Background Ventilation/perfusion single-photon emission computed tomography (V/Q-SPECT) is the standard first-line imaging method for chronic thromboembolic pulmonary hypertension (CTEPH), but it lacks anatomical detail. Photon-counting computed tomography (PCCT) enables high-resolution assessment of perfusion, vasculature, and parenchyma in one scan, potentially improving diagnostic accuracy. Objectives To compare quantitative lobar lung perfusion between PCCT and V/Q-SPECT in patients with suspected or confirmed CTEPH. Materials and methods This retrospective single-centre study included twenty-three patients (ten females, thirteen males; mean age 67.9 ± 10.7 years). The median interval between PCCT and V/Q-SPECT imaging was 3 days (range: 0–11 days). Lung perfusion was analysed on a lobar basis using PCCT-derived perfused blood volume (PBV) maps and V/Q-SPECT perfusion images. Data were normalised using a z-score approach based on the 95% confidence interval. Lobar segmentation was performed with TotalSegmentator. Pearson correlation and Bland–Altman analyses compared lobar and whole-lung perfusion metrics. Perfusion defect volumes were quantified from normalised maps. Results Whole-lung perfusion correlated strongly between PCCT and V/Q-SPECT (r = 0.72, p < 0.05). Lobar correlations ranged from r = 0.62 to r = 0.85. PCCT yielded slightly higher perfusion values (mean PBV 0.50 ± 0.04) than V/Q-SPECT (0.49 ± 0.09). Bland–Altman analysis showed a bias of +0.015 (limits −0.13 to +0.16). Perfusion defect volumes correlated moderately (whole-lung r = 0.60, lobes r = 0.49–0.77, p < 0.05). Conclusion PCCT-based perfusion imaging shows high concordance with V/Q-SPECT in this cohort, supporting its feasibility as a single-modality tool for functional and anatomical lung evaluation in CTEPH. Key Points <Emphasis Type="BoldItalic">Question</Emphasis> PCCT perfusion may address the unmet need for a combined functional and anatomical evaluation of CTEPH in a single examination. <Emphasis Type="BoldItalic">Findings</Emphasis> PCCT showed strong correlation with V/Q-SPECT for lobar and whole-lung perfusion, with minimal bias and consistent quantitative agreement. <Emphasis Type="BoldItalic">Clinical relevance</Emphasis> PCCT enables simultaneous high-resolution assessment of perfusion, vasculature, and parenchyma, potentially improving diagnostic confidence and streamlining CTEPH work-up in clinical practice. Graphical Abstract

Photon-counting CT vs V/Q SPECT for lobar perfusion quantification in chronic thromboembolic pulmonary hypertension

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2026年4月24日

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Matthias M. V. Moeskes,
Thorsten Derlin,
Anna M. Hunkemöller,
Cornelia Schäfer-Prokop,
Norman Kornemann,
Jan W. Eckstein,
Bernhard Meyer,
Jens Vogel-Claussen,
Frank K. Wacker,
Hoen-oh Shin

摘要

Background

Ventilation/perfusion single-photon emission computed tomography (V/Q-SPECT) is the standard first-line imaging method for chronic thromboembolic pulmonary hypertension (CTEPH), but it lacks anatomical detail. Photon-counting computed tomography (PCCT) enables high-resolution assessment of perfusion, vasculature, and parenchyma in one scan, potentially improving diagnostic accuracy.

Objectives

To compare quantitative lobar lung perfusion between PCCT and V/Q-SPECT in patients with suspected or confirmed CTEPH.

Materials and methods

This retrospective single-centre study included twenty-three patients (ten females, thirteen males; mean age 67.9 ± 10.7 years). The median interval between PCCT and V/Q-SPECT imaging was 3 days (range: 0–11 days). Lung perfusion was analysed on a lobar basis using PCCT-derived perfused blood volume (PBV) maps and V/Q-SPECT perfusion images. Data were normalised using a z-score approach based on the 95% confidence interval. Lobar segmentation was performed with TotalSegmentator. Pearson correlation and Bland–Altman analyses compared lobar and whole-lung perfusion metrics. Perfusion defect volumes were quantified from normalised maps.

Results

Whole-lung perfusion correlated strongly between PCCT and V/Q-SPECT (r = 0.72, p < 0.05). Lobar correlations ranged from r = 0.62 to r = 0.85. PCCT yielded slightly higher perfusion values (mean PBV 0.50 ± 0.04) than V/Q-SPECT (0.49 ± 0.09). Bland–Altman analysis showed a bias of +0.015 (limits −0.13 to +0.16). Perfusion defect volumes correlated moderately (whole-lung r = 0.60, lobes r = 0.49–0.77, p < 0.05).

Conclusion

PCCT-based perfusion imaging shows high concordance with V/Q-SPECT in this cohort, supporting its feasibility as a single-modality tool for functional and anatomical lung evaluation in CTEPH.

Key Points

Question PCCT perfusion may address the unmet need for a combined functional and anatomical evaluation of CTEPH in a single examination.

Findings PCCT showed strong correlation with V/Q-SPECT for lobar and whole-lung perfusion, with minimal bias and consistent quantitative agreement.

Clinical relevance PCCT enables simultaneous high-resolution assessment of perfusion, vasculature, and parenchyma, potentially improving diagnostic confidence and streamlining CTEPH work-up in clinical practice.

Graphical Abstract