# Diagnostic performance comparison of two ultrasound classification systems for hepatic alveolar echinococcosis: a single-center retrospective study

## TL;DR

This study compares two ultrasound systems for diagnosing hepatic alveolar echinococcosis, finding each has strengths in sensitivity and specificity for different stages of the disease.

## Contribution

The study introduces a complementary diagnostic strategy using two ultrasound classification systems for hepatic alveolar echinococcosis.

## Key findings

- EMUC-US has high sensitivity (96.7%) and NPV (90.3%) for early detection of atypical HAE lesions.
- EMNHCC-US has high specificity (94.2%) and PPV (95.5%) for diagnosing advanced HAE lesions.
- The two systems are complementary, enabling a stratified diagnostic approach for HAE.

## Abstract

Hepatic alveolar echinococcosis (HAE) is a severe zoonotic parasitic disease for which ultrasonography is the primary diagnostic tool. However, the heterogeneous imaging characteristics of HAE lesions present significant challenges to accurate diagnosis. To improve diagnostic reliability, this study compared the performance of two established ultrasound classification systems: the Echinococcus multilocularis National Health Commission Classification-Ultrasound (EMNHCC-US) and the E. multilocularis Ulm Classification-Ultrasound (EMUC-US).

This study compared EMUC-US and EMNHCC-US systems in 169 HAE cases (179 lesions) and 99 non-HAE controls. Both systems identified heterogeneous echotexture as a universal feature but differed in lesion categorization and diagnostic performance. Inter-observer agreement was moderate for EMUC-US (κ = 0.57) and substantial for EMNHCC-US (κ = 0.73). The EMUC-US system included atypical patterns such as metastasis-like, found in 10.6% of cases, and ossified lesions, found in 6.1%. This contributed to its high sensitivity of 96.7% and a negative predictive value (NPV) of 90.3%. The EMNHCC-US system focused on advanced patterns, identifying infiltration in 49.7% of cases and liquefactive necrosis in 31.8%. It demonstrated superior specificity of 94.2% and a positive predictive value of 95.5%. Receiver operating characteristic analysis confirmed a better overall discriminative ability for EMNHCC-US, with an area under curve of 0.88 compared to 0.72 for EMUC-US. Sensitivity analysis revealed that EMUC-US maintained a near-perfect NPV of approximately 100% across all prevalence levels. In contrast, EMNHCC-US offered a higher PPV in high-prevalence settings.

The EMUC-US and EMNHCC-US systems share core features, but EMUC-US includes smaller, atypical lesions (e.g., ossification, metastasis-like), enhancing early HAE detection with higher sensitivity and NPV, ideal for screening. EMNHCC-US focuses on advanced lesions, offering high specificity for confirmation. They are complementary: EMUC-US for sensitive screening, EMNHCC-US for specific diagnosis. Together, they enable a stratified strategy, optimizing case identification and clinical decisions despite lesion heterogeneity.