Photon-Counting CT Clinical Case Reports - Cardiology Edition

Clinical case reports – Cardiology edition Photon-counting CT – impacting clinical outcomes with NAEOTOM Alpha® siemens-healthineers.com/naeotom-alpha SIEMENS Healthineers 2 Photon-counting CT case reports Cardiology Beneath the calcified plaque in the distal right coronary artery 04 Coronary stenosis assessment prior to a transcatheter aortic valve replacement – 06 revascularization? Extensive coronary calcifications with high-risk plaques 08 Multi-vessel coronary stents and high-risk plaques 11 Triple coronary artery bypass grafts and stents 14 Multiple coronary stents with in-stent re-stenosis and a high-risk plaque 17 Single-vessel coronary stents accompanied by high-risk plaques 20 Multi-vessel coronary atherosclerosis – significant stenoses? 23 Severe stenoses in a coronary saphenous vein graft with an external VEST support 25 Photon-counting CT case reports 3 Beneath the calcified plaque in the distal right coronary artery Tilman Emrich, MD1; Moritz Halfmann, MD1; Michaela Hell, MD2 1 Department of Diagnostic and Interventional Radiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany 2 Department of Cardiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany History The lesion in the LAD showed no and negative predictive value. A 62-year-old female patient hemodynamic relevance on invasive However, conventional cCTA presented to the institutional chest FFR. Alongside this lesion, there was examinations suffer from moderate pain unit with typical angina and an diffuse coronary sclerosis, however specificity and positive predictive extensive cardiovascular risk profile. no further relevant stenosis. value. This is mainly due to calcium The combination of the new onset Interestingly, using UHR recon- blooming, an artifact which is caused of symptoms, normal Troponin levels structions (0.2 mm, kernel Bv64), by high density structures such and ECG, as well as a history of a fibrous cap was visualized on top as calcified plaques and metallic arterial hypertension, hyperlipidemia of the calcified plaque in the distal objects, which appear larger than and obesity (BMI 35.6 kg/m2) led to segment 3 of the right coronary their true size. Beside the effect on an intermediate pre-test probability artery (RCA), with a minimal lumen the stenosis grading, calcium for coronary artery disease (CAD). area of 2.2 mm2, which could not blooming also suppresses accurate To assess or rule-out CAD, a be depicted in standard resolution plaque characterization. Hence, coronary CT angiography (cCTA) reconstructions (0.6 mm, kernel small, but relevant components of was performed using a dual source Bv40) from the same examination, plaques such as fibro-fatty lesions photon-counting detector (PCD) CT with a minimum lumen area of and/or fibrous caps may be not (NAEOTOM Alpha®) in ultra-high 1.6 mm2. OCT confirmed a fibro-fatty recognizable in conventional cCTA resolution (UHR) mode. lesion with a fibrous cap beneath the examinations because of limited calcification and a minimal luminal spatial resolution and blooming Diagnosis area of 2.3 mm2, in good agreement artifacts. UHR PCD-cCTA offers with the UHR-reconstruction. improved spatial resolution and A calcium score scan demonstrated Angiographic findings led to the may be a promising technical a severe coronary plaque burden initiation of an intensified medical development to overcome these (P3), with calcifications in all three therapy with statins for secondary limitations as demonstrated coronary territories (calcium volume prevention. in this case report. The fibro-fatty 795 mm3, Agatston score 993). lesion with a fibrous cap was verified cCTA images revealed a CAD-RADS 3 by invasive OCT as ground truth. (moderate stenosis, 50%–69%) Comments Since invasive coronary angiography lesion in the left anterior descending CAD is the leading cause of morbidity with functional testing did not coronary artery (LAD), combined and mortality in the western world. reveal flow-limiting disease, and with the clinical presentation, cCTA has emerged into one of the a high Agatston Score (993) as well triggered an invasive coronary most clinically used diagnostic as a high blood cholesterol level angiography (ICA) with fractional procedures for the workup of patients (248 mg/dL) were present, the flow reserve (FFR) and optical with stable angina and suspected patient was put on an intensified coherence tomography (OCT). CAD due to its excellent sensitivity medical therapy with statins. 4 Photon-counting CT case reports 1a Examination Protocol Scanner NAEOTOM Alpha Scan area Heart Scan mode Quantum HD Cardiac Scan length 150 mm Scan direction Cranio-caudal Scan time 7 s Tube voltage 120 kV Effective mAs 54 mAs Dose modulation CARE Dose4D CTDIvol 8.8 mGy 1b DLP 113 mGy*cm Rotation time 0.25 s Pitch 1.0 Slice collimation 120 × 0.2 mm Slice width 0.2 mm Reconstruction 0.2 mm increment Reconstruction kernel Bv64, QIR 4 Heart rate 65 bpm Contrast 370 mg/mL Volume 70 mL + 20 mL saline 1c Flow rate 5 mL/s Start delay Test bolus + 5 s 1 In the image reconstructed with standard resolution (Bv40, 0.6 mm) (Fig. 1a), only calcified plaques are visible in the distal segment 3 of the RCA. In the UHR image (Bv64, 0.2 mm) (Fig. 1b), a fibrous cap beneath the calcified plaque is visualized, due to reduced calcium blooming. OCT correlation (Fig. 1c) of the same plaque confirms the plaque composition. 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. Photon-counting CT case reports 5 Coronary stenosis assessment prior to a transcatheter aortic valve replacement – revascularization? Prof. Hatem Alkadhi, MD Diagnostic and Interventional Radiology, University Hospital Zurich, Switzerland History UHR images, showing less than 50% Examination Protocol A 62-year-old male patient with diameter stenosis. Subsequently, severe symptomatic low-flow, the cCTA results from the UHR image Scanner NAEOTOM Alpha low-gradient aortic stenosis was evaluation were confirmed by an Scan area Heart scheduled for transcatheter aortic invasive catheter coronary angio- Scan mode Quantum HD valve replacement (TAVR). A coronary graphy. Coronary revascularization Cardiac CT angiography (cCTA) was performed was considered not necessary, and prior to the procedure, using an the patient underwent the TAVR Scan length 145 mm ultra-high resolution (UHR) scan procedure with a good outcome. Scan direction Cranio-caudal mode due to the patient’s high Scan time 5.5 s coronary calcium load. Comments Tube voltage 120 kV In the diagnostic workup of patients Diagnosis Effective mAs 58 mAs with suspected coronary artery The assessment of the calcium disease, cCTA has shown an excellent Dose modulation CARE Dose4D scoring revealed an Agatston score sensitivity and negative predictive CTDIvol 28.8 mGy of 1,188, being beyond the 90th value. However, it is still challenging DLP 471 mGy*cm age- and gender-percentile. The in patients with a high coronary calci- um burden – in the presence of severe Rotation time 0.25 s cCTA images were reconstructed at 0.6 mm with a standard resolution calcifications, calcium blooming may Pitch 0.26 kernel of Bv40 (reference images), affect the delineation of the luminal Slice collimation 120 x 0.2 mm as well as at 0.2 mm with a sharper stenosis leading to an overestimation of the stenosis grade. To overcome Slice width 0.2 mm kernel of Bv60 (UHR images). A this shortcoming, an increased spatial Reconstruction 0.2 mm stenosis at the proximal right resolution, which reduces partial increment coronary artery (RCA) caused by calcified plaques was seen and volume effects, is desired. [1] Reconstruction Bv40/Bv60, therefore an evaluation of the vessel This case was performed on a newly kernel QIR4 lumen was performed using both developed Dual Source CT scanner, Heart rate 74 bpm the reference images and the UHR NAEOTOM Alpha®, with photon- images. The reference images counting detectors (QuantaMax®). showed a moderate stenosis (84% It provides energy-resolved CT data Contrast 370 mg/mL in area and 60% in diameter) while with improved spatial resolution, Volume Triphasic injection: the latter revealed a mild stenosis without electronic noise, which is • 55 mL pure CM (61% in area and 38% in diameter). eliminated by setting up a predefined • 55 mL (20% CM, The blooming effect of the calcified digital threshold for counting X-ray 80% Saline) plaques affecting the visualization photons far above the electronic • 20 mL pure Saline of the vessel lumen and the stenosis