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Fig. 4. 47-year-old man with hypertrophic cardiomyopathy due to MYBPC3 mutation (hematocrit level, 0.46 %).

(A) Short-axis view of late iodine enhancement (iodine map) with photon-counting CT.
(B) Short-axis view of late gadolinium enhancement with cardiac MRI.
(C-D) Extracellular volume polar maps (17-segment model of the American Heart Association) derived from C. Photon-counting CT and D. Cardiac MRI. Eingefügter Text(20261024-07534…

Protocol

Key Results

Source:
Gkizas C, Longere B, Bechrouri S, Ridon H, Rodriguez Musso A, Haidar M, Croisille C, Montaigne D, De Groote P, Pontana F. Photon-counting CT myocardial extracellular volume: A non-invasive biomarker for fibrosis in patients with hypertrophic cardiomyopathy. Diagnostic and Interventional Imaging. 2026;107(1):17–24. doi:10.1016/j.diii.2025.09.001.

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Figure 4. A, B Cardiac examination on photon-counting detector CT of a 7-month-old female patient, born with tetralogy of Fallot. Volume CT dose index (CTDIvol) of this examination was 0.11 mGy, dose length product (DLP) was 1.9 mGycm, water-equivalent diameter was 118 mm. C, D Cardiac examination on energy-integrating detector CT of a 5-month-old female patient, born with atrioventricular septal defect. CTDIvol of this examination was 0.35 mGy, DLP was 5.8 mGycm, water-equivalent diameter was 118 mm. The cardiac anatomy can be very well depicted in both studies, including the coronary arteries (arrows in the axial orientations A and C). B and D show the aortic arch in parasagittal orientation.

Protocol

The study used a CARE keV Image Quality level of 45 as the PCCT reference-mAs control parameter. Acquisition was performed without ECG triggering, using free-breathing high-pitch scanning.

Key Results

Source:
Hellms S, Werncke T, Böttcher J, Happel CM, Eckstein J, Krueger MB, Panknin C, Pfeil A, Kaireit TF, Beerbaum P, Vogel-Claussen J, Wacker F, Renz DM. Reduction of radiation exposure and preserved image quality using photon-counting detector cardiac computed tomography without electrocardiographic gating in children with congenital heart disease. European Radiology. 2026;36:324–333. doi:10.1007/s00330-025-11719-6.

Városmajor Heart and Vascular Centre, Cardiac CT Working Group, Budapest, Hungary

September 29, 2026

History

Why did the patient come for a CT exam?

A 63-year-old female patient, presenting with typical chest pain, was referred for coronary imaging to clarify her coronary status and exclude acute coronary syndrome.

Laboratory tests showed marked myocardial injury and neurohormonal activation, with highly elevated high-sensitivity troponin I of 2032 ng/L, CK of 565 U/L, CK-MB of 43 U/L, and NT-proBNP of 1589.7 pg/mL.

Mild inflammatory activity was also present, with leukocytosis of 12.86 G/L, neutrophilia, and mildly elevated CRP of 6.2 mg/L. Renal function was preserved, with an eGFR of 107 mL/min.

An initial transthoracic echocardiography showed mildly to moderately reduced global left ventricular systolic function, with a left ventricular ejection fraction of 42% by Simpson’s method. Regional wall motion abnormalities were present, with hypokinesis of the midventricular segments and near akinesia of the apical third of the left ventricle. Mild mitral regurgitation and moderate tricuspid regurgitation were present.

Right ventricular size was normal, and right ventricular longitudinal systolic function was preserved. The estimated pulmonary artery systolic pressure was mildly elevated.

Coronary CT angiography (CCTA) was recommended to exclude obstructive coronary artery disease.

Diagnosis

What were the CT findings, and what happened to the patient after CT?

Coronary CT angiography was performed using a dual-source photoncounting detector CT scanner (Siemens NAEOTOM Alpha Peak).

The estimated CCTA radiation dose was 397 mGy·cm. Iomeron 400 was administered with a contrast volume of 90 mL and a flow of 5.5 ml/s. The patient received 0.8 mg sublingual nitroglycerin prior to the examination. Heart rate during the scan was 93–97/min with sinus rhythm.

