Abstract: Objective:To summarize the features of computed tomography (CT) and magnetic resonance imaging (MRI) of hepatic cystic echinococcosis, and investigate the key points of identification and diagnosis. 〖HQK〗
Methods:The clinical data of 58 patients with hepatic cystic echinococcosis who were admitted to the Affiliated Hospital of Inner Mongolia Medical University from August 2011 to August 2014 were retrospectively analyzed. Patients received plain and enhanced scan of CT and MRI. Hepatic cystic echinococcosis was divided into the 5 types according to the literatures, including unilocular echinococcasis in type Ⅰ,  multivesicular hydatid cysts in type Ⅱ, anechoic content with detachment of laminated membrane from the 〖HJ〗cyst wall in type Ⅲ, calcification of lesions in type Ⅳ and mixed echinococcosis in type Ⅴ. Patients who were diagnosed as with definite or suspected hepatic cystic echinococcosis underwent surgery. The followup including observing the recurrence of hepatic cystic echinococcosis was performed by outpatient examination and telephone interview at postoperative month 3, 6, 12 for 1 year and then once every year up to August 2015, and was ended if there was no recurrence for more than 5 years.
Results: (1) The results of CT and MRI examinations: of the 58 patients, 54 received scan of CT and 21 received scan of MRI. Seventeen patients were detected in type I with clearboundary and lowdensity cystic lesions by CT examination; MRI examinations showed there were single or multiple, round or oval abnormal signal including low T1WI signal, high T2WI signal and low T1WI and T2WI signal of cyst wall. Thirteen patients were detected in type Ⅱ, CT examination showed the “daughter” cysts of multiple sizes were found in the “mother” cyst, arranged in “honeycomb” or “wheel” shape; MRI examination showed there were lower T1WI signal in the “daughter” cyst and higher T2WI signal in the “daughter” cyst compared with signal in the “mother” cyst, and low signal in the cyst wall of the “daughter” cyst and “mother” cyst. Six patients were detected in type III with “capsule in capsule” sign and “water snake” sign by CT examination and “ribbon” sign by MRI examination. Thirteen patients were detected in type Ⅳ, CT examination showed there were irregular highdensity calcified shadow with the performances for “return sample” or “sample volume skins” changes. Nine patients in type Ⅴ had more than 2 kinds of lesions. (2) Diagnosis: 4 patients were misdiagnosed by CT examination including 3 with preoperative diagnosis of hepatic cyst and 1 with preoperative diagnosis of metastatic carcinoma of liver, with an accurate rate of diagnosis of 92.6%(50/54). Two patients with preoperative diagnosis of hepatic cystic adenocarcinoma were misdiagnosed by MRI examination, with an accurate rate of diagnosis of 90.5% (19/21). (3) Treatment and followup: 58 patients underwent surgery, including 40 undergoing internal capsule removal with external capsule suturing (31 with open operation and 9 with laparoscopic operation), 10 undergoing partial hepatectomy and 8 undergoing external capsule enucleation. Of 58 patients, 3 were complicated with effusion of residual cavity, 2 with unclosed external capsule, 1 with bile leakage and then was cured after 4-8 week drainage. Fifty patients were followed up for 12.0-48.0 months with a median time of 27.1 months and a followup rate of 86.2%(50/58). During the followup, 1 patient undergoing internal capsule removal had recurrence at postoperative month 8 and was cured by CTguided interventional therapy using absolute alcohol, and other patients had no recurrence.
Conclusions:There was a higher accuracy in CT and MRI examinations for hepatic cystic echinococcosis. “Honeycomb” and “wheel” shapes are characteristic findings of hepatic cystic echinococcosis in type II. The characteristic performances of CT examination for hepatic cystic echinococcosis in type III are “capsule in capsule ” and “water snake” signs, and characteristic performances of MRI examination is “ribbon” sign. The ringlike enhancement of edge by MRI examination is an essential of identification and diagnosis between hepatic cystic echinococcosis and hepatic cyst, and irregular calcification is a differential point between hepatic echinococcosis and hepatic tumor.