Elsevier

Academic Radiology

Volume 13, Issue 9, September 2006, Pages 1072-1081
Academic Radiology

Medical image computing and computer-assisted intervention
Registration-Based Approach for Reconstruction of High-Resolution In Utero Fetal MR Brain Images

https://doi.org/10.1016/j.acra.2006.05.003Get rights and content

Rationale and Objectives

This paper describes a novel approach to forming high-resolution MR images of the human fetal brain. It addresses the key problem of fetal motion by proposing a registration-refined compounding of multiple sets of orthogonal fast two-dimensional MRI slices, which are currently acquired for clinical studies, into a single high-resolution MRI volume.

Materials and Methods

A robust multiresolution slice alignment is applied iteratively to the data to correct motion of the fetus that occurs between two-dimensional acquisitions. This is combined with an intensity correction step and a super-resolution reconstruction step, to form a single high isotropic resolution volume of the fetal brain.

Results

Experimental validation on synthetic image data with known motion types and underlying anatomy, together with retrospective application to sets of clinical acquisitions, are included.

Conclusion

Results indicate that this method promises a unique route to acquiring high-resolution MRI of the fetal brain in vivo allowing comparable quality to that of neonatal MRI. Such data provide a highly valuable window into the process of normal and abnormal brain development, which is directly applicable in a clinical setting.

Section snippets

Super Resolution Methods

The principle of super-resolution is to combine low-resolution images to produce an image that has a higher spatial resolution than the original images (9). This is a large research field encompassing many applications; however, the majority of the work has focused on using lower-resolution data acquired on a regular grid and often assuming simple translational motion between the lower-resolution sample grids, unlike our data, which are corrupted by full three-dimensional (3D) rigid motion on a

Application to MRI

Building a high-resolution 3D MR image of the fetal brain is challenging because of the original 2D slice thickness, the intensity distortion, and the unpredictable fetal motion that can occur in any direction and can be a much as several centimeters in distance between slice acquisitions. As far as we know, this problem, which has been discussed before in the literature (18, 19), is still an open issue. Super-resolution has previously been investigated in MRI using a specialized protocol to

Methods

Our overall aim is to reconstruct an image of the fetal brain that has increased and isotropic sampling resolution, increased overall spatial resolution (reduced point spread function), and consistent tissue intensity over the field of view. The resolution of the source data is typically 1 × 1 mm in plane with 3-mm-thick slices. Multiple sets consisting of between 20 and 40 slices each are acquired over a period of around 20 seconds for each set. The slices are commonly acquired in an

Results

From the simulated motion experiments on premature neonatal data, we evaluated the RMS registration error for four points at the corners of a box within the brain tissue of size 100 mm × 100 mm for each slice. These are presented in Figure 6. The simulated starting RMS error is up to 12 mm. Each point represents the result of one simulation and its coordinates are the starting RMS error and the final RMS error. For all cases, the final overall slice alignment error was significantly reduced by

Discussion

The ability to study the developing fetal brain in high-resolution promises to provide a vital source of clinical information that could contribute directly to a number of challenging clinical questions. It will permit the use of many quantitative morphometric analysis methods, originally developed to study the adult (32) and neonatal (33, 34) brain, to be applied to examine the process of in utero brain development. Critically, high-resolution imaging is the key to seeing the process of

References (36)

  • C. Studholme et al.

    A deformation tensor morphometry study of semantic dementia with quantitative validation

    NeuroImage

    (2004)
  • D. Levine

    Fetal magnetic resonance imaging

    J Maternal-Fetal Neonat Med

    (2004)
  • F.V. Coakley et al.

    Fetal MR imagingA developing modality for the developing patient

    AJR Am J Roentgenol

    (2004)
  • P.C. Sonigo et al.

    MR imaging of fetal cerebral anomalies

    Pediatr Radiol

    (1998)
  • C. Garel et al.

    Fetal cerebral cortexNormal gestational landmarks identified using prenatal MR imaging

    AJNR Am J Neuroradiol

    (2001)
  • D. Prayer et al.

    Fetal MRITechniques and protocols

    Pediatr Radiol

    (2004)
  • S. Borman

    Topics in multiframe superresolution restoration

    (2004)
  • A. Mitiche et al.

    Computation and analysis of image motionA synopsis of current problems and methods

    Int J Comput Vision

    (1996)

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    This work was supported by a Whitaker Foundation award (RG-01-0115), NIH grant R01-MH65392, and NIH Biomedical Research Partnership grant R01-EB0822.

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