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Figure 5. Examples of the clinical implementation of the pediatric abdomen protocol. Axial computed tomography slices in the portal venous phase after intravenous contrast demonstrate the appearances of contrast and noise of the protocol at different ages. Protocol: 70 kV Quantum mode at 53 keV virtual monoenergetic image, IQ level 120, body reconstruction kernel 40, quantum iterative reconstruction 2, 1.0-mm slice thickness. a Six-month-old girl after liver transplantation. b Two-year-old girl prior to liver transplantation. c Six-year-old boy after liver transplantation

Source note for image: Braaksma et al., Pediatric Radiology, 2025.

Standard Protocol

Complex Protocol (not used clinically, optimized for noise & thinner slices)

Source: Braaksma J, Greuter MJW, Verhagen MV. Physics and rationale in pediatric abdomen photon counting detector computed tomography: an investigative review towards development of a pediatric abdomen protocol. Pediatr Radiol. 2025;55:1556–1567. doi:10.1007/s00247-025-06274-7

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Figure 3

Representative CT pulmonary artery scans from both a PCD-CT and an EID-CT. Images A and B were rated by both observers as moderate, and C and D were rated as good by both observers. Images E and F are examples of PE findings for both scanners.

Protocol

Stammen L, Hoeijmakers EJI, Flohr TG, et al. Reducing contrast media dosage for pulmonary embolism CTPA in PCCT. Eur Radiol. 2026;36:3206–3215. doi:10.1007/s00330-025-12054-6

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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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SUPPLEMENTAL APPENDIX

Figure 2. LSA visualisation on DSA, EID-CTA and PCD-CT Note: (A) Rotational angiography; (B) Conventional anterior-to-posterior imaging; (C) 3D angiography cone beam CT (D) Second-generation dual source EID-CTA [flash]; (E) Third-generation dual source EID-CTA [force]; (F) PCD-CT.

Table S1: Detailed information on employed CTA imaging protocols

Protocol

Key Results

Source:
Huijberts I, Wagemans BAJM, Pinckaers FME, Robbe MMQ, van Zwam WH, van Oostenbrugge RJ, Postma AA. Visualisation of lenticulostriate arteries using photon counting detector CT angiography: A retrospective cohort study. European Journal of Radiology. 2026;195:112618. doi:10.1016/j.ejrad.2025.112618.

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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.

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Fig. 3. Case #8. Spheno-orbital meningioma. Coronal T1w post-contrast MRI (A), post-contrast CT (B), and pure-lumen reconstruction (C) delineate the lesion, demonstrating clearer differentiation between tumor parenchyma and vascular structures. Sagittal MIP CTA (D) shows extensive intratumoral radial vascularity and underlying hyperostosis (*). 3D reconstructions show tumor vascularization (E) and a hypertrophic middle meningeal artery (F: arrow).

Figure 4. Case #13. Left fronto-parietal (precentral gyrus) AVM with a large (>4 cm) nidus. DSA (A) demonstrates the AVM nidus with arterial supply from the left ACA and MCA, and superficial venous drainage without deep venous outflow. A 3D reconstruction of contrast-enhanced PCCT (B) depicts the AVM in relation to the surrounding vasculature. Coronal 0.2 mm PCCT reconstruction (C) provides high-resolution and highly detailed delineation of the nidus and adjacent vessels, while a matched 1.6 mm post-contrast MRI reconstruction (D) through the same plane provides cross-modality correlation.

Protocol

Key Results

Source:
Volovici V, Sadigh Y, Dijkshoorn M, van der Eerden A, Gahrmann R, et al. Pre-operative visualization of cerebral vasculature using photon-counting CT ultra-high resolution pure lumen imaging. Brain and Spine. 2026;107451. doi:10.1016/j.bas.2026.107451.

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Figure 5. Typical CT images used to evaluate the incudomalleolar joint. (a), (b), (c), and (d) correspond to the images reconstructed using Hr60, Hr72, Hr76, and Hr84, respectively. Sharper kernels enhanced the visualization of fine structures.

