AUTOMATED INHOMOGENEITY CORRECTION By Anuradha Subramanian MRI Institute Image Retreat 2005

What is RF inhomogeneity? Inhomogeneity refers to the slowly varying intensity patterns that occur in MRI and that tend to obfuscate anatomic detail Inhomogeneity refers to the slowly varying intensity patterns that occur in MRI and that tend to obfuscate anatomic detail The causes: The causes: * Non-uniform B1 field * Non-uniform sensitivity in a receive only coil a receive only coil

Why is this correction important? * Inhomogeneity in RF causes unnecessary intensity variations in an image * Causes problems for threshold-based segmentation * Causes problems in the analysis of structural information in high field MR images

Overview of the correction Algorithm * The approach is to normalize the input image by smoothed version of itself, so that the low spatial frequencies are removed. * The advantage of this method, is that it does not cause any prominent artifacts at the edges of structures. * No large artificial increase in MR signal intensity in the image contents at the edges of objects – This is achieved because filling is done locally by using the technique of Analytic Continuation.

Original Corrected

Other Projects * Filter to remove Gibbs Ringing Artifacts. * 3 Dimensional Reformatting and Visualization. Reformatting of images can be achieved from any orthogonal view to any other orthogonal view Reformatting of images can be achieved from any orthogonal view to any other orthogonal view