The role of contrast-enhanced ultrasound in the diagnosis of hepatic alveolar echinococcosis

Pictorial review of hepatic echinococcosis: Ultrasound imaging and differential diagnosis

Echinococcosis is a zoonotic disease caused by parasites belonging to the genus Echinococcus that primarily affect the liver. The western plateau and pastoral areas of China are high-risk regions for hepatic cystic echinococcosis and hepatic alveolar echinococcosis (HAE). The high late mortality rate associated with HAE underscores the critical need for early diagnosis to improve cure rates and mitigate the disease burden in endemic areas. Currently, the World Health Organization recommends ultrasonography as the preferred initial screening method for hepatic echinococcosis. However, distinguishing between specific types of lesions, such as those of hepatic cystic echinococcosis and HAE, and other focal liver lesions is challenging. To address this issue, contrast-enhanced ultrasound is recommended as a tool to differentiate solid and cysto-solid hepatic echinococcosis from other focal liver lesions, significantly enhancing diagnostic accuracy. In this comprehensive review, we discuss the progression of hepatic echinococcosis and detail the imaging features of various types of echinococcosis using conventional, contrast-enhanced, and intraoperative ultrasound techniques. Our objective is to provide robust imaging evidence and guidance for early diagnosis, clinical decision making, and postoperative follow-up in regions with high disease prevalence.

A Case Series and Literature Review of Alveolar Echinococcosis in Kashmir, India: An Emerging Endemic Zone for Echinococcus multilocularis

A prospective study on 110 patients with echinococcosis at Dr. Khuroo's Medical Clinic, Srinagar, Kashmir, India, from March 2019 to April 2024 identified 12 cases (4 males, 8 females; mean age of 46.58 ± 11.97 years) of Alveolar echinococcosis (AE). Two patients were detected through ultrasound examinations carried out for unrelated causes; one presented with features of liver abscess, and nine had pain in the right upper quadrant for a mean period of 2.2 ± 1.79 years. All had the liver as the primary organ involved, with 15 tumor masses of a mean maximum diameter of 9.22 ± 3.21 cm and volume of 426 ± 374.61 cm3. Tumors placed centrally had invaded vessels and the biliary tract in eight patients, and those placed peripherally had invaded the liver capsule and adjacent organs in nine patients. Histologic examination of liver biopsies or resected organs revealed necrotic lesions, calcifications, and granulomatous inflammation with slender, thin-walled vesicles of bizarre configuration that stained strongly eosinophilic with periodic acid Schiff. Two patients had segmental liver resections; one was treated with liver aspiration, while the other nine with advanced disease received chemotherapy with albendazole along with praziquantel. Patients showed clinical improvement on a median follow-up of 12 months (range 1 to 60 months); however, MRI T2-weighted images and 18F-FDG-PET-CECT scans in two patients showed active disease on follow-up at one and five years, respectively. A systematic review detected 146 cases of AE in India from 1980 to April 2024. Twenty cases were from foreign countries, mostly from Central Asian republics, and 118 (93.65%) of the remaining 126 Indian patients were permanent residents of Kashmir Valley. The disease affected a population of 79,197 residing in 22 villages from 5 border districts of the valley. These villages were either high in or adjacent to the Himalayan mountain range. Disease prevalence in the affected population was 146.47/105 (males 131.53/105 and females 163.18/105) and the incidence was 12.41/105/year (males 11.16/105/year and females 13.81/105/year). Possible causes of the emergence of AE are discussed, and future directions for research to face this challenge arebeen identified.

Past and Present of Diagnosis of Echinococcosis: A Review (1999-2021)