Protocol

Key Results

Source:
Nishii S, Asahara T, Morimitsu Y, Kajisaki S, Akagi N, Honda M, Hayashi H, Sugaya A, Munetomo K, Higaki F, Hiraki T, Iguchi T. Optimization of the reconstruction kernel for temporal bone imaging using photon-counting detector CT: A combined physical and visual evaluation. Radiography. 2026;32(2):103274. doi:10.1016/j.radi.2025.103274.

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 1. Examples of IM hyperattenuating areas that are clearly hyperattenuating on BW images (a,b), only mildly hyperattenuating on BW images (c,d), or not clearly hyperattenuating on BW images (e,f).

Protocol

Key Results

Source:
Pali M-C, Mangesius S, Eisenschink CE, Deisl P, Neumann L, Knoflach M, Pechlaner R, Glodny B, Lenhart L, Gizewski ER, Grams AE. From Iodine Maps to Brain Window Images: Quantitative Visibility Thresholds of Iodine Staining Using Photon-Counting CT—A Retrospective Observational Study. Diagnostics. 2026;16(18):2915. doi:10.3390/diagnostics16182915.

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Figure 3. llustrative case 2. Dynamic (A) and delayed (B and C) contrast-enhanced T1-weighted images at 3T demonstrate a hypoenhancing lesion in the left pituitary (blue arrows). This area is more conspicuous on color-coded iodine maps from the PCD-CT (D–F, white arrows).

Protocol

Key Results

Source:
Mark IT, Michalopoulos G, Van Gompel J, Peris Celda M, Bancos I, Donegan D, Gruber L, Erickson D, Nagelschneider A, Yu L. Pituitary Photon-Counting Detector CT for Cushing Disease: Preoperative Lesion Localization, Intraoperative Findings, and Postoperative Outcomes. American Journal of Neuroradiology. 2025;46(12):2610–2616. doi:10.3174/ajnr.A8893.

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Figure 2. CT scans during follow-up of a patient known with a coiled pulmonary AV malformation in the left upper lobe (red arrow). Axial (a) and coronal (b) images obtained on energy-integrating-detector CT (with intravenous contrast) when the patient was 9 years old (CTDI 3.43 mGy, SSDE 6 mGy, WED 20.5 cm). Axial (c) and coronal (d) images obtained on PCCT using ULDCT protocol (without intravenous contrast) when the patient was 13 years old (CTDI 0.01 mGy, SSDE 0.02 mGy, WED 22.5 cm).

Protocol

Key Results

Source:
Limantoro I, Torfs K, Binst J, Proesmans M, Breysem L, Bosmans H, Aertsen M. Next-gen paediatric imaging: ultra-low dose chest photon-counting CT approaching chest radiograph doses. European Radiology Experimental. 2026;10:119. doi:10.1186/s41747-026-00783-2.

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Figure 1. Comparison of CXR and ULD-CT in 6 patients of our study cohort demonstrating the clinical significance and the limitations of ULD-CT. a, b Consolidation in the right lower lobe, occult in the CXR hidden behind the right diaphragm. c, d Bilateral opacities, occult in the CXR due to the low density. e, f Bilateral opacities in the CXR; the ULD-CT shows the pattern of an organizing pneumonia as additional information. g, h Bilateral opacities in the CXR; the ULD-CT shows the pattern of sarcoidosis as additional information. i, j Bilateral opacities in the CXR; the ULD-CT shows pleural masses. k, l Basal opacities in CXR and consolidation and pleural effusion in ULD-CT; for the diagnosis of a pleural empyema, the ULD-CT was not sufficient and a standard CT with contrast was needed.

Protocol

Key Results

Source:
Dettmer S, Werncke T, Nikolova Mitkovska V, Brod T, Joean O, Vogel-Claussen J, Wacker F, Welte T, Rademacher J. Photon Counting Computed Tomography with the Radiation Dose of a Chest X-Ray: Feasibility and Diagnostic Yield. Respiration. 2024;103(2):88–94. doi:10.1159/000536065.

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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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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.