noise floor. This leads to less image Flow rate 5.5 mL/s grading was clearly reduced in the noise. [2] An UHR mode is predefined UHR images. Other stenoses caused for cCTA scans, featuring a slice Start delay Bolus tracking by calcified plaques in the left main collimation of 120 x 0.2 mm, in triggered at (LM) and the left anterior descending which the sub-pixels of the detector 100 HU in the artery (LAD) were also evaluated with with a size of 0.15 x 0.18 mm2 ascending aorta +5 s 6 Photon-counting CT case reports 1a 1b 1c (at the isocenter) are read out 1 Curved MPR images (Figs. 1a & 1b) show a proximal RCA stenosis caused by calcified individually. There are no physical plaques (arrows). Images are reconstructed at 0.6 mm with kernel Bv40 (Fig. 1a) and septa between the sub-pixels. at 0.2 mm with kernel Bv60 (Fig. 1b). The corresponding axial slices, perpendicular To reduce scattered radiation, each to the vessel centrelines at the stenosis, are shown in the left lower corners. group of 4 x 6 sub-pixels is confined The blooming effect of the calcified plaques affecting the visualization of the vessel by collimator grids. This increases lumen and the stenosis grading is clearly reduced in the UHR images. An invasive catheter coronary angiography (Fig. 1c) confirmed a mild stenosis in the proximal the spatial resolution without RCA (arrow) consistent with the result from the UHR image evaluation. degrading the geometric dose effi- ciency of the detector, resulting in an improved anatomic delineation 2a 2b of plaque characteristics and vessel lumen. Image noise can be further reduced by applying a model-based iterative reconstruction approach – Quantum Iterative Reconstruction (QIR) – in the image reconstruction process. Owing to the reduced image noise, even UHR images can be used for three-dimensional reconstructions, such as cinematic volume rendering technique (cVRT), demonstrating a photo-realistic visualization of anatomical details. 2 cVRT images reconstructed with reference images (Fig. 2a) and UHR images As shown in this case, the UHR (Fig. 2b), using the same preset, show the differences in the delineation of the mode, provided by a photon- calcified plaques, the stenosis (arrows) and the small vessels in three dimensions. Note that even UHR images as thin as 0.2 mm reconstructed with sharper kernel counting CT for cCTA examinations, of Bv60 can be used to create a cVRT image with optimal image quality, owing to enables the visualization of calcified the reduced image noise. coronaries with reduced blooming effect and improved sharpness. This may enhance the confidence References The statements by customers of Siemens of the physicians in evaluating Healthineers described herein are based on coronary stenosis for patient with [1] V. Mergen, et al. Ultra-High-Resolution results that were achieved in the customer’s Coronary CT Angiography with Photon- unique setting. Because there is no “typical” high coronary calcium burden Counting Detector CT – Feasibility and hospital and many variables exist (e.g., hospital and, as the decision on coronary Image Characterization. Invest Radiol. size, case mix, level of IT and/or automation revascularization depends upon 2022 Dec 1; 57(12):780-788. adoption) there can be no guarantee that other customers will achieve the same results. the degree of stenosis, may have an impact on the management of [2] Thomas Flohr, et al. Photon-counting The products/features (mentioned herein) are CT review. Physica Medica 79 (2020) not commercially available in all countries. the patient. 126–136. Their future availability cannot be guaranteed. Photon-counting CT case reports 7 Extensive coronary calcifications with high-risk plaques Muhammad Taha Hagar, MD; Prof. Christopher L. Schlett, MD, MPH; Prof. Fabian Bamberg, MD Department of Diagnostic and Interventional Radiology, University Medical Center Freiburg, Germany History Diagnosis A 64-year-old male patient, with a The assessment of the calcium score consensus statements, [2] this positive family history of myocardial revealed a severe coronary plaque patient’s CCTA was classified as ischemia and coronary artery burden (P4) with an Agatston score CAD-RADS 2/P4/HRP. Subsequently, disease, presented himself to the of 1172, being beyond the 90th the patient was referred to an hospital complaining of atypical age- and gender-percentile. Extensive outpatient cardiologist. Risk factor chest discomfort during exercise calcifications were shown in the modification, intensive preventive and palpitations at rest. A blood proximal left anterior descending pharmacotherapy with statins test revealed a normal level of artery (LAD) and proximal right and a short-term clinical follow up cholesterol and a slight elevation of coronary artery (RCA). To reduce were recommended. triglycerides (204 mg/dl). In a recent the potential calcium blooming stress-ECG examination, ventricular interferences and to improve the visualization of the spatial details, Comments extrasystoles were observed during the maximum exercise phase and a UHR mode was selected for the High risk plaque (HRP), previously the primary post-exercise phase. following cCTA which provided diag- known as “vulnerable plaque”, Given the low to intermediate nostic images – two mixed plaques featuring spotty calcifications, pretest probability of coronary artery with high-risk features in the proximal low attenuation plaque (< 30 HU), disease (CAD), in line with current LAD and RCA were evident, character- positive remodeling, and the “napkin international guidelines, [1] a ized by a hypoattenuating plaque ring sign”, is associated with a coronary CT angiography (CCTA) component (<30HU) and positive higher risk of future acute coronary was performed on a Dual Source remodeling. Mild coronary stenoses syndrome (ACS) and lesion specific photon-counting CT (PCCT), (25–49%) were visualized in the proxi- ischemia, independent of stenosis NAEOTOM Alpha®, using an mal LAD and RCA. The circumflex severity. HRP has been incorporated ultra-high resolution (UHR) mode (Cx) showed non-calcified plaques, in the CAD-RADS recommendations (Quantum HD cardiac) to rule however, was free from stenosis. as a modifier, suggesting that the out exercise-induced coronary The left ventricle was of a normal size, identification of the HRP should insufficiency as a potential with a normal ejection fraction (EF) signify the need for more aggressive underlying cause of his symptoms. of 69%, without any hypertrophy. preventive therapies, also including According to the CAD-RADS 2.0 nonobstructive lesions. [2] Studies 1a 1b 1 Axial images from the calcium scoring scan show extensive calcifications in the proximal LAD (Fig. 1a) and RCA (Fig. 1b) resulting in an Agatston score of 1172, being beyond the 90th age- and gender-percentile. 8 Photon-counting CT case reports have shown that half of culprit management to a more patient- and of Quantum iterative reconstruction plaques that cause major adverse lesion-specific targeted approach. at full strength (QIR level 4) further cardiovascular events (MACE) arise reduces image noise and enhances from plaques that had previously Identifying the HRP features in CT image clarity. caused a stenosis < 50% [3]. It is imaging requires optimal spatial of crucial importance for patient and temporal resolution, as well As shown in this case, CCTA with UHR management to have a more as minimization of blooming mode provides crucial information accurate, patient-specific risk interference caused by calcified about the patient's cardiac health stratification. In this case, a statin plaques. This case applies a UHR even in the presence of severe therapy is primarily indicated due to mode featuring a slice collimation of coronary calcifications – it helps the the presence of extensive coronary 120 x 0.2 mm for image acquisition physicians identify HRP and rule out calcification, patient’s age and family and a sharp kernel (Bv64) for image obstructive coronary heart disease. history, despite the absence of an reconstruction – a special scan mode Owing to the optimal image quality elevated cholesterol level and severe that is currently only available on achieved by Quantum HD cardiac, coronary stenosis. However, the PCCT. [4] Recent clinical studies have CT findings help in patient risk identification of the HRP warrant a reported an impressive success rate stratification, and guiding patient closer clinical follow-up, and imaging and diagnostic accuracy using this management. As this patient did monitoring of lesion-specific plaque mode for coronary evaluation, not need to undergo invasive angio- progression, inducing changes even in the presence of extensive graphy after CT evaluation, the in the decision making of patient calcification. [5] The incorporation associated cost could be reduced. 