Anblagan, Devasuda

Bastin, Mark

Denison, Fiona

Norman, Jane

Reynolds, Rebecca

Roberts, Neil

Semple, Scott

Studholme, Colin

Yin, Kaiming

Edinburgh Research Explorer

     Edinburgh Research Explorer                                      Mathematically Reliable Stereological Measurement of MotionCorrected Fetal Brain VolumeCitation for published version:Anblagan, D, Yin, K, Reynolds, R, Denison, F, Bastin, M, Studholme, C, Norman, J, Semple, S & Roberts, N2013, 'Mathematically Reliable Stereological Measurement of Motion Corrected Fetal Brain Volume'Organization for Human Brain Mapping, Seattle, United States, 16/06/13 - 20/06/13, .Link:Link to publication record in Edinburgh Research ExplorerDocument Version:Peer reviewed versionGeneral rightsCopyright for the publications made accessible via the Edinburgh Research Explorer is retained by the author(s)and / or other copyright owners and it is a condition of accessing these publications that users recognise andabide by the legal requirements associated with these rights.Take down policyThe University of Edinburgh has made every reasonable effort to ensure that Edinburgh Research Explorercontent complies with UK legislation. If you believe that the public display of this file breaches copyright pleasecontact openaccess@ed.ac.uk providing details, and we will remove access to the work immediately andinvestigate your claim.Download date: 05. Apr. 201910/01/2013 18:06OHBMPage 1 of 3https://ww4.aievolution.com/hbm1301/index.cfm?do=abs.viewAbs&subView=1&abs=1373Mathematically Reliable Stereological Measurement of MotionCorrected Fetal Brain VolumeAbstract Submission No:1500 Authors:Devasuda Anblagan1, Kaiming Yin1, Rebecca Reynolds1, Fiona Denison1, Mark Bastin1, ColinStudholme2, Jane Norman1, Scott Semple1, Neil Roberts1Institutions:1University of Edinburgh, Edinburgh, United Kingdom, 2University of Washington, Seattle, WA, UnitedStatesIntroduction:Motion correction is now possible for fetal brain (FB) MRI studies in both the 2nd and 3rd trimester,however techniques to segment these images are still under development. We describe the firstapplication and practicality, time efficiency and precision of Isotropic Cavalieri (IsoC), Invariator (InV)and Discretized Nucleator (DNuc) stereology methods for estimating fetal brain volume (FBV) onmotion corrected 3D images.Methods:15 pregnant women were recruited and gave informed consent to be imaged on a MAGNETOM Verio 3Tsystem (Siemens AG, Germany): 9 at 24–26 weeks and 6 at 35–37 weeks gestation. HASTEacquisitions of the fetal brain were obtained (25–45 slices, TE = 94 ms and TR = 4200 ms, SAR<2.0 Wkg-1, 0.55×0.55×3 mm3 voxels) three times in each of axial, sagittal and coronal scanning directions.The image series were motion corrected using Slimmer tool1 to form a single 3D high-resolution brainimage (1×1×1 mm3 voxels) and used to estimate FBV using stereological methods2 (IsoC, InV andDNuc) using Analyze 10.0 software (MAYO Foundation, USA). Beginning from a random startingposition, the IsoC method involves sampling the brain with a series of images a constant distance Tapart along a random orientation in 3D. Sections were analyzed using point counting. The InV methodalternatively requires only a single isotropic section to be obtained through a fixed point in the 3Dimage volume. Orthogonal chord lengths within the brain are then measured using a T-shapedmeasurement tool as shown in Fig. 1b (yellow line). The DNuc method is similar to InV, except thatnow the length of the radial arm of the T-shaped measurement tool is directly measured from the fixedpoint to each test point lying within the brain (Fig. 1b, blue line). All three methods were applied inthree random mutually orthogonal orientations. The Cavalieri method was also applied directly to theoriginal axial, sagittal, and coronal HASTE datasets.10/01/2013 18:06OHBMPage 2 of 3https://ww4.aievolution.com/hbm1301/index.cfm?do=abs.viewAbs&subView=1&abs=1373 Results:Reconstruction of the fetal brain was possible in all cases except for a dataset acquired at 25 weeksdue to excessive fetal motion. Efficiency measures (time, precision) was lowest for the InV (10–15minutes, 2–37%), followed by IsoC and DNuc (both 5–10 minutes, 0–5% and 4–37% respectively). Asexpected, there was excellent agreement between the FBV estimates obtained from each of theorthogonal IsoC series, and much greater variation between the FBV estimates obtained from the 3-orthogonal InV or DNuc sections but with the mean always close to the results obtained using the IsoCmethod. Estimates obtained by applying the Cavalieri method to the uncorrected datasets werevariable depending on the scale of motion (Fig. 2). The quality of fetal head motion correction usingSLIMMER depends greatly on the degree of fetal motion; this was generally greater during the 2ndtrimester and more challenging to correct for than in the 3rd trimester when the fetal head isfrequently engaged in the maternal pelvis. Furthermore, even when the motion correction algorithmhas been successfully applied, the gyri and sulci of the fetal brain may still not be clearly depicted onthe reconstructed 3D image. This affects the ease of performing surface area measurement (Fig. 1d),which as well as being interesting in its own right, is a prerequisite for application of the mathematicalformula developed by Cruz-Orive2 for predicting the precision of volume estimates obtained using theIsoC method. Accordingly, surface area measurements were only possible on 3 datasets from 2nd and6 from 3rd trimester.10/01/2013 18:06OHBMPage 3 of 3https://ww4.aievolution.com/hbm1301/index.cfm?do=abs.viewAbs&subView=1&abs=1373 Conclusions:We have demonstrated high levels of agreement between FBV measurements obtained by applyingthree new stereological methods to motion corrected 3D MR images of the fetal brain. IsoC is the mostprecise method and is recommended for detailed studies in individual subjects while InV and DNuccould be used in measuring the change in mean brain volume in a cohort of subjects.Modeling and Analysis Methods:Other Methods[1] Kim, K. (2010), ‘Intersection Based Motion Correction of Multi-Slice MRI for 3D in utero Fetal BrainImage Formation’, IEEE Trans. Med. Imaging, vol. 29, no. 1, pp. 146-158. [2] L.M.Cruz-Orive (2010),‘Stereology of isolated objects with the invariator’, Journal of Microscopy, vol. 240, no. 2, pp. 94-110.

Mathematically Reliable Stereological Measurement of Motion Corrected Fetal Brain Volume

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Mathematically Reliable Stereological Measurement of Motion Corrected Fetal Brain Volume

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