The larval forms of taeniid cestodes belonging to the genus Echinococcus are the source of the zoonotic infection known as echinococcosis. Alveolar and cystic echinococcosis are caused by Echinococcus multilocularis and Echinococcus granulosus (s. s) respectively. It is endemic in several regions of the world. In this systematic review, we describe diagnosis, and the species (human, canids, livestock, and small rodents) affected by cystic (CE) and alveolar echinococcosis (AE). From 1999 to 2021, we searched the online directory through PubMed, SCOPUS, Web of Science, and google scholar. Among the 37,700 records found in the online databases, 187 publications met our eligibility requirements. The majority of investigations employed a range of diagnostic methods, such as ELISA, imaging, copro-PCR, necropsy or arecoline hydrobromide purgation, morphological cestode confirmation, and fecal sieving/flotation to detect and confirm Echinococcus infection. ELISA was the most commonly used method followed by PCR, and imaging. The research team retrieved data describing the incidence or assessment of the diagnostic test for E. multilocularis in humans (N = 99), canids (N = 63), small ruminants (N = 13), large ruminants (N= 3), camel (N= 2), pigs (N=2) and small mammals (N= 5). This study was conducted to explore the diagnostic tools applied to detect echinococcosis in humans as well as animals in prevalent countries, and to report the characteristic of new diagnostic tests for disease surveillance. This systematic review revealed that ELISA (alone or in combination) was the most common method used for disease diagnosis and diagnostic efficacy and prevalence rate increased when recombinant antigens were used. It is highly recommended to use combination protcols such as serological with molecular and imaging technique to diagnose disease. Our study identified scarcity of data of reporting echinococcosis in humans/ animals in low-income or developing countries particularly central Asian countries. Study reports in small rodents indicate their role in disease dissemination but real situation in these host is not refected due to limited number of studies. Even though echinococcosis affects both public health and the domestic animal sector, therefore, it is important to devise new and strengthe implementation of the existing monitoring, judging, and control measures in this estimate.

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

BACKGROUND

Hepatic echinococcosis (HE) is a zoonotic disease caused by Echinococcus, and Echinococcus granulosus and E. multilocularis are the most common, causing cystic echinococcosis (CE) and alveolar echinococcosis (AE), respectively. Contrast-enhanced ultrasound (CEUS) is an imaging technique which has been recommended for identifying focal lesions in the liver. However, the effect of CEUS on the differentiation of hepatic echinococcosis type 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 (US) and CEUS examinations, respectively. After US was completed, the CEUS study was performed. A bolus injection of 1.0-1.2 ml of a sulfur hexafluoride-filled microbubble contrast agent (SonoVue^®) was administered. The images and clips of the lesions by US and CEUS were reviewed retrospectively. The lesions detected using US were evaluated including the location, size, morphology, margin, internal echogenicity and the internal Doppler signal. The lesions detected using CEUS were evaluated including the enhancement degree, enhancement pattern and enhancing boundary in different phases. The diagnoses of lesions by US or CEUS were respectively recorded. By taking the histopathology as the gold standard, the paired Chi-square test was performed with statistical software (IBM SPSS; IBM Corp., Armonk, NY, USA), and the results of differentiation of HE type by US 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%) aged 15-55 (42.9 ± 10.3) years. By histopathology, 24 lesions of nine patients were diagnosed as CE and 22 lesions of 16 patients were diagnosed as AE. Among the 46 HE lesions, compared with histopathological examination, the accuracy rate was 65.2% and 91.3% in US and CEUS findings, respectively. Among the 24 CE lesions, 13 lesions were correctly differentiated by US, and 23 by CEUS. The difference between US and CEUS was statistically significant (Chi-square test, [Formula: see text] = 8.10, df = 23, P < 0.005). Among the total 46 HE lesions, 30 lesions were correctly differentiated by US, and 42 by CEUS. The difference between US and CEUS was statistically significant (Chi-square test, [Formula: see text] = 10.08, df = 45, P < 0.005).

CONCLUSIONS

CEUS is a more effective technique than US for differentiating the type of HE between CE and AE. It could be a reliable tool in the differentiation of HE.

Differentiation of hepatic alveolar echinococcosis with a hemangioma-like pattern compared to typical liver hemangioma using contrast-enhanced ultrasound: a pilot study

PURPOSE

Echinococcus multilocularis infects humans as a false intermediate host, primarily with intrahepatic manifestation. Incorrect diagnostic interpretation of these liver tumors, especially the hemangioma-like pattern, can lead to progressive disease. The aim of the study was to investigate the differentiation of typical hemangioma and a hemangioma-like pattern of E. multilocularis using contrast-enhanced ultrasound (CEUS).

METHODS

This prospective clinical pilot study comprised patients with hemangioma (n = 14) and patients with alveolar echinococcosis (AE) and hemangioma-like pattern (n = 7). Inclusion criteria were the detection of a liver lesion according to a hemangioma-like pattern on E. multilocularis Ulm classification-ultrasound (EMUC-US) and "confirmed" or "probable" AE according to WHO case definition. The comparison group had hepatic hemangioma with typical B-scan sonographic morphology. All participants underwent conventional and contrast-enhanced ultrasonography.

