The original case report was published at JACC: Case reports
Nguyen KV, Nguyen VT, Nguyen NT, et al. Photon-Counting Computed Tomography for In-Stent Occlusion: Lumen Visualization and Myocardial Viability. JACC Case Rep. 2026;108566. doi:10.1016/j.jaccas.2026.108566.
Authors:
Khoi Viet Nguyen PhD a, Van Tu Nguyen MSc a, Ngoc Trang Nguyen PhD a, Van Hoa Hoang Thi MSc a, Bao Ngoc Phung MSc a, Thuy Lien Le Thi MSc a, Thi Quynh Tran MSc a, Thi Ly Tran MSc a, Thi Huyen Nguyen MSc a, Dang Luu Vu MD, PhD b
Affiliation:
a Institute of Diagnostic and Interventional Radiology, Bach Mai Hospital, Hanoi, Vietnam
b Department of Radiology, Hanoi Medical University, Hanoi, Vietnam
History of Presentation
A 58-year-old man presented with a 2-day history of progressive crescendo chest pain. He remained symptomatic despite strict adherence to dual antiplatelet therapy and high-intensity statins.
Take-Home Message Photon-counting detector computed tomography may improve diagnostic workflows and enhance precision for the management of complex coronary artery disease.
Past Medical History
His medical history was notable for percutaneous coronary intervention 12 months prior with the deployment of 2 drug-eluting stents (3.8 mm and 2.8 mm) in the right coronary artery (RCA). Differential Diagnosis Differential diagnoses for the patient’s recurrent chest pain included in-stent restenosis, acute in-stent thrombosis, and progression of native coronary artery disease.
Investigations
To evaluate stent patency, the patient underwent ultra-high-resolution photon-counting detector computed tomography (UHR PCCT) in UHR cardiac mode (120 kVp, 0.2 mm slice thickness; temporal resolution 66 milliseconds) after injection of 60 mL contrast (370 mgI/mL at 5.5 mL/s). Images were reconstructed with a 1,024 x 1,024 matrix using the Quantum pure lumen algorithm to reduce blooming artifacts and optimize in-stent lumen assessment, with simultaneous acquisition of iodine maps from intrinsic spectral data without additional scan phases, which definitively identified a chronic total in-stent occlusion of the RCA (Figure 1A). Crucially, the scan also clearly delineated a robust network of intercoronary collaterals originating from the left anterior descending artery, which retrogradely filled the distal RCA territory (Figure 1D).
Figure 1. Photon-Counting Computed Tomography of Coronary Stent Occlusion and Collateral Perfusion (A) UHR PCCT acquisition of the RCA. The arrow below indicates a total in-stent occlusion. Axial images (arrow above) demonstrate high-fidelity delineation between the metallic struts and the intraluminal thrombus. (B) The LAD is widely patent without significant stenosis. (C and D) Whole-heart reconstruction highlighting the recruitment of rich collateral circulation from the LAD to the distal RCA territory (arrow). LAD = left anterior descending artery; PCCT = photon-counting detector computed tomography; RCA = right coronary artery; UHR = ultra-high-resolution.
A comprehensive, noninvasive study was performed using UHR PCCT spectral datasets. Arterial-phase iodine perfusion maps revealed a distinct transmural perfusion defect in the posteroinferior wall, matching the anatomical distribution of the occluded RCA (Figure 2). This functional assessment was complemented by late iodine enhancement acquired 5 minutes postcontrast, which demonstrated dense transmural hyperenhancement in the same territory, identifying a chronic myocardial scar and confirming the lack of viability (Figure 3A).
Figure 2. Photon-Counting Detector Computed Tomography Spectral Perfusion (A and B) Spectral-derived iodine map: a transmural perfusion defect (red/blue) (arrow) is clearly visible in the posteroinferior wall, matching the right coronary artery territory. (C and D) LV transmurality index and binary enhanced volume maps showing predominantly transmural abnormal enhancement and advanced myocardial injury in the inferoposterior wall (arrows). CTA = computed tomography angiography; LV = left ventricle; UHR = ultra-high-resolution.
Figure 3. Myocardial Scar on Photon-Counting Computed Tomography and Magnetic Resonance Imaging (A) Photon-counting detector computed tomography late iodine enhancement map and (B) magnetic resonance imaging late gadolinium enhancement show matching transmural scar (arrow) in the posteroinferior wall, consistent with nonviable right coronary artery territory myocardium.
To confirm the PCCT findings, the patient underwent digital subtraction angiography (DSA) and cardiac magnetic resonance. DSA corroborated the chronic total in-stent occlusion of the dominant RCA, demonstrating a complete interruption of antegrade flow at the proximal edge of the stent. Crucially, DSA and PCCT together provided a complementary evaluation of the complex collateral network: DSA visualized the dynamic recruitment of robust intercoronary collaterals (Werner class CC2) originating from the left anterior descending artery, which retrogradely filled the distal RCA territory (Figure 4). Subsequent cardiac magnetic resonance sequences (perfusion and late gadolinium enhancement) showed high concordance with the PCCT-derived findings; magnetic resonance perfusion imaging verified a rest perfusion defect that precisely matched the iodine maps in location and transmurality. Furthermore, quantitative PCCT-derived extracellular volume estimates showed high agreement with cardiac magnetic resonance reference standards; the late gadolinium enhancement mirrored the PCCT-derived late iodine enhancement with high spatial fidelity (Figure 3B). This multimodality alignment confirmed a nonviable transmural scar, providing the definitive evidence required for the heart team to opt for a management strategy.