The coronary calcium score was 4.

The patient had a left-dominant coronary artery system and normal origin and course of the coronary arteries. No relevant coronary atherosclerosis or luminal stenosis were detected. Only minimal vessel wall irregularities were observed, with small specks of calcified plaque in the distal left anterior descending (LAD) artery (Figure 1. and 2.)

Figure 1. CT coronary angiography demonstrating
normal coronary artery anatomy with no
evidence of a significant stenosis.

Figure 2. Electrocardiogram (ECG) during Prospective
Sequential Cardiac CT Acquisition.

Coronary CT angiography was performed using a prospectively ECG-triggered sequential axial acquisition. Given the patient’s heart rate, exceeding 90 beats/min, multiphase image reconstruction was performed to ensure optimal image quality and to allow simultaneous assessment of coronary anatomy and left ventricular function.

In addition to coronary artery evaluation, the multiphase datasets were analyzed for regional wall-motion abnormalities and cardiac chamber volumetry.

Coronary analysis demonstrated non-obstructive coronary artery disease, with only minimal calcified plaque in the distal left anterior descending artery. Functional assessment revealed severe apical hypokinesis/akinesis with associated midventricular dyskinesis and preserved basal contractility, resulting in the characteristic apical ballooning pattern of a classical Takotsubo syndrome (Figure 3).

Figure 3. Left Ventricular Apical Dysfunction Consistent with Takotsubo Pattern on Multiphase Cardiac CT Functional
Analysis. Multiphase cardiac CT-derived left ventricular wall-motion bull’s-eye map demonstrating a regional
gradient of myocardial contractility with preserved basal function (red–yellow), reduced mid-ventricular motion,
and markedly impaired apical wall motion (blue–purple). The pattern shows an apical-dominant distribution of
dysfunction, consistent with a classical Takotsubo-type contraction abnormality in the appropriate clinical context
(left). Mildly increased left ventricular end-diastolic and end-systolic volume indices (indexed to body surface area)
were detected, with mildly reduced systolic function (LVEF 45%) based on the available cardiac phases.

Mildly increased left ventricular end-diastolic and end-systolic volume indices were detected, with mildly reduced systolic function (LVEF 45%).

As an incidental extracardiac finding, scattered bilateral ground-glass opacities with patchy consolidations were detected, most consistent with bronchopneumonia given the elevated inflammatory laboratory markers.

Comments

Is there any clinically interesting aspect of the case to discuss?
What difference did photon-counting CT make for the patient?

This case highlights the clinical value of the photon-counting coronary CT angiography in the diagnostic work-up of patients presenting with acute chest pain, elevated cardiac biomarkers, and electrocardiographic changes suggestive of acute coronary syndrome.

Beyond excluding obstructive coronary artery disease, CT angiography enables comprehensive myocardial functional assessment, allowing identification of the characteristic apical ballooning pattern consistent with Takotsubo syndrome, thereby supporting a working diagnosis of MINOCA – now defined as myocardial injury with non-obstructive coronary arteries (Fifth Universal Definition of Myocardial Infarction, 2026) – with Takotsubo syndrome as the most likely final diagnosis.

The ability of photon-counting CT to simultaneously evaluate coronary anatomy, plaque burden, and left ventricular function in a single examination may facilitate rapid differentiation between obstructive coronary disease and alternative causes of acute myocardial injury, potentially reducing the need for additional imaging or invasive angiography in selected patients.

This case also demonstrates the technical advantages of photoncounting coronary CT angiography for combined coronary and functional cardiac assessment in an acute setting.

The system provides excellent spatial and temporal resolution, enabling high-quality coronary plaque evaluation, even at elevated heart rates (>90 beats/min), with minimal motion artefact. This allows for a reliable assessment of the coronary lumen and detection of only minimal calcified plaque in the distal LAD.

In addition, multiphase ECG-gated reconstructions offer excellent temporal resolution for detailed motion analysis of all cardiac chambers, permitting accurate depiction of regional wall-motion abnormalities.

