Comparison of Fetal Ultrasonography and Fetal Magnetic Resonance Imaging for the Detection of Additional Anomalies In Cases of Fetal Ventriculomegaly

INTRODUCTION: To compare fetal US and fetal MRI techniques for the detection of additional findings in cases of fetal venticulomegaly diagnosed by antenatal US.
METHODS: 46 Patients diagnosed with ventriculomegaly by ultrasonography between May 2009 – April 2010 have been included in the study. Gestational (FETAL age mi demek gerek, tam terimi bilmiyorum?) age (GA) was between 21 and 35 weeks. MRI examination couldn’t be performed in 4 patients due to clostrophoby and 2 patients didn’t give consent for the procedure. Those 6 patients have been excluded from the study and the examination was carried in 40 patients. The ventriculomegaly was graded in 2 groups as mild (10-14 mm) or as severe (15 mm or higher). MRI has been performed in maximum 4 days following ultrasonography with a 1,5 T MRI unit (Sympony, Siemens, Erlangen, Germany), using a “phased array” body coil. The fetal anatomy was evaluated by the “Half-Fourier acquisition single-shot turbo spin-echo” (HASTE) sequence (TR: 4.4, TE: 64, flip angle: 150°, slice thickness: 6 mm, gap: 0.1 mm, matriks: 160x256, FOV: 350 mm) in three planes adjusted to the fetal position. The frequency of the patients where MRI and US results were in concordance and teh frequency of the patients where MRI provided additional diagnostic information were given by a confidence interval of 95%. Chi-square test (Yates) was used to compare the groups. The significance was evaluated at p<0.05.
RESULTS: Mild ventirculomegaly (10-14 mm) was detected in 28 patients (Group 1), and severe ventriculomegaly (>15 mm) was detected in 12 patients (Group II). MRI detected additional findings compared to ultrasonography in 7 of the 28 patients in Group I (25% [CI 95%; 0.11-0.45]) and 5 of the 12 patients in Group II (%42 [CI 95%; 0.15-0.72]), a total of 12 patients (30% [CI 95%; 0.16-0.46]). When 2 groups were compared for the additional findings provided by MRI, MRI detected more abnormalities in severe ventriculomegaly group (42%), however the difference with mild ventriculomegaly group (25%) was not statistically significant ( x² yates: 0.459, p: 0.498). MRI changed patient management in 4 patients in Group I (14% [95% CI; 0.09-0.34]) and 3 patients in Group II (25% [95% CI; 0.14-0.94]). In total, MRI changed patient management in 17% [95% CI; 0.13-0.41] of the patients.
DISCUSSION AND CONCLUSION: Our study demonstrated that, while US has a high accuracy in diagnosing ventriculomegaly, fetal MRI examination can provide additional findings to US, especially in detecting co-existing CNS abnormalities