Objective: To assess the value of the area of ground glass opacities (GGOs) in lungs displayed by high-resolution computed tomography (HRCT) in paraquat (PQ) poisoned patients in evaluating prognosis.
Methods: Clinical and imaging data of 137 patients with acute PQ poisoning admitted to Affiliated Hospital of the Medical College of Chinese People's Armed Police Forces from January 2012 to August 2014 were analyzed retrospectively. The plasma concentration of PQ on admission and the area of GGOs were compared between two groups. The lung HRCT within 10 days of poisoning was performed every 3 days, and the areas of GGOs were evaluated on five levels, including aortic arch, aortic pulmonary window, left upper lobe bronchial, right inferior pulmonary vein, and left diaphragmatic dome. Receiver operating characteristic curve (ROC) was plotted to evaluate the value of all the parameters for prognosis.
Results: Among 137 patients, 45 died within 28 days after poisoning, with the mortality rate of 32.85%. The plasma PQ level in the non-survivors was significantly higher than that in the survivors (mg/L: 7.06 ± 0.67 vs. 3.51 ± 0.34, t = 5.280, P = 0.000). The areas of GGOs at three time points in the non-survivors were significantly higher than those in the survivors [ 1-3 days: (32.0 ± 5.0)% vs. (2.5 ± 0.4)%, t = 7.860, P = 0.000; 4-6 days: (45.5 ± 5.7)% vs. (2.8 ± 0.5)%, t = 12.420, P = 0.000; 7-10 days: (68.0 ± 4.8)% vs. (3.0 ± 0.6)%, t = 23.950, P = 0.00 ]. ROC analysis demonstrated that the area under the ROC curve (AUC) of GGOs in 7-10 days was 1.000, which could be used to determine the prognosis, but it was too late for the treatment. The AUC of GGOs in 4-6 days was 0.979, with the threshold of > 12.0%, the specificity of 96.15%, the sensitivity of 85.19%, the positive predictive value of 88.46%, and the negative predictive value of 94.94%, which presented good effect in predicting prognosis in the early stage of acute PQ intoxication. But plasma PQ concentration was relatively poor for determining prognosis, AUC was 0.821, with the threshold of > 1.95 mg/L, the specificity of 34.52%, the sensitivity of 88.64%, the positive predictive value of 41.49%, and the negative predictive value of 85.29%.
Conclusions: The area of GGOs displayed by HRCT can be used to evaluate the fully developed acute PQ lung injury, and it is superior to plasma PQ concentration. The area of GGOs displayed by HRCT 4-6 days after intoxication can be used for the evaluation of PQ induced pulmonary injury in the early stage and the evaluation of clinical prognosis.