Overall, the combination of high spatial fidelity for plaque characterization and high temporal resolution for functional assessment underscores the robustness of photon-counting CT for integrated “one-stop” coronary and myocardial evaluation, even under challenging heart rate conditions.

Note that the role of CT in this case should be interpreted within its limits. CCTA was requested to rule out obstructive coronary artery disease in a haemodynamically stable patient; because of the elevated heart rate, a multiphase acquisition was used, which additionally depicted the wall-motion pattern. CCTA can therefore exclude obstructive coronary artery disease and further reinforce echocardiographic findings suggestive of Takotsubo syndrome, but it does not establish the diagnosis on its own. Current recommendations advise cardiac magnetic resonance imaging when the final diagnosis remains uncertain—particularly in the presence of inflammatory red flags—and follow-up echocardiography to document recovery of left ventricular function. In our patient, who was referred to our centre for CT only, further diagnostic work-up and follow-up were performed at the referring institution.

Examination Protocol

DISCLAIMER

The statements by customers of Siemens Healthineers described herein are based on results that were achieved in the customer’s unique setting. Because there is no “typical” hospital and many variables exist (e.g., hospital size, case mix, level of IT and/or automation adoption) there can be no guarantee that other customers will achieve the same results.

The products/features (mentioned herein) are not commercially available in all countries. Their future availability cannot be guaranteed.

Ferenc Imre Suhai, Barbara Sipos, Milán Vecsey-Nagy, Bálint Szilveszter

Városmajor Heart and Vascular Centre, Cardiac CT Working Group, Budapest, Hungary

September 29, 2026

History

Why did the patient come for a CT exam?

A 29-year-old male patient, with a history of hypertension and bronchial asthma, was referred to the Városmajor Heart and Vascular Centre from the emergency department due to acute retrosternal chest pain and markedly elevated cardiac biomarkers.

His symptoms occurred in the setting of a recent upper respiratory tract infection with fever and follicular tonsillitis. He had been treated with azithromycin before admission.

At the emergency department, laboratory tests showed significant inflammatory activity and myocardial injury, with elevated C-reactive protein, leukocytosis with neutrophilia, and markedly elevated high-sensitivity troponin T, which increased from 1302 ng/L to 1689 ng/L. CK-MB was also elevated.

Electrocardiography showed ST-segment elevation in the inferior leads with reciprocal ST depression in aVL.

Transthoracic echocardiography revealed preserved left ventricular systolic function without regional wall motion abnormalities. Given the combination of acute chest pain, elevated troponin, inflammatory syndrome, and ECG changes, acute myocarditis was suspected; however, acute coronary syndrome had to be excluded.

Therefore, a coronary CT angiography was performed as the initial imaging modality to assess the coronary status. Cardiac magnetic resonance imaging was subsequently performed for detailed myocardial tissue characterization and confirmation of the diagnosis.

Diagnosis

What were the CT findings, and what happened to the patient after CT?

Coronary CT angiography was performed using a photon-counting detector CT on a Siemens NAEOTOM Alpha Peak scanner. Native calcium scoring, contrast-enhanced ECG-gated coronary CTA, and a 6-minute delayed-phase acquisition for myocardial tissue characterization and visual assessment of late iodine enhancement were performed.

The estimated radiation dose was 350 mGy·cm for the CCTA and 245 mGy·cm for the delayed scan.

Iomeron 400 was administered with a contrast volume of 80 mL. The patient received 75 mg oral metoprolol and 0.8 mg sublingual nitroglycerin prior to the examination. Heart rate during the scan was 85/min with sinus rhythm.

The coronary calcium score was 0.

The patient had a left-dominant coronary artery system and normal origin and course of the coronary arteries. No relevant coronary atherosclerosis or luminal stenosis were detected (Figure 1).

Figure 1. CT coronary angiography demonstrating normal coronary artery anatomy with no evidence of significant stenosis.

Cardiac magnetic resonance imaging was performed on a 1.5-T Siemens Aera scanner. Short-axis images demonstrate myocardial edema on T2-weighted fat-suppressed imaging and corresponding non-ischemic late gadolinium enhancement on LGE imaging in the mid-ventricular anterior-anterolateral and inferior-inferolateral left ventricular segments, predominantly in a subepicardial to midmyocardial distribution.

