Friday, May 9, 2025
5/9/2025
Developing novel MR tools to optimize surgical planning and fetal outcome in TTTS - Project Summary/Abstract Twin-to-Twin Transfusion Syndrome (TTTS) is a serious complication of twin pregnancies, affecting up to 15% of twins sharing the same placenta (monochorionic twins). TTTS occurs when monochorionic twins develop abnormal connections (anastomosis) in placental vessels resulting in imbalanced blood flow: one twin (the recipient) receives more blood at the expense of the other (donor) twin with both at increased risk for demise and compromised neurodevelopmental outcomes. The natural history of TTTS is dismal with perinatal losses up to 70-100%. Although fetoscopic laser photocoagulation of the placental anastomoses has improved outcomes, losses remain as high as 34% with cerebral palsy and neurodevelopmental impairment occurring in 10-18%. Thus, margins for improvement remain and controversy exists over optimal type of laser surgery, appropriate definition of TTTS and when to intervene. Surgical planning requires accurate localization of the umbilical cord insertions and placenta surface vessels, which remains challenging with 2D magnetic resonance (MR) or ultrasound (US) images. Diagnosis of TTTS and response to laser surgery is based on user dependent, indirect measures of placental function (e.g. umbilical arterial and venous Doppler assessment, maximum vertical pocket of amniotic fluid, fetal bladder size). In addition, fetal growth discordance, a critical reflection of TTTS severity, is also based on user dependent 2D US techniques. Improved preoperative placental vascular visualization, direct measures of placental function and user independent measures of fetal size are needed. We propose to build on our prior work developing CNN to perform rapid 3D uterine reconstructions with 2D HASTE images with flattening of placental images to improve visualization of the placental surface vessels. To directly assess placental function, we will build upon our prior work where we found oxygen transport correlated with discordance and predicted birth weight in monochorionic twins. Instead of monitoring relative T2* changes, we propose to quantify T2* at baseline and with maternal oxygen. We also use intravoxel incoherent motion (IVIM) with and without flow compensation (FC) to explore pulsatile flow in the fetal villous tree. Finally, we will extend our prior work that identified key points for fetal pose providing limb length and motion statistics in singletons, to twins and add estimation of fetal intracranial, bladder and body volumes. In summary, to address the unmet needs in monochorionic twins, we propose the following aims: Aim 1) Provide rapid visualization of the placental surface vessels and umbilical cord insertion in native and flattened space; Aim 2) Characterize local placental function pre and post laser ablation; and Aim 3) Calculate discordance of intracranial, bladder and body volumes, fetal limb biometrics and motion statistics pre and 4-6 weeks post treatment. If successful, we will be poised to perform a clinical study assessing the impact of these advancements on surgical planning and outcomes and determine application to earlier gestational ages.
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