A very simple, robust and fast method for estimating and displaying average time constants of T2 decays from multiecho MRI images using color intensity projections

TL;DR

This paper introduces a simple, robust, and fast method for estimating and visualizing the average T2 decay time constants from multiecho MRI images using color intensity projections, aiding in differentiating tissue structures.

Contribution

The paper presents a novel approach that efficiently estimates and displays average T2 decay constants from multiecho MRI data, improving robustness and simplicity over existing methods.

Findings

Effective visualization of T2 decay constants using color intensity projections.

Robust estimation method resistant to artifacts and multiexponential decays.

Demonstrated usefulness in differentiating healthy tissue and multiple sclerosis lesions.

Abstract

While the multiexponential nature of T2 decays measured in vivo is well known, characterizing T2 decays by a single time constant is still very useful when differentiating among structures and pathologies in MRI images. A novel, robust, fast and very simple method is presented for both estimating and displaying the average time constant for the T2 decay of each pixel from a multiecho MRI sequence. The average time constant is calculated from the average of the values measured from the T2 decay over many echoes. For a monoexponential decay, the normalized decay average varies monotonically with the time constant. Therefore, it is simple to map any normalized decay average to an average time constant. This method takes advantage of the robustness of the normalized decay average to both artifacts and multiexponential decays. Color intensity projections (CIPs) were used to display 32 echoes acquired at a 10ms spacing as a single color image. The brightness of each pixel in each color image was determined by the intensity of the corresponding pixel in the earliest image and the hue was determined by the normalized decay average. Examples demonstrate the effectiveness of using CIPs to display the results of a multiecho sequence for a healthy subject and a multiple sclerosis patient.