Rapid relaxation times measurements by MRI: an in vivo application to contrast agent modeling for muscle fiber types characterization

Dedieu, V.; Fau, Pierre; Otal, Philippe; Renou, Jean-Pierre; Emerit, V.; Joffre, F.; Vincensini, D.

doi:10.1016/s0730-725x(00)00222-8

Cited by 8 publications

(4 citation statements)

References 49 publications

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“…Knowing that Gd‐DOTA relaxivities measured in plasma at 37°C and at 3T are very close: r 1 = 3.5 L/mmol/s and r 2 = 4.9 L/mmol/s (27), some variation in muscle T 2 might at first glance have been expected following the CA injection. Assuming also almost identical r 1 and r 2 relaxivities of Gd‐DOTA CA in skeletal muscle, as was demonstrated at 1T in rabbit muscles (28), the estimated change in T 2 in our experimental setting was calculated to be only of 0.5 msec. The small amplitude of this effect is easily explained by the already fast intrinsic T 2 relaxation of skeletal muscle.…”

Section: Discussionsupporting

confidence: 59%

Fast monitoring of T₁, T₂, and relative proton density (M₀) changes in skeletal muscles using an IR‐TrueFISP sequence

Sousa

Vignaud

Fleury

et al. 2011

Magnetic Resonance Imaging

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Purpose: To investigate the feasibility of fast and simultaneous assessment of T 1 , T 2 , and M 0 (relative proton density) changes in skeletal muscle studies using an inversion recovery true fast imaging with steady-state precession (TrueFISP) sequence.Materials and Methods: NMR signal dynamics in calf muscles were analyzed under four different conditions: intravenous injection of a low-molecular weight Gd contrast agent (CA), postarterial occlusion reactive hyperemia, local cooling, and an exercise bout. Experiments were conducted on a clinical 3T whole-body scanner.Results: At rest, average muscle T 1 and T 2 values obtained from the IR-TrueFISP experiments were 1.34 6 0.13 seconds and 45 6 5 msec, respectively (median 6 standard deviation). 1) Noticeable T 1 decreases (DT 1 max %À30%) were measured in the calf muscles after CA injection, while no significant changes were observed for T 2 and M 0 . 2) T 2 increased rapidly during reactive hyperemia and reached a peak value (þ6%) at about 1 minute postischemia. During ischemia, a significant decrease was observed only in the soleus muscle. No significant paradigm-related changes in M 0 and T 1 were noted in all muscle groups, except in the m. soleus (DT 1 %þ1% during reactive hyperemia). 3) Opposite variations in muscle T 1 (DT 1 max %À30%) and M 0 (DM 0 max %þ25%) associated with local cooling were detected. 4) Concomitant changes in T 1 (DT 1 max %þ15%), T 2 (DT 2 max %þ35%), and M 0 (DM 0 max %þ16%) were observed in the activated muscles following the exercise bout.Conclusion: IR-TrueFISP was sufficiently fast and sensitive to detect small and transient T 1 , T 2 , and M 0 changes in the calf muscles under different experimental conditions. The sequence offers a time-resolution adequate to track rapid physiological adaptations in skeletal muscle.

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Section: Discussionsupporting

confidence: 59%

Fast monitoring of T₁, T₂, and relative proton density (M₀) changes in skeletal muscles using an IR‐TrueFISP sequence

Sousa

Vignaud

Fleury

et al. 2011

Magnetic Resonance Imaging

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“…About 2000 noisy decay curves were simulated for various SNR values. For monoexponential decay, T 2 was assumed to be around 40 ms (Dedieu et al 2000, Stanisz et al 2005. For biexponential decay, relaxation tissue parameters were those of fat with two proton components having a short and a long relaxation times, T 2s ∼ 40 ms and T 2l ∼ 150 ms with relative fractions a s ∼ 70% and a l ∼ 30%, respectively (Kamman et al 1987, Brix et al 1993.…”