2a 2b 2c LAD RCA CX 02 5L min min 2 Curved Multiplanar Reformations (MPR, 0.2 mm) of the coronary arteries reveal non-obstructive stenoses (<50%) in the proximal LAD (Fig. 2a) and RCA (Fig. 2b) with a clear lumen exhibiting no noticeable blooming artifact interference despite of the presence of extensive calcifications. Two mixed plaques with high-risk features, characterized by a hypoattenuating plaque component (<30HU) and positive remodeling, are evident in the proximal LAD and RCA. The Cx (Fig. 2c) shows non-calcified plaques, and is free from stenosis. Photon-counting CT case reports 9 References 3a 3b [1] J. Knuuti, et al. 2019 ESC Guidelines for the diagnosis and management of chronic coronary syndromes. The Task Force for the diagnosis and management of chronic coronary syndromes of the European Society of Cardiology (ESC), Russ. J. Cardiol. 25 (2020) 119–180. https://doi.org/10.15829/1560-4071- 2020-2-3757. [2] R.C. Cury, et al. CAD-RADS™ 2.0 – 2022 Coronary Artery Disease – Reporting and Data System: An Expert Consensus Document of the Society of Cardio- vascular Computed Tomography (SCCT), the American College of Cardiology (ACC), the American College of Radiology (ACR), and the North America Society 3 Three-dimensional Cinematic Rendering images highlight the calcified plaques in the proximal LAD and RCA (in blue). Note that the images used for the rendering of Cardiovascular Imaging (NASCI), are reconstructed at 0.2 mm with a sharp kernel of Bv64. J. Cardiovasc. Comput. Tomogr. 16 (2022) 536–557. https://doi.org/10.1016/j. jcct.2022.07.002. Examination Protocol [3] J. Taron, et al. A review of serial coronary computed tomography angiography Scanner NAEOTOM Alpha (CTA) to assess plaque progression and therapeutic effect of anti-atherosclerotic Scan area Heart Heart drugs. Int J Cardiovasc Imaging. 2020 December ; 36(12): 2305–2317. Scan mode Calcium score, CCTA, doi:10.1007/s10554-020-01793-w. Turbo Flash mode UHR mode [4] V. Mergen, et al. Ultra-High-Resolution Scan length 138 mm 124.5 mm Coronary CT Angiography With Scan direction Cranio-caudal Cranio-caudal Photon-Counting Detector CT: Feasibility and Image Characterization, Invest. Scan time 0.18 s 8.8 s Radiol. (2022). https://doi.org/10.1097/ RLI.0000000000000897. Tube voltage 90 kV 120 kV Effective mAs 12 mAs 48 mAs [5] M.T. Hagar, et al. Accuracy of Ultrahigh- Resolution Photon-counting CT for Dose modulation CARE Dose4D CARE Dose4D Detecting Coronary Artery Disease in a High-Risk Population, Radiology. CTDIvol 0.85 mGy 29.9 mGy 307 (2023) e223305. https://doi. DLP 16.7 mGy*cm 421 mGy*cm org/10.1148/radiol.223305. Rotation time 0.25 s 0.25 s Pitch 3.2 0.15 Slice collimation 144 x 0.4 mm 120 x 0.2 mm Slice width 2.0 mm 0.2 mm Reconstruction increment 2.0 mm 0.1 mm Reconstruction kernel Bv40 Bv64, QIR 4 Reconstruction matrix 512 x 512 1024 x 1024 The statements by customers of Siemens Healthineers described herein are based on Heart rate 47 bpm 51 bpm results that were achieved in the customer’s unique setting. Because there is no “typical” Contrast N/A 370 mg/mL hospital and many variables exist (e.g., hospital size, case mix, level of IT and/or automation Volume N/A 85 mL + 49 mL saline adoption) there can be no guarantee that other customers will achieve the same results. Flow rate N/A 6 mL/s The products/features (mentioned herein) are Start delay N/A Test Bolus not commercially available in all countries. Their future availability cannot be guaranteed. 10 Photon-counting CT case reports Multi-vessel coronary stents and high-risk plaques Muhammad Taha Hagar, MD1; Tobias Krauss, MD1; Constantin von zur Mühlen, MD2; Fabian Bamberg, MD, MPH1 1 Department of Radiology, University of Freiburg, Freiburg, Germany 2 Department of Cardiology, University of Freiburg, Freiburg, Germany History connected (3.5 mm) in the distal left x-ray photons in a semiconductor. A 48-year-old male patient, suffering anterior descending artery (LAD), The individual detector pixels are from a Non-ST-Elevation Myocardial and a large one (3 mm) in the distal defined by a strong electric field Infarction (NSTEMI), underwent circumflex (Cx). All the stents were without the need of septa between percutaneous coronary intervention free of in-stent stenosis. A non- them, therefore, small subpixels can (PCI) with multi-vessel coronary calcified plaque in the proximal be realized without loss of radiation stent implantations two years ago. RCA was seen, causing mild stenosis dose efficiency. This enables imaging The patient had no traditional risk (25 – 49%). Two other non-calcified at an improved spatial resolution factors for coronary artery disease plaques with high-risk plaque (HRP) of 110 × 110 × 160 µm3. [4] (CAD). This unexpected incident had features of spotty calcifications and The significance of these techno- profoundly affected his life, causing positive remodeling, were seen in logical advancements is underscored substantial stress, and even panic the proximal and mid LAD, causing attacks leading to several emergency mild stenosis. CT findings were classi- by recent studies, which have department visits. The patient also fied as CAD-RADS 2/P2/HRP/S. Due to demonstrated the potential of PCD- absence of acute symptoms, further CT to reduce artifacts and improve discontinued his statin therapy due invasive workup was not necessary. image quality in non-invasive stent to adverse effects. Given the patient's assessment, compared to traditional relatively young age and the psycho- energy-integrating detector (EID) CT. logical impact on his symptoms, a Comments [5] Initial human studies and phan- non-invasive diagnostic method was tom studies have shown promising preferred over an invasive catheter- CCTA is an indispensable diagnostic ization procedure for follow-up. tool for ruling out obstructive CAD results for UHR PCD-CT in stent evalu- in patients with a low to intermedi- ation, particularly when employing Therefore, a coronary CT angiography ate risk profile. [1] While its use in a sharp vascular convolution kernel. (CCTA) was performed on a novel dual- patients with pre-existing CAD is [6,7] This approach has facilitated source photon-counting detector (PCD) CT scanner, NAEOTOM Alpha®, generally more restrained, recent optimal in vivo visualization of using an ultra-high resolution (UHR) guidelines from the American Heart stent lumens, with a recent study Association have recognized the achieving a 100% negative predictive scan mode (Quantum HD Cardiac) to value of assessing stent patency for value for stent patency evaluation evaluate the coronary plaque burden against invasive angiography as the and associated risks, as well as the patients experiencing symptomatic changes despite guideline-directed reference standard. [8] patency of the stents. The patient was prepared with intravenous management and therapy – if stents The use of Quantum HD Cardiac CT administration of 10 mg Metoprolol with an internal diameter of 3 mm in this case was beneficial for the and two sublingual doses of or greater are present. [2] patient, allowing for a non-invasive Nitroglycerin prior to the CT scan. The diagnostic challenge posed by assessment of stent patency and blooming artifacts, resulting from coronary artery disease. Further- Diagnosis severely calcified plaques or the more, the detection of the HRPs stents’ material, has limited the util- necessitates a more aggressive UHR CCTA images showed five patent ity of CCTA in this context. [3] The preventive pharmacotherapy. stents with different diameters* – introduction of the novel PCD-CT Given the patient's adverse reaction one (4 mm) in the proximal right technology represents a significant to statins, alternative medications coronary artery (RCA), another small advancement in overcoming these such as PCSK9 inhibitors or ezetimibe one (2.5 mm) in the posterolateral challenges: This technology relies on could be considered, which have branch of the distal RCA, two inter- a direct conversion of the incoming been shown to reduce LDL choles- Photon-counting CT case reports 11 1a 1b 1c 1 Curved MPR images show 5 patent stents with different diameters – one (4 mm) in the proximal RCA, another small one (2.5 mm) in the