Effects of nonlinear signal detection on NMR relaxation time analysis

Newcomb, C.; Graham, Simon J.; Bronskill, Michael

doi:10.1016/0022-2364(90)90134-u

Cited by 7 publications

(7 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Spencer et al (24), and Horska et al (25) have shown that under conditions of exchange equilibrium (M i,S ϫ k ST ϭ M i,T ϫ k TS ), Eq. [14] has the closed-form solution…”

Section: Theorymentioning

confidence: 99%

See 1 more Smart Citation

Investigating the effect of exchange and multicomponent T₁ relaxation on the short repetition time spoiled steady‐state signal and the DESPOT1 T₁ quantification method

Deoni

Rutt

Jones

2007

Magnetic Resonance Imaging

View full text Add to dashboard Cite

Purpose: To examine the spoiled steady-state (spoiled gradient-recalled echo sequence [SPGR]) signal arising from two-compartment systems and the role of experimental parameters, in particular TR for resolving signal from each compartment. Materials and Methods:Using Bloch-McConnell simulations, we examined the SPGR signal from two-component systems in which T 1 is much greater than the mean residence time ( m ) of proton spins in each component. Specifically, we examined the role of TR on the ability to resolve each components signal, as well as the influence of experimental parameters on derived DESPOT1 T 1 values. Results:Results revealed that when TR Յ 0.01 m , the measured SPGR signal may be modeled as a summation of signal from each species using a no-exchange approximation. Additionally, under this short TR condition, the driven equilibrium single pulse observation of T 1 (DESPOT1) mapping approach provides T 1 values preferentially biased toward the short or long T 1 species, depending on the choice of flip angles. Conclusion:The ability to model the SPGR signal using a no-exchange approximation may permit the quantification multicomponent T 1 relaxation in vivo. Additionally, the ability to preferentially weight the DESPOT1 T 1 value toward the short or long T 1 may provide a useful window into these components.

show abstract

“…Spencer et al (24), and Horska et al (25) have shown that under conditions of exchange equilibrium (M i,S ϫ k ST ϭ M i,T ϫ k TS ), Eq. [14] has the closed-form solution…”

Section: Theorymentioning

confidence: 99%

“…In biological systems, however, relaxation can rarely be fully characterized by single relaxation times (13,14). Observation of multicomponent T 2 relaxation, for instance, has been well documented in several biological tissues, most notably in white and gray matter (15)(16)(17), articular cartilage (18), and skeletal muscle (19).…”

mentioning

confidence: 99%

Investigating the effect of exchange and multicomponent T₁ relaxation on the short repetition time spoiled steady‐state signal and the DESPOT1 T₁ quantification method

Deoni

Rutt

Jones

2007

Magnetic Resonance Imaging

View full text Add to dashboard Cite

show abstract

“…From Eq. [4], this offresonance will yield a phase offset of the fat signal compared with the water signal, i.e., TR FAT TR WATER in the SSFP signal equations. A simple correction for this is to choose TR such that TR FAT ϭ which corresponds to TR ϭ 4.5 msec.…”

Section: Imaging Methodsmentioning

confidence: 99%

“…Unfortunately, this assumption may not be appropriate in many biological tissues, owing to the heterogeneous biochemical and microstructural nature of the tissue on the voxel scale (3,4). Within human white and gray matter, for instance, the presence of at least two transverse relaxation times has been well established (Refs.…”

mentioning

confidence: 99%

Investigating exchange and multicomponent relaxation in fully‐balanced steady‐state free precession imaging

