Abstract:

Objective

To analyze the safety and efficacy of diagnosis of single photon emission computed tomography （SPECT） lung perfusion imaging/low-dose computed tomography （CT） in patients with chronic obstructive pulmonary disease （COPD） complicated by pulmonary embolism （PE）.

Methods

Eighty COPD patients suspected of PE admitted to our hospital from January 2014 to December 2024 were selected as subjects. The patients underwent SPECT lung perfusion imaging and low-dose lung CT examination （samemachine examination），followed by image post-processing fusion. Adverse reactions during imaging were recorded. Using the final discharge results as the gold standard，the diagnostic results and value of SPECT，lowdose CT，and SPECT/CT were analyzed and compared. The detection rates and imaging characteristics of different imaging techniques for lesion locations were recorded.

Results

Among the 80 COPD patients suspected of PE，the gold standard confirmed 43 cases of PE and 37 cases of non-PE. The diagnostic results of SPECT/CT fusion，SPECT，and low-dose CT were 40 positive cases，30 positive cases，and 35 positive cases，and 35 negative cases，25 negative cases，and 28 negative cases，respectively. The diagnostic consistency of SPECT/CT fusion （Kappa=0.843） was higher than that of SPECT and low-dose CT. The diagnostic sensitivity（93.02%），specificity （94.59%），positive predictive value （95.24%），negative predictive value （92.11%），and accuracy （93.75%） of SPECT/CT fusion were higher than those of SPECT （69.77%，67.57%，71.43%，65.79%，68.75%） and low-dose CT （81.40%，75.68%，79.55%，77.78%，78.75%） （P＜0.05）. Among the 43 PE cases diagnosed by the gold standard，there were 91 segmental lesions and 97 subsegmental lesions. The detection rates of segmental lesions by different imaging techniques （92.31% vs. 83.52% vs. 85.71%） showed no statistically significant difference （P＞0.05）. However，the detection rate of subsegmental lesions by SPECT/CT fusion （95.88%） was higher than that by SPECT （76.29%） and low-dose CT （81.44%） （P＜0.05）. In PE patients，SPECT lung perfusion imaging showed single or multiple radioactive sparse defect area，with uniform or uneven radioactive distribution. Low-dose CT images revealed filling defects in the pulmonary vascular pathways，increased lung translucency，and sparse lung texture. In SPECT/CT fusion images，the radioactive sparse defect area in the lung of PE patients matched the filling defects in the pulmonary vascular pathways.

Conclusion

Low-dose SPECT/CT lung perfusion fusion imaging is effective and safe for diagnosing COPD complicated with PE，providing accurate information for clinical PE diagnosis.

Key words: Chronic obstructive pulmonary disease, Pulmonary embolism, Single photon emission computed tomography, Pulmonary perfusion, Computed tomography, Low-dose