Section: Uncertainty In T 2 Measurements: Simulation Resultsmentioning

confidence: 99%

High spatial resolution quantitative MR images: an experimental study of dedicated surface coils

et al. 2006

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Measuring spin-spin relaxation times (T2) by quantitative MR imaging represents a potentially efficient tool to evaluate the physicochemical properties of various media. However, noise in MR images is responsible for uncertainties in the determination of T2 relaxation times, which limits the accuracy of parametric tissue analysis. The required signal-to-noise ratio (SNR) depends on the T2 relaxation behaviour specific to each tissue. Thus, we have previously shown that keeping the uncertainty in T2 measurements within a limit of 10% implies that SNR values be greater than 100 and 300 for mono- and biexponential T2 relaxation behaviours, respectively. Noise reduction can be obtained either by increasing the voxel size (i.e., at the expense of spatial resolution) or by using high sensitivity dedicated surface coils (which allows us to increase SNR without deteriorating spatial resolution in an excessive manner). However, surface coil sensitivity is heterogeneous, i.e., it--and hence SNR--decreases with increasing depth, and the more so as the coil radius is smaller. The use of surface coils is therefore limited to the analysis of superficial structure such as the hypodermic tissue analysed here. The aim of this work was to determine the maximum limits of spatial resolution and depth compatible with reliable in vivo T2 quantitative MR images using dedicated surface coils available on various clinical MR scanners. The average thickness of adipose tissue is around 15 mm, and the results obtained have shown that obtaining reliable biexponential relaxation analysis requires a minimum achievable voxel size of 13 mm3 for a conventional volume birdcage coil and only of 1.7 mm3 for the smallest available surface coil (23 mm in diameter). Further improvement in spatial resolution allowing us to detect low details in MR images without deteriorating parametric T2 images can be obtained by image filtering. By using the non-linear selective blurring filter described in a previous work, the voxel size was reduced to 0.8 mm3, allowing us to detect microstructures such as fibrous septae while preserving precision in T2 measurements. This paper provides practical information allowing us to perform reliable T2 quantitative MR micro images. High resolution imaging with dedicated surface coils, which is only well-suited to near surface organs, might lead to highly valuable results in this context, especially to analyse the hypodermis involved in the lipodystrophy seen in patients with human immuno-deficiency virus (HIV).

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“…where (λ 0 ) represents the value of the relaxometry parameters obtained from a noise-free decay curve. In this study, for both the adipose and neighbouring muscle tissues to be analysed by quantitative MRI, the protons can be divided into two populations, with short T 2s and long T 2l transverse relaxation times, with relative proportions a s and a l respectively (Fransson et al 1993, Hazlewood et al 1969, Clark et al 2003, Dedieu et al 2000. In such a case, according to relation 1, the pixel signal is biexponential:…”

Section: Precision Of Mri Relaxometry Parameter Determination: Simula...mentioning

confidence: 99%

A post-processing method for multiexponential spin–spin relaxation analysis of MRI signals

Gensanne¹,

Josse²,

Lagarde³

et al. 2005

Phys. Med. Biol.

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Quantitative MR imaging is a potential tool for tissue characterization; in particular, proton density and proton relaxation times can be derived from MR signal analysis. However, MR image noise affects the accuracy of measurements and the number of tissue parameters that can be reliably estimated. Filtering can be used to limit image noise; however this reduces spatial resolution. In this work we studied, using both simulations and experiments, a filter called a 'selective blurring filter'. Compared to other classical filters, this filter achieves the best compromise between spatial resolution and noise reduction. The filter was specifically used to reliably determine the bi-component transverse relaxation of protons in adipose tissue. Long and short relaxation times and the relative proton fraction of each component were obtained with a degree of uncertainty of less than 10% and an accuracy of 95%.

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Rapid relaxation times measurements by MRI: an in vivo application to contrast agent modeling for muscle fiber types characterization

Cited by 8 publications

References 49 publications

Fast monitoring of T₁, T₂, and relative proton density (M₀) changes in skeletal muscles using an IR‐TrueFISP sequence

Fast monitoring of T₁, T₂, and relative proton density (M₀) changes in skeletal muscles using an IR‐TrueFISP sequence

High spatial resolution quantitative MR images: an experimental study of dedicated surface coils

A post-processing method for multiexponential spin–spin relaxation analysis of MRI signals

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Rapid relaxation times measurements by MRI: an in vivo application to contrast agent modeling for muscle fiber types characterization

Cited by 8 publications

References 49 publications

Fast monitoring of T1, T2, and relative proton density (M0) changes in skeletal muscles using an IR‐TrueFISP sequence

Fast monitoring of T1, T2, and relative proton density (M0) changes in skeletal muscles using an IR‐TrueFISP sequence

High spatial resolution quantitative MR images: an experimental study of dedicated surface coils

A post-processing method for multiexponential spin–spin relaxation analysis of MRI signals

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Product

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Fast monitoring of T₁, T₂, and relative proton density (M₀) changes in skeletal muscles using an IR‐TrueFISP sequence

Fast monitoring of T₁, T₂, and relative proton density (M₀) changes in skeletal muscles using an IR‐TrueFISP sequence