Prenatal MRI and postnatal CT image manifenstations of meconium peritonitis pseudo-cyst

Objective: To investigate fetal MRI and infant CT features of meconium peritonitis pseudo-cyst (MPC). Methods: The fetal and infant imaging data of 10 surgical pathologically confirmed MPC were analyzed retrospectively. Four patients received plain fetal MRI and four cases underwent plain and dual-phase enhanced CT scan, while two patients underwent both fetal MR and postnatal CT scan. Both CT and MRI manifestations were compared with pathological findings. Results: Three cases had lesions located in the mid upper abdomen, 4 under the liver in the right upper quadrant, 1 in the right lower abdomen, 2 in the left abdomen. On T2WI, all 6 fetuses showed slightly higher/high signal intensity. On T1WI, 1 fetuse showed high signal intensity, 3 fetuses showed low signal intensity and 2 showed iso-/slightly lower signal intensity. Plain CT showed that 5 cases had thin capsule wall while 1 had thick wall; enhanced CT scan demonstrated that the capsule wall of all 6 cases presented slight to moderate enhancement; a close relationship with adjacent bowel with unclear boundary was found in 5 cases; multiple calcifications in cyst wall and cavity were found in 4 cases. Among the 2 cases with both fetal and infant imaging data, fetal ascites disappeared postpartum in 1 case. Two cases appeared calcification in cyst wall and cavity on postnatal CT which was not seen on prenatal MRI. Conclusion: Prenatal MRI and postnatal CT imaging of MPC have some characteristic manifestations. Recognition the pathophysiology and imaging findings of MPC will be helpful for accurate diagnosis.