Introduction: The key characteristics of positron emission tomography (PET) are its quantitative capability and its sensitivity, which allow the in vivo imaging of biochemical interactions with small amounts of tracer concentrations. Therefore, accurate quantification is important. However, it can be sensitive to several physical factors. The aim of this investigation is the assessment of the e...

We propose a fast algorithm to estimate brain tissue concentrations from conventional T1-weighted images based on a Bayesian maximum a posteriori formulation that extends the "mixel" model developed in the 90's. A key observation is the necessity to incorporate additional prior constraints to the "mixel" model for the estimation of plausible concentration maps. Experiments on the ADNI standardi...

BACKGROUND Quantitative myocardial PET perfusion imaging requires partial volume corrections. METHODS Patients underwent ECG-gated, rest-dipyridamole, myocardial perfusion PET using Rb-82 decay corrected in Bq/cc for diastolic, systolic, and combined whole cycle ungated images. Diastolic partial volume correction relative to systole was determined from the systolic/diastolic activity ratio, s...

This paper presents a new method for partial volume estimation using standard eigenimage method and B-splines. The proposed method is applied on the multi-parameter volumetric images such as MRI. The proposed approach uses the B-spline bases (kernels) to interpolate a continuous 2D surface or 3D density function for a sampled image dataset. It uses the Fourier domain to calculate the interpolat...

Introduction and aim: In SPECT imaging, the finite spatial resolution of the imaging system leads to a blurring of the reconstructed image. Consequently, counts originating from each point in the source distribution will be spread out over a volume in the reconstructed image, leading to spill-over of counts between different structures and distortion of the apparent activity concentration. This...

Tomographic biomedical images are commonly affected by an imaging artefact known as the partial volume (PV) effect. The PV effect produces voxels composed of a mixture of tissues in anatomical magnetic resonance imaging (MRI) data resulting in a continuity of these tissue classes. Anatomical MRI data typically consist of a number of contiguous regions of tissues or even contiguous regions of PV...

In this thesis, a two-dimensional pixel-wise deconvolution method for partial volume correction (PVC) for combined Positron Emission Tomography and Computer Tomography (PET/CT) imaging has been developed. The method is based on Van Cittert's deconvolution algorithm and includes a noise reduction method based on adaptive smoothing and median filters. Furthermore, a technique to take into account...

This paper discusses three aspects that have not been looked into within mechanistic model for rationalizing observed behavior of nanocrystalline materials. (1) For the nano-materials with low energy barrier to emit the trailing partial after the leading partial, such as nanocrystalline Al (nc-Al), both partials extend intra-granularly in strengthening effect. (2) In the transition grain-size r...

As early as 1785 Claude Louis Berthollet (17481822) studied the decomposition of ammonia by electric sparking. He found that 0.725 by volume of hydrogen and 0.275 by volume of nitrogen were produced. Several other workers confirmed this effect of sparking but noted that some NH3 always remains. The partial formation of NH3 when mixtures of H2 and N2 were subjected to various forms of electrical...

Partial volume effect is still considered one of the main limitations in brain PET imaging given the limited spatial resolution of current generation PET scanners. The accuracy of anatomically guided partial volume effect correction (PVC) algorithms in brain PET is largely dependent on the performance of MRI segmentation algorithms partitioning the brain into its main classes, namely gray matte...