postero- lateral branch of distal RCA (Fig. 1a), two interconnected (3.5 mm) in the distal LAD (Fig. 1b) and a large one (3 mm) in the mid Cx (Fig. 1c). No signs of in-stent re-stenosis were evident in all stents, including the small one in the distal RCA. A non-calcified plaque (Fig. 1a, arrow) in the proximal RCA is seen causing mild stenosis. Two other non-calcified plaques are seen in the proximal and mid LAD causing mild stenoses (Fig. 1b, arrows). Note that the stent struts and the calcified plaque components can be visually well distin- guished (Fig. 1c). terol effectively. [9] As there were In summary, PCD-CT's ability to with PCD-CT grows, it might start no target lesions observed, no accurately assess patients with stents to shape management practices additional invasive workup was has confirmed its value in cardiac and influence clinical guidelines. required. The unspecific symptoms imaging. This reliable method could the patient experienced was expand the use of non-invasive considered unlikely derived from techniques. As clinical availability, progression of his previous CAD. experience and scientific evidence * Stent diameters were measured on CT images. The specific stent sizes were unknown due to external referral. Examination Protocol Scanner NAEOTOM Alpha Scan area Heart Rotation time 0.25 s Scan mode UHR mode Pitch 0.16 (Quantum HD Cardiac) Slice collimation 120 × 0.2 mm Scan length 129.6 mm Slice width 0.2 mm Scan direction Cranio-caudal Reconstruction increment 0.1 mm Scan time 7.6 s Reconstruction matrix 1024 × 1024 Tube voltage 120 kV Reconstruction kernel Bv60 / Bv72 (QIR Level 4) Effective mAs 59 mAs IQ level 79 Contrast 370 mg/mL Dose modulation CARE Dose4D Volume 80 mL + 50 mL saline CTDIvol 41.4 mGy Flow rate 6.0 mL/s DLP 581 mGy*cm Start delay Test Bolus 12 Photon-counting CT case reports 2a 2b 2 An axial image and a curved MPR image show two non-calcified plaques (arrows) with HRP features of spotty calcifications and positive remodelling in the proximal and mid LAD causing mild stenosis. 3a 3b 3 Two cinematic rendering images show an overview of 5 patent stents with different diameters – one (4 mm) in the proximal RCA, another small one (2.5 mm) in the postero- lateral branch of the distal RCA, two interconnected (3.5 mm) in the distal LAD and a large one (3 mm) in the mid Cx. Mild stenoses are shown in the proximal RCA, proximal LAD and mid LAD (arrows). References [1] Knuuti J. 2019 ESC Guidelines for the [4] Mergen V, Sartoretti T, Baer-Beck M, [8] Hagar MT, Soschynski M, Saffar R, et al. diagnosis and management of chronic et al. Ultra-High-Resolution Coronary CT Ultra-high-resolution photon-counting coronary syndromes The Task Force for Angiography With Photon-Counting detector CT in evaluating coronary stent the diagnosis and management of Detector CT: Feasibility and Image patency: a comparison to invasive chronic coronary syndromes of the Characterization. Invest Radiol. coronary angiography. Eur Radiol. 2024; European Society of Cardiology (ESC). 2022;57(12):780–788. doi: 10.1097/ doi: 10.1007/s00330-023-10516-3. Russ J Cardiol. 2020;25(2):119–180. RLI.0000000000000897. doi: 10.15829/1560-4071-2020-2-3757. [9] Hao Q, Aertgeerts B, Guyatt G, et al. [5] Boccalini S, Si-Mohamed SA, Lacombe H, PCSK9 inhibitors and ezetimibe for [2] Gulati M, Levy PD, Mukherjee D, et al. et al. First In-Human Results of Computed the reduction of cardiovascular events: 2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/ Tomography Angiography for Coronary a clinical practice guideline with SCMR Guideline for the Evaluation and Stent Assessment With a Spectral Photon risk-stratified recommendations. BMJ. Diagnosis of Chest Pain: A Report of the Counting Computed Tomography. 2022;377:e069066. doi: 10.1136/ American College of Cardiology/American Invest Radiol. 2022;57(4):212–221. bmj-2021-069066. Heart Association Joint Committee on doi: 10.1097/RLI.0000000000000835. Clinical Practice Guidelines. Circulation. American Heart Association; 2021; [6] Geering L, Sartoretti T, Mergen V, et al. 144(22):e368–e454. doi: 10.1161/ First in-vivo coronary stent imaging with clinical ultra high resolution CIR.0000000000001029. photon-counting CT. J Cardiovasc Comput The statements by customers of Siemens Healthineers described herein are based on [3] Pack JD, Xu M, Wang G, Baskaran L, Tomogr. 2023;S1934-5925(23)00085-0. results that were achieved in the customer’s Min J, De Man B. Cardiac CT blooming doi: 10.1016/j.jcct.2023.02.009. unique setting. Because there is no “typical” artifacts: clinical significance, root causes and potential solutions. Visual [7] Decker JA, O’Doherty J, Schoepf UJ, et al. hospital and many variables exist (e.g., hospital size, case mix, level of IT and/or automation Computing for Industry, Biomedicine, Stent imaging on a clinical dual-source adoption) there can be no guarantee that and Art. 2022;5(1):29. doi: 10.1186/ photon-counting detector CT system- other customers will achieve the same results. impact of luminal attenuation and sharp s42492-022-00125-0. kernels on lumen visibility. Eur Radiol. The products/features (mentioned herein) are 2023;33(4):2469–2477. doi: 10.1007/ not commercially available in all countries. s00330-022-09283-4. Their future availability cannot be guaranteed. Photon-counting CT case reports 13 Triple coronary artery bypass grafts and stents Lili Száraz, MD; Prof. Pál Maurovich-Horvat, MD, PhD, MPH; Bálint Szilveszter, MD, PhD Semmelweis University, Medical Imaging Center, Budapest, Hungary History A 46-year-old male patient, been laid over the main pulmonary patency of the grafts, the anastomo- complaining of atypical chest pain, artery and were anastomosed end-to- ses and the stents. Traditionally, presented himself to the hospital. side to the first (D1) and the inter- graft patency is assessed using He had an elevated cardiovascular mediate (IM) diagonal branches of invasive coronary angiography (ICA); risk including a history of smoking the LAD. All grafts and anastomoses however, the procedure carries an and hypertension. Five years ago, remained patent, with no evidence associated risk of complications and he had suffered a Non-ST-Elevation of stenosis or occlusion. Three inter- encounters technical difficulties. Myocardial Infarction (NSTEMI) and connected stents (3 mm in diameter, Over the past decade, CCTA has been had undergone triple coronary artery 71 mm in length), from the origin increasingly performed in post-CABG bypass grafting (CABG) of the left through the middle segment of the assessment, as it is non-invasive and coronary arteries, as well as coronary RCA, were seen free of in-stent can reliably depict the entire course stenting with three drug-eluting restenosis. of the grafts with a single bolus of stents (DES) of the right coronary contrast media with a short acquisi- artery (RCA). Grafting was not con- Extensive calcifications were visual- tion time. [1] CCTA assessment for sidered suitable for the RCA at the ized in the original coronary arteries, the patency of coronary stents, using time. The patient had been on a causing moderate stenosis (50–69%) conventional CT, has been limited to pharmacotherapy regimen including in the left main coronary artery (LM) a borderline of 3 mm stent diameter aspirin, Clopidogrel and beta-blocker. and the posterior descending artery in the American Heart Association A CT follow-up scan was requested (PDA), severe stenosis (70–99%) guidelines for patients who experi- to evaluate the patency of the grafts, in the proximal LAD, occlusions in ence symptomatic changes despite the anastomoses and the stents. the mid-LAD, proximal and mid-Cx. guideline-directed management and An ultra-high resolution (UHR) The coronary system was right therapy. [2] coronary CT angiography (CCTA) dominant. The gracile Cx was not was therefore performed on a dual- considered suitable for intervention. A recent study using the UHR mode source photon-counting detector There was no evidence of any cardiac of PCD-CT achieved a 100% negative CT (PCD-CT), NAEOTOM Alpha®. structural abnormalities. predictive value for coronary stent The patient received oral Metoprolol patency evaluation against invasive (50 mg) and sublingual spray of Based on the CCTA findings, no angiography as the reference Nitrate (0.8 mg) prior to the CT scan. further invasive examination was standard. [3] This result showed the considered and the patient was potential improvement of PCD-CT in Diagnosis recommended to begin with the stent imaging. The combination intensified statin treatment. of high temporal resolution (66 ms) CCTA images revealed triple bypass from the dual source principle and grafts with three coronary anastomo- the increased spatial resolution pro- ses. A left internal mammary artery Comments vided by PCD-CT improves optimal (LIMA) graft, originating off the left CABG and coronary stenting are image quality, effectively overcoming subclavian artery (LSA), was anasto- performed in patients with obstruc- the blooming artifact caused by stent mosed end-to-side to the distal LAD. tive coronary artery disease to struts or calcifications. [4] The Two right saphenous vein grafts improve myocardial blood flow and photon-counting detectors do not (SVGs), originating from the anterior alleviate symptoms. The long-term require optical crosstalk to be pre- wall of the ascending aorta, had clinical outcome depends upon the vented by separating layers between 14 Photon-counting CT case reports 1a 1b 1 Cinematic VRT images show an overview of three patent bypass grafts – a LIMA graft anastomosed to the distal LAD (arrowhead) and two SVG anastomosed to the D1 (arrow) and the IM (dotted arrow) of the LAD. The stented RCA is also patent. 