quality of previous exams on an EID-CT system.

KEY POINTS

Question How do image quality and iodine attenuation intra-individually compare in portal venous phase photon-counting detector CT (PCD-CT) scans using protocols with different contrast medium volume. Findings PCD-CT scans exhibit superior quantitative and qualitative image quality compared to energy-integrating detector-CT acquisitions and are not negatively affected by contrast volume reductions up to 17%. Clinical relevance This study provides further evidence that PCD-CT enables a considerable reduction in iodine dose for portal venous phase acquisition, benefiting both patients and healthcare system costs.

Feasibility of very low iodine dose aortoiliac CT angiography using dual-source photon-counting detector CT

PURPOSE

To evaluate the feasibility of aortoiliac CT-Angiography (CTA) using dual-source photon-counting detector (PCD)-CT with minimal iodine dose.

METHODS

This IRB-approved, single-center prospective study enrolled patients with indications for aortoiliac CTA from December 2022 to March 2023. All scans were performed using a first-generation dual-source PCD-CT. Images were acquired with fast pitch and full spectral capabilities (collimation 144 × 0.4 mm). The contrast protocol included a mixture of sodium chloride and iodinated contrast agent (Iopromide, total iodine dose: 9.5-9.8 g). Virtual monoenergetic images (VMIs) were reconstructed at 40, 50, 60, and 68 keV. Two blinded radiologists evaluated image quality on a 4-point scale. Attenuation was measured across eight regions in the aorta and iliac arteries, and contrast-to-noise ratio (CNR) was calculated. Statistical comparisons were performed using repeated measures ANOVA and Bonferroni post-hoc tests.

RESULTS

The final cohort consisted of 39 subjects (mean age: 69.6 ± 9.6 years; 30.8 % female). VMI at 40 keV provided significantly higher attenuation: 478 ± 114 HU, compared to 50 keV (331 ± 74 HU), 60 keV (241 ± 51 HU), and 68 keV (190 ± 48 HU) (p < 0.01). This translated in increased CNR for 40 keV reconstructions (11.8 ± 3.9), followed by 50 keV (9.1 ± 3.0), 60 keV (7.0 ± 2.3), and 68 keV (6.1 ± 1.9) (p < 0.01). Subjective image quality was rated excellent at 40 keV (4 [3,4]), though associated with highest noise (38 ± 7.4 HU, p = 0.02).

CONCLUSION

Aortoiliac CTA using dual-source PCD-CT at 40 keV achieved high attenuation and CNR, enabling effective imaging with only 9.8 g of iodine.

Photon-Counting Versus Dual-Source CT for Transcatheter Aortic Valve Implantation Planning

BACKGROUND

Cardiovascular CT is required for planning transcatheter aortic valve implantation (TAVI).

PURPOSE

To compare image quality, suitability for TAVI planning, and radiation dose of photon-counting CT (PCCT) with that of dual-source CT (DSCT).

MATERIAL AND METHODS

Retrospective study on consecutive TAVI candidates with aortic valve stenosis who underwent contrast-enhanced aorto-ilio-femoral PCCT and/or DSCT between 01/2022 and 07/2023. Signal-to-noise (SNR) and contrast-to-noise ratio (CNR) were calculated by standardized ROI analysis. Image quality and suitability for TAVI planning were assessed by four independent expert readers (two cardiac radiologists, two cardiologists) on a 5-point-scale. CT dose index (CTDI) and dose-length-product (DLP) were used to calculate effective radiation dose (eRD).

RESULTS

300 patients (136 female, median age: 81 years, IQR: 76-84) underwent 302 CT examinations, with PCCT in 202, DSCT in 100; two patients underwent both. Although SNR and CNR were significantly lower in PCCT vs. DSCT images (33.0 ± 10.5 vs. 47.3 ± 16.4 and 47.3 ± 14.8 vs. 59.3 ± 21.9, P < .001, respectively), visual image quality was higher in PCCT vs. DSCT (4.8 vs. 3.3, P < .001), with moderate overall interreader agreement among radiologists and among cardiologists (κ = 0.60, respectively). Image quality was rated as "excellent" in 160/202 (79.2%) of PCCT vs. 5/100 (5%) of DSCT cases. Readers found images suitable to depict the aortic valve hinge points and to map the femoral access path in 99% of PCCT vs. 85% of DSCT (P < 0.01), with suitability ranked significantly higher in PCCT vs. DSCT (4.8 vs. 3.3, P < .001). Mean CTDI and DLP, and thus eRD, were significantly lower for PCCT vs. DSCT (22.4 vs. 62.9; 519.4 vs. 895.5, and 8.8 ± 4.5 mSv vs. 15.3 ± 5.8 mSv; all P < .001).

CONCLUSION

PCCT improves image quality, effectively avoids non-diagnostic CT imaging for TAVI planning, and is associated with a lower radiation dose compared to state-of-the-art DSCT. Radiologists and cardiologists found PCCT images more suitable for TAVI planning.

