[The usefulness of MRI for the diagnosis of abnormal pregnancies]

The clinical usefulness of MRI for the diagnosis of abnormal pregnancies was evaluated. Pelvic MRI was carried out on 29 cases suspected of abnormal pregnancy by ultrasonography and clinical examinations. The abnormal pregnancies were classified into three categories: (1) maternal abnormalities, (2) fetal abnormalities and (3) placental abnormalities. (1) MRI was of great value for the diagnosis of maternal abnormalities, particularly in cases of coexistent pelvic tumors. MRI allowed diagnosis of uterine leiomyomas and dermoid cyst through its excellent tissue characterization and broad range of vision. (2) MRI was useful in making diagnoses of fetal central nervous anomalies and fetal death, since the lack of fetal movement and the lesions were clear enough to be detected by MRI. However, anomalies in the fetal trunk or extremities could only be demonstrated, but not diagnosed, by MRI owing to its inferior spatial and time resolution. (3) MRI showed placenta accreta and placental hematoma. Although accurate diagnosis was difficult because of their rarity, MRI revealed the hemorrhagic component of the lesions, which was not shown by ultrasonography. The author believes MRI has potential usefulness in making diagnoses of placental abnormalities through its tissue characterization. MRI was superior to ultrasonography in the soft tissue characterization, field of view, while MRI was inferior in time and spatial resolution. In summary MRI should be used in case of abnormal pregnancies such as pelvic tumors, fetal nervous anomalies and placental hemorrhagic lesions. MRI will become useful for the diagnosis of other abnormalities as its spatial resolution and fast scan technology advances.