18F-FDG-PET/MR in Alveolar Echinococcosis: Multiparametric Imaging in a Real-World Setting

Human Alveolar Echinococcosis-A Neglected Zoonotic Disease Requiring Urgent Attention

Alveolar echinococcosis (AE) in humans is caused by the larval (metacestode) stage of Echinococcus multilocularis, commonly known as the 'fox tapeworm'. This disease predominantly targets the liver and has an invasive growth pattern, allowing it to spread to adjacent and distant tissues. Due to its gradual progression and tumour-like characteristics, early diagnosis and prompt intervention are crucial, particularly as there are currently no highly effective vaccines or chemotherapeutics against AE. Current estimates suggest that ~10,500 new infections occur annually worldwide; however, more research is required to refine the prevalence and incidence data for both human and animal hosts in endemic areas of the world. This article discusses the biology of E. multilocularis, outlines aspects of the pathogenesis, diagnosis, treatment, and management of AE, reviews its global distribution, annual incidence, and prevalence, highlights the role of molecular parasitology in advancing therapeutic strategies, and presents recommendations for improving the prevention and control of AE in human populations.

Advances in Novel Diagnostic Techniques for Alveolar Echinococcosis

Alveolar echinococcosis (AE), caused by the larval stage of the tapeworm Echinococcus multilocularis, is a serious parasitic disease that presents significant health risks and challenges for both patients and healthcare systems. Accurate and timely diagnosis is essential for effective management and improved patient outcomes. This review summarizes the latest diagnostic methods for AE, focusing on serological tests and imaging techniques such as ultrasonography (US), computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography/computed tomography (PET/CT). Each imaging modality has its strengths and limitations in detecting and characterizing AE lesions, such as their location, size, and invasiveness. US is often the first-line method due to its non-invasiveness and cost-effectiveness, but it may have limitations in assessing complex lesions. CT provides detailed anatomical information and is particularly useful for assessing bone involvement and calcification. MRI, with its excellent soft tissue contrast, is superior for delineating the extent of AE lesions and their relationship to adjacent structures. PET/CT combines functional and morphological imaging to provide insights into the metabolic activity of lesions, which is valuable for monitoring treatment response and detecting recurrence. Overall, this review emphasizes the importance of a multifaceted diagnostic approach that combines serological and imaging techniques for accurate and early AE diagnosis, which is crucial for effective management and improved patient outcomes.

Chemotherapy for the treatment of alveolar echinococcosis: Where are we?

Alveolar echinococcosis (AE) is a severe liver disease due to infection with the Echinococcus multilocularis larval stage, called the metacestode. Management of AE is based on benzimidazole chemotherapy (albendazole or mebendazole), associated with surgery when possible. Benzimidazoles are the only compounds recommended for the treatment of AE; however, these are parasitostatic, which means that the parasite can resume growth when treatment is interrupted. Also, benzimidazoles can cause liver dysfunction which may prevent their use. Numerous drugs have been reported to have in vitro activity against E. multilocularis, but few had satisfactory in vivo activity, and none were clearly more effective than benzimidazoles. These drugs belong to various therapeutic categories including anti-infective agents (e.g. amphotericin B, mefloquine, pentamidine derivatives), anti-neoplastic compounds (e.g. imatinib, nilotinib, bortezomib), plant-extracted compounds (e.g. thymol, crocin, carvacrol) and others (e.g. metformin, verapamil, thiaclopride). These treatments are generally of limited interest due to their toxicity, their unfavorable pharmacokinetics, or the scarcity of studies involving humans. Apart from benzimidazoles, only amphotericin B, mefloquine and nitazoxanide have been reported to be used for human AE treatment, with unsatisfactory results. Few studies have aimed at developing innovative strategies for AE drug therapy, such as vectorization of drugs using nanoparticles. Altogether, this review emphasizes the urgent need for new therapeutic strategies in AE management, for which there is currently no curative chemotherapy.

