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Published online before print February 28, 2006, 10.1148/radiol.2391050221
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Comparison of Manual and Automatic Section Positioning of Brain MR Images1

Thomas Benner, PhD, Jonathan J. Wisco, PhD, André J. W. van der Kouwe, PhD, Bruce Fischl, PhD, Mark G. Vangel, PhD, Fred H. Hochberg, MD and A. Gregory Sorensen, MD

1 From the Department of Radiology (T.B., J.J.W., A.J.W.v.d.K., B.F., A.G.S.) and General Clinical Research Center (M.G.V.), Massachusetts General Hospital, Athinoula A. Martinos Center, Harvard Medical School, 149 13th St, Rm 2301, Charlestown, MA 02129; Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, Cambridge, Mass (B.F.); and Department of Neurology and Brain Tumor Center, Massachusetts General Hospital, Boston, Mass (F.H.H.). Received February 8, 2005; revision requested April 6; revision received May 4; final version accepted June 13. Supported in part by the National Center for Research Resources (P41 RR14075, R01 RR16594-01A1 and BIRN Morphometric Project BIRN002, U24 RR021382, R21 EB02530), the National Institute for Biomedical Imaging and Bioengineering (R01 EB001550), the National Cancer Institute (NCI 5T32CA09502), and the Mental Illness and Neuroscience Discovery Institute. Address correspondence to T.B. (e-mail: thomas.benner{at}nmr.mgh.harvard.edu).


Figure 1
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  		Figure 1: Top row of each panel shows section 10 of original transverse T2-weighted MR images in patient 8 for all four series with manual (M1–M4) and automatic (A1–A4) section prescription. Bottom row of each panel shows images after coregistration of follow-up series (M2--M4, A2–A4) to the initial series (M1, A1). Note higher variation in manually aligned sections versus automatically aligned sections, as well as slight blurring caused by the coregistration procedure.

 

Figure 2
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  		Figure 2: Middle section of transverse T2-weighted MR images from all 13 patients for manual (top panel) and automatic (bottom panel) section prescription. Automatic prescription images show similar anatomic section location, good hemispheric symmetry, and vertical midline. Manually prescribed images show deviations from vertical midline because imager software did not allow manual rotation within the section plane. Hemispheric symmetry with manual prescription is comparable to that with automatic prescription, but more variation in rotation around right-left axis and in overall inferior-superior position can be seen.

 

Figure 3
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  		Figure 3: Box plots of translations (dx, dy, and dz on x-, y-, and z-axis, respectively, in millimeters) and rotations (ax, ay, and az on x-, y-, and z-axis, respectively, in degrees) resulting from coregistration to intrasubject T2-weighted MR images for section prescription performed manually and automatically. The ranges of translations and rotations for manual prescription clearly exceed those for automatic prescription. Factor "method" was found to be significant (P < .001) for all translations and rotations.

 

Figure 4
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  		Figure 4: Box plots of RMSE values (in arbitrary units [a.u.]) before and after intrasubject coregistration by using the FLIRT tool for manual and automatic section prescription. Note the greater reduction in RMSE from before to after coregistration for prescription performed manually compared with that performed automatically. Factor "method" was found to be significant (P < .001) for the log reduction in RMSE.

 

Figure 5
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  		Figure 5: Box plots of translations (dx, dy, and dz on x-, y-, and z-axis, respectively, in millimeters) and rotations (ax, ay, and az on x-, y-, and z-axis, respectively, in degrees) resulting from coregistration to a T2-weighted imaging template for section prescription performed manually and automatically. All ranges of translations and rotations for manual prescription—with the exception of y-axis translations—exceed those for automatic prescription. Factor "method" was found to be significant for translations along the x-axis (P < .01) and rotations around the x-axis and z-axis (P < .001).

 




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