Comparison of single-voxel 1H-cardiovascular magnetic resonance spectroscopy techniques for in vivo measurement of myocardial creatine and triglycerides at 3T

Figures

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  Fig. 1. a Spectra from the homemade phantom containing fat acquired with three different sequences (PRESS, sLASER and STEAM) showing the resonances of water (W, 4.7 ppm) and fatty acid (FA, 1.2 ppm). b Acquisitions were realized without water suppression using a voxel of 20 × 20 × 30mm3 (dashed line) that surrounded the fat-containing cylindrical tube. Excitation was prescribed through-plane, and both refocusing pulses were prescribed in-plane, according to the dotted box

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  Fig. 2. a Examples of spectra obtained on the same healthy subject with the same volume of interest placed on the interventricular septum (c). Black curves represent the spectra assessed during one breath hold (BH). Red curves represent the spectra assessed during free breathing (FB). BH spectra tended to exhibit higher noise levels than FB. b The fitting processing was designed to quantify trimethyl amide (TMA, 3.2 ppm), creatine (CR, 3.1 ppm) and the total myocardial triglyceride (TG) resonance, which includes fatty acids (FA, 0.9, 1.3, and 1.6 ppm) and unsaturated fatty acids (UFA, 2.1 and 2.3 and 2.8 ppm). Residual signal enables to evaluate the adequacy of the model

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  Fig. 3. a Average of water linewidths measured from 10 subjects from non-water suppressed spectrum assessed during BH (white) and FB (red) for PRESS, sLASER and STEAM. b Average of FA linewidths measured from 10 subjects from water suppressed spectrum assessed during BH (white) and FB (red) for PRESS, sLASER and STEAM. Data expressed as mean ± SD. PRESS: BH, n = 20 & FB n = 10; sLASER: BH, n = 20 & FB n = 10; STEAM: BH, n = 9 for Cr, n = 14 for FA & FB n = 8 for both Cr and FA

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  Fig. 4. Graphs of mean Cr (blue) and FA (orange) SNR for PRESS, sLASER and STEAM. Data expressed as mean ± SD. PRESS: BH, n = 20 & FB n = 10; sLASER: BH, n = 20 & FB n = 10; STEAM: BH, n = 9 for Cr, n = 14 for FA & FB n = 8 for both Cr and FA. *: p < 0.05; **: p < 0.01 and ***: p < 0.001 compared with the same metabolite (Cr or FA) measured in BH with PRESS. #: p < 0.05 and ##: p < 0.01 compared with the same SNR metabolite (Cr or FA) measured during FB with PRESS. No difference was found between sLASER and STEAM

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  Fig. 5. Bland–Altman plots showing reproducibility between two repeated 1H-CMRS measures within a single CMR session in the 10 subjects regarding myocardial creatine (a) and fatty acids (b). Metabolite contents were acquired using two single breath-hold methods with PRESS (n = 10), sLASER (n = 10) and STEAM (n = 6). The solid line represents the mean of differences between levels obtained with the repeated BH methods, the dashed lines indicate the confidence intervals ± 1.96 SD. Peak at 1.2 ppm was used to calculate FA levels. BH: breath hold; Cr: creatine; FA: fatty acids; SD: standard deviation; W: water

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  Fig. 6. Linear regression analysis showing the correlation between myocardial creatine (a) and fatty acids (b) content relative to water in two acquisitions in breath-hold with PRESS (n = 10), sLASER (n = 10) and STEAM (n = 6). BH: breath-hold; Cr: creatine; FA: fatty acids; FB: free-breathing; W: water

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  Fig. 7. Linear regression analysis showing the correlation between myocardial creatine (a) and fatty acid (b) content relative to water in acquisitions realized in breath-hold and free-breathing with PRESS and sLASER. BH: breath-hold; Cr: creatine; FA: fatty acids; FB: free-breathing; W: water

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  Fig. 8. Ratio of signals from fatty acids to water given by PRESS and STEAM compared to that given by sLASER. The dashed red line represents the linear regression analysis between ratio measured with PRESS and sLASER or STEAM and sLASER. The dashed grey lines indicate unity