Animal experimental study on multiple imaging methods for the diagnosis of acute pulmonary embolism by SPECT/CT

Abstract

Objective To evaluate the diagnostic efficiency of Q-SPECT, CTPA, Q-SPECT/CT, and Q-SPECT/CTPA for pulmonary embolism (PE) in rabbit models. Methods (1) The PE models were constructed by injecting Gelfoam into the femoral vein of New Zealand rabbits (n=30). Q-SPECT, CTPA, Q-SPECT/CT and Q-SPECT/CTPA fusion images were obtained by integrated SPECT/CT. (2) All images were interpreted by two experienced nuclear radiologists who were blind to pathologic findings. The locations and numbers of lung lobes with PE were recorded respectively. (3) Serial sectioning of the lungs was performed and pathologically determined. (4) Se, Sp and Ac of different methods were compared using McNemar test; PPV and NPV were compared using χ2 test. Kappa test was used to analyze the consistency between two nuclear radiologists. Kappa values 0.75 as good consistency. Results (1) Histologically confirmed emboli were present in a total of 26 pulmonary lobes and absent in 79 lobes. (2)The Se, Sp, Ac, PPV, and NPV of 4 imaging methods were: 53.8%(14/26), 93.7%(74/79), 83.8%(88/105), 14/19, 86.0%(74/86) for Q-SPECT; 73.1%(19/26), 96.2%(76/79), 90.5%(95/105), 86.4%(19/22), 91.6%(76/83) for CTPA; 76.9%(20/26), 93.7%(74/79), 89.5%(94/105), 80.0%(20/25), 92.5%(74/80)for Q-SPECT/CT; 88.5%(23/26), 91.1%(72/79), 90.5%(95/105), 76.7%(23/30), 96.0%(72/75) for Q-SPECT/CTPA. (3) McNemar test showed Q-SPECT/CT and Q-SPECT/CTPA had higher diagnostic Se for the detection of PE than Q-SPECT (χ2=4.167, 7.111, both P 0.05). Q-SPECT/CT had higher diagnostic Ac than Q-SPECT (χ2=4.167, P 0.05). (4)Kappa values of 4 imaging methods for radiologist 1 and 2 were 0.902, 0.915, 0.973, and 0.884. Conclusions Q-SPECT/CT imaging provides good Se and Sp. The diagnostic efficiency of Q-SPECT/CT is better than that of Q-SPECT and is corresponded roughly to the efficiency of CTPA, Q-SPECT/CTPA. The diagnosis of two radiologists on Q-SPECT/CT images has the best consistency. Key words: Pulmonary embolism; Tomography, emission-computed, single-photon; Tomography, X-ray computed; Radionuclide imaging; MAA; Rabbits