Complex quotient nuclear magnetic resonance imaging

Claim 2

In a nuclear magnetic resonance imaging system, including a magnet for producing a magnetic field in which an imaging subject is to be located, a radio frequency coil and a gradient field coil, apparatus comprising: means for collecting a first sequence of NMR signals, including means for applying a first excitation pulse sequence, means for applying a given gradient field, and means for detecting and storing said first sequence of NMR signals; means for collecting a second sequence of NMR signals, including means for applying a second excitation pulse sequence, means for applying said given gradient field, and means for detecting and storing said second sequence of NMR signals; means for performing a two-dimensional Fourier transform of said first and second sequences, respectively, to form first and second images having data values at spatially defined image locations; and means for forming a ratio of data values of said first and second images at each spatially defined image location.

Claim 3

The nuclear magnetic resonance imaging system of claim 1, wherein said first and second images formed by Fourier transformation each comprises an array of complex pixel values; and wherein said means for forming a ratio of data values performs a complex division of said first and second images on a pixel-by-pixel basis.

Claim 4

The nuclear magnetic resonance imaging system of claim 2, wherein said given gradient field extends in two dimensions.

Claim 5

The nuclear magnetic resonance imaging system of claim 3, wherein said first and second excitation pulse sequences differ in the respective timings of the excitation pulses.

Claim 6

In a nuclear magnetic resonance imaging system, including a magnet for producing a magnetic field in which an imaging subject is to be located, a radio frequency coil and a gradient field coil, apparatus comprising: means for collecting a first sequence of NMR signals, including means for applying a first excitation pulse sequence, means for applying a given gradient field, and means for detecting and storing said first sequence of NMR signals; means for collecting a second sequence of NMR signals, including means for applying a second excitation pulse sequence, means for applying said given gradient field, and means for detecting and storing said second sequence of NMR signals; means for performing a two-dimensional Fourier transform of said first and second sequences, respectively, to form first and second images having data values at spatially defined image locations; and means for forming a ratio of data value of said first and second images at each spatially defined image location. wherein said given gradient field extends in two-dimensions; and wherein said first excitation pulse sequence acquires NMR signals by saturation recovery, and wherein said second excitation pulse sequence acquires NMR signals by inversion recovery.

Claim 7

In a nuclear magnetic resonance imaging system, including a magnet for producing a magnetic field in which an imaging subject is to be located, a radio frequency coil and a gradient field coil, apparatus comprising: means for collecting a first sequence of NMR signals, including means for applying a first excitation pulse sequence, means for applying a given gradient field, and means for detecting and storing said first sequence of NMR signals; means for collecting a second sequence of NMR signals, including means for applying a second excitation pulse sequence, means for applying said given gradient field, and means for detecting and storing said second sequence of NMR signals; means for performing a two-dimensional Fourier transform of said first and second sequences, respectively, to form first and second images having data values at spatially defined image locations; and means for forming a ratio of data value of said first and second images at each spatially defined image location. wherein said given gradient field extends in two-dimensions; and wherein said first excitation pulse sequence acquires NMR signals by saturation recovery, and wherein said second excitation pulse sequence acquires NMR signals by inversion recovery.

Claim 8

The nuclear magnetic resonance imaging system of claim 5, wherein each ratio value comprises the complex ratio of an inversion recovery pixel value divided by a saturation recovery pixel value.

Claim 9

The nuclear magnetic resonance imaging system of claim 6, wherein said means for forming a ratio of data values forms a ratio image in which each pixel includes a real part and an imaginary part; and further including: means for displaying an image of the real parts of said ratio image.

Claim 10

The nuclear magnetic resonance imaging system of claim 5, wherein said first image includes a magnetization value M s at each saturation recovery pixel, and said second image includes a magnetization value M ir at each inversion recovery pixel; and further comprising: means for solving the Block equations for M ir and M s to form a T 1 dependent ratio expresion; and means for solving said T 1 dependent ratio expression for T 1 .

Claim 11

In a nuclear magnetic resonance imaging system, a method for reducing the effects of phase errors in an NMR image comprising the steps of: (a) collecting a first sequence of NMR signals by applying a first excitation pulse sequence and a given gradient field and detecting and storing said first sequence of NMR signals; (b) collecting a second sequence of NMR signals by applying a second excitation pulse sequence and said given gradient field and detecting and storing said second sequence of NMR signals; (c) performing at least a two-dimensional Fourier transformation of said first and second sequences, respectively, to form first and second spatially representative images of complex pixel values; and (d) forming a ratio of said complex pixel values at each corresponding image location.

Claim 12

In a nuclear magnetic resonance imaging system, a method for reducing the effects of phase errors in an NMR image comprising the steps of: (a) collecting a first sequence of NMR signals by applying a first excitation pulse sequence and a given gradient field and detecting and storing said first sequence of NMR signals; (b) collecting a second sequence of NMR signals by applying a second excitation pulse sequence and said given gradient field and detecting and storing said second sequence of NMR signals; (c) performing at least a two-dimensional Fourier transformation of said first and second sequences, respectively, to form first and second spatially representative images of complex pixel values; and (d) forming a ratio of said complex pixel values at each corresponding image location.

Claim 13

In a nuclear magnetic resonance imaging system, a method for reducing the effects of phase errors in an NMR image comprising the steps of: (a) collecting a first sequence of NMR signals by applying a first excitation pulse sequence and a given gradient field and detecting and storing said first sequence of NMR signals; (b) collecting a second sequence of NMR signals by applying a second excitation pulse sequence and said given gradient field and detecting and storing said second sequence of NMR signals; (c) performing at least a two-dimensional Fourier transformation of said first and second sequences, respectively, to form first and second spatially representative images of complex pixel values; and (d) forming a ratio of said complex pixel values at each corresponding image location, wherein step (a) comprises collecting a sequence of NMR signals by saturation recovery, step (b) comprises collecting a sequence of NMR signals by inversion recovery, and step (d) comprises forming a complex ratio of a complex inversion recovery pixel divided by a complex saturation recovery pixel at each corresponding image location.

Claim 14

In a nuclear magnetic resonance imaging system, a method for reducing the effects of phase errors in an NMR image comprising the steps of: (a) collecting a first sequence of NMR signals by applying a first excitation pulse sequence and a given gradient field and detecting and storing said first sequence of NMR signals; (b) collecting a second sequence of NMR signals by applying a second excitation pulse sequence and said given gradient field and detecting and storing said second sequence of NMR signals; (c) performing at least a two-dimensional Fourier transformation of said first and second sequences, respectively, to form first and second spatially representative images of complex pixel values; and (d) forming a ratio of said complex pixel values at each corresponding image location, wherein step (a) comprises collecting a sequence of NMR signals by saturation recovery, step (b) comprises collecting a sequence of NMR signals by inversion recovery, and step (d) comprises forming a complex ratio of a complex inversion recovery pixel divided by a complex saturation recovery pixel at each corresponding image location.

Claim 15

The method of claim 10, further comprising a step (e) of presenting an image of the real number portions of each complex ratio value.

Claim 16

The method of claim 10, further comprising the steps of: (e) solving the Block equations for the inversion recovery and saturation recovery pixel values to obtain a T 1 dependent ratio expression; and (f) solving said T 1 dependent ratio expression for T 1 .