WOMEN’S IMAGING Iran J Radiol. 2019 January; 16(1):e81254. Published online 2018 December 11. doi: 10.5812/iranjradiol.81254. Research Article Correlating Placental ADC Values with Gestational Age and Grannum Class in Normal Placentas Sepideh Sefidbakht 1, 2 , Banafsheh Zeinali-Rafsanjani 1 , Maryam Safari 2 , Fariba Zarei 1, 2, * , Bijan Bijan 3 , Reza Jalli 1, 2 , Maryam Kasraeian 4 , Homeira Vafaei-Cisakht 4 and Nasrin Asadi 4 1 Medical Imaging Research Center, Shiraz University of Medical Sciences, Shiraz, Iran 2 Department of Radiology, Shiraz University of Medical Sciences, Shiraz, Iran 3 Sutter Medical Group, University of California Davis, Sacramento, United States 4 Maternal-Fetal Medicine Research Center, Shiraz University of Medical Sciences, Shiraz, Iran * Corresponding author: Department of Radiology, Shiraz University of Medical Sciences, Shiraz, Iran. Tel: +98-7116474329, Email: zareifari@sums.ac.ir Received 2018 June 25; Revised 2018 November 21; Accepted 2018 November 27. Abstract Background: Recently there have been attempts to link fetal growth retardation to placental morphology as well as apparent- diffusion coefficient (ADC) values. Objectives: The purpose of this study was to investigate the possible correlation of apparent diffusion coefficient (ADC) values of normal placentas with different gestational ages and various Grannum grades (Gg). Patients and Methods: Thirty-eight women were included in this study. All women with singleton pregnancies referred for fetal MRI who were proven normal in pre/postnatal follow-up were included in the study. All placentas were evaluated by ultrasound trans-abdominally. The placenta was assessed for maximal thickness, subjective shape, presence of possible infarcts, sub-placental, and subchorionic hemorrhage. Placentas were also evaluated for G-grading and signal intensities in T2 half-fourier acquisition single-shot turbo spin-echo (HASTE) images. Diffusion weighted imaging (DWI) images were done using two b-value sets (0, 1000 and 50, 400, 800). Largest possible regions of interest (ROI) were drawn over the placenta and ADC values were correlated with gestational-age and Gg using linear regression and Kruskal-Wallis, respectively. Results: There were 11, 18, 9, 0 patients with normal looking placentas with Gg of 0, 1, 2, and 3 respectively. ADC values obtained from b values of 0, and 1000 show a significant correlation with gestational-age (R 2 = 0.60, P = 0.000) and Gg (P = 0.004) respectively, while ADC values obtained from b values of 50, 400, and 800 did not show significant correlation with gestational age (R 2 = 0.087, P = 0.073) or Gg (P = 0.236). Conclusion: ADC values which were obtained from sets of b values of 0 and 1000 correlated with placental maturity (both gesta- tional age (GA) and Grannum grades). This can be attributed to lower b-values covering the microperfusion in addition to diffusion characteristics of the tissue. Keywords: ADC Value, Gestational Age, Grannum Grades, Placenta 1. Background Since the advent of fetal magnetic resonance imag- ing (MRI), this method has been established as a problem- solving tool for placental ultrasound in order to assess pos- sible fetal anomalies (1-5). As an adjunct to conventional MRI, diffusion weighted imaging (DWI) has been increas- ingly used in imaging of the fetal brain and recently also the fetal kidney (6-8). Conventional MR as well as DWI has however been only recently and sparingly used in the eval- uation of the placenta (9). Utilization of MR in the pla- centa has been mainly restricted to evaluation of placental masses and to assessment of suspected myometrial inva- sion in cases of placenta accreta (10-12). Normal placental maturation has been a topic rarely described in MRI (13, 14). More recently, however, there have been attempts to link fetal growth retardation to placental morphology as well as placental apparent diffusion coefficient (ADC) val- ues (15, 16). Any attempt for diagnosis of placental insuffi- ciency using DWI images or ADC values should be derived from values of placental ADC in the normal population (17- 20). In their study of placental DWI in fetal growth retarda- tion and placental insufficiency, Bonel et al. used the ADC value threshold of their own high risk population due to the lack of normal values in the literature (16). Manganaro et al. evaluated ADC values in relation to gestational age (GA). Although they found an inverse relationship between Copyright © 2018, Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.