The concordant presence of edema and LGE supports acute myocarditis rather than ischemic infarction.

On the 6-minute delayed-phase PCCT images, visually detectable late iodine enhancement was observed, in a non-ischemic distribution. The enhancement involved the basal and midventricular anterolateral and inferolateral regions, the inferior segment in a subepicardial to midmyocardial pattern, and the apical inferior and lateral segments (Figure 2).

Figure 2. Electrocardiogram (ECG) During Prospective Sequential Cardiac CT Acquisition. Multimodality comparison of an acute myocardial injury from basal to apical short-axis images. The first column shows 6-minute delayed-phase PCCT images, the second column shows corresponding color-coded LUT maps, the third column shows iodine maps, and the fourth column shows matched cardiac MRI late gadolinium enhancement images. Blue arrows indicate areas of abnormal myocardial iodine enhancement on PCCT and corresponding non-ischemic myocardial injury on CMR. The abnormalities are predominantly located in the anterolateral, inferolateral, and inferior left ventricular segments, with a subepicardial to midmyocardial distribution, consistent with acute myocarditis.

The visual delayed iodine enhancement pattern indicated abnormal myocardial tissue characteristics and supported the diagnosis of an acute myocarditis.

Cardiac magnetic resonance (CMR) imaging was performed on a 1.5-T Siemens Aera scanner using Gadovist contrast agent. The CMR protocol included cine b-SSFP imaging, T2-weighted imaging, native T1 and T2 mapping, first-pass perfusion, late gadolinium enhancement imaging, and post-contrast T1 mapping for extracellular volume assessment.

CMR demonstrated mildly reduced left ventricular systolic function, with an LVEF of 45.4%. Left ventricular volumes were within the normal range, stroke volume was preserved, and left ventricular myocardial mass was normal. Right ventricular size and systolic function were preserved, with an RVEF of 52.2%.

T2-weighted images demonstrated myocardial edema in the basal and midventricular anterolateral and inferolateral segments, the midventricular inferior and partly anterior segments, and the apical inferior segment, predominantly in a subepicardial to midmyocardial distribution (Figure 3).

Figure 3. Cardiac MRI confirmation of acute myocarditis: myocardial edema and non-ischemic injury

After gadolinium administration, pathological late gadolinium enhancement was observed in the same edematous myocardial segments.

Parametric mapping further supported the diagnosis. Native T1, T2, and ECV values were elevated in the affected lateral myocardial regions. ECV was increased in the basal lateral wall and midventricular lateral wall, while septal values remained within the normal range.

Overall, the CMR findings confirmed acute myocarditis with mildly reduced left ventricular ejection fraction and mild diffuse hypokinesis.

Comments

Is there any clinically interesting aspect of the case to discuss?
What difference did photon-counting CT make for the patient?

This case highlights the potential diagnostic value of photon-counting CT in patients presenting with acute chest pain, elevated cardiac biomarkers, and electrocardiographic changes suggestive of acute coronary syndrome.

The 6-minute delayed-phase acquisition allowed visual assessment of myocardial iodine retention. Delayed-phase spectral reconstruction using monoenergetic plus images and color-coded iodine maps improved visualization of myocardial iodine distribution and enabled myocardial tissue characterization.

Focal subepicardial to mid-myocardial iodine accumulation indicated abnormal myocardial tissue characteristics. The distribution of delayed iodine enhancement corresponded closely to the edema, late gadolinium enhancement, and elevated CMR-derived ECV values in the affected myocardial segments.

An important limitation is the additional radiation exposure associated with the delayed-phase of CT imaging. This is particularly relevant in young patients, in whom radiation dose should be carefully justified and minimized.

Therefore, delayed-phase PCCT acquisitions should not be considered for routine in all patients with suspected myocarditis, but rather reserved for selected cases in which the expected diagnostic benefit outweighs the additional dose, such as when CMR is contraindicated, unavailable, or unlikely to be feasible.

