Improved optimization for the robust and accurate linear registration and motion correction of brain images

Whole brain segmentation: automated labeling of neuroanatomical structures in the human brain.

A global optimisation method for robust affine registration of brain images

Anisotropic water diffusion in neural fibres such as nerve, white matter in spinal cord, or white matter in brain forms the basis for the utilization of diffusion tensor imaging (DTI) to track fibre pathways. The fact that water diffusion is sensitive to the underlying tissue microstructure provides a unique method of assessing the orientation and integrity of these neural fibres, which may be useful in assessing a number of neurological disorders. The purpose of this review is to characterize the relationship of nuclear magnetic resonance measurements of water diffusion and its anisotropy (i.e. directional dependence) with the underlying microstructure of neural fibres. The emphasis of the review will be on model neurological systems both in vitro and in vivo. A systematic discussion of the possible sources of anisotropy and their evaluation will be presented followed by an overview of various studies of restricted diffusion and compartmentation as they relate to anisotropy. Pertinent pathological models, developmental studies and theoretical analyses provide further insight into the basis of anisotropic diffusion and its potential utility in the nervous system.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/nbm.782

The basis of anisotropic water diffusion in the nervous system – a technical review

http://ee.sharif.edu/~miap/Files/A%20Survey%20of%20Medical%20Image%20Registration.pdf

A survey of medical image registration.

To assess the effect of stimulus correlated motion on the appearance of functional magnetic resonance images, conventional visual and motor protocols were each performed by four normal volunteers and an image co-registration technique was used to retrospectively monitor subject motion. In three studies synthetic data sets were constructed from single baseline images using the positional information obtained from the co-registration procedure. Cumulative difference images were then created from both the synthetic and functional image sets. Stimulus correlated motion was detected in all eight studies and the synthetic cumulative difference images showed striking similarities to the equivalent functional images in each case.

Artifacts due to stimulus correlated motion in functional imaging of the brain

PURPOSE Results from conventional T2-weighted spin-echo sequences were compared with those obtained using fluid attenuated inversion recovery (FLAIR) pulse sequences in order to assess their relative merits in detecting disease.

METHODS Forty adult patients with suspected disease of the brain were examined with spin-echo sequences (TE = 20 and TE = 80), and results were compared with FLAIR sequences of several types with inversion times of 1800-3000 msec and echo times of 130-240 msec. Scans were assessed by two radiologists for lesion number, conspicuity, and extent.

RESULTS A total of 48 lesions or groups of lesions were recognized with both sequences. In 22 instances, more lesions were seen with FLAIR sequences, and, in the remaining 26, equal numbers were seen. In 42 lesions, conspicuity was better with FLAIR sequences, equal in five and worse in one cystic lesion. Lesion extent was better assessed in 28 of the 48 cases with FLAIR sequences and equally well seen in the remainder.

CONCLUSION By virtue of their long echo time and relative freedom from cerebrospinal fluid artifact FLAIR sequences provide high sensitivity to a wide range of disease. The basic sequence is easy to implement but is relatively time consuming.

http://www.ajnr.org/content/ajnr/13/6/1555.full.pdf

MR of the brain using fluid-attenuated inversion recovery (FLAIR) pulse sequences.

Objective Methods for automatically registering and reslicing MR images using an interpolation function that matches the structure of the image data are described. Materials and methods Phantom and human brain images were matched by rigid body rotations and translations in two and three dimensions using a least-squares optimization procedure. Subvoxel image shifts were produced with linear or sinc interpolation. Results The use of sinc interpolation ensured that the repositioned images were faithful to the original data and enabled quantitative intensity comparisons to be made. In humans, image segmentation was vital to avoid extraneous soft tissue changes producing systematic errors in registration. Conclusions The sinc-based interpolation technique enabled serially acquired MR images to be positionally matched to subvoxel accuracy so that small changes in the brain could be distinguished from effects due to misregistration.

A registration and interpolation procedure for subvoxel matching of serially acquired MR images.

Fluid attenuated inversion recovery pulse sequences with a long echo time (TE) have been used to image the brain in one volunteer and four patients. The long inversion time used with this sequence suppresses the signal from CSF and the long TE produces very heavy T2 weighting. The marked reduction in flow artefact from CSF and the high T2 weighting enabled anatomical detail to be seen within the brain stem and produced high lesion contrast in areas close to CSF. Lesions were demonstrated with greater conspicuity than with conventional T2-weighted sequences in patients with cerebral infarction, low grade astrocytoma, and diplegia.

Angela Oatridge

Papers

Artifacts due to stimulus correlated motion in functional imaging of the brain

MR of the brain using fluid-attenuated inversion recovery (FLAIR) pulse sequences.

A registration and interpolation procedure for subvoxel matching of serially acquired MR images.

Use of fluid attenuated inversion recovery (FLAIR) pulse sequences in MRI of the brain

Brain swelling in first hour after coronary artery bypass surgery.