Can contrast-enhanced ultrasound differentiate the subtype of hepatic echinococcosis: cystic echinococcosis or alveolar echinococcosis?

Background Hepatic echinococcosis (HE) is a zoonotic disease caused by Echinococcus, and Echinococcus granulosus and Echinococcus multilocularis are the most common, causing cystic echinococcosis (CE) and alveolar echinococcosis (AE) respectively. Contrast-enhanced ultrasound (CEUS) is a new imaging technique which has been recommended for identifying focal lesions in the liver. However, the effect of CEUS on the differentiation of hepatic echinococcosis subtype remains unclear. Methods Twenty-five patients with 46 HE lesions confirmed by histopathology in our Hospital from December 2019 to May 2022 were reviewed by conventional ultrasound (CUS) and CEUS examinations respectively. The images and clips of the lesions by CUS and CEUS were reviewed retrospectively. The lesions by CUS were evaluated including the location, size, morphology, margin, internal echogenicity and the internal Dopper’s signal. The lesions by CEUS were evaluated including the enhancement degree, enhancement pattern and enhancing boundary in different phases. The diagnoses of lesions by CUS or CEUS were recorded respectively. By taking the histopathology as the gold standard, the paired X2 test was performed with statistical software (SPSS, Inc., Chicago, IL) and the results of differentiation of the subtype of HE by CUS and CEUS were statistically analyzed. Results A total of 46 lesions were involved in 25 patients, including 10 males (40.0%) and 15 females (60.0%) with aged 15 to 55 (42.9 ± 10.3) years. By histopathology, 9 patients with 24 lesions were diagnosed as CE and 16 patients with 22 lesions were diagnosed as AE. Among the 46 lesions of HE, compared with histopathological examination, the accuracy rate was 65.2% and 91.3% in CUS and CEUS findings respectively. Among the 24 CE lesions, 13 lesions were correctly differentiated by CUS, while 23 by CEUS. The difference between CUS and CEUS was statistically significant (Chi-square test, X2 = 8.10, df = 23, P < 0.005). Among the total 46 HE lesions, 30 lesions were correctly differentiated by CUS, while 42 by CEUS. The difference between CUS and CEUS was statistically significant (Chi-square test, X2 = 10.08, df = 45, P < 0.005). Conclusions CEUS is a more valid technique that can differentiate the subtype of HE from CE or AE than CUS. It could be a reliable tool in the differentiation of HE.