2a 2b 2c 2d 2 Curved MPR images show the patency of the anastomoses (arrows): LIMA-distal LAD (Fig. 2a–2b), SVG-D1 (Fig. 2c) and the SVG-IM (Fig. 2d). the individual detector elements. resulting in small subpixels without clinician using the UHR images. The individual detector pixels are loss of radiation dose efficiency. No additional invasive workup was defined by a strong electric field. In this case, the patency of the required, as no target lesions were Therefore, they can be more finely triple CABG and the stents, as well observed, which spared the associat- structured than scintillation detec- as the original coronary arteries, ed risks and costs of invasive coro- tors, [5] are successfully evaluated by the nary angiography for this patient. Photon-counting CT case reports 15 Examination Protocol 3 Scanner NAEOTOM Alpha Scan area Heart Scan mode UHR mode (Quantum HD Cardiac) Scan length 226.8 mm Scan direction Caudal-cranial Scan time 13.4 s Tube voltage 120 kV Effective mAs 61 mAs IQ level 64 Dose modulation CARE Dose4D CTDIvol 35.3 mGy DLP 838 mGy*cm Rotation time 0.25 s Pitch 0.18 Slice collimation 120 × 0.2 mm Slice width 0.2 mm Reconstruction increment 0.2 mm 3 A curved MPR image shows the Reconstruction kernel Bv64, QIR3 patency of the three interconnected stents in the RCA without in-stent Reconstruction matrix 1024 × 1024 restenosis. Moderate stenoses, mostly caused by calcified plaques, Heart rate 66–73 bpm are shown in the PDA. Contrast Iomeron 400 mg/mL Volume Four-phasic injection protocol: The statements by customers of Siemens Healthineers described herein are based on • 10 ml pure Saline • 83 mL pure CM results that were achieved in the customer’s unique setting. Because there is no “typical” • 30 mL (40% CM, 60% Saline) hospital and many variables exist (e.g., hospital • 50 mL pure Saline size, case mix, level of IT and/or automation adoption) there can be no guarantee that Flow rate 5 mL/s other customers will achieve the same results. Start delay Bolus tracking triggered at 150 HU The products/features (mentioned herein) are in the left atrium + 3 s not commercially available in all countries. Their future availability cannot be guaranteed. References [1] K. M. Elmaghraby, et al. Multi-slice CT American Heart Association Joint [4] Vattay B, et al. Qualitative and quanti- coronary angiography versus invasive Committee on Clinical Practice tative image quality of coronary CT coronary angiography in the assessment Guidelines. Circulation. American Heart angiography using photon-counting of graft patency after coronary artery Association; 2021;144(22):e368–e454. computed tomography: Standard and bypasses graft surgery. The Egyptian doi: 10.1161/CIR.0000000000001029. Ultra-high resolution protocols. Eur J Heart Journal (2023) 75:100. doi. org/10.1186/s43044-023-00424-8. [3] Hagar MT, Soschynski M, Saffar R, et al. Radiol. 2024 Jun;175:111426. doi: Ultra-high-resolution photon-counting 10.1016/j.ejrad.2024.111426. Epub 2024 Mar 12. PMID: 38493558. [2] Gulati M, Levy PD, Mukherjee D, et al. detector CT in evaluating coronary stent 2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/ patency: a comparison to invasive [5] Flohr T, Schmidt B, Ulzheimer S, SCMR Guideline for the Evaluation and coronary angiography. Eur Radiol. 2024; Alkadhi H. Cardiac imaging with Diagnosis of Chest Pain: A Report of the doi: 10.1007/s00330-023-10516-3. photon counting CT. Br J Radiol (2023) American College of Cardiology/ 10.1259/bjr.20230407. 16 Photon-counting CT case reports Multiple coronary stents with in-stent re-stenosis and a high-risk plaque Yujie Gao, MD1; Song Luo, MD1; Xi Zhao, MD2 1 Department of Radiology, Geriatric Hospital of Nanjing Medical University, Jiangsu, P. R. China 2 Siemens Healthineers, China History A 76-year-old male patient, com- classified as CAD-RADS 4/P2/HRP/S. without electronic noise. [3] plaining of palpitations and chest The patient was recommended to The photon-counting detectors do tightness, was presented to the undergo interventional coronary not require optical crosstalk to be hospital. Fourteen years ago, the angioplasty, he however refused and prevented by separating layers patient had undergone coronary continued with pharmacotherapy. between the individual detector stenting, with 3 overlapping stents elements. Therefore, they can placed in the left main (LM) and left Comments be more finely structured than anterior descending artery (LAD) and scintillation detectors. [4] a single stent in the circumflex (Cx). Coronary stenting is commonly per- An electric field, instead of physical A follow-up coronary CT angiography formed for coronary revascularization separation, is applied to define (CCTA), performed 11 years later with to improve the blood flow in the smaller sub-pixels which are read an energy-integrating detector (EID) myocardium. The long-term clinical out separately to increase the CT, showed satisfactory results with outcome depends upon the patency spatial resolution. This approach no indication for further interventions. of the stents. It has been recognized also improves the geometrical The patient was then treated with in the guidelines of American Heart dose efficiency of the detector. The pharmacotherapy. Now, an ECG- Association that CCTA assessment combination of the increased spatial triggered sequential ultra-high for the patency of coronary stents resolution and the high temporal resolution (UHR) CCTA with a dual (≥3mm in diameter) has its value. [1] resolution (66 ms) effectively source photon-counting detector However, blooming artifacts caused overcomes the blooming artifacts [5]. (PCD) CT, NAEOTOM Alpha®, was by severely calcified plaques or the performed to assess the coronary stent struts impair the visualization In this case, the patency of the stents, arteries and the patency of the stents. of the coronary lumen, posing a the in-stent restenosis caused by a diagnostic challenge. Numerous non-calcified plaque and the HRP are Diagnosis advances in CT technology, such successfully evaluated by the clinician as improvements in the temporal using the UHR mode, providing CCTA images showed 3 overlapping resolution from the dual source essential information for the stents in the LM, proximal and mid CT principle, optimization of scan physicians to outline an appropriate LAD, and a single stent in the protocols and refined iterative treatment and follow-up plan within proximal Cx. All stents were patent, reconstruction algorithms, have the given situation. except for the one in the Cx, where been made, aiming at increasing the a non-calcified plaque was present diagnostic accuracy of CCTA for stent in the distal stent, causing severe imaging. The introduction of a dual stenosis (>70%). Another non-calci- source PCD-CT with UHR mode has fied plaque, with high-risk plaque shown further improvements in this The statements by customers of Siemens (HRP) features of spotty calcifications area. A recent study using the UHR Healthineers described herein are based on results that were achieved in the customer’s and positive remodeling in the mid mode of PCD-CT achieved a 100% unique setting. Because there is no “typical” right coronary artery (RCA), was also negative predictive value for coronary hospital and many variables exist (e.g., hospital seen causing mild stenosis (<50%). stent patency evaluation against size, case mix, level of IT and/or automation adoption) there can be no guarantee that Multiple calcified plaques were seen invasive angiography as the reference other customers will achieve the same results. in the LM, proximal LAD, mid RCA, standard. [2] and proximal Cx, causing no signifi- The PCD-CT provides energy-resolved The products/features (mentioned herein) are not commercially available in all countries. cant stenosis. CT findings were CT data at increased spatial resolution Their future availability cannot be guaranteed. Photon-counting CT case reports 17 LAD LAD 1a 1b LAD 1d LAD 1c 1 Curved MPR images of the LM and LAD show a comparison of different reconstructions: 0.2 mm with kernel Bv72 (Fig. 1a, PCD-CT), 0.2 mm with kernel Bv60 (Fig. 1b, PCD-CT), 0.6 mm with kernel Bv48 (Fig. 1c, PCD-CT) and 0.75 mm with kernel Bv49 (Fig. 1d, EID-CT). The patency of the stents is clearly visualized in the image reconstructed at 0.2 mm with a kernel of Bv72. 