Role of magnetic resonance imaging ( MRI ) in diagnosis of placental lesions

Abstract

The placenta is often overlooked in the routine evaluation of a normal gestation, receiving attention only when an abnormality is detected. Although uncommon, abnormalities of the placenta are important to recognize owing to the potential for maternal and fetal morbidity and mortality. Although ultrasound is and possibly will remain the main tool for obstetrical imaging, MRI is creating a niche in the areas where ultrasound does not provide complete details or as a second opinion tool to confirm equivocal ultrasonographic findings. Although ultrasound is preferred tool for antenatal monitoring, MRI is a powerful developing technology that allows quantitative analysis of several indices that relate tissue structure and function. MRI provides quantified volume assessments of the placenta and insights into equivocal ultrasound evidence of placenta accrete, increta or percreta. Uterine and umbilical artery dopplers currently reflects integrated flow to the entire utero-placenta, while MRI can measure localized flow within the placenta per second. Abnormal placental formation results in a spectrum of gestational trophoblastic diseases including complete hydatidiform mole, partial mole, invasive mole, choriocarcinoma, and placental site trophoblastic tumor. All of these entities may be demonstrated with MR imaging, although usually US is sufficient to suggest the diagnosis and MR imaging is reserved for difficult cases.