To study the diagnostic accuracy of subtraction computed tomography pulmonary angiography (CTPA) compared to single-photon emission computed tomography combined with computed tomography (SPECT/CT) in the assessment of lung perfusion in patients with chronic thromboembolic pulmonary hypertension (CTEPH).

Materials and methods. Subtraction CTPA was performed 15 patients with known and suspected diagnosis of CTEPH (7 men, 8 women, age 27-69 years) by 320-detector row CT scanner (Aquilion ONE 640 VISION Edition, Toshiba) using the standard protocol Lung substraction during the period between October 2015 and July 2017. Lung perfusion parameters were assessed. The data obtained using CT were compared with the results of SPECT/CT and conventional (invasive) pulmonary angiography.

Results. In total 300 lung segments were evaluated in 15 patients with CTEPH. Predominantly distal lesion of the pulmonary vascular bed was recorded in 10 patients. Perfusion defects weren’t determined according to data of subtraction CTPA and SPECT/CT with an assessment of the perfusion defect score.

Mean difference of the perfusion defect score in the two methods was 9,2±14,8% using the Bland-Altman method. There weren’t defects in ventilation scintigraphy in all patients.

The sensitivity of subtraction CTPA for detection of perfusion defects in patients with CTEPH was 94%, the specificity was 72,6%, the positive predictive value (PPV) was 77,5% and the negative predictive value (NPV) was 92,4%. To comparing the subtraction data of CTPA and SPECT/CT with the results of invasive pulmonary angiography, the sensitivity, the specificity, the PPV and the NPV of subtraction CTPA were 94.2% and 96.6%, 92.8% and 93.3%, respectively.

Discussion. The results of our study showed a good comparability of subtraction CTPA compare with SPECT/CT in detecting lung perfusion defects in patients with CTEPH, which is consistent with the data of foreign studies in this area.

Conclusion. The assessment of lung perfusion using method of substraction CTPA is a promising direction in the diagnosis of CTEPH mainly in distal lesions of the vascular bed of the lungs.