Imaging features and management of focal liver lesions

Table 4 Classification of hydatid cyst and imaging features

Gharbi	WHO-IWGE	US findings	CT findings	MRI findings
Type 1	CE1	Unilocular cyst with wall	Well-defined hypoattenuating cyst	T1 hypointense
		Hydatid sand	Perceptible wall with mild delayed enhancement	Very T2 hyperintense
		Snowstorm sign	No internal enhancement	Perceptible wall with mild delayed enhancement
		No internal vascularity		No internal enhancement
Type 3	CE2	Multilocular, multiseptated cyst	Multivesicular multiseptated cyst	Multivesicular multiseptated
		Honeycomb sign	Hypoattenuating daughter cysts	T2 hyperintense daughter cysts
		Daughter cysts	No septal enhancement	No septal enhancement
Type 2	CE3	Cyst with detached membrane, water-lily sign (CE3a)	Heterogeneous	Heterogeneous
		Cyst with daughter vesicles in a solid matrix (CE3b)	High-attenuating internal content	T2 hypointense detached membranes
			Detached membranes	No internal enhancement
			No internal enhancement
Type 4	CE4	Cyst with heterogenous content	Solid appearance	T2 iso- to hypointense
		No daughter cysts	No daughter cysts	No daughter cysts
		Ball of wool sign	Avascular	Avascular
Type 5	CE5	Thick calcified wall	Capsular and/or central calcifications	Very hypointense wall and intermediate to low internal signal intensity on T2-weighted images
			Complete calcification	No internal enhancement
			No internal enhancement

Classification of hydatid cyst and imaging features[119,121]. CT: Computed tomography; MRI: Magnetic resonance imaging; US: Ultrasound; WHO-IWGE: World Health Organization Informal Working Group on Echinococcosis.