PCCT could serve as a comprehensive first-line imaging tool in selected patients with suspected myocarditis and possible acute coronary syndrome. Its inherent spectral capabilities, together with its high spatial resolution, allow rapid exclusion of obstructive coronary artery disease while also enabling visual myocardial tissue characterization through delayed-phase spectral imaging, monoenergetic reconstructions, and iodine mapping.

These capabilities support comprehensive coronary artery evaluation while simultaneously providing additional insights into myocardial tissue characteristics within a single examination.

Examination Protocol

Disclaimer

The statements by customers of Siemens Healthineers described herein are based on results that were achieved in the customer’s unique setting. Because there is no “typical” hospital and many variables exist (e.g., hospital size, case mix, level of IT and/or automation adoption) there can be no guarantee that other customers will achieve the same results.

The products/features (mentioned herein) are not commercially available in all countries. Their future availability cannot be guaranteed.

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Figure 1. Schematic overview of the CT-based workflow for post-TAVI hemodynamic assessment. Time-resolved cardiac CT was used to derive prosthetic valve hemodynamics after TAVI by combining multiphase left-ventricular volumetry, valve orifice area planimetry, quality control for excluding cases with severe mitral regurgitation and hemodynamic modeling of transvalvular flow.

Protocol

Key Results

Source:
Hyska S, Osoria-Velasquez J, Hagar MT, et al. Photon-counting detector CT for prediction of valve dysfunction after transcatheter aortic valve implantation: Comparison with echocardiography. Journal of Cardiovascular Computed Tomography. Articles in Press. Published September 18, 2026.

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Figure 2: Photon-counting detector CT scan for pre–transcatheter aortic valve replacement planning in an 81-year-old female patient (with contrast material). (A) Electrocardiogram shows a highly irregular heart rate was present at the time of scanning. (B) Contrast-enhanced visualization of the aortic annulus and native aortic valve in the sagittal plane with sharp delineation of the leaflets and a small calcification in the nodule of Arantius (white arrow). (C) Ultra-high-resolution image shows the coronary arteries (Bv56 kernel, multiplanar reformatted image). (D) Conventional reconstructions at 0.6-mm section thickness (Bv40 kernel) for comparison (multiplanar reformatted image). (E, F) Axial reconstructions at the level of the femoral arteries (arrows) without (E) and with (F) iterative metal artifact reduction (IMAR) reconstruction. QIR = quantitative iterative reconstruction.

Protocol

Key Results

Source:
van der Bie J, Sharma SP, van Straten M, Bos D, Hirsch A, Dijkshoorn ML, Adrichem R, van Mieghem NMDA, Budde RPJ. Photon-counting Detector CT in Patients Pre- and Post-Transcatheter Aortic Valve Replacement. Radiology: Cardiothoracic Imaging. 2023;5(2). doi:10.1148/ryct.220318.

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Figure 2. Axial CT images at the level of the aortic aneurysm acquired with photon-counting detector CT in a 60-year-old man referred for follow-up imaging after EVAR: (A) true noncontrast images, (B) arterial phase, (C) venous phase with an arrow pointing at the endoleak, and (D) virtual noniodine images reconstructed from venous phase images.

Protocol

Key Results

Source:
Turrion Gomollon AM, Mergen V, Sartoretti T, Polacin M, Nakhostin D, Puippe G, Alkadhi H, Euler A. Photon-Counting Detector CT Angiography for Endoleak Detection After Endovascular Aortic Repair: Triphasic CT With True Noncontrast Versus Biphasic CT With Virtual Noniodine Imaging. Investigative Radiology. 2023;58(11):816–821. doi:10.1097/RLI.0000000000000993.

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Source: Qin L, et al. Improvement of coronary stent visualization using ultra-high-resolution photon-counting detector CT. 2024.

