Objective This study evaluates the feasibility of photon-counting detector CT (PCD-CT)-based coronary CT angiography (CCTA) using ultra-low flow contrast rate while maintaining diagnostic image quality. Materials and methods In this prospective trial, 292 patients underwent CCTA assigned to one of three protocols: ultra-low (1.5–1.8 mL/s) or routine (4.0–5.0 mL/s) contrast injection with PCD-CT, or routine injection with EID-CT. All scans utilized a high-pitch prospective electrocardiogram-triggering acquisition. PCD-CT images were reconstructed at 45 keV (ultra-low) or 60 keV (routine). Objective image quality was quantitatively assessed by measuring vessel attenuation, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Subjective image quality parameters (vascular contrast, image noise, artifacts, and vessel clarity) were independently evaluated by two blinded readers using a 4-point Likert scale (1: non-diagnostic; 2: adequate; 3: good; 4: excellent). Results Objective image quality demonstrated comparable attenuation, CNR, and SNR in proximal coronary segments across all groups (all p > 0.05). The ultra-low PCD-CT protocol significantly lowers attenuation in the distal LAD (373.20 ± 49.58 HU) compared to routine protocols (PCD-CT: 393.52 ± 49.38 HU; EID-CT: 396.72 ± 47.55 HU; p = 0.01). While distal vessel clarity scores were modestly reduced in distal vessel clarity (ultra-low PCD-CT: 2.91 ± 0.81 versus routine PCD-CT: 3.58 ± 0.50 versus routine EID-CT: 3.54 ± 0.50; p < 0.01). Conclusion For patients with difficulty establishing venous access routes, ultra-low contrast agent flow rates in PCD-CT maintain objective image quality comparable to that of standard protocols, with acceptable diagnostic performance despite slight reductions. Relevance statement Photon-counting detector CT (PCD-CT) maintains objective coronary CT angiography image quality comparable to standard protocols even at ultra-low contrast flow rates (1.5–1.8 mL/s), offering a clinically acceptable and safer alternative for patients with challenging venous access. Key Points <UnorderedList Mark="Bullet"> <ItemContent> First validation of ultra-low flow contrast rate CCTA using photon-counting CT (PCD-CT). </ItemContent> <ItemContent> Ultra-low flow rates maintain objective image quality (CNR/SNR) versus routine protocols. </ItemContent> <ItemContent> PCD-CT enables 50% contrast reduction without diagnostic compromise. </ItemContent> </UnorderedList> Graphical Abstract

Feasibility of ultra-low flow rate coronary CT angiography using photon-counting detector CT: a prospective randomized trial

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2026年2月24日

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Shuangxiang Lin,
Cuiliu Liu,
Yalan Zhou,
Qinlan Chen,
Shuyue Wang,
Jiaxing Wu,
Xinhong Wang,
Jianzhong Sun

摘要

Objective

This study evaluates the feasibility of photon-counting detector CT (PCD-CT)-based coronary CT angiography (CCTA) using ultra-low flow contrast rate while maintaining diagnostic image quality.

Materials and methods

In this prospective trial, 292 patients underwent CCTA assigned to one of three protocols: ultra-low (1.5–1.8 mL/s) or routine (4.0–5.0 mL/s) contrast injection with PCD-CT, or routine injection with EID-CT. All scans utilized a high-pitch prospective electrocardiogram-triggering acquisition. PCD-CT images were reconstructed at 45 keV (ultra-low) or 60 keV (routine). Objective image quality was quantitatively assessed by measuring vessel attenuation, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Subjective image quality parameters (vascular contrast, image noise, artifacts, and vessel clarity) were independently evaluated by two blinded readers using a 4-point Likert scale (1: non-diagnostic; 2: adequate; 3: good; 4: excellent).

Results

Objective image quality demonstrated comparable attenuation, CNR, and SNR in proximal coronary segments across all groups (all p > 0.05). The ultra-low PCD-CT protocol significantly lowers attenuation in the distal LAD (373.20 ± 49.58 HU) compared to routine protocols (PCD-CT: 393.52 ± 49.38 HU; EID-CT: 396.72 ± 47.55 HU; p = 0.01). While distal vessel clarity scores were modestly reduced in distal vessel clarity (ultra-low PCD-CT: 2.91 ± 0.81 versus routine PCD-CT: 3.58 ± 0.50 versus routine EID-CT: 3.54 ± 0.50; p < 0.01).

Conclusion

For patients with difficulty establishing venous access routes, ultra-low contrast agent flow rates in PCD-CT maintain objective image quality comparable to that of standard protocols, with acceptable diagnostic performance despite slight reductions.

Relevance statement

Photon-counting detector CT (PCD-CT) maintains objective coronary CT angiography image quality comparable to standard protocols even at ultra-low contrast flow rates (1.5–1.8 mL/s), offering a clinically acceptable and safer alternative for patients with challenging venous access.

Key Points

First validation of ultra-low flow contrast rate CCTA using photon-counting CT (PCD-CT).

Ultra-low flow rates maintain objective image quality (CNR/SNR) versus routine protocols.

PCD-CT enables 50% contrast reduction without diagnostic compromise.

Graphical Abstract