Figure 4. Invasive Angiography (Digital Subtraction Angiography) (A) Right coronary artery (RCA) angiogram showing total in-stent occlusion of the RCA (right arrow), while the left arrow points to collateral branches arising from the proximal RCA. (B) Left anterior descending artery (LAD) angiogram showing patent LAD with septal and epicardial collaterals supplying retrograde flow to the distal RCA (arrow).
Within this multimodality framework, each imaging modality contributed complementary and incremental value: PCCT provided a comprehensive anatomical and functional assessment, DSA enabled real-time characterization of collateral flow dynamics, and cardiac magnetic resonance served as the reference standard for myocardial viability. Together, these integrated findings confirmed a nonviable transmural scar and provided the decisive evidence for confident clinical decision-making.
Management
The heart team’s decision-making was guided by an integrated anatomical-functional assessment. PCCT played a pivotal role by providing high-confidence confirmation of true in-stent occlusion and co-registered perfusion assessment, thereby reducing diagnostic uncertainty beyond angiography alone. In conjunction with magnetic resonance imaging–confirmed nonviable myocardium and robust collateral supply on DSA, these findings supported a conservative management strategy, avoiding potentially unnecessary high-risk intervention.
Outcome and Follow-Up
The patient was discharged following conservative medical management in stable condition. At short-term follow-up, he remained asymptomatic with no recurrence of chest pain.
Discussion
Accurate assessment of in-stent restenosis and total occlusions remains challenging with conventional CT techniques, particularly in small-caliber stents. PCCT marks a paradigm shift in cardiovascular imaging, effectively overcoming the “3-mm imaging barrier” that has long hampered conventional energy-integrating detector CT (EID-CT). In conventional coronary computed tomography angiography, metallic stent struts frequently produce pronounced stent blooming artifacts and electronic noise, which lead to a significant overestimation of stenosis severity and a high rate of nondiagnostic evaluations in small-caliber vessels. In our case, in-stent patency assessment on UHR PCCT was based on direct visualization of intraluminal contrast opacification and distal runoff, allowing reliable differentiation between severe stenosis and complete occlusion. This overcomes the key limitation of EID-CT, where blooming artifacts hinder accurate lumen evaluation and reduce diagnostic confidence.The diagnostic accuracy of PCCT in stent assessment has been robustly validated in recent literature. A landmark study by Sakai et al involving over 7,800 patients reported that PCCT increases per-patient specificity to 98% (compared with 93% for EID-CT) and significantly reduces unnecessary invasive coronary angiography referrals. Furthermore, Hagar et al demonstrated that UHR PCCT achieves a sensitivity of 100% and a specificity of 87% for coronary stent patency, even in high-risk populations with heavy calcification. By accurately delineating the 2.8-mm distal stent lumen in our patient, PCCT demonstrated high-resolution visualization beyond the limitations of conventional imaging, matching the diagnostic precision of DSA.A key transformative feature of PCCT is its capacity for a “one-stop-shop” assessment, combining high-resolution anatomical detail with functional myocardial characterization. The integration of spectral-derived iodine mapping in our case identified a transmural perfusion defect with perfect concordance with cardiac magnetic resonance findings. This synergy mirrors the outcomes of the ADVANTAGE study, which established that the addition of CT perfusion to computed tomography angiography significantly boosts diagnostic accuracy for in-stent restenosis to 96.1%. Recent data from Klambauer et al further confirm this reliability, reporting a Kappa coefficient of up to 0.956 for the agreement between PCCT late enhancement and cardiac magnetic resonance. Despite its promising capabilities, PCCT has several important limitations that may restrict its broader clinical application. Its availability remains limited to select advanced centers, and the associated high acquisition and maintenance costs further constrain widespread use. Radiation dose and contrast use are comparable to contemporary coronary computed tomography angiography protocols, although optimization is ongoing. In addition, broader clinical adoption is currently limited by the lack of large multicenter outcome studies, as well as the absence of standardized interpretation criteria and practical challenges in integrating PCCT into routine clinical workflows.Finally, the ability of PCCT to provide a comprehensive, noninvasive evaluation of both stent patency and myocardial viability directly influenced high-stakes clinical decision-making. The visualization of total in-stent occlusion alongside robust collateralization and a confirmed transmural scar allowed the heart team to confidently prioritize a conservative management strategy. This approach avoided high-risk invasive revascularization in a stable patient by definitively identifying nonsalvageable myocardium, highlighting the potential utility of PCCT as a noninvasive imaging tool in complex coronary artery disease.
Conclusions
UHR PCCT provides a comprehensive, noninvasive “one-stop-shop” for managing complex coronary artery disease. By integrating UHR anatomical detail with definitive tissue characterization, PCCT facilitates clinical decision-making while simplifying diagnostic workflows. This technology represents a shift toward high-fidelity, less invasive diagnostic imaging and suggests a potential role for PCCT in cardiovascular care. However, this is a single case report and is not sufficient to draw definitive conclusions, and should be further validated in larger-scale studies.
Funding Support and Author Disclosures
The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
