Quantitative Evaluation of Lung Perfusion by Dynamic Chest Radiography in Chronic Thromboembolic Pulmonary Hypertension: Comparison With Lung Perfusion Scintigraphy.

Pulmonary perfusion assessment is essential for the management of chronic thromboembolic pulmonary hypertension (CTEPH). Lung perfusion scintigraphy and contrast-enhanced CT are occasionally limited by the need for radionuclides or allergy to the contrast agents. Dynamic chest radiography (DCR) can evaluate the pulmonary perfusion non-invasively using conventional X-ray technology. We validated pulmonary perfusion measurements using DCR by comparing them with those obtained using perfusion scintigraphy in CTEPH. Thirty-three patients with CTEPH who underwent both DCR and lung perfusion scintigraphy within 1-month interval from December 2019 to December 2022 were included. DCR was performed with patients in both standing and supine positions. To assess lung perfusion, each lung was divided into six fields (right and left; upper, middle, and lower). The blood flow rates per field were quantified by using analysis software as 100% of the sum of the six sites. The correlation between blood flow rates of each area in DCR and perfusion scintigraphy was evaluated using intraclass correlation coefficients (ICC). DCR showed a strong correlation with pulmonary perfusion scintigraphy in both standing (ICC(2,1) = 0.86; confidence interval [CI], 0.81-0.89) and supine (ICC(2,1) = 0.82; CI, 0.77-0.86) positions. When analyzed by region, all regions except the left lower lung showed significant correlations with perfusion scintigraphy findings. Intra- and intra-inspector reliabilities at both positions were excellent. The quantitative assessment of lung perfusion using DCR is reliable in patients with CTEPH. However, perfusion in the left lower lung was underestimated using DCR.