background: in treating patients with radiation, the degree of accuracy for the delivery of tumor dose is recommended to be within ± 5% by icru in report 24. the experimental studies have shown that the presence of low-density inhomogeneity in areas such as the lung can lead to a greater than 30% change in the water dose data. therefore, inhomogeneity corrections should be used in treatment pla...

Intensity inhomogeneity is a smooth intensity change inside originally homogeneous regions. The intensity inhomogeneity degrades performance of image processing algorithms. Intensity inhomogeneity correction methods are important image processing algorithms which are used to reduce the inhomogeneity. Brain image intensity inhomogeneity correction is one of the most important parts of clinical d...

....................................................................................................................... iv INTRODUCTION ................................................................................................................ 1 CHAPTER 1 MAGNETIC RESONANCE INHOMOGENEITY CORRECTION................ 3 1.1 Magnetic Resonance Image Acquisition Process ............................

This paper presents a patch-based non-parametric approach to the correction of intensity inhomogeneity from magnetic resonance (MR) images of the human brain. During image acquisition, the inhomogeneity present in the radio-frequency coil, is usually manifested on the reconstructed MR image as a smooth shading effect. This artifact can significantly deteriorate the performance of any kind of im...

Multiple passages of light through an absorption inhomogeneity of finite size deep within a turbid medium are analyzed for optical imaging by use of the self-energy diagram. The nonlinear correction becomes more important for an inhomogeneity of a larger size and with greater contrast in absorption with respect to the host background. The nonlinear correction factor agrees well with that from M...

In magnetic resonance imaging (MRI), image intensity inhomogeneity hampers the quantitative analysis, e.g. segmentation or registration. Intensity inhomogeneity is an effect perceived as a smooth variation in intensities across the image. This study provides an efficient, fully automated intensity inhomogeneity correction method that makes no a priori assumptions on the image intensity distribu...

Introduction: Echo volumar imaging (EVI) is a 3D extension of echo-planar imaging (EPI) that allows data from an entire volume to be acquired following a single excitation. However, only a few studies to date have applied EVI to functional MRI (fMRI) due to its high sensitivity to field-inhomogeneity induced distortions. In this study, we extend two EPI distortion correction techniques to EVI: ...

Introduction Although the first-pass myocardial perfusion MRI has proven its effectiveness in the diagnosis of ischemic heart disease, this technique is still not routinely used. Certain technical difficulties prevent perfusion MRI from being added into the clinical workflow, including complex cardiac motion, limited imaging time, and B1-field inhomogeneity caused by non-uniform characteristics...

While cardiovascular disease is the leading cause of death in most developed countries, SPAMM-MRI can reduce morbidity by facilitating patient diagnosis. An image analysis method with a high degree of automation is essential for clinical adoption of SPAMM-MRI. The degree of this automation is dependent on the amount of thermal noise and surface coil-induced intensity inhomogeneity that can be r...