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Figure 3. Representative case demonstrating potential nitroglycerin-related overestimation of coronary stenosis severity. A 73-year-old man presenting with chest pain underwent photon-counting CCTA following administration of 0.4 mg sublingual nitroglycerin. (A) Curved multiplanar reformatted CCTA image demonstrates a proximal coronary artery diameter of 3.5 mm, a stenotic segment diameter of 1.8 mm, and a distal reference diameter of 3.0 mm. Based on CCTA findings, the lesion was classified as moderate stenosis (CAD-RADS 3, obstructive disease). (B) Invasive coronary angiography demonstrated slightly smaller reference vessel diameters and a slightly larger residual lumen at the stenotic segment, with measurements of 3.3 mm proximally, 1.9 mm at the stenosis, and 2.7 mm distally. Consequently, the lesion was classified as mild stenosis (non-obstructive disease) by invasive coronary angiography. The discrepancy is likely attributable to nitroglycerin-induced vasodilation of adjacent healthy coronary segments, resulting in approximately 10% enlargement of the reference vessel diameter without substantial dilation of the diseased segment. This differential vasodilatory response increases the apparent percentage stenosis on CCTA and may contribute to overestimation of stenosis severity.

Protocol

Key Results

Source:
Kabakus IM, Maisuria DM, Chamberlin JH, Mencken IL, Lopez Rodriguez CG, Sagatelian MM, Burt JR, Baruah D. Is nitroglycerin still necessary for coronary CT angiography in the era of photon-counting CT? Journal of Cardiovascular Computed Tomography. 2026. In Press, Corrected Proof. Available online August 22, 2026. doi:10.1016/j.jcct.2026.08.007.

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Figure1. Representative CTA images of coronary plaques reconstructed in T3D and different VMI energy levels (40, 70, 120, and 180 keV). Quantitative plaque analyses of a partially calcified-predominantly non-calcified (panel A) and partially calcified-predominantly calcified (panel B) plaque are shown in T3D and different VMI reconstructions at 40, 70, 120, and 180 keV levels. The red line illustrates the border of the vessel wall and the orange line illustrates the lumen border segmented on T3D images. Corresponding cross-sectional images are also depicted at the point of the maximal narrowing of the lesion. The same window setting was applied for all represented images: window: 800; level: 250. Abbreviations: CP, calcified plaque; HU, Hounsfield unit; LAP, low-attenuation non-calcified plaque; NCP, non-calcified plaque.

Protocol

Key Results

Source:
Vattay B, Szilveszter B, Boussoussou M, Vecsey-Nagy M, Lin A, Konkoly G, Kubovje A, Schwarz F, Merkely B, Maurovich-Horvat P, Williams MC, Dey D, Kolossváry M. Impact of virtual monoenergetic levels on coronary plaque volume components using photon-counting computed tomography. European Radiology. 2023;33:8528–8539. doi:10.1007/s00330-023-09876-7.

Tateishi, R, Nishimura, T, Tao, S. et al. Photon-Counting Detector Computed Tomography Depicts a Ventricular Tachycardia Substrate: Periaortic Septal Intramural Late Iodine Enhancement. J Am Coll Cardiol Case Rep. 2026 Apr, 31 (15) . https://doi.org/10.1016/j.jaccas.2026.107250

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Visual Summary Spatial Relationship Between LIE on PCD-CT and Arrhythmogenic Substrate(A) Preprocedural photon-counting detector computed tomography image and three-dimensional visualization using ADAS 3D software. The red arrow indicates late iodine enhancement. (B) Isochronal late activation map. Lines of conduction block with split potentials (yellow arrows) were observed in the RVOT and periaortic septal region of the LVOT, spatially corresponding to the edge of the late iodine enhancement area. Ao = aorta; LIE = late iodine enhancement; LV = left ventricle; LVOT = left ventricular outflow tract; RV = right ventricle; RVOT = right ventricular outflow tract; PA = pulmonary artery; PCD-CT = photon-counting detector computed tomography.

Background

Recent studies have demonstrated that delayed enhancement using contrast-enhanced computed tomography corresponds with late gadolinium enhancement on cardiac magnetic resonance imaging. However, few studies have evaluated scar-related ventricular tachycardia (VT) substrates using high-resolution photon-counting detector computed tomography (PCCT).

