Comparison of pulmonary ventilation/perfusion tomography and conventional diagnostic techniques in the diagnosis of pulmonary thromboembolism.

BACKGROUND: Pulmonary thromboembolism (PTE) is a common and potentially fatal cardiopulmonary vascular disease. Early and accurate diagnosis is crucial for improving patient prognosis. Computed tomography pulmonary angiography (CTPA) is widely used as a first-line imaging modality, while the clinical value of pulmonary ventilation/perfusion single-photon emission computed tomography (V/Q SPECT) in specific patient populations is increasingly recognized. However, systematic evidence comparing the diagnostic performance and corresponding patient clinical phenotypes across different imaging techniques remains limited. This study aimed to compare the application differences between V/Q SPECT and CTPA in diagnosing PTE, along with their associated clinical characteristics, physiological functional status, and risk stratification features, thereby providing evidence-based support for optimizing imaging diagnostic pathways.

METHODS: A retrospective case-control study was conducted, enrolling hospitalized patients diagnosed with PTE between January 1, 2017, and April 30, 2022, at a tertiary hospital in Shandong Province. Initially, 1,124 cases were retrieved via electronic medical record (EMR) and imaging databases. After screening, 726 patients were finally included: 312 in the V/Q SPECT group and 414 in the CTPA group. Demographic characteristics, clinical manifestations, laboratory indicators [D-dimer, troponin I, N-terminal pro-brain natriuretic peptide (NT-proBNP), partial pressure of arterial oxygen to the fraction of inspired oxygen (PaO2/FiO2), etc.], lower limb venous ultrasound, and echocardiographic parameters were systematically collected. Propensity score weighting was employed to balance baseline differences. Multivariable logistic regression and receiver operating characteristic (ROC) curve analyses were performed.

RESULTS: After weighting, baseline characteristics were well-balanced between the two groups. Patients in the V/Q SPECT group more frequently presented with central or lobar emboli, accompanied by more significant hypoxemia and right ventricular dysfunction (RVD). Their levels of D-dimer, NT-proBNP, and myocardial injury markers were higher than those in the CTPA group. The CTPA group in our cohort predominantly consisted of patients with relatively milder clinical symptoms and biomarker profiles. Multivariable analysis revealed that elevated NT-proBNP, RVD, and lower limb deep vein thrombosis (DVT) were significantly associated with the use of V/Q SPECT. The multi-parameter combined model demonstrated good discriminative ability, with an area under the curve (AUC) of 0.832 [95% confidence interval (CI): 0.801-0.862].

CONCLUSIONS: V/Q SPECT and CTPA are associated with distinct clinical phenotypes in real-world practice, largely reflecting systematic selection patterns driven by patient-specific contraindications and baseline risk profiles. In our cohort, V/Q SPECT was more commonly utilized in patients with higher clinical risk and biomarker levels, reflecting a clinical selection pattern where this modality was assigned to a more physiologically compromised population, while CTPA was applied to a relatively lower-risk cohort. The selection of imaging modality should integrate comprehensive assessment of clinical probability, biomarkers, and cardiopulmonary function to achieve individualized diagnostic decision-making.