k-space is a formalism widely used in magnetic resonance imaging introduced in 1979 by Likes and in 1983 by Ljunggren and Twieg.In MRI physics, k-space is the 2D or 3D Fourier transform of the MR image measured. Its complex values are sampled during an MR measurement, in a premeditated scheme controlled by a pulse sequence, i.e. an accurately timed sequence of radiofrequency and gradient pulses.

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dbpedia-owl:abstract
  • Espacio K, es una matriz de datos sin procesar, obtenida a la salida del equipo de resonancia magnética antes de aplicarle la transformada de Fourier y conseguir la imagen final.Su principal problema radica en que el espacio k es un concepto abstracto ya que, aunque se puede visualizar, sus datos tienen poco sentido y no tienen relación directa con la imagen final de la resonancia magnética.
  • k-space is a formalism widely used in magnetic resonance imaging introduced in 1979 by Likes and in 1983 by Ljunggren and Twieg.In MRI physics, k-space is the 2D or 3D Fourier transform of the MR image measured. Its complex values are sampled during an MR measurement, in a premeditated scheme controlled by a pulse sequence, i.e. an accurately timed sequence of radiofrequency and gradient pulses. In practice, k-space often refers to the temporary image space, usually a matrix, in which data from digitized MR signals are stored during data acquisition. When k-space is full (at the end of the scan) the data are mathematically processed to produce a final image. Thus k-space holds raw data before reconstruction.k-space is in spatial frequency domain. Thus if we define and such thatandwhere FE refers to frequency encoding, PE to phase encoding, is the sampling time (the reciprocal of sampling frequency), is the duration of GPE, (gamma bar) is the gyromagnetic ratio, m is the sample number in the FE direction and n is the sample number in the PE direction (also known as partition number), the 2D-Fourier Transform of this encoded signal results in a representation of the spin density distribution in two dimensions. Thus position (x,y) and spatial frequency (, ) constitute a Fourier transform pair.Typically, k-space has the same number of rows and columns as the final image and is filled with raw data during the scan, usually one line per TR (Repetition Time).An MR image is a complex-valued map of the spatial distribution of the transverse magnetization Mxy in the sample at a specific time point after an excitation. Conventional qualitative interpretation of Fourier Analysis asserts that low spatial frequencies (near the center of k-space) contain the signal to noise and contrast information of the image, whereas high spatial frequencies (outer peripheral regions of k-space) contain the information determining the image resolution. This is the basis for advanced scanning techniques, such as the keyhole acquisition, in which a first complete k-space is acquired, and subsequent scans are performed for acquiring just the central part of the k-space; in this way, different contrast images can be acquired without the need of running full scans.A nice symmetry property exists in k-space if the image magnetization Mxy is prepared to be proportional simply to a contrast-weighted proton density and thus is a real quantity. In such a case, the signal at two opposite locations in k-space is:where the star denotes complex conjugation.Thus k-space information is somewhat redundant then, and an image can be reconstructed using only one half of the k-space, either in the PE (Phase Encode) direction saving scan time (such a technique is known as half Fourier or half scan) or in the FE (Frequency Encode) direction, allowing for lower sampling frequencies and/or shorter echo times (such a technique is known as half echo). However, these techniques are approximate due to phase errors in the MRI data which can rarely be completely controlled (due to imperfect static field shim, effects of spatially selective excitation, signal detection coil properties, motion etc.) or nonzero phase due to just physical reasons (such as the different chemical shift of fat and water in gradient echo techniques).
  • Il k-spazio è un formalismo matematico introdotto nel 1983 per spiegare in maniera semplice e univoca la formazione dell'immagine nell'imaging a risonanza magnetica.
  • 核磁気共鳴画像法 (MRI) において、k空間(kくうかん、k-space)は実空間の画像データのフーリエ変換である空間をさす。すなわちk空間と実空間は互いにフーリエ変換の関係にある。実空間の座標軸は位置座標 (x , y ) であり、k空間 (kx , ky ) での軸は空間周波数である。MRIでは、信号読みとりの間に傾斜磁場を印加し位置のエンコードを行い、時間軸をk軸に対応させており、ローデータ(raw data, 画像生データ)の集合がk空間を構成する。k空間の低周波部分(中央部)は信号強度あるいは画像コントラストを決定し、外側の高周波成分は画像の分解能を決めている。
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  • Espacio K, es una matriz de datos sin procesar, obtenida a la salida del equipo de resonancia magnética antes de aplicarle la transformada de Fourier y conseguir la imagen final.Su principal problema radica en que el espacio k es un concepto abstracto ya que, aunque se puede visualizar, sus datos tienen poco sentido y no tienen relación directa con la imagen final de la resonancia magnética.
  • Il k-spazio è un formalismo matematico introdotto nel 1983 per spiegare in maniera semplice e univoca la formazione dell'immagine nell'imaging a risonanza magnetica.
  • 核磁気共鳴画像法 (MRI) において、k空間(kくうかん、k-space)は実空間の画像データのフーリエ変換である空間をさす。すなわちk空間と実空間は互いにフーリエ変換の関係にある。実空間の座標軸は位置座標 (x , y ) であり、k空間 (kx , ky ) での軸は空間周波数である。MRIでは、信号読みとりの間に傾斜磁場を印加し位置のエンコードを行い、時間軸をk軸に対応させており、ローデータ(raw data, 画像生データ)の集合がk空間を構成する。k空間の低周波部分(中央部)は信号強度あるいは画像コントラストを決定し、外側の高周波成分は画像の分解能を決めている。
  • k-space is a formalism widely used in magnetic resonance imaging introduced in 1979 by Likes and in 1983 by Ljunggren and Twieg.In MRI physics, k-space is the 2D or 3D Fourier transform of the MR image measured. Its complex values are sampled during an MR measurement, in a premeditated scheme controlled by a pulse sequence, i.e. an accurately timed sequence of radiofrequency and gradient pulses.
rdfs:label
  • K-space (MRI)
  • Espacio k
  • Espace réciproque
  • K-spazio
  • K空間
  • K空間
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