Novel matrix-valued imaging techniques such as diffusion tensor magnetic resonance imaging require the development of edgepreserving nonlinear filters. In this paper we introduce a median filter for such tensor-valued data. We show that it inherits a number of favourable properties from scalar-valued median filtering, and we present experiments on synthetic as well as on real-world images that ...

Brain capillary telangiectasia is an incidental vascular malformation found usually in pons and sometimes in extra- pontine sites. Typical MRI features are enhancement on post contrast T1 weighted images and signal loss on gradient echo images. We evaluated 10 patients with various MR techniques. Susceptibility weighted imaging was superior to GRE T2 in showing decreased signal due to susceptib...

Diffusion tensor imaging (DTI) is a quantitative magnetic resonance imaging (MRI) method that is used to study the microstructural properties of white matter in the brain. Tensor-derived quantities, such as the trace and fractional anisotropy (FA), are important for characterizing the normal, diseased, and developing brain. Consequently, determining the statistical properties of the diffusion t...

We present a methodology to achieve 3D high resolution in-utero fetal brain DTI that shows excellent ADC as well as promising FA maps. After continuous DTI scanning to acquire a repeated series of parallel slices with 15 diffusion directions, image registration is used to realign the images to correct for fetal motion. Once aligned, the diffusion images are treated as irregularly sampled data w...

This paper describes a method for model-based averaging of sets of diffusion weighted magnetic resonance images (DW-MRI) under space transformations (resulting for example from registration methods). A robust weighted least squares method is developed. Synthetic validation experiments show the improvement of the proposed estimation method in comparison to standard least squares estimation. The ...

PURPOSE Our aim was to determine whether diffusion anisotropy and diffusivity of white matter tracts of the temporal stem in patients with Alzheimer (AD) can be evaluated independently by using diffusion tensor tractography. MATERIALS AND METHODS Subjects included 15 patients with AD (11 women and 4 men; mean age, 74 years) and 15 age-matched control subjects (11 women and 4 men; mean age, 72...

In this paper we extend anisotropic diffusion with a diffusion tensor to be applicable to data that is well modeled by linear models. We focus on its variational theory, and investigate simple discretizations and their performance on synthetic data fulfilling the underlying linear models. To this end, we first show that standard anisotropic diffusion with a diffusion tensor is directly linked t...

results stereoscopic displays of the nerves were obtained in all 24 elbows by vr, mip, and fiber tractography post-processing methods. the vr/mip post-processing methods were easier to perform compared to fiber tractography. there was no significant difference among the scores of fiber tracking and vr/mip reconstruction for single direction. the imaging quality scores of fiber tractography and ...

Ultrasound images are prone to speckle noises. Speckles blur features which are essential for diagnosis and assessment. Thus despeckling is a necessity in ultrasound image processing. Linear filters can suppress speckles, but they smooth out features. Median filter based despeckling algorithms produce better results. However, they may produce artifact patterns in the resulted images and oversmo...

BACKGROUND AND PURPOSE Compared with conventional T2-weighted MR imaging, diffusion tensor MR imaging provides quantitative indices with increased specificity to the most destructive aspects of multiple sclerosis. In this study, we obtained brain mean diffusivity (_D) and fractional anisotropy histograms of patients with multiple sclerosis to compare them with those of healthy volunteers and to...