Abstract:

Objective To investigate the value of conventional ultrasound combined with contrast-enhanced ultrasonography in the differential diagnosis of pleural-based pulmonary tuberculosis and bacterial pneumonia.Methods A total of 35 patients with pulmonary tuberculosis (tuberculosis group) and 16 cases with bacterial pneumonia (pneumonia group) diagnosed by pathology, bacteriology or diagnostic therapy in Shanghai Pulmonary Hospital from January to May 2019 were enrolled. Conventional and contrast-enhanced ultrasound images of lesions between the two groups were analyzed, and the size, location, shape, echogenicity, enhancement pattern, arrival time, time to peak, clearance speed, incidence and characteristics of necrosis were compared.Results (1) Conventional ultrasound showed 28 cases (80.00%) with wedge shape, 5 cases (14.29%) with round-like shape, and 2 cases (5.71%) with irregular shape in the tuberculosis group; and 10 cases (62.50%) with wedge shape, and 6 cases (37.50%) with round-like shape in the pneumonia group, without significant difference between the two groups (χ²=4.109, P=0.128). There was hyperechoic between the deep lesion and the normal lung tissue, among which, “fragment sign” appeared 11 cases (31.43%) in the tuberculosis group and 13 cases (81.25%) in the pneumonia group, with the significant difference between the two groups (χ²=10.940, P=0.001); “Waterfall sign” appeared in 22 cases (62.86%) in the tuberculosis group and 3 cases (18.75%) in the pneumonia group, with the significant difference between the two groups (χ²=8.548, P=0.003). (2) Contrast-enhanced ultrasonography showed that arrival time of lesions was (8.43 (4.79,10.83)) s in the tuberculosis group and (7.80 (5.51,12.26)) s in the pneumonia group, without the significant difference between the two groups (U=0.721, P=0.471); arrival time difference between lesion and lung tissue was (1.47 (0.56,2.01)) s in the tuberculosis group and (2.00 (1.28,2.67)) s in the pneumonia group, without the significant difference between the two groups (U=1.453, P=0.146); peak intensity was (-41.89±5.72) dB in the tuberculosis group and (-44.89±5.72) dB in the pneumonia group, without the significant difference between the two groups (t=1.738, P=0.089); half time of intensity descent was (153.33 (124.02,180.00)) s in the tuberculosis group and (138.45 (128.70,147.09)) s in the pneumonia group, without the significant difference between the two groups (U=1.326, P=0.185). Necrosis occurred in 29 cases (82.86%, 29/35) in the tuberculosis group and 5 cases (31.25%, 5/16) in the pneumonia group, with the significant difference between the two groups (χ²=13.160, P=0.000). In terms of the characteristics of necrosis, 15 cases (51.72%, 15/29) presented with multiple non-interconnected sieve-like necrosis, 11 cases (37.93%, 11/29) presented with large patchy necrosis with regular shape and regular inner wall, and 3 cases (10.35%, 3/29) presented with almost total necrosis with circular enhancement of residual active margin in the tuberculosis group; 1 case (1/5) presented with large patchy necrosis with regular shape and regular inner wall, and 4 cases (4/5) presented with small patchy necrosis with regular shape and regular inner wall in the pneumonia group. There was significant difference between the two groups (χ²=26.692, P=0.000).Conclusion Conventional ultrasound shows the characteristic of “irregular fragment-like” hyperechoic behind the lesions of bacterial pneumonia. Contrast-enhanced ultrasonography shows that the incidence of necrosis in pulmonary tuberculosis is significantly higher than that in bacterial pneumonia, with the characteristics of “sieve-like” and “regular large patch” necrosis. These founds can provide diagnostic basis for the differential diagnosis.

Key words: Tuberculosis, pulmonary, Pneumonia, bacterial, Ultrasonography, Evaluation studies, Contrast-enhanced ultrasound