Magnetic resonance imaging signal characteristics in hydatid cysts.

The MRI features of hydatid cysts were retrospectively studied in 12 patients to look for specific signal characteristics. Twelve patients in the series included eight with abdominal, two with abdominal-pelvic, one with a sacral and one with a lung hydatid cyst. The T1-, T2- and proton density (PD)-weighted images of spin-echo sequence were used for imaging. The signal characteristics of the hydatid parent cyst capsule and fluid, daughter cyst fluid, detached germinal membrane and surrounding soft tissue reaction were noted. Observations revealed that the capsule is best seen on T2- and PD-weighted images. The daughter cysts are best demonstrated on T1-weighted images, whereas the difference in the signal intensities of parent cyst and daughter cyst fluid is better demonstrated on T2-weighted and T1-weighted images, and the detached germinal membrane is best seen on T2- and PD-weighted images. The signal characteristics of hydatid cyst morphology can help distinguish it from other entities.