2a CX 2b CX 2c CX 2d CX 2 Curved MPR images of the Cx show a comparison of different reconstructions in the same sequence as in Fig. 1. The non-calcified plaque in the distal stent, causing a severe stenosis (Fig. 2a, arrow), is clearly shown in the image reconstructed at 0.2 mm with a kernel of Bv72. RCA RCA RCA RCA 3a 3b 3c 3d 3 Curved MPR images of the RCA show a comparison of different reconstructions in the same sequence as in Fig. 1 & 2. The HRP with spotty calcification and positive remodelling in the mid RCA (arrow), causing mild stenosis, is clearly seen in the image reconstructed at 0.2 mm with a kernel of Bv72. 18 Photon-counting CT case reports 4a 4b 4 Curved MPR images of the Cx (Fig. 4a) and the RCA (Fig. 4b) show an enlarged view of a severe in-stent stenosis, caused by a non-calcified plaque, in the distal Cx stent (Fig. 4a, arrow), and a non-calcified plaque, with HRP features of spotty calcifi- cations and positive remodelling, in the mid RCA (Fig. 4b, dotted arrow). Images are reconstructed at 0.2 mm with a kernel of Bv72. 5a 5b 5 Cinematic VRT images show a three- dimensional view of the coronary arteries. The stents and the calcified plaques are highlighted. The axial images used were reconstructed at 0.2 mm with a kernel of Bv72. Examination Protocol Scanner NAEOTOM Alpha Scan area Heart Rotation time 0.25 s Scan mode UHR (Quantum HD Cardiac), Slice collimation 120 × 0.2 mm Prospectively ECG triggered sequential mode Slice width 0.2 mm Scan length 128.8 mm Reconstruction increment 0.2 mm Reconstruction kernel Scan direction Cranio-caudal Bv60 / Bv72, QIR4 Heart rate 59–61 bpm Scan time 10 s Tube voltage 120 kV Effective mAs Contrast 350 mg/mL 58 mAs IQ level Volume 52 mL + 40 mL saline 85 Dose modulation Flow rate CARE Dose4D 4 mL/s CTDIvol 11.8 mGy Start delay Bolus tracking triggered at 100 HU in the DLP 152 mGy*cm descending aorta + 6 s References [1] Gulati M, Levy PD, Mukherjee D, et al. [2] Hagar MT, Soschynski M, Saffar R, et al. photon counting CT. Br J Radiol (2023) 2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/ Ultra-high-resolution photon-counting 10.1259/bjr.20230407. SCMR Guideline for the Evaluation and detector CT in evaluating coronary stent Diagnosis of Chest Pain: A Report of the patency: a comparison to invasive [5] Vattay B, et al. Qualitative and American College of Cardiology/ coronary angiography. Eur Radiol. 2024; quantitative image quality of coronary American Heart Association Joint doi: 10.1007/s00330-023-10516-3. CT angiography using photon-counting Committee on Clinical Practice computed tomography: Standard and Guidelines. Circulation. American Heart [3] Thomas Flohr, et al. Photon-counting Ultra-high resolution protocols. Association; 2021;144(22):e368–e454. CT review. Physica Medica 79 (2020) Eur J Radiol. 2024 Jun;175:111426. doi: 10.1161/CIR.0000000000001029. 126–136. doi: 10.1016/j.ejrad.2024.111426. [4] Flohr T, Schmidt B, Ulzheimer S, Epub 2024 Mar 12. PMID: 38493558. Alkadhi H. Cardiac imaging with Photon-counting CT case reports 19 Single-vessel coronary stents accompanied by high-risk plaques Jie Liu, RT1; Yanbo Gu, RT1, Yonggao Zhang, MD1; Jianbo Gao, MD1; Xi Zhao, MD2 1 Department of Radiology, The First Affiliated Hospital of Zhengzhou University, Henan, P. R. China 2 Siemens Healthineers, China History A 60-year-old male patient, complain- causing mild stenoses. Multiple calci- diovascular events (MACE), have pre- ing of intermittent chest pain and fied plaques were present in the left viously caused a stenosis <50%. [3] shortness of breath for the past main (LM), proximal and middle LAD, month, came to the hospital for a circumflex (Cx) as well as right coro- CCTA assessment of coronary stent check-up. He had suffered a myocar- nary artery (RCA), these causing no patency and HRP posts a technical dial infaction four years ago and had significant stenoses. The left ventricle challenge, requiring a combination undergone coronary stenting of the was enlarged and an apical aneurysm of high spatial and temporal resolu- left anterior descending artery (LAD) was evident. The coronary system tion. Potential improvement has been using two interconnected stents was right dominant. shown with the introduction of a (3.5 mm x 20 mm and 3.0 mm x dual-source PCD-CT, NAEOTOM Alpha. 38 mm). A year later, he was diag- CT findings were classified as CAD- The UHR mode with PCD-CT works nosed with lung cancer and has been RADS 2/P2/HRP/S. No further invasive differently from that of conventional treated with chemotherapy. A follow- workup was considered. The patient EID-CT. Smaller detector pixels are up coronary CT angiography (CCTA) continued pharmacotherapy for not defined by physical separation performed six months ago, with hiscoronary artery disease (CAD) as in EID-CT, causing reduced geo- a conventional energy-integrating and chemotherapy for lung cancer. metrical dose efficiency, but an detector (EID) CT, resulted in no A short-term clinical follow-up was electric field is applied to define remarkable findings other than a recommended. smaller sub-pixels which are read left ventricular apical aneurysm. out separately to increase the spatial Now, another CCTA was requested Comments resolution. A recent study using to assess the coronaries and the stent this mode achieved a 100% negative patency. A prospectively ECG trig- CCTA assessment for the patency of predictive value for coronary stent gered sequential CCTA, using an coronary stents, using conventional patency evaluation against invasive ultra-high resolution (UHR) mode, CT, has been challenged by blooming angiography as the reference stan- was performed with a dual-source artifacts caused by stent struts. In the dard. [4] The identification of the photon-counting detector (PCD) American Heart Association guide- HRP features also benefits from CT, NAEOTOM Alpha®. lines, it is limited to a borderline of the improved spatial resolution of 3 mm stent diameter for patients who the UHR mode and the high tempo- Diagnosis experience symptomatic changes de- ral resolution of 66 ms through spite guideline-directed management the dual-source principle. [5] This CCTA images showed two inter- and therapy. [1] HRP, associated with combination can effectively mini - connected stents in the LAD, both a higher risk of future acute coronary mize the blooming interference clearly identified as patent. A non- syndrome (ACS) and lesion specific caused by calcified plaques and calcified plaque was seen proximal ischemia, has been incorporated as stent struts. to the stent, causing mild stenosis a modifier in the CAD-RADS recom- (<50%). Further two mixed plaques, mendations, which suggests that In this case, the stent patency is with high-risk plaque (HRP) features the identification of the HRP would assessed and the HRP is identified of spotty calcifications and positive signify the need for more aggressive successfully by the clinician using remodeling in the mid Cx and RCA, preventive therapies, even if the the UHR mode. As no further invasive were also seen causing mild steno- lesion is nonobstructive. [2] Studies coronary angiography is deemed nec- ses. Two non-calcified plaques, distal have shown that half of culprit essary, the associated costs and risks to the HRP in the RCA, were seen, plaques causing major adverse car- could be spared for this patient. 