Fetal anomalies: comparison of MR imaging and US for diagnosis.

Purpose: To compare prenatal ultrasonography (US) and magnetic resonance (MR) imaging for the diagnosis of fetal anomalies.

Materials And Methods: Images of 27 fetuses (28 diagnostic cases) with anomalies diagnosed at US were evaluated; in these fetuses, prenatal MR imaging was performed within 15 days of US. Prenatal US and MR imaging findings were compared with postnatal diagnoses. Postnatal evaluation included US, MR imaging, autopsy, surgery, voiding cystourethrography, computed tomography, angiography, and physical examination.

Results: In seven diagnostic cases, US and MR imaging findings were in complete agreement with postnatal diagnoses. MR imaging correctly provided additional information to the US-determined diagnosis in another seven and correctly changed the US diagnosis in three. The MR imaging-determined diagnosis was incorrect and the US diagnosis was correct in four cases. In seven cases, the diagnoses at both US and MR imaging were incorrect when correlated with the postnatal outcome. MR imaging was most valuable in the assessment of anomalies of the central nervous system.

Conclusion: MR imaging may have a place as an adjunct to US in evaluation of fetal anomalies, particularly those involving the central nervous system.