Comparison of ventilation/perfusion scintigraphy and pulmonary CT angiography: Findings in the diagnosis of CTEPH and CTED.

Objective: Despite the high sensitivity and specificity of ventilation/perfusion (VQ) scintigraphy in the diagnosis of chronic thromboembolic pulmonary hypertension (CTEPH) and chronic thromboembolic disease (CTED), V/Q scintigraphy cannot distinguish whether the thrombus is acute or chronic. In our study, we aimed to compare pulmonary computed tomography angiography (CTA) findings with V/Q scintigraphy findings in CTEPH and CTED patients and to identify findings that would indicate chronic thrombus.

Subjects and methods: Eighteen patients diagnosed with CTEPH and CTED at our institution were included in the study between January 2020 and January 2024. Computed tomography angiographyfindings were recorded as V/Q findings [location (segmental, subsegmental, lobar), number, appearance (wedge or patchy) of mismatch perfusion defects], and the correlation of these findings was investigated.

Results: The average age of 18 patients was 63.3±11.7, 66.7% were female and the majority of the patients were non-smokers, and no significant difference was detected between the CTED and CTEPH groups. Apart from the areas where chronic thrombus was localized on CTA, more widespread mismatch defects were observed by VQ scintigraphy. Most of the mismatch defects were wedge-shaped and there was similarity between groups. The presence of mosaic perfusion was detected in 62.5% of those with mismatch patchy defects (P=0.043). A negative correlation was detected between pulse oxygen saturation and the number of mismatch subsegmentary defects (r: -0.651, P=0.005). Systolic pulmonary artery pressure (sPAP) was found to be positively correlated with the number of mismatch defects (r: 0.523, P=0.026).

Conclusion: Ventilation/perfusionscintigraphy is superior in the diagnosis of CTEPH/CTED. The presence of mismatch patch defects on V/Q scintigraphy in patients with clinical, echocardiographic, and CTA findings suggests that the presence of mismatch patch defects on V/Q scintigraphy may be a sign of chronic thrombus and the number of mismatch defects may be correlated with the severity of the disease.