With the limited understanding of the aetiology and pathogenesis of placenta in fetal growth restriction (FGR), more in vivo information could be helpful for the diagnosis and treatment of FGR. The evaluation of the placenta’s blood capillary network plays an important role in the investigation and clinic classification of FGR with different subtypes. The intravoxel incoherent motion (IVIM) has already been widely applied in the evaluation of both perfusion and diffusion in many diseases^1-2 without the exposure to radiation and the employment of contrast agent, which is especially meaningful for pregnant patients. The purpose of this study is to explore the feasibility of assessing perfusion and diffusion information of placenta with different FGR types.Patients: 23 patients (age 28±9 years old, 30±5 weeks) with FGR and 11 healthy cases (age 29±7 years old, 31±4 weeks )were involved with the approval of local IRB. Patients were divided into three subgroups: endogenous symmetrical (ens-FGR, n=9), extrinsic asymmetric (exa-FGR, n=8) and extrinsic symmetric (exs-FGR, n=6), according to the weight of fetus, duration of the disease and etiology¹, MRI was performed on a 1.5T scanner (Intera Achieva, Philips Medical Systems, The Netherlands),including routine sequences and multi-b value DWI. The axial spin-echo echo-planar DWI with b-values of 0,1,3,15,47,80,115,206,246,346,468s/mm² were scanned perpendicularly to the long axis of =placenta with following parameters: TR/TE:5860/84ms, FOV 400mm, acquisition matrix:256x256, slices with the thickness of 5mm and 1mm gap, NSA 1, total scan time 6.47 min. The post process was performed on a home-made software and the bi-exponential model4 S(b)/S(0)=(1-f)*D+fD* was used. The placenta was averagely divided into outer and inner zones (fig.1 e). ROIs were drawn on three consecutive slices and the result was averaged. The paired-t test was used to compare IVIM parameters in inner and outer zones of placenta in all groups. q-test was used for assessing D,D* and f of ens-FGR, exa-FGR, exs-FGR and normal separately.D* and f were significantly higher in inner zone of placenta in ens-FGR compared with outer (P=0.03 and P=0.001,respectively) ( Table 1). f was statistically higher in the inner zone of exa-FGR compared with outer (P=0.04). D was higher in inner zone of placenta in exs-FGR than outer. D, f and D* of entire placenta in exa-FGR showed a statistically significantly lower compared with other groups, D and D* were significantly lower in the whole placenta in ens-FGR compared with other groups, where f was significantly higher ( P=0.008 with ens FGR, P=0.01 with exs FGR, P=0.03 with normal for D; P=0.04 with ens FGR, P=0.003 with exs FGR, P=0.001 with normal for D*; P=0.002 with ens FGR, P=0.03 with exs FGR, P=0.04 with normal for f) (Table 2).There is difference of pressure between the maternal and fetal placenta in woman with normal pregnancy. This study demonstrated that the inner and outer zones of placenta in ens-FGR may impair pressure gradient, while exa-FGR and exs-FGR could not affect placenta pressure gradient. There was only increased f in inner placenta of ens-FGR, which might be due to damage in villus resistance of placenta (the a,d,g of Fig1.). In addition, damaged placenta trophocyte in exa-FGR were more widespread than both ens-FGR and exs-FGR, D of entire placenta in exa-FGR was lower than other groups, which reflected to restrict movement of water molecules and deficits placenta trophocyte proliferation (the b,e,h of Fig1.), indicated placental insufficiency due to infarction, calcification. D,D* and f of placenta had slightly reduce in exs-FGR (the c,f,i Fig 1.), these finding suggested that, relative to ens-FGR and exa-FGR, exs-FGR could bring more mild destruction to placenta and might indicate a better outcome. In this work, the inner zone of the placenta is considered as fetal and the outer zone is considered as maternal, there are different diffusion and perfusion characteristic in different in placenta of FGR hypotype.This study firstly demonstrated the diffusion and perfusion information in the outer and inner zone of placenta with FGR subtypes by using IVIM. This technique will provide valuable information for the investigation of the aetiology and the assessment of placental function. More data will be collected in further work to get more reliable results.