20 Photon-counting CT case reports 1a 1b 1c 1 Curved MPR images of the LAD show a comparison of the details in the stent patency and in a non-calcified plaque (arrow) proximal to the stent causing mild stenosis. The axial images, acquired from PCD-CT, are reconstructed at 0.2 mm with a kernel of Bv72 (Fig. 1a) and an enlarged view (Fig. 1c). Axial images, acquired from a conventional EID-CT, are reconstructed at 0.625 mm with a standard kernel (Fig. 1b). 2a 2b 2c 2 Curved MPR images show a comparison of a HRP (arrow) details in the mid Cx. The axial images, acquired from PCD-CT, are reconstructed at 0.2 mm with a kernel of Bv72 (Fig. 2a) and an enlarged view (Fig. 2c). Axial images, acquired from a conventional EID-CT, are reconstructed at 0.625 mm with a standard kernel (Fig. 2b). 3a 3b 3c 3 Curved MPR images show a comparison of the details of a HRP (arrow) and two non-calcified plaques (dotted arrows) distal to the HRP in the mid RCA causing mild stenoses. The axial images, acquired from PCD-CT, are reconstructed at 0.2 mm with a kernel of Bv72 (Fig. 3a) and an enlarged view (Fig. 3c). Axial images, acquired from a conventional EID-CT, are reconstructed at 0.625 mm with a standard kernel (Fig. 3b). 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. Photon-counting CT case reports 21 References 4a 4b [1] Gulati M, Levy PD, Mukherjee D, et al. 2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/ SCMR Guideline for the Evaluation and Diagnosis of Chest Pain: A Report of the American College of Cardiology/ American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. American Heart Association; 2021;144(22):e368–e454. doi: 10.1161/ CIR.0000000000001029. [2] R.C. Cury, et al. CAD-RADS™ 2.0 – 2022 Coronary Artery Disease – Reporting and Data System: An Expert Consensus Document of the Society of Cardiovascular Computed Tomography (SCCT), the American College of Cardiology (ACC), the American College of Radiology (ACR), and the North America Society of Cardiovascular Imaging (NASCI), J. Cardio- vasc. Comput. Tomogr. 16 (2022) 536–557. https://doi.org/10.1016/j. jcct.2022.07.002. 4c 4d [3] J. Taron, et al. A review of serial coronary computed tomography angiography (CTA) to assess plaque progression and therapeutic effect of anti-atherosclerotic drugs. Int J Cardiovasc Imaging. 2020 December; 36(12): 2305–2317. doi:10.1007/s10554-020- 01793-w. [4] Hagar MT, Soschynski M, Saffar R, et al. Ultra-high-resolution photon-counting detector CT in evaluating coronary stent patency: a comparison to invasive coronary angiography. Eur Radiol. 2024; doi: 10.1007/s00330-023- 10516-3. [5] Mergen V, Eberhard M, Manka R, Euler A, Alkadhi H. First in-human quantitative plaque 4 Cinematic VRT images show a three-dimensional view of the coronary arteries, characterization with ultra-high resolution the enlarged left ventricle with an apical aneurysm. The stents and the calcified coronary photon-counting CT angiography. plaques are highlighted in green. Front Cardiovasc Med. 2022 Sep 6;9:981012. Examination Protocol Scanner NAEOTOM Alpha Scan area Heart Rotation time 0.25 s Scan mode UHR mode (Quantum HD Slice collimation 120 x 0.2 mm Cardiac), Prospectively ECG Slice width 0.2 mm triggered sequential mode Reconstruction increment 0.2 mm Scan length 128.8 mm Reconstruction kernel Bv72, QIR 4 Scan direction Cranio-caudal Heart rate 51–55 bpm Scan time 6.9 s Tube voltage 120 kV Contrast 400 mg/mL Effective mAs 59 mAs Volume 51 mL + 41 mL saline IQ level 85 Flow rate 4.1 mL/s Dose modulation CARE Dose4D CTDIvol 14.3 mGy Start delay Bolus tracking triggered at 100 HU in the descending DLP 184 mGy*cm aorta + 7s 22 Photon-counting CT case reports Multi-vessel coronary atherosclerosis – significant stenoses? Prof. Jan Baxa, MD, PhD Department of imaging methods, University Hospital Pilsen and Medical Faculty of Charles University, Pilsen, Czech Republic History Comments A 78-year-old female diabetic CCTA is considered a first-line test in the ZeeFree reconstruction, patient, with clinical symptoms (Class I) for use in acute and chronic enabling the morphology to be seen of a suspected stable angina, coronary syndromes by various car- as intended. This helps the physician came to the hospital for a check-up. diological societies and guidelines. to make a confident assessment and A coronary CT angiography (CCTA) [1] One of the remaining challenges confirmation on coronary atheroscle- was requested to evaluate the in CCTA imaging is the occurrence of rosis without significant stenoses, coronary arteries and to rule out stair-step artifacts in the transition obviating further examinations. coronary stenosis. A prospectively areas of an acquisition over multiple ECG-triggered sequential mode cardiac cycles, hampering diagnostic References was performed with a dual source interpretability of the images. This [1] Ricardo C. Cury, et al. CAD-RADS™ 2.0 2022 Coronary Artery Disease - - photon-counting detector (PCD) can occur in prospectively ECG-trig- CT, NAEOTOM Alpha®. gered sequential scanning, as well as Reporting and Data System. An Expert Consensus Document of the Society of in retrospectively ECG-gated spiral Cardiovascular Computed Tomography Diagnosis scanning. Potential causes consid- (SCCT), the American College of ered are insufficient patient breath- Cardiology (ACC), the American College CCTA images in a standard recon- hold or movement or irregular heart of Radiology (ACR), and the North struction showed calcified plaques rate during the acquisition. [2] Imag- America Society of Cardiovascular Imaging (NASCI). Journal of Cardiovascular in the proximal left anterior es using TrueStack reconstruction Computed Tomography 16 (2022) descending artery (LAD) with signs can make the presence of misalign- 536–557. https://doi.org/10.1016/j. of suspicious stair-step artifacts. ment clear, however, may be difficult jcct.2022.07.002. This was clearly identified in the to interpret, if analyzed as curved TrueStack reconstruction, showing planar reformation (CPR). ZeeFree [2] L. J. Moser, et al. A Novel Reconstruction Technique to Reduce Stair-Step Artifacts misalignment of image stacks most is a novel reconstruction technique, in Sequential Mode Coronary CT likely due to an incomplete patient using a non-rigid registration in the Angiography. Investigative Radiology; breath-hold. The misalignment was reconstruction process between the Jan. 30, 2024. doi:10.1097/ corrected in the image reconstruc- transition of adjacent cardiac cycle RLI.0000000000001066. tion using the ZeeFree algorithm, acquisition to correct and reduce [3] Thomas Allmendinger, PhD, FSCCT; which resulted in clear visualization misalignment. This is a detector Giovanni Boemio; Vishal Karpatri, MD. of mild stenoses. A non-calcified width-independent algorithm and Optimal Cardiac CT imaging with ZeeFree. plaque in the mid LAD, as well can be applied to both prospectively White paper. siemens-healthineers.com/ as multiple calcified plaques in ECG-triggered sequential and retro- computed-tomography/clinical-imaging- the proximal right coronary artery spectively ECG-gated spiral acquisi- solutions/cardiovascular-imaging. (RCA), mid LAD and proximal tions. [3] A recent study has demon- The statements by customers of Siemens circumflex (Cx), causing mild strated significant reduction of Healthineers described herein are based on stenoses (<50%), were also seen. non-diagnostic coronary segments results that were achieved in the customer’s CT findings were classified as using the ZeeFree algorithm. [2] unique setting. Because there is no “typical” hospital and many variables exist (e.g., hospital CAD-RADS 2/P2. As shown in this case, the size, case mix, level of IT and/or automation adoption) there can be no guarantee that Based on CCTA findings, an inter- misalignment caused by stair-step other customers will achieve the same results. ventional coronary angioplasty artifacts, observed in the standard was obviated. The patient was reconstruction and identified in the The products/features (mentioned herein) are not commercially available in all countries. recommended for pharmacotherapy. TrueStack reconstruction, is resolved Their future availability cannot be guaranteed. Photon-counting CT case reports 23 1a H Examination Protocol Scanner NAEOTOM Alpha Scan area Heart Scan mode Quantum Scan length 126.2 mm Scan direction Cranio-caudal Scan time 1b H 9.2 s Tube voltage 90 kV Effective mAs 155 mAs IQ level 75 Dose modulation CARE Dose4D CTDIvol 21.2 mGy DLP 398 mGy*cm Rotation time 0.25 s 1c H Slice collimation 144 x 0.4 mm Slice width 0.4 mm Reconstruction increment 0.2 mm Reconstruction kernel Bv60, QIR 4 keV level 60 keV Heart rate 61 – 65 bpm Contrast 370 mg/mL 2a 2b Volume 50 mL + 40 mL saline Flow rate 6 mL/s Start delay Test bolus - time of peak density at ascending aorta + 4 s 1 MPR images show a comparison of calcified plaques seen in the proximal LAD. Misalignment is observed in standard reconstruction (Fig. 1a), identified in the TrueStack recon- struction (Fig. 1b) and resolved in the ZeeFree reconstruction (Fig. 1c). Mild stenoses are clearly visualized (arrows). 