A Prospective, Comparative Study of Ventilation–Perfusion Planar Imaging and Ventilation–Perfusion SPECT for Chronic Thromboembolic Pulmonary Hypertension

This study compared the diagnostic performance of ventilation–perfusion (V/Q) planar imaging and V/Q SPECT and determined whether combining perfusion SPECT with low-dose CT (Q-LDCT) may be equally effective in a prospective study of patients with chronic thromboembolic pulmonary hypertension (CTEPH). V/Q scanning is recommended for excluding CTEPH during the diagnosis of pulmonary hypertension (PH). However, V/Q planar imaging and V/Q SPECT have yet to be compared in patients with CTEPH. Methods: Patients with suspected PH were eligible for the study. PH attributable to left heart disease or lung disease was excluded, and patients whose PH was confirmed by right heart catheterization and who completed V/Q planar imaging, V/Q SPECT, Q-LDCT, and pulmonary angiography were included. V/Q images were interpreted and patients were diagnosed as instructed by the 2009 European Association of Nuclear Medicine guidelines, and pulmonary angiography analyses were used as a reference standard. Results: A total of 208 patients completed the study, including 69 with CTEPH confirmed by pulmonary angiography. V/Q planar imaging, V/Q SPECT, and Q-LDCT were all highly effective for diagnosing CTEPH, with no significant differences in sensitivity or specificity observed among the 3 techniques (respective sensitivity and specificity: 94.20% and 92.81% for V/Q planar imaging, 97.10% and 91.37% for V/Q SPECT, and 95.65% and 90.65% for Q-LCDT). However, V/Q SPECT was significantly more sensitive (V/Q SPECT, 79.21%; V/Q planar imaging, 75.84% [P = 0.012]; Q-LDCT, 74.91% [P < 0.001]), and V/Q planar imaging was significantly more specific (V/Q planar imaging, 54.14%; V/Q SPECT, 46.05% [P < 0.001]; Q-LDCT, 46.05% [P = 0.001]) than the other 2 techniques for identifying perfusion defects in individual lung segments. Conclusion: Both V/Q planar imaging and V/Q SPECT were highly effective for diagnosing CTEPH, and Q-LDCT may be a reliable alternative method for patients who are unsuitable for ventilation imaging.