Deoni

Rutt

Jones

2008

Magnetic Resonance Imaging

View full text Add to dashboard Cite

Purpose:To investigate the effect of chemical exchange and multicomponent relaxation on the rapid T 2 mapping method, DESPOT2 (driven equilibrium single pulse observation of T 2 ) and the steady-state free precession (SSFP) sequence upon which it is based. Although capable of rapid T 2 determination, an assumption implicit of the method is single-component relaxation. In many biological tissues (such as white and gray matter), it is well established that the T 2 decay curve is more accurately described by the summation of more than one relaxation species. Materials and Methods:The effects of exchange were first incorporated into the general SSFP magnetization expressions and its effect on the measured SSFP signal investigated using Bloch-McConnell simulations. Corresponding imaging experiments were performed to support the presented theory. Results:Simulations show the measured multicomponent SSFP signal may be expressed as a linear summation of signal from each species under usual imaging conditions where the repetition time is much less than T 2 . Imaging experiments performed using dairy cream demonstrate strong agreement with the presented theory. Finally, using a dairy cream model, we demonstrate quantification of multicomponent relaxation from multiangle SSFP data for the first time, showing good agreement with reference spin-echo values.Conclusion: SSFP and DESPOT2 may provide a new method for investigating multicomponent systems, such as human brain, and disease processes, such as multiple sclerosis. THE COMBINATION of DESPOT1 and DESPOT2 (driven equilibrium single pulse observation of T 1 and T 2 , respectively), offers a rapid and signal-to-noise ratio (SNR) efficient (SNR per unit scan time) means for voxelwise determination, or mapping, of both the longitudinal (T 1 ) and transverse relaxation times (T 2 ) over large image volumes (i.e., full brain) and with high spatial resolution (1-mm 3 isotropic voxels) (1,2). Typical acquisition times for whole-brain T 1 and T 2 maps is approximately 12-15 minutes (2), with the DESPOT2 acquisition requiring four to six minutes. As has been described in detail previously, the DESPOT2 method derives T 2 information from a series of fully-balanced steady-state free precession (SSFP or true fast imaging with steady precession [TrueFISP]) images, acquired with constant repetition time (TR) and incremented flip angle (␣) (1).An implicit assumption of DESPOT2, however, is that of single-component relaxation, with only a single T 2 value calculated at each imaging voxel. Unfortunately, this assumption may not be appropriate in many biological tissues, owing to the heterogeneous biochemical and microstructural nature of the tissue on the voxel scale (3,4). Within human white and gray matter, for instance, the presence of at least two transverse relaxation times has been well established (Refs. 5-7, among many others), with a fast component (short T 2 less than 50 msec) attributed to a myelin-bound water pool, and a slower T 2 component (long T 2 between 80 and 200 msec) ...

show abstract

“…Quantitative interpretation of nuclear magnetic resonance data has been performed in [4][5][6] using the nonnegative least square with constraints method and, also, using the Contin package [7]. In both these cases, the regularization parameter has to be determined.…”

Section: Introductionmentioning

confidence: 99%

Retrieval of transverse relaxation time distribution from spin-echo data by recurrent neural network

Sebastião

Braga

2005

Journal of Magnetic Resonance

View full text Add to dashboard Cite

Effects of nonlinear signal detection on NMR relaxation time analysis

Cited by 7 publications

References 21 publications

Investigating the effect of exchange and multicomponent T₁ relaxation on the short repetition time spoiled steady‐state signal and the DESPOT1 T₁ quantification method

Investigating the effect of exchange and multicomponent T₁ relaxation on the short repetition time spoiled steady‐state signal and the DESPOT1 T₁ quantification method

Investigating exchange and multicomponent relaxation in fully‐balanced steady‐state free precession imaging

Retrieval of transverse relaxation time distribution from spin-echo data by recurrent neural network

Contact Info

Product

Resources

About

Effects of nonlinear signal detection on NMR relaxation time analysis

Cited by 7 publications

References 21 publications

Investigating the effect of exchange and multicomponent T1 relaxation on the short repetition time spoiled steady‐state signal and the DESPOT1 T1 quantification method

Investigating the effect of exchange and multicomponent T1 relaxation on the short repetition time spoiled steady‐state signal and the DESPOT1 T1 quantification method

Investigating exchange and multicomponent relaxation in fully‐balanced steady‐state free precession imaging

Retrieval of transverse relaxation time distribution from spin-echo data by recurrent neural network

Contact Info

Product

Resources

About

Investigating the effect of exchange and multicomponent T₁ relaxation on the short repetition time spoiled steady‐state signal and the DESPOT1 T₁ quantification method

Investigating the effect of exchange and multicomponent T₁ relaxation on the short repetition time spoiled steady‐state signal and the DESPOT1 T₁ quantification method