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Purpose Quantitative cardiac MRI, and more particularly T1 mapping, has become a most important modality to characterize myocardial tissue. In this work, the value of a radial variant of the conventional modified Look-Locker inversion recovery sequence (raMOLLI) is demonstrated. Methods The raMOLLI acquisition scheme consisted of five radial echo trains of 80 spokes acquired using either a fast low-angle shot (FLASH) or a true fast imaging with steady-state-precession (TrueFISP) readout at different time points after a single magnetization inversion. View sharing combined with a compressed sensing algorithm allowed the reconstruction of 50 images along the T1 relaxation recovery curve, to which a dictionary-fitting approach was applied to estimate T1 . The sequence was validated on a nine-vial phantom, on 19 healthy subjects, and one patient suffering from dilated cardiomyopathy. Results The raMOLLI sequence allowed a significant decrease of myocardial T1 map acquisition time down to five heartbeats, while exhibiting a higher degree of accuracy and a comparable precision on T1 value estimation than the conventional modified Look-Locker inversion recovery sequence. The FLASH readout demonstrated a better robustness to B0 inhomogeneities than TrueFISP, and was therefore preferred for in vivo acquisitions. Conclusions This sequence represents a good candidate for ultrafast acquisition of myocardial T1 maps. Magn Reson Med 79:1387-1398, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

PURPOSE To introduce an ultrashort echo time (UTE) based method for quantitative mapping of short-T2 signals in skeletal muscle (SKM) in the presence of fat, with the aim of monitoring SKM fibrosis. METHODS From a set of at least five UTE images of the same slice, a long- T2* map, a fat-fraction map, and a map of short-T2 -signal fraction are extracted. The method was validated by numerical simulations and in vitro studies on collagen solutions. Finaly, the method was applied to image the short-T2 signals in the leg of eight healthy volunteers. RESULTS The imaged short-T2 -signal fractions in the collagen solutions correlated with their respective collagen concentrations ( R=0.999, P=0.009). Short-T2 tissues such as cortical bone and fasciae were highlighted in the resulting short-T2 fraction maps. A significant fraction of short-T2 signal was systematically observed in the skeletal muscle of all of the subjects (4.5±1.2%). CONCLUSION The proposed method allows the quantitative imaging of short-T2 components in tissues containing fat. By also having the fat-fraction and T2* maps as outcomes, long-T2 suppression is accomplished without requiring modifications to the basic UTE sequence. Although the hypersignal observed in the fasciae suggests that the short-T2 signal observed in SKM might arise from interstitial connective tissue, further investigation is necessary to confirm this statement. Magn Reson Med 78:997-1008, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

A fast and robust methodology for in vivo T2 mapping is presented. The approach is based on the partially spoiled steady state free precession technique recently proposed by Bieri et al. (Magn Reson Med 2011). The accuracy of this method was demonstrated in simulations and phantom experiments. Variations in skeletal muscle T2 relaxation time have been correlated with cell damage and inflammatory response. Nonetheless, the lack of easily implementable, fast, accurate and reproducible methods has hampered the adoption of T2 measurement as a noninvasive tool for skeletal muscle characterization. The applicability of the partially spoiled steady state free precession method for tissue characterization in muscle disease is illustrated in this work by several examples. Quantitative MRI, in particular T2 mapping based on partially spoiled steady state free precession acquisitions, might provide objective markers of muscle damage and degenerative changes, and an alternative to serial muscle biopsies. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.

The classical double-quantum editing sequence 90 degrees,x-tau-180 degrees y-tau-90 degrees x-t1-90 degrees x-tau-180 degrees y-tau-AQ (tau = 1/4J) was rendered volume selective, by making slice selective the first 90 degrees pulse and the two 180 degrees pulses. Using simple rules to ensure optimum radio frequency phase coherence, this single-voxel editing sequence, reminiscent of a basic PRESS localization technique, was implemented on a whole-body 3 T spectrometer, and in vitro editing of lactate methyl protons was demonstrated without any significant loss in intrinsic sensitivity. The effectiveness of the proposed approach in vivo was also illustrated through the localized monitoring of lactate in the human leg during and after exercise.

The purpose of this work was to investigate the temporal relationship between intensity changes in T2*-weighted NMR images and tissue oxygen content, measured by myoglobin proton NMR spectroscopy, in the skeletal muscle. During an ischemic stress test, the calf muscles of five healthy volunteers were studied at 3 Tesla. An interleaved NMRI-NMRS sequence was used, which made it possible to record T2*-weighted images and myoglobin spectra simultaneously. During ischemia, rapid changes in muscle signal intensity were observed on T2*-weighted images, which immediately preceded myoglobin desaturation. Bearing in mind the respective P50 of hemoglobin and myoglobin, this observation clearly favored the hypothesis that hemoglobin desaturation was responsible for the changes in T2*. This interpretation was further supported by the temporal coincidence between the experimental NMR data and a model of hemoglobin desaturation solely derived from physiological considerations.