RESULTS

The patient group comprised five men (71.4%) and two women (28.6%) with a mean average age of 64.1 ± 11.2 years. The patient group with hemangioma comprised nine female subjects (64.3%) and five male subjects (35.7%) with a mean average age of 56.1 ± 12.0 years. Early arterial bulbous ring enhancement (p < 0.0001) and iris diaphragm phenomenon could only be visualized in the patients with hemangioma (p < 0.0001). Furthermore, the patients with hemangioma exhibited hyperenhancement in the late phase (p = 0.0003). In contrast, the patients exhibited typical early arterial rim enhancement (p < 0.0001) and, in the portal venous and late phase, complete or incomplete non-enhancement (black hole sign; p = 0.0004).

CONSLUSION

The behavior of hemangioma-like AE lesions and typical liver hemangiomas is significantly different on CEUS. AE should be considered as a possible differential diagnosis, especially in high-endemic areas.

Uncommon abdominal “egg-shelled” lesions mimic hepatic echinococcosis: Two cases report

Background

Primary abdominal “egg-shelled” lesions with positive anti-echinococcus IgG antibody were misdiagnosed as echinococcosis.

Case presentation

Herein we report two cases with primary abdominal “egg-shelled” lesions were misdiagnosed as echinococcosis. Case 1: A 44-year-old woman presented to our department with a history of slight abdominal pain for 4 months. After admission, the laboratory tests indicated a positive anti-echinococcus IgG antibody status. The contrast-enhanced CT scan showed a 12 × 12 cm “me contrast-mass located in the hepatorenal area. The patient had the entire mass and the right adrenal gland resected. This patient recovered smoothly and was discharged uneventfully 20 days after the operation. The pathologic diagnoses was adrenal lymphangioma. Case 2: A 55-year-old woman was admitted with a history of an abdominal mass for over 10 years. After admission, her anti-echinococcus IgG antibody was positive. The contrast-enhanced CT scan revealed a heterogeneous, solid mass measuring 10 × 9 × 8 cm in the right hepatic lobe. A laparoscopic exploration was performed, and the surgery revealed that the mass arose from the retroperitoneal tissue rather than the liver. Finally, the pathologic diagnoses were paraganglioma with necrosis and cystic changes.

Conclusion

Enhanced CT scan and contrast-enhanced ultrasound scans are important for distinguishing echinococcosis disease from the other “egg-shelled” lesions. Surgical resection is the main treatment method for this disease. Minimally invasive surgery is recommended but should be performed by experienced surgical teams. Immunohistochemical examination is important for the pathologic diagnosis.

Contrast-enhanced ultrasound (CEUS) in patients with metastasis-like hepatic alveolar echinococcosis: a cohort study

PURPOSE

Hepatic alveolar echinococcosis (HAE) of the metastasis-like pattern, according to the Echinococcus Ulm classification, is usually discovered as an incidental finding, and the diagnostic differentiation from "true metastases" is difficult. The aim of this study was to investigate whether lesions of the "metastasis-like pattern" in HAE show a typical contrast behavior that can be used for differentiation from metastasis in malignancies.

METHODS

This prospective clinical study included 11 patients with histologically confirmed HAE of the metastasis-like pattern (7 female and 4 male; mean age, 57.1 years; mean disease duration, 59.5 months), who had been examined by B-scan sonography and CEUS, from the National Echinococcosis Registry Germany.

RESULTS

On contrast-enhanced sonography, 11/11 reference lesions showed annular rim enhancement in the arterial and portal venous phases. Throughout the entire 4-min study period, none of the reference lesions showed central contrast enhancement-i.e., all exhibited a complete "black hole sign". A small central scar was seen in 81.8% of cases.

CONCLUSION

In clinically unremarkable patients with incidentally detected metastasis-like lesions of the liver, contrast-enhanced sonographic detection of rim enhancement without central contrast uptake (black hole sign) should be considered evidence supporting a diagnosis of hepatic alveolar echinococcosis with a rare metastasis-like pattern. This can help to differentiate HAE from metastases, especially in high-endemic areas.

Long-term follow-up of liver alveolar echinococcosis using echinococcosis multilocularis ultrasound classification

BACKGROUND

When Echinococcus multilocularis infects humans as a false intermediate host, alveolar echinococcosis (AE) usually manifests primarily intrahepatically and is initially asymptomatic. If the disease remains undiagnosed and untreated, progressive growth occurs, reminiscent of malignant tumours. The only curative therapy is complete resection, which is limited to localised stages, and palliative drug therapy is used otherwise. Consequently, early diagnosis and reliable detection of AE lesions are important. For this reason, abdominal ultrasonography, as the most common primary imaging for AE, relies on classification systems.

AIM

To investigate how hepatic AE lesion sonomorphology changes over time in the Echinococcosis Multilocularis Ulm Classification (EMUC)-ultrasound (US) classification.

