Factors affecting the probability of pulmonary embolism in lung ventilation/perfusion scintigraphy

Probabilities for Pulmonary Embolism (PE) are reported on V/Q scintigraphy, though the clinical implications of these probabilities remain unclear. This study examined the factors influencing PE probability groups determined by V/Q scintigraphy.

Demographic and radiologic data, V/Q scintigraphy results, echocardiographic findings, and pulse oxygen saturation (SpO₂) were recorded for 95 patients admitted to the Nuclear Medicine Clinic between January 2022-2023. Patients were categorized into normal, low, intermediate, and high probability groups for PE based on V/Q scintigraphy findings.

The median age of the group with normal perfusion scintigraphy was 63 years (range: 19-85 years), which was significantly lower compared to other groups (p = 0.003). There was a weak positive correlation between the probability of PE and an increased right ventricle/left ventricle (RV/LV) ratio on CT (r = 0.256, p = 0.034), while no correlation was found with pulmonary artery (PA) diameter. Although systolic pulmonary artery pressure (sPAP) was not correlated with increased PE probability, a positive correlation was found with the presence of tricuspid regurgitation (TR) (r = 0.241, p = 0.037). A strong positive correlation was observed between PE probability and perfusion defect size (r = 0.758, p < 0.001), while a weak negative correlation was found with SpO₂ (r = -0.330, p = 0.014). Multivariable regression analysis revealed a significant relationship only with SpO₂.

An increased probability of PE on V/Q scintigraphy is associated with a higher RV/LV ratio on thorax CT, TR detection on echocardiography, hypoxemia, and larger perfusion defect size. These findings suggest that V/Q scintigraphy could also be useful in determining the prognosis of PE.