2 Two corresponding curved MPR images, using standard (Fig. 2a) and ZeeFree (Fig. 2b) reconstruction, demonstrate a clear visualization of mild stenoses in the proximal LAD, caused by calcified plaques, after the ZeeFree correction (Fig. 2b, arrows). A non-calcified plaque in the mid LAD is also seen (dotted arrows). 24 Photon-counting CT case reports Severe stenoses in a coronary saphenous vein graft with an external VEST support Prof. Jan Baxa, MD, PhD Department of imaging methods, University Hospital Pilsen and Medical Faculty of Charles University, Pilsen, Czech Republic History A 59-year-old male patient, who had mained patent, with no evidence of The VEST device, an external support undergone triple coronary artery stenosis or occlusion. A hypoattenu- for SVGs, has been proposed as a bypass grafting (CABG) three months ating area in the stent implemented mechanical approach to minimize ago, came to the hospital with non- in the mid LAD was seen suggesting the post-implantation dilatation of specific symptoms. He had a history an in-stent re-stenosis. the SVGs and to improve the graft of coronary stenting five years ago and had been under anticoagulation Evaluation of the native coronary flow patterns and the subsequent therapy. A prospectively ECG-trig- arteries showed extensive calcifica- development of intimal hyperplasia. gered sequential CT scan with a dual tions. Mixed plaques were seen in [1] As a SVG failure may have sig- the left main coronary artery (LM), nificant adverse clinical effects in source photon-counting detector CT, patients, follow-ups on its patency NAEOTOM Alpha®, was performed the proximal LAD, and the left marginal branch of the circumflex are important. CCTA has been in- to evaluate the patency of the grafts, the anastomoses and the stent. (Cx), causing moderate stenoses creasingly performed in post-CABG (50–69%). Calcified plaques, causing assessment, as it is non-invasive and severe stenoses (>70%) in the proxi- can reliably depict the entire course of the grafts with a single bolus of Diagnosis mal D1 and the distal right coronary artery (RCA), as well as moderate contrast media at a short acquisition CCTA images revealed triple bypass stenoses in the LM, the PDA and the time. The challenge, in this case, is grafts with three coronary anastomo- first proximal marginal branch of to visualize the graft lumen without ses. A left internal mammary artery the RCA (RMA1) were also seen. The the interference of the blooming (LIMA) graft, originating off the coronary system was right dominant. and/or metal artifacts caused by proximal left subclavian artery (LSA), There was no evidence of any cardiac the metal struts of the VEST device. was anastomosed end-to-side to the structural abnormalities. PCD-CT provides energy-resolved CT distal left anterior descending artery (LAD). Two right saphenous vein Based on CCTA findings, a selective data at increased spatial resolution, grafts (SVGs), originating from the coronary angiography was consid- with inherent spectral information, without electronic noise. [2] Virtual anterior wall of the ascending aorta, ered, however, not performed imme- diately, as the patient had no specific monoenergetic images (VMIs) can were present – the upper one, laid symptoms. be reconstructed and displayed at a over the main pulmonary artery, was low energy level (55 keV in this case) anastomosed end-to-side to the first to achieve an increased contrast en- diagonal branch (D1) of the LAD; the hancement and an improved visual- lower one, with an external support Comments ization of the vessel lumen. ZeeFree, of a VEST device, was anastomosed SVGs are the most frequently used a novel reconstruction technique, end-to-side to the posterior de- conduits in CABG. The main limita- using a non-rigid registration in the scending artery (PDA). The middle tion to their use is a higher rate reconstruction process between segment of this SVG appeared thin. of occlusion compared to arterial the transitions of adjacent cardiac Two severe stenoses were visualized conduits. Previous studies have cycle acquisitions, is implemented in the distal segment. The anastomo- shown that SVG failure is mainly in standard image reconstruction to sis was patent, however, narrowed. driven by intimal hyperplasia, an correct and reduce potential mis- The LIMA graft and the upper SVG adaptative response to higher alignment caused by insufficient along with their anastomoses re- pressures of the arterial circulation. patient breathhold, movement or Photon-counting CT case reports 25 1a HRA 1b 1c 1 A cinematic VRT image (Fig. 1a) and a curved MPR image (Fig. 1b) show the SVG with a VEST device anastomosed to the PDA. The middle segment appears thin. Two severe stenoses (arrows) are visualized in the distal segment. An oblique MPR image shows the anastomosis of the SVG to the PDA, which is patent, but narrowed (Fig. 1c, arrow). irregular heart rate during the acqui- References sition. [3] Furthermore, a combina- [1] Giovanni Jr. Soletti, et al. The VEST tion of a high temporal resolution External Support for Saphenous Vein of 66 ms from the dual source CT Grafts in Coronary Surgery: A Review principle also in spectral reconstruc- of Randomized Clinical Trials. J Cardiovasc Dev Dis. 2023 Nov; 10(11): tions such as VMIs, a refined Quan- 453. Published online 2023 Nov 7. tum Iterative Reconstruction algo- doi:10.3390/jcdd10110453. PMCID: rithm (QIR), an optimized image PMC10672571. PMID: 37998511. reconstruction kernel (Bv56) and an increased spatial resolution [2] Thomas Flohr, et al. Photon-counting CT review. Physica Medica 79 (2020) contributes to a clear visualization 126–136. The statements by customers of Siemens of the two severe stenoses of the Healthineers described herein are based on results that were achieved in the customer’s SVG inside the VEST device, without [3] L. J. Moser, et al. A Novel Reconstruction unique setting. Because there is no “typical” interference of blooming or metal Technique to Reduce Stair-Step Artifacts hospital and many variables exist (e.g., hospital artifacts. The assessment of the in Sequential Mode Coronary CT size, case mix, level of IT and/or automation LIMA grafts, the SVG without the Angiography. Investigative Radiology. adoption) there can be no guarantee that Jan. 30, 2024. doi:10.1097/ other customers will achieve the same results. VEST device, the anastomoses, the RLI.0000000000001066. stent and the native coronary The products/features (mentioned herein) are not commercially available in all countries. arteries is also successful. Their future availability cannot be guaranteed. 26 Photon-counting CT case reports 2a 2b 2c 2 A cinematic VRT image (Fig. 2a) and curved MPR images (Fig. 2b & 2c) show a patent anasto- mosis of the LIMA graft to the distal LAD (Fig. 2a & 2b, arrows) and the SVG to the D1 (Fig. 2a & 2c, dotted arrows). 3a 3b 3c 3 A cinematic VRT image (Fig. 3a) and curved MPR images of the LAD (Fig. 3b) and the left marginal branch of the Cx (Fig. 3c) show extensive calcification. Moderate stenoses caused by mixed plaques (arrows) in the LM, the proximal LAD, and the left marginal branch of the Cx are also seen. Examination Protocol Scanner NAEOTOM Alpha Scan area Heart Slice collimation 144 x 0.4 mm Scan mode Quantumplus Slice width 0.4 mm Scan length 204 mm Reconstruction increment 0.2 mm Scan direction Caudo-cranial Reconstruction kernel Bv56, QIR 4 Scan time 7.9 s keV level 55 keV Tube voltage 140 kV Spectral reconstruction Monoenergetic Plus Effective mAs 34 mAs Heart rate 60 – 62 bpm IQ level 64 Dose modulation CARE Dose4D Contrast 350 mg/mL CTDIvol 13.8 mGy Volume 60 mL + 50 mL saline DLP 332 mGy*cm Flow rate 6 mL/s Rotation time 0.25 s Start delay Peak time of test bolus + 2 s Photon-counting CT case reports 27 Siemens Healthineers Headquarters Siemens Healthineers AG Siemensstr. 3 91301 Forchheim, Germany Phone: +49 9191 18-0 siemens-healthineers.com Published by Siemens Healthineers AG · Order No. CT-00112-10C1-7600 · Printed in Germany · 15638 1024 · ©Siemens Healthineers AG, 2024