The accuracy of the measurement of total muscle glucose by in vivo 13C NMR spectroscopy was tested in five normal volunteers during a euglycemic [1-13C]glucose infusion. The NMR visible concentration calibrated using an external reference was compared with that calculated from plasma glucose concentration, assuming that glucose remained extracellular. The NMR measurement always provided higher values than the calculation from plasma glucose: 0.51 +/- 0.035 (mean +/- SE) versus 0.38 +/- 0.005 mmol/liter of muscle on average. This systematic difference was interpreted as reflecting the presence of muscle glucose-6-phosphate, co-resonating with free glucose. Thus, glucose appeared to be virtually 100% NMR visible in human skeletal muscle.

1H NMR simultaneous editing of 13C-coupled and 13C-uncoupled methyl protons resonance, using the selection of double quantum coherences by a gradient pulse, was analyzed in vitro and demonstrated in situ on the hindlimb of an exercised rat model postmortem. In vitro calibration showed agreement with theoretical analysis. High-resolution NMR of muscle extract confirmed the accuracy of the lactate 13C-enrichment calculated using the in situ NMR data and the calibration factor obtained in vitro.

A fast and robust methodology for in vivo T(2) mapping is presented. The approach is based on the partially spoiled steady state free precession technique recently proposed by Bieri et al. (Magn Reson Med 2011). The accuracy of this method was demonstrated in simulations and phantom experiments. Variations in skeletal muscle T(2) relaxation time have been correlated with cell damage and inflammatory response. Nonetheless, the lack of easily implementable, fast, accurate and reproducible methods has hampered the adoption of T(2) measurement as a noninvasive tool for skeletal muscle characterization. The applicability of the partially spoiled steady state free precession method for tissue characterization in muscle disease is illustrated in this work by several examples. Quantitative MRI, in particular T(2) mapping based on partially spoiled steady state free precession acquisitions, might provide objective markers of muscle damage and degenerative changes, and an alternative to serial muscle biopsies.

To elucidate the low proton nuclear magnetic resonance (NMR) visibility of muscle lactate previously demonstrated in excised rat muscle, lactate transverse relaxation was investigated in the same model using double quantum editing sequences with effective echo times ranging from 55 to 475 msec. On this time scale, muscle lactate clearly exhibits a bi-exponential transverse relaxation with a short T 2 of 33 ± 5 msec (mean ± SE, n = 3) and a long T 2 of 230 ± 10 msec. The relative populations (84 ± 4% vs. 16 ± 4%, respectively) of these two lactate pools are compatible with compartmentation between intra- and extracellular muscle lactate.

Lipid linewidths were measured in the plasma proton spectra of young women. The individuals taking a contraceptive pill associating ethinyloestradiol and levonorgestrel or norethisterone were found with an average linewidth 2.5 Hz narrower than controls. As this drug regimen systematically induces an increase in plasma VLDL and a decrease in HDL/LDL ratio, our observation supports the theory that the Fossel test reflects plasma lipids abnormalities in cancer patients.Physicians enrolled at least 140 female soldiers and military employees in a screening program to detect breast and gynecologic cancers at the outpatient clinic of the military hospital in Liege, Belgium using the Fossel test, a magnetic resonance (NMR) spectroscopy of plasma. They also underwent a clinical examination, including a pap smear. Only 1 patient had a grade I cervical lesion and the remaining women had no disease. The plasma lipid average linewidths were distributed normally. The values ranged from 20-48.5Hz with a mean of 33.4Hz + or - .5Hz. 26.9Hz represented the 10th percentile and 41Hz the 90th percentile. The only correlation between test results and clinical parameters was chronic intake of sex steroids (p=.03). A significant association between chronic intake of sex steroids and a decrease in plasma lipids proton NMR linewidths existed (p=.04). Specifically, the association was only significant with oral contraceptives (OCs) containing levonorgestrel or norethisterone (p=.02) which produce androgenic activity. Moreover those who used the higher dose estrogen OCs (50ug ethinyl estradiol) had lower results than the lower dose estrogen OCs or the controls (p=.06). In fact, the OCs with ethinyl estradiol combined to levonorgestrel or norethisterone narrowed plasma lipids linewidths on average 2.5Hz. Such Ocs increase very low density lipids (VLDL) and the low density level-cholesterol to high density level-cholesterol ratio. Continuous administration of sex steroid hormones to cancer patients also increases lipid metabolism and narrows the plasma methyl and methylene resonances. In conclusion, the Fossel test does detect abnormal distribution of plasma lipoproteins in cancer patients, particularly in the proportion of VLDL.