Early detection by diffusion-weighted sequence magnetic resonance imaging of severe brain lesions after fetoscopic laser coagulation for twin-twin transfusion syndrome

Objective Monochorionic twins treated by fetoscopic laser coagulation (FLC) for twin-twin transfusion syndrome (TTTS) are at increased risk of neurodevelopmental impairment. Our aim was to evaluate the additional value of diffusion-weighted imaging (DWI) over fetal sonography and T2 magnetic resonance imaging (MRI) in the detection of acute ischemic cerebral lesions shortly following FLC. Methods This was a prospective cohort study of fetuses with TTTS treated by FLC. All fetuses underwent brain DWI and T2-MRI within 24-96 h after the procedure and a follow-up MRI at 30-32 weeks' gestation. All fetuses also had frequent ultrasound evaluation until delivery. Results Thirty pregnancies with TTTS were included in the study. Eight resulted in survival of only one twin after the procedure (Group A), while the other 22 pregnancies resulted in the survival of both twins (Group B), as assessed at the time of initial MRI. Two fetuses in Group A and four in Group B had evidence of transient bleeding in the germinal matrix. Three fetuses in Group B and none in Group A had diffuse ischemic changes in the white matter. One fetus died in utero 24 h after MRI. The other two fetuses in Group B demonstrated an acute infarct 24-48 h after the procedure. Subsequent scans at 28-29 and 32 weeks showed brain atrophy compatible with an old infarct. Conclusions DWI can demonstrate cerebral damage immediately after FLC. Larger cohorts are needed to determine the role of fetal MRI in the prenatal assessment and follow-up of patients with TTTS.