METHODS

Based on data from Germany’s national echinococcosis database, we evaluated clinical and US imaging data for 59 patients according to the AE case definition in our preliminary retrospective longitudinal study. There had to be at least two liver sonographies ≥ 6 mo apart, ≥ 1 hepatic AE lesion, and complete documentation in all US examinations. The minimum interval between two separately evaluated US examinations was 4 wk. The AE reference lesion was the largest hepatic AE lesion at the time of the first US examination. To classify the sonomorphologic pattern, we used EMUC-US. In addition to classifying the findings of the original US examiner, all reference lesions at each examination time point were assigned EMUC-US patterns in a blinded fashion by two investigators experienced in US diagnosis. Statistical analysis was performed using SAS version 9.4 (SAS Institute Inc., Cary, NC, United Stated). P values < 0.05 were considered statistically significant.

RESULTS

The preliminary study included 59 patients, 38 (64.5%) women and 21 (35.6%) men. The mean age at initial diagnosis was 59.9 ± 16.9 years. At the time of initial ultrasonography, a hailstorm pattern was present in 42.4% (25/59) of cases, a hemangioma-like pattern in 16.9% (10/59), a pseudocystic pattern in 15.3% (9/59), and a metastasis-like pattern in 25.4% (15/59). For the hailstorm pattern, the average lesion size was 67.4 ± 26.3 mm. The average lesion size was 113.7 ± 40.8 mm with the pseudocystic pattern and 83.5 ± 27.3 mm with the hemangioma-like pattern. An average lesion size of 21.7 ± 11.0 mm was determined for the metastasis-like pattern. Although the sonomorphologic pattern remained unchanged in 84.7% (50/59) of AE reference lesions, 15.3% (9/59) showed a change over time. A change in pattern was seen exclusively for AE lesions initially classified as hemangioma-like or pseudocystic. A total of 70% (7/10) of AE lesions initially classified as hemangioma-like showed a relevant change in pattern over time, and 85.7% (6/7) of these were secondarily classified as having a hailstorm pattern, with the remainder (1/7; 14.3%) classified as having a pseudocystic pattern. A total of 22.2% (2/9) of AE lesions initially classified as pseudocystic showed a relevant change in pattern over time and were classified as having a hailstorm pattern. For AE lesions initially classified as having a hailstorm or metastatic pattern, no pattern change was evident. All patients with pattern change were on continuous drug therapy with albendazole.

CONCLUSION

The sonomorphology of hepatic AE lesions may change over time. The hemangioma-like and pseudocystic patterns are affected.

Recent advances in ultrasound in the diagnosis and evaluation of the activity of hepatic alveolar echinococcosis

Echinococcosis is a worldwide neglected zoonotic disease. Alveolar echinococcosis (AE) poses a more serious threat to life and health than cystic echinococcosis, and has been one of the world's most lethal chronic parasitosis. Assessment of metacestode activity status is essential for individual treatment strategy design for a given AE patient, and fluorodeoxyglucose positron-emission tomography (FDG-PET) has been the gold standard. In this study, we reviewed previous evidence on AE activity assessment using contrast-enhanced ultrasound (CEUS), and its comparison with FDG-PET. The results showed good consistency between them, indicating CEUS as a suitable substitute for FDG-PET. With its advantage as being readily portable, widely available, and not costly, CEUS is more suitable for use in the developing countries and rural areas.

Characteristics of hepatic solitary necrotic nodules on contrast-enhanced ultrasonography

Background

To summarize the characteristics of solitary necrotic nodules (SNN) in the liver observed under contrast-enhanced ultrasonography (CEUS).

Methods

Conventional ultrasonography (US) and CEUS were performed in 24 patients who were confirmed to have SNN by pathological assessment. The US data and dynamic enhancement patterns of CEUS were recorded and retrospectively analyzed.

Results

Ten of 24 patients underwent surgical resection, while the other 14 patients underwent a puncture biopsy to be confirmed as SNN. Among the 24 patients, 13 patients had a single lesion and 11 patients had multiple lesions. The largest lesion was selected for CEUS examination for patients with multiple lesions. Eleven patients presented no enhancement in all three phases, while the other 13 patients presented with a peripheral thin rim-like enhancement in the arterial phase, an iso-enhancement in the portal phase and delayed phase. However, no enhancement in the interior of the lesions was detected during three phases of CEUS.

Conclusions

SNN has characteristic findings on the CEUS, which play an important role in the differential diagnoses of liver focal lesions.