Case Summary

A 49-year-old man with cardiac sarcoidosis underwent catheter ablation of monomorphic VT. Preoperative iodine mapping on PCD-CT showed late iodine enhancement (LIE) localized to the septal region between the periaortic region and right ventricular outflow tract. Electroanatomic mapping revealed a localized abnormal voltage area and line of conduction block with split potentials colocalized with the LIE. Radiofrequency ablation was performed from both the right and left ventricular outflow tracts and successfully eliminated the VT inducibility. No ICD shocks have occurred after the procedure.

Discussion

PCD-CT provides improved signal detection and superior spatial resolution, enabling visualization of VT substrates in anatomically challenging regions. In patients who are contraindicated for cardiac magnetic resonance imaging, PCD-CT serves as a valuable alternative imaging modality.

Take-Home Messages

The higher spatial resolution of PCD-CT enables a more precise detection of periaortic substrates, whereas detecting late gadolinium enhancement on cardiac magnetic resonance imaging is challenging given a thin myocardium and anatomical complexity.•Because PCD-CT does not have the same restrictions as cardiac magnetic resonance imaging, it can be used in patients with non–MRI-conditional implantable cardioverter-defibrillators to accurately identify and locate ventricular tachycardia substrates.

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Figure 4. Ultra-high-resolution photon-counting detector CT angiography (PCD-CTA) of the heart of a 69-year-old male patient with severe aortic valve stenosis and a history of coronary stent implantation in the distal left main and proximal left anterior descending artery (LAD) (arrowhead in A, B, and C). A Three-dimensional cinematic rendering of the heart, showing the stent in the LAD. B Curved multiplanar reformation showing the absence of in-stent stenosis. The stent was rated as “excellent”—Likert 1 by one reader—and as “good”—Likert 2 by the other reader. C Invasive coronary angiography at caudal 30° view, verifying stent patency

Protocol

Key Results

Source:
Hagar MT, Soschynski M, Saffar R, Molina-Fuentes MF, Weiss J, Rau A, Schuppert C, Ruile P, Faby S, Schibilsky D, von zur Muehlen C, Schlett CL, Bamberg F, Krauss T. Ultra-high-resolution photon-counting detector CT in evaluating coronary stent patency: a comparison to invasive coronary angiography. European Radiology. 2024;34:4273–4283. doi:10.1007/s00330-023-10516-3.

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Figure 2. Representative images of coronary artery calcifications in true noncontrast coronary artery calcium scoring (CACS) (left column), PureCalcium images from coronary CT angiography (CCTA) (middle column), and contrast-enhanced CCTA (right column). All patients underwent CCTA for evaluation of coronary artery disease, with reconstruction in the axial orientation. (A) Images in a 47-year-old female patient with no coronary artery calcifications, P0 in the Coronary Artery Disease Reporting and Data System, or CAD-RADS 2.0. (B) Images in a 70-year-old male patient with mild coronary artery calcifications, P1 in CAD-RADS 2.0. (C) Images in a 72-year-old female patient with moderate coronary artery calcifications, P2 in CAD-RADS 2.0. (D) Images in a 65-year-old male patient with severe coronary artery calcifications, P3 in CAD-RADS 2.0. PureCalcium is a customized algorithm for virtual noncontrast image reconstruction derived from photon-counting CCTA specifically for the purpose of CACS.

Protocol

Key Results

Source:
Haag NP, Michael AE, Lennartz S, Panknin C, Niehoff JH, Borggrefe J, Shahzadi I, Zwanenburg A, Kroeger JR. Coronary Artery Calcium Scoring Using Virtual Versus True Noncontrast Images From Photon-Counting Coronary CT Angiography. Radiology. 2024;310(3). doi:10.1148/radiol.230545.

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Figure 1. Representation of the systematic step-by-step protocol optimization approach. In Step 1, the optimal quantum iterative reconstruction level (14) was identified. In Step 2, the different slice thicknesses were tested from 0.4 to 8 mm. In Step 3, the virtual monoenergetic image reconstruction level of the late iodine enhancement scan was optimized from 40 to 90 keV. The parameter with the best diagnostic performance in each step was retained in the subsequent step.