Alveolar echinococcosis

Alveolar echinococcosis is a much-feared parasitic zoonosis caused by the larval stage of Echinococcus multilocularis. Mainland Norway is free from infection, but alveolar echinococcosis is, on rare occasions, imported from endemic regions. Those infected develop slow-growing, multicystic tumours that are clinically and radiologically reminiscent of malignant disease. The disease mainly attacks the liver. Treatment often consists of extensive surgical resection in combination with prolonged use of albendazole. In this clinical review article we summarise the life cycle, clinical findings, diagnosis, treatment and epidemiology of alveolar echinococcosis, and provide examples of the disease course with two patient case reports.

Value of intralesional and perilesional radiomics for predicting the bioactivity of hepatic alveolar echinococcosis

Objectives

To investigate the value of intralesional and perilesional radiomics based on computed tomography (CT) in predicting the bioactivity of hepatic alveolar echinococcosis (HAE).

Materials and methods

In this retrospective study, 131 patients who underwent surgical resection and diagnosed HAE in pathology were included (bioactive, n=69; bioinactive, n=62). All patients were randomly assigned to the training cohort (n=78) and validation cohort (n=53) in a 6:4 ratio. The gross lesion volume (GLV), perilesional volume (PLV), and gross combined perilesional volume (GPLV) radiomics features were extracted on CT images of portal vein phase. Feature selection was performed by intra-class correlation coefficient (ICC), univariate analysis, and least absolute shrinkage and selection operator (LASSO). Radiomics models were established by support vector machine (SVM). The Radscore of the best radiomics model and clinical independent predictors were combined to establish a clinical radiomics nomogram. Receiver operating characteristic curve (ROC) and decision curves were used to evaluate the predictive performance of the nomogram model.

Results

In the training cohort, the area under the ROC curve (AUC) of the GLV, PLV, and GPLV radiomic models was 0.774, 0.729, and 0.868, respectively. GPLV radiomic models performed best among the three models in training and validation cohort. Calcification type and fibrinogen were clinical independent predictors (p<0.05). The AUC of the nomogram-model-based clinical and GPLV radiomic signatures was 0.914 in the training cohort and 0.833 in the validation cohort. The decision curve analysis showed that the nomogram had greater benefits compared with the single radiomics model or clinical model.

Conclusion

The nomogram model based on clinical and GPLV radiomic signatures shows the best performance in prediction of the bioactivity of HAE. Radiomics including perilesional tissue can significantly improve the prediction efficacy of HAE bioactivity.

Disseminated alveolar echinococcosis in a patient diagnosed by metagenomic next-generation sequencing: A case report

Background

Alveolar echinococcosis (AE) is a parasitic zoonosis with high mortality and disability rates. Diverse clinical manifestations and mimicking of differential diagnoses such as tuberculosis and malignancy pose a diagnostic dilemma. With the rapid development of molecular diagnostic techniques in recent years, metagenomic next-generation sequencing (mNGS) has become an attractive approach for the etiological diagnosis of infectious diseases.

Case presentation

we report a case of 51-year-old Chinese Tibetan male presented with 3-year low-back pain and 4-month discomfort in the right upper quadrant of the abdomen. He had been in good health. He was diagnosed with tuberculosis and was given anti-tuberculosis treatment a month prior to the visit, but the symptoms were not relieved. Abdominal computerized tomography (CT) revealed a hypodense lesion with uneven enhancement in the liver, and two ring-enhancing cystic lesions in the right abdominal wall. Lumbar spine enhanced MRI showed lesions of mixed density with uneven enhancement in the L1 vertebra and paraspinal tissue. The pathological results of the liver biopsy revealed parasitic infection and possibly echinococcosis. The metagenomic next-generation sequencing (mNGS) of the puncture fluid of abdominal cysts using Illumina X10 sequencer revealed 585 sequence reads matching Echinococcus multilocularis. Disseminated AE was diagnosed. Albendazole (400 mg, twice daily) was used, and the patient was in stable condition during follow-up.

Conclusions

mNGS may be a useful tool for the diagnosis of AE. The case would help clinicians to improve their diagnostic skills.