Comparison of Photon-Counting CT and V/Q SPECT for Assessing Lobar Perfusion

Overview

This study evaluates the agreement between photon-counting computed tomography (PCCT) and ventilation/perfusion single-photon emission computed tomography (V/Q-SPECT) in assessing lobar perfusion in patients with chronic thromboembolic pulmonary hypertension (CTEPH). The findings suggest that PCCT provides comparable results to V/Q-SPECT, potentially enhancing diagnostic accuracy and treatment planning.

Background

Chronic thromboembolic pulmonary hypertension (CTEPH) is often underdiagnosed, leading to advanced disease stages at the time of diagnosis. Accurate assessment of pulmonary perfusion is critical for treatment planning, particularly for surgical interventions. V/Q-SPECT is currently the standard imaging modality, but its limitations necessitate exploration of alternative technologies like photon-counting CT (PCCT).

Data Highlights

This study included 23 patients with a median age of 69.8 years, comparing PCCT-derived perfusion maps with V/Q-SPECT results.

Key Findings

• PCCT demonstrated strong agreement with V/Q-SPECT for whole-lung and lobar perfusion metrics in CTEPH patients.
• PCCT offers improved spatial resolution and iodine quantification compared to conventional imaging methods.
• The study cohort consisted of 23 patients, with a median age of 69.8 years.
• PCCT can evaluate pulmonary perfusion, ventilation, vascular anatomy, and parenchymal morphology in a single examination.
• Technical advancements in PCCT may reduce the need for additional perfusion imaging in clinical settings.

Clinical Implications

The findings support the use of PCCT as a reliable alternative to V/Q-SPECT for assessing lobar perfusion in CTEPH, which may streamline diagnostic workflows. Clinicians should consider integrating PCCT into routine practice for enhanced imaging capabilities and improved patient management.

Conclusion

PCCT shows promise as a comparable imaging modality to V/Q-SPECT for evaluating lobar perfusion in CTEPH, potentially improving diagnostic accuracy and treatment planning.

References

1. European Radiology, 2025 -- High-Resolution Photon-Counting Detector CT Findings of Lung Microvasculopathy in Patients with Chronic Thromboembolic Pulmonary Hypertension: A Study of 29 Cases
2. European Radiology, 2023 -- Utilizing Photon-Counting CT for Acute Pulmonary Embolism Diagnosis: Opportunities for Reducing Contrast Agent Use and Radiation Exposure
3. European Radiology, 2023 -- Evaluation of Pulmonary Perfusion via Dual-Layer Dual-Energy CT for Distinguishing Acute Pulmonary Embolism from Chronic Thromboembolic Pulmonary Hypertension
4. ESC/ERS GUIDELINES, 2022 -- Clinical Guidelines for CTEPH
5. European Radiology — Automated Bayesian Approach for Assessing the Degree and Distribution of Pulmonary Perfusion Alterations in CT Pulmonary Angiography for CTEPH
6. ESC/ERS GUIDELINES
7. The diagnostic performance of dual-energy CT in detecting chronic thromboembolic pulmonary hypertension: A systematic-review and Meta-analysis - PubMed
8. Assessment of perfusion on ventilation/perfusion scan after balloon pulmonary angioplasty in chronic thromboembolic pulmonary hypertension: expert opinion versus guidance by reference chart - PubMed