Diffusion weighted imaging (DWI) can reflect the microstructure and pathological changes of tissue, and diffusion tensor imaging (DTI) can quantitatively evaluate the fine structure of white matter in brain. In this study, conventional and diffusion-weighted MRI (DWI, DTI) sequences were used to analyze the brain of monochorionic twin pregnancies with demise of one fetus.

With the incidence rate of twin pregnancy increasing, the incidence of intrauterine death of twin pregnancies is also rising, which has great impact on the morbidity and mortality of the other fetus, and increases the mortality of fetal survival, premature birth, brain damage and long-term sequela. Therefore, it is necessary to examine the central nervous system of the surviving fetus of twin pregnancy and intrauterine death. When the surviving fetus is complicated with nervous system abnormalities, conventional MRI can generally make a diagnosis. However, some of the surviving fetuses may not find other structural or echo abnormalities on B-mode ultrasonography, and even these fetuses do not find structural or signal abnormalities on routine MRI examination. Whether the surviving fetuses may have brain abnormalities cannot be detected early by the above methods. Diffusion weighted imaging (DWI) can reflect the microstructure and pathological changes of tissue, and diffusion tensor imaging (DTI) can quantitatively evaluate the fine structure of white matter in brain.

The present study is to use conventional sequence and diffusion-weighted imaging (DWI, DTI) to analyze the brain of monochorionic twin pregnancies with demise of one fetus, which aims to find the potential brain abnormalities early and provide some guidance for the clinical diagnosis and treatment in the next step.

Inclusion Criteria:

1. Twin pregnancy was diagnosed and one fetus died in utero
2. Twin pregnancy with one abnormal fetus
3. Singleton pregnancy with abnormalities outside the fetal brain

Exclusion Criteria:

1. Those who can't cooperate with MRI examination, such as those who have metal, claustrophobia or can't insist on scanning.
2. Pregnant women with gestational age less than 20 weeks.

1. Twin pregnancy was diagnosed and one fetus died in utero
2. Twin pregnancy with one abnormal fetus
3. Singleton pregnancy with abnormalities outside the fetal brain