Protocol

Key Results

Source:
Gnasso C, Pinos D, Schoepf UJ, Vecsey-Nagy M, Aquino GJ, Fink N, Zsarnoczay E, Holtackers RJ, Stock J, Suranyi P, Varga-Szemes A, Emrich T. Impact of reconstruction parameters on the accuracy of myocardial extracellular volume quantification on a first-generation, photon-counting detector CT. European Radiology Experimental. 2024;8:70. doi:10.1186/s41747-024-00469-7.

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Figure 7: Example axial CT reconstructions of in vivo coronary artery calcium scoring (CACS) without and with calcium scoring overlay, comparing CACSTNC (left column: 70 keV, quantum iterative reconstruction [QIR] off) and CACSVNC (middle column: 55 keV, QIR 1, as previously recommended) (9) at standard CACS settings with CACSVNC at the proposed safety net reconstruction (right column: 55 keV, QIR 2). The upper row (participant 1) shows CT scans in a 90-year-old male, the middle row (participant 2) in a 62-year-old male, and the lower row (participant 3) in a 59-year-old female. The safety net reconstruction allowed improved detection of small and/or low-density in vivo plaques (arrowheads) that initially were detected in reference TNC scans but not in standard VNC reconstructions. LAD = left anterior descending artery, RCA = right coronary artery, TNC = true noncontrast, VNC = virtual noncontrast.

Protocol

Key Results

Source:
Fink N, Emrich T, Schoepf UJ, Zsarnoczay E, O’Doherty J, Halfmann MC, Griffith JP III, et al. Improved Detection of Small and Low-Density Plaques in Virtual Noncontrast Imaging–based Calcium Scoring at Photon-Counting Detector CT. Radiology: Cardiothoracic Imaging. 2024;6(4). doi:10.1148/ryct.230328.

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Source: Emrich T, Aquino G, Schoepf UJ, et al. Coronary Computed Tomography Angiography-Based Calcium Scoring: In Vitro and In Vivo Validation of a Novel Virtual Noniodine Reconstruction Algorithm on a Clinical, First-Generation Dual-Source Photon Counting-Detector System. Investigative Radiology. 2022;57(8):536–543. doi:10.1097/RLI.0000000000000868.

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Figure 3. Images show subepicardial late enhancement in a 50-year-old woman with history of arrhythmogenic right ventricular cardiomyopathy. Short- and long-axis cardiac MRI and CT scans demonstrate patchy left ventricular midmyocardial and subepicardial involvement. Enhancement pattern may suggest arrhythmogenic right ventricular cardiomyopathy with left ventricular involvement, although remote myocarditis cannot be ruled out. (A–C) Top row: Images show (A) basal and (B) midventricular short-axis late gadolinium enhancement (LGE) MRI scans with subepicardial involvement (arrows), similarly in (C) the long-axis image. (D–F) Middle row: Images are corresponding CT extracellular volume (ECV) maps showing a similar pattern of myocardial involvement (arrows). (G–I) Bottom row: Images show (G, H) corresponding, short-axis MRI ECV maps demonstrating similar areas of involvement (arrows), and a (I) representative CT ECV American Heart Association 17-segment subepicardiac (50% to outer 10% of the myocardial wall) polar map, which shows the hematocrit (Hct) and the global ECV mean, as well as the means and SDs of ECV for each myocardial segment.

Protocol

Key Results

Source:
Aquino GJ, O’Doherty J, Schoepf UJ, Ellison B, Byrne J, Fink N, Zsarnoczay E, et al. Myocardial Characterization with Extracellular Volume Mapping with a First-Generation Photon-counting Detector CT with MRI Reference. Radiology. 2023;307(2). doi:10.1148/radiol.222030.

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Source: Dang NH, Zhou W, Arguello Fletes GM, et al. Pediatr Radiol. Published online November 18, 2025. doi:10.1007/s00247-025-06467-0.

Furthermore, there is a commentary by Kelly Horst and Lifeng Yu.

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PDF commentary

Source: Horst K, Yu L. Pediatr Radiol. 2025;56:554–555.

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Source: Tóth A, Hagar MT, Halfmann MC, et al. Investigative Radiology. Published ahead of print August 18, 2026. doi:10.1097/RLI.0000000000001309.