Abstract
Chronic thromboembolic pulmonary hypertension (CTEPH), which is classified as a group 4 pulmonary hypertension (PH), is a life-threatening complication of acute pulmonary embolism (PE). With the introduction of multidisciplinary approaches and innovative treatment strategies for CTEPH, it is currently regarded not as a fatal disease, but as a curable form of PH. Ventilation/perfusion (V/Q) scan is the preferred imaging method for screening for CTEPH, with superior sensitivity to CT pulmonary angiography. The findings and interpretations of V/Q scan in CTEPH may differ from those observed in acute PE. The use of V/Q scan in combination with SPECT or SPECT/CT is becoming more popular than planar scan alone. Comprehensive understanding of the role of V/Q scan in CTEPH will assist in providing early diagnosis, proper therapeutic decision making, and improved prognosis. This review outlines the current roles and potential clinical applications of V/Q scan in the diagnosis and evaluation of CTEPH.