Tungsten-Based Contrast Agent for Photon-Counting Detector CT Angiography in Calcified Coronaries: Comparison to Iodine in a Cardiovascular Phantom

OBJECTIVES

Calcified plaques induce blooming artifacts in coronary computed tomography angiography (CCTA) potentially leading to inaccurate stenosis evaluation. Tungsten represents a high atomic number, experimental contrast agent with different physical properties than iodine. We explored the potential of a tungsten-based contrast agent for photon-counting detector (PCD) CCTA in heavily calcified coronary vessels.

MATERIALS AND METHODS

A cardiovascular phantom exhibiting coronaries with calcified plaques was imaged on a first-generation dual-source PCD-CT. The coronaries with 3 different calcified plaques were filled with iodine and tungsten contrast media solutions equating to iodine and tungsten delivery rates (IDR and TDR) of 0.3, 0.5, 0.7, 1.0, 1.5, 2.0, 2.5, and 3.0 g/s, respectively. Electrocardiogram-triggered sequential acquisitions were performed in the spectral mode (QuantumPlus). Virtual monoenergetic images (VMIs) were reconstructed from 40 to 190 keV in 1 keV increments. Blooming artifacts and percentage error stenoses from calcified plaques were quantified, and attenuation characteristics of both contrast media were recorded.

RESULTS

Blooming artifacts from calcified plaques were most pronounced at 40 keV (78%) and least pronounced at 190 keV (58%). Similarly, percentage error stenoses were highest at 40 keV (48%) and lowest at 190 keV (2%), respectively. Attenuation of iodine decreased monotonically in VMIs from low to high keV, with the strongest decrease from 40 keV to 100 keV (IDR of 2.5 g/s: 1279 HU at 40 keV, 187 HU at 100 kV, and 35 HU at 190 keV). The attenuation of tungsten, on the other hand, increased monotonically as a function of VMI energy, with the strongest increase between 40 and 100 keV (TDR of 2.5 g/s: 202 HU at 40 keV, 661 HU at 100 kV, and 717 HU at 190 keV). For each keV level, the relationship between attenuation and IDR/TDR could be described by linear regressions ( R2 ≥ 0.88, P < 0.001). Specifically, attenuation increased linearly when increasing the delivery rate irrespective of keV level or contrast medium. Iodine exhibited the highest relative increase in attenuation values at lower keV levels when increasing the IDR. Conversely, for tungsten, the greatest relative increase in attenuation values occurred at higher keV levels when increasing the TDR. When high keV imaging is desirable to reduce blooming artifacts from calcified plaques, IDR has to be increased at higher keV levels to maintain diagnostic vessel attenuation (ie, 300 HU), whereas for tungsten, TDR can be kept constant or can be even reduced at high keV energy levels.

CONCLUSIONS

Tungsten's attenuation characteristics in relation to VMI energy levels are reversed to those of iodine, with tungsten exhibiting high attenuation values at high keV levels and vice versa. Thus, tungsten shows promise for high keV imaging CCTA with PCD-CT as-in distinction to iodine-both high vessel attenuation and low blooming artifacts from calcified plaques can be achieved.

PCD-CT enables contrast media reduction in abdominal imaging compared to an individualized kV-adapted contrast media injection protocol on EID-CT

OBJECTIVES

This study aims to demonstrate reduced iodine contrast media (CM) in routine abdominal CT scans in portal venous phase (PVP) using a photon-counting detector CT (PCD-CT) compared to total body weight (TBW) and kV-adapted CM injection protocols on a state-of-the-art energy-integrating detector CT (EID-CT) while maintaining sufficient image quality (IQ).

MATERIALS AND METHODS

Consecutive contrast-enhanced abdominal PVP CT scans from an EID-CT (Nov 2022-March 2024) and a PCD-CT (Sep 2023-Dec 2023) were compared. CM parameters (total iodine load (TIL), iodine delivery rate (IDR) and dosing factor (DF)) were reported. An individualized acquisition and CM injection protocol based on TBW and kV was applied for the EID-CT and a TBW adapted CM injection protocol was used for the PCD-CT. Objective IQ was evaluated with mean attenuation (Hounsfield Units, HU), signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR)). Subjective IQ was assessed via a 5-point Likert scale by 2 expert readers based on diagnostic confidence.

RESULTS

Based on 91 EID-CT scans and 102 PCD-CT scans a TIL reduction of 20.1 % was observed for PCD-CT. PCD-CT demonstrated significantly higher SNR (9.9 ± 1.7 vs. 9.1 ± 1.8, p < 0.001) and CNR (5.1 ± 1.7 vs. 4.3 ± 1.3, p < 0.001) compared to EID-CT. Subjective IQ assessment showed that all scans had sufficient diagnostic IQ.

CONCLUSIONS

PCD-CT allows for CM reduction while providing higher SNR and CNR compared to EID-CT, using clinical individualized scan and CM injection protocols.

