Demographic characteristics of patients with extrahepatic AE were shown in table 1. In this study, 33 patients (18 men and 15 women, age range 21-74 years (average 40.67±12.62 years) were suffering from extrahepatic AE rather than hepatic AE. In this group, 31 patients were inhabitants of Xinjiang from birth and two patients were from Kazakhstan. The patients were from multiple ethnic groups, including 19 (57.6%) Han, 8 (24.2%) Kazak, 4 (12.1%) Hui and 2 (6.1%) Tibetan. The most common symptoms were 10 (30.3%) abdominal pain and distention, followed by 8 (24.2%) headache, and 6 (18.2%) masses in the upper abdomen. 31 patients had both hepatic and extrahepatic AE.
Distribution of the extrahepatic AE
The distribution of the extrahepatic AE were shown in table 1. In this study, 31 patients had both hepatic and extrahepatic AE, and 2 cases were primary extrahepatic AE (brain and lung). The organs involved included 19 (57.6%) lung, 10 (30.3%) adrenal gland, 9 (27.3%) brain, 5 (15.2%) peritoneal cavity, 5 (15.2%) spleen, 4 (12.1%) diaphragm, 3 (9.1%) kidney, 3 (9.1%) retroperitoneal, and 2 (6.1%) vertebra; Involvement of 1 (3.0%) heart, 1 (3.0%) mediastium, 1 (3.0%) muscle, and 1 (3.0%) pancreas was rare.
MSCT and MR imaging findings of the extrahepatic AE
AE of the lung
Multiple AE lesions were found in 15 (78.9%) cases and a single AE lesion in 4 (21.1%) cases. Bilateral lung was found in 11 (57.9%) cases. Typically, AE lesions appeared as multiple nodules (14 cases) with peripheral locations (18 cases). Those nodules showed infiltrating contours (15 cases) with heterogeneous density (16 cases). Calcification was string-like or patch-like within the lesions in 16 cases. Small vacuoles and eccentric cavities were found inside the lesions in 12 cases. Multiple nodules with different morphology were seen in 9 cases (Figure 1). One case presented multiple hypodense masses without calcification, leading to a misinterpretation of the MSCT images.
AE of the adrenal gland
AE lesions were located in the adrenal gland in 10 cases. All lesions were recognized as a single mass in the right adrenal gland. Five cases seemed to be invaded by hepatic AE lesions; 5 cases were metastatic lesions of the liver and the spleen. On MSCT scan, lesions were slightly hypodense with different degrees of necrosis in 4 cases, and lesions were mixed-density masses with various calcification degrees in 6 cases (Figure 2). Six cases underwent MRI scan; all masses exhibited hypo- or isointense in a T1-weighted image and heterogeneous hyperintense in a T2-weighted image. No enhancement of lesions was seen after a contrast enhancement scan, but the alveoli-like pattern inside the lesions was seen more clearly.
AE of the brain
Multiple lesions were found in all 8 cases and the number of lesions ranged from 2 to 7; The single lesion was seen in one patient. The cerebrum was involved in 5 cases, and both cerebrum and cerebellum were involved in 3 cases. AE lesions appeared in the MSCT scan as hypodense nodules in 7 cases and as isodense nodules in 1 case. All lesions were enhanced in the periphery after the injection of contrast. Five cases also underwent an MRI scan; all lesions were isointense on T1-weighted images and were heterogeneously hypointense on T2-weighted images. Cerebral lesions were enhanced peripherally after the injection of contrast (Figure 3). Three more nodules were found in enhanced MR images than those found in the MSCT images. Edema of different degrees was detected within the lesion in all cases, accompanied by the ventricle system’s displacement in 4 cases.
AE of the spleen
AE lesions were located in the spleen in 5 cases; Altogether, 6 lesions with sizes ranging from 1.8 cm to 6.5 cm were found. Four lesions showed hypodensity in MSCT images. One case showed nodular calcification within 2 lesions (Figure 4). All lesions detected by MRI were hypointense in T1-weighted images and were homogeneously hyperintense in T2 -weighted images.
Vertebral involvement was found in 2 cases. One case had metastatic lesions of the liver and the other case was disseminated from the spleen AE. Heterogeneous osteolysis and irregular bone destruction were seen in both cases. In the soft tissues, MSCT revealed heterogeneous masses with irregularly thickened septations and scattered calcification and the MRI scan showed multi-vesicular morphology more clearly.
Heart involvement was found in 1 case. The lesion located in the myocardium of the left ventricle showed a mixed density mass with several irregular or ring-like calcifications in the periphery and multiple vacuoles dispersed inside. The mass compressed the chamber of the left ventricle and extended into the pericardial cavity. The mass showed no enhancement after injection of contrast.
Difform nodules or masses were seen in the AE lesions of the peritoneal cavity (5cases), diaphragm (4 cases), kidney (3 cases), retroperitoneal (3 cases), pancreas (1 case), mediastinum (1 case) and muscle (1 case). Calcification and necrosis were the common features of these lesions.
The agreements between MSCT and MRI for detecting imaging features of the extrahepatic AE
The agreements between MSCT and MRI for detecting the extrahepatic AE imaging features were shown in table 2. Altogether 25 organs of 18 patients underwent both MSCT and MRI examinations. Very good agreements were seen between MSCT and MR for detecting number (κ=0.841, p=0.000), border (κ=0.911, p=0.000) and size (κ=0.864, p=0.000) of extrahepatic AE.
A moderate agreement was seen for detecting necrosis inside the lesions (κ=0.540, p=0.002), and a fair agreement was seen for detecting calcification inside the lesions (κ=0.260, p=0.053).
Treatment and follow-up of the extrahepatic AE patients
Treatment and follow-up of patients with extrahepatic AE was shown in table 1. Treatment and management was provided according to the location, number and size of the lesions and the general condition of the patients; 16 patients underwent radical resection following albendazole therapy, 3 accepted liver transplantation plus albendazole therapy, 2 received albendazole therapy and palliative management and 12 received albendazole therapy only. The patients’ medical history was traced back for 1-7 years (average 2.64±1.49 years). There were 23 cases of improvement, 7 cases of recurrence, and 3 cases of death.