Background: The current staging system of twin-twin transfusion syndrome (TTTS) is based on the ultrasound criteria and does not consider the cerebral injury.
Objective: To assess the incidence of cerebral damage on fetal MRI and correlate abnormal cerebral diffusion-weighted imaging (DWI) findings with survival outcome and the ultrasound staging of TTTS.
Materials and methods: We conducted a retrospective review of MRI/DWI of fetal brains and the electronic medical records in monochorionic diamniotic twin gestations. Axial DWI of each fetal brain was performed on 1.5-tesla (T) clinical magnet with b values of 0 s/mm2 and 700 s/mm2. We correlated MRI/DWI abnormalities with the Quintero staging system and survival outcomes of the fetuses.
Results: Thirty-four pregnancies (68 fetuses) with 42 fetal cerebral abnormalities were identified by MRI/DWI alone. Of these 42 fetal cerebral abnormalities, 33 fetal brain lesions were visible only on DWI (n=25 donor, n=8 recipients; n=30 unilateral, n=3 bilateral; n=26 diffuse, n=7 focal). Quintero staging in these 34 pregnancies was as follows: 9 Stage I, 7 Stage II, 13 Stage III, 4 Stage IV, 1 Stage V. There was no significant correlation between the presence of cerebral infarction or hemorrhage using MRI/DWI and ultrasound staging (P=0.138). The overall survival rate was 63.2% (43/68). There was a significant correlation between the presence of cerebral infarction or hemorrhage on MRI/DWI and delivery status (P=0.009).
Conclusion: Abnormal cerebral imaging findings on MRI/DWI from hypoxic-ischemic injury or hemorrhage can be seen at the beginning of the second trimester and do not correlate with the current ultrasound staging system; however, they do correlate with decreased survival. Fetal cerebral abnormalities could be incorporated into the TTTS staging system as an independent risk factor.
Keywords: Diffusion-weighted imaging; Fetus; Magnetic resonance imaging; Monochorionic diamniotic twin gestation; Outcomes; Staging; Twin–twin transfusion syndrome.