Cardiac computed tomography with late contrast enhancement: A review

Cardiac computed tomography (CCT) has assumed an increasingly significant role in the evaluation of coronary artery disease (CAD) during the past few decades, whereas cardiovascular magnetic resonance (CMR) remains the gold standard for myocardial tissue characterization. The discovery of late myocardial enhancement following intravenous contrast administration dates back to the 1970s with ex-vivo CT animal investigations; nevertheless, the clinical application of this phenomenon for cardiac tissue characterization became prevalent for CMR imaging far earlier than for CCT imaging. Recently the technical advances in CT scanners have made it possible to take advantage of late contrast enhancement (LCE) for tissue characterization in CCT exams. Moreover, the introduction of extracellular volume calculation (ECV) on cardiac CT images combined with the possibility of evaluating cardiac function in the same exam is making CCT imaging a multiparametric technique more and more similar to CMR. The aim of our review is to provide a comprehensive overview on the role of CCT with LCE in the evaluation of a wide range of cardiac conditions.

Photon-Counting Detector Computed Tomography (PCD-CT): A New Era for Cardiovascular Imaging? Current Status and Future Outlooks

Photon-counting detector computed tomography (PCD-CT) represents a revolutionary new generation of computed tomography (CT) for the imaging of patients with cardiovascular diseases. Since its commercial market introduction in 2021, numerous studies have identified advantages of this new technology in the field of cardiovascular imaging, including improved image quality due to an enhanced contrast-to-noise ratio, superior spatial resolution, reduced artifacts, and a reduced radiation dose. The aim of this narrative review was to discuss the current scientific literature, and to find answers to the question of whether PCD-CT has yet led to a true step-change and significant progress in cardiovascular imaging.

Application of a Denoising High-Resolution Deep Convolutional Neural Network to Improve Conspicuity of CSF-Venous Fistulas on Photon-Counting CT Myelography

Photon-counting detector CT myelography is a recently described technique that has several advantages for the detection of CSF-venous fistulas, one of which is improved spatial resolution. To maximally leverage the high spatial resolution of photon-counting detector CT, a sharp kernel and a thin section reconstruction are needed. Sharp kernels and thin slices often result in increased noise, degrading image quality. Here, we describe a novel deep-learning-based algorithm used to denoise photon-counting detector CT myelographic images, allowing the sharpest and thinnest quantitative reconstruction available on the scanner to be used to enhance diagnostic image quality. Currently, the algorithm requires 4-6 hours to create diagnostic, denoised images. This algorithm has the potential to increase the sensitivity of photon-counting detector CT myelography for detecting CSF-venous fistulas, and the technique may be valuable for institutions attempting to optimize photon-counting detector CT myelography imaging protocols.

Advantages of Photon-Counting Detector CT in Aortic Imaging

Photon-counting Computed Tomography (PCCT) is a promising imaging technique. Using detectors that count the number and energy of photons in multiple bins, PCCT offers several advantages over conventional CT, including a higher image quality, reduced contrast agent volume, radiation doses, and artifacts. Although PCCT is well established for cardiac imaging in assessing coronary artery disease, its application in aortic imaging remains limited. This review summarizes the available literature and provides an overview of the current use of PCCT for the diagnosis of aortic imaging, focusing mainly on endoleaks detection and characterization after endovascular aneurysm repair (EVAR), contrast dose volume, and radiation exposure reduction, particularly in patients with chronic kidney disease and in those requiring follow-up CT.

Cardiac imaging with photon counting CT

CT of the heart, in particular ECG-controlled coronary CT angiography (cCTA), has become clinical routine due to rapid technical progress with ever new generations of CT equipment. Recently, CT scanners with photon-counting detectors (PCD) have been introduced which have the potential to address some of the remaining challenges for cardiac CT, such as limited spatial resolution and lack of high-quality spectral data. In this review article, we briefly discuss the technical principles of photon-counting detector CT, and we give an overview on how the improved spatial resolution of photon-counting detector CT and the routine availability of spectral data can benefit cardiac applications. We focus on coronary artery calcium scoring, cCTA, and on the evaluation of the myocardium.

Cardiovascular Applications of Photon-Counting CT Technology: A Revolutionary New Diagnostic Step

Photon-counting computed tomography (PCCT) is an emerging technology that can potentially transform clinical CT imaging. After a brief description of the PCCT technology, this review summarizes its main advantages over conventional CT: improved spatial resolution, improved signal and contrast behavior, reduced electronic noise and artifacts, decreased radiation dose, and multi-energy capability with improved material discrimination. Moreover, by providing an overview of the existing literature, this review highlights how the PCCT benefits have been harnessed to enhance and broaden the diagnostic capabilities of CT for cardiovascular applications, including the detection of coronary artery calcifications, evaluation of coronary plaque extent and composition, evaluation of coronary stents, and assessment of myocardial tissue characteristics and perfusion.