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TECHNIQUE FOR T1-BAIS CORRECTION IN THE CHEMICAL SHIFT BASED QUANTITATIVE SEPERATION OF MRI FAT AND WATER PROTON SIGNALS

IP.com Disclosure Number: IPCOM000236785D
Publication Date: 2014-May-15
Document File: 8 page(s) / 601K

Publishing Venue

The IP.com Prior Art Database

Abstract

The invention proposes a technique to correct a bias resulting from transverse relaxation or T1 weighting for quantitative separation of water and fat proton signal in a magnetic resonance (MR) system. The technique describes four different algorithms for correcting the T1 bias in estimates of water, fat and fat-fraction.

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TECHNIQUE FOR T1-BAIS CORRECTION IN THE CHEMICAL SHIFT BASED QUANTITATIVE SEPERATION OF MRI FAT AND WATER PROTON SIGNALS

 

BRIEF ABSTRACT

The invention proposes a technique to correct a bias resulting from transverse relaxation or T1 weighting for quantitative separation of water and fat proton signal in a magnetic resonance (MR) system. The technique describes four different algorithms for correcting the T1 bias in estimates of water, fat and fat-fraction.

KEYWORDS

MR image, Fat, Water, Proton density, T1 bias

 

DETAILED DESCRIPTION

Quantitative separation of a magnetic resonance imaging (MRI) water and fat proton signal is clinically important in various scenarios. Various scenario includes magnetic resonance-positron emission tomography (MR-PET) attenuation correction, tissue characterization, identification of brown adipose tissue, detection of drug toxicity, adipose tissue fat quantification, diagnosis and staging of various diseases, which includes fatty liver, viral hepatitis, cystic fibrosis liver disease, genetic lipo dystrophies, fibro fatty infiltration of myocardium and human immunodeficiency virus (HIV) disease. Quantitative measurement of fat utilizing MRI is challenging due to confounding factors, such as, B0 and B1 in homogeneities, eddy current, gradient non-linearity, spectral complexity, noise bias and bias from longitudinal (T1) and transverse (T2/T2*) relaxation. There is requirement to correct effects arising from the confounding factors for reducing the bias in estimates of fat, water and fat-fraction. Fat-fraction is ratio of fat proton density to cumulative fat and water proton densities.

A conventional technique includes a low flip angle and dual flip angle to improve estimate of fat, water and fat-fraction in MR system. However, the technique has longer scan time and decreases sound to noise ratio (SNR) of acquisition.

Therefore, there is a need for a technique to reduce scan time with increased SNR of acquisition for quantitative separation of water and fat proton signal in a MR system

The invention proposes techniques to correct a bias resulting from transverse relaxation or T1 weighting for quantitative separation of water and fat proton signal in the MR system. The techniques describe four different algorithms for correcting the T1 bias in estimates of water, fat and fat-fraction. The invention also includes method used for developing a simulation phantom used for validation of the described technique.

Techniques for a T1 bias correction nomenclature includes, for instance, S1...SN which are N echoes acquired in an N-point fat water separation technique. T1Wc and T1Fc are correction constants empirically chosen value in accordance to the field strength of the B0 magnetic field.

In one of the techniques, the first step includes division of N echo data points S1…SN by a correctionfactor CW.

Then water (We) and fat (Fe) proton densities are estimated by utilizing the N-point fat-water separation technique. Subsequen...