Phosphorus‐31 magnetic resonance spectroscopy in humans by spectroscopic imaging: Localized spectroscopy and metabolite imaging

Abstract

In in vivo phosphorus magnetic resonance spectroscopy (MRS), spectroscopic imaging (SI) can be used as a flexible localization technique, producing spectra from multiple volumes in a single examination. Presented here are phosphorus SI studies of human organs in which a selective-volume SI reconstruction was used rather than the usual array-format SI reconstruction. A linear predictor technique was used to estimate the initial points of the free induction decay missing because of the delay needed for phase-encoding gradients, significantly reducing the baseline artifacts which commonly complicate interpretation of SI spectra. In studies of heart, brain, liver, and kidney, the performance of SI was found to compare favorably with that of ISIS. SI phosphorus metabolite intensity images from a brain tumor patient were obtained at 2 X 2-cm in-plane resolution (with "slice" thickness of roughly 16 cm, determined by coil sensitivity) in 34 min, demonstrating the feasibility of obtaining clinically useful metabolite images in clinically reasonable examination times.

Skeletal muscle energetics with PNMR: personal views and historic perspectives

“…In that study, a significant reduction in PCr/ATP, PCr and ATP in the myocardium of infarct was shown (155). Similar results have also been reported in type II diabetes mellitus (151). In another study, ischemia induction and arterial insufficiency resulting in reduction in bioenergetic reserve of the ischemic muscle region were shown using contrastenhanced MRI and 31 P MRS in rats (156).…”

“…This technology advancement has brought tremendous impact and potential, especially for human skeletal and cardiac muscle studies, and the results of these studies are promising. Several different localization techniques, such as depth-resolved spectroscopy (DRESS) (149), imageselected in vivo spectroscopy (ISIS) (150) and chemical shift imaging (CSI) (151,152), have been adapted and applied for better localization and signal sensitivity of the muscle of interest. Adaptation of such image-guided spatially localized 31 P MRS has allowed the examination of better defined regions of interest as well as heterogenic response of localized muscle activation within the same muscle group with better spatial and temporal resolution.…”

Theoretical Evaluation and Comparison of Fast Chemical Shift Imaging Methods

“…ematically similar to the acquisition of a signal in the presTo avoid excessive calculations, only for the first method ence of a read gradient, as described by Eq. [23]. Since are all terms in Eq.…”

NMR Studies of Bioenergetic Impairment in Human Epilepsy

“…Although spatial interpolation of the data set by zero filling can help to offset this problem, the resulting data sets become large (>1 GB for 1.5 mm spatial accuracy) resulting in significant data handling problems. To overcome this effect, the reconstruction grid can be arbitrarily shifted post-acquisition using the 3D anatomical images to calculate the necessary phase shifts to allow precise centering of the voxels of interest with 1.5 mm accuracy (64). Using the this method, the variation in gray and white matter content of the selected voxels was dramatically reduced, also reducing the measured variation in PCr/ATP, providing for greater accuracy in comparing specific anatomical locations between subjects and controls.…”