Postprocessing method to segregate and quantify the broad components underlying the phosphodiester spectral region of in vivo31P brain spectra

Stanley, Jeff; Pettegrew, Jay W.

doi:10.1002/1522-2594(200103)45:3<390::aid-mrm1051>3.0.co;2-d

Cited by 37 publications

(28 citation statements)

References 37 publications

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“…phospholipid metabolites and the less mobile molecules with PME and PDE moieties. 11 The less mobile molecules (broad-PDE) were increased in the HR-P subjects compared to comparison subjects. This observation is consistent with the increased broad-PDE observed in first-episode never-medicated subjects with schizophrenia 42 and in chronic medicated subjects.…”

Section: Discussionmentioning

confidence: 99%

“…Taking the total amplitude difference between the two DT fits resulted in the broad-PDE level. 11 In all cases, the metabolite levels were expressed as a percentage relative to the total amplitude of the short DT results. Expressing metabolite levels as a mole percent requires no correction for the amount of cerebral spinal fluid (CSF) within the sampled voxel.…”

Section: P Mrs Acquisitionmentioning

confidence: 99%

“…Under typical in vivo acquisition conditions, this broad signal comprises of molecules with PDE (and PME) moieties that are less mobile than the free-PDE and free-PME molecules and more mobile than the larger membrane phospholipid-containing bilayer structures. These molecules with 'intermediate' mobility (termed broad-PDE) may include synaptic/ transport vesicles and micelles, and to a lesser degree phosphorylated proteins, [11][12][13][14][15][16] and can also be reliably quantified.…”

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confidence: 99%

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Prefrontal membrane phospholipid metabolism of child and adolescent offspring at risk for schizophrenia or schizoaffective disorder: an in vivo 31P MRS study

et al. 2003

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In vivo31 P magnetic resonance spectroscopy ( 31 P MRS) studies have shown abnormal membrane phospholipid metabolism in the prefrontal cortex (PF) in the early course of schizophrenia. It is unclear, however, whether these alterations also represent premorbid risk indicators in schizophrenia. In this paper, we report in vivo 31 P MRS data on children and adolescents at high risk (HR) for schizophrenia. In vivo 31 P MRS studies of the PF were conducted on 16 nonpsychotic HR offspring of parents with schizophrenia or schizoaffective disorder, and 37 age-matched healthy comparison (HC) subjects. While 11 of the HR subjects had evidence of Axis I psychopathology (HR-P), five HR subjects had none (HR-NP). We quantified the freely mobile phosphomonoester (PME) and phosphodiester (PDE) levels reflecting membrane phospholipid precursors and breakdown products, respectively, and the relatively broad signal underlying PDE and PME peaks, comprised of less mobile molecules with PDE and PME moieties (eg, synaptic vesicles and phosphorylated proteins). Compared to HC subjects, HR subjects had reductions in freely mobile PME; the differences were accounted for mainly by the HR-P subjects. Additionally, HR-P subjects showed increases in the broad signal underlying the PME and PDE peaks in the PF. To conclude, these data demonstrate new evidence for decreased synthesis of membrane phospholipids and possibly altered content or the molecular environment of synaptic vesicles and/or phosphoproteins in the PF of young offspring at risk for schizophrenia. Follow-up studies are needed to examine the predictive value of these measures for future emergence of schizophrenia in at-risk individuals.

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Section: Discussionmentioning

confidence: 99%

Section: P Mrs Acquisitionmentioning

confidence: 99%

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confidence: 99%

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Prefrontal membrane phospholipid metabolism of child and adolescent offspring at risk for schizophrenia or schizoaffective disorder: an in vivo 31P MRS study

et al. 2003

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“…• Measurement of the background signal and subtraction in the time domain [6]. • Truncation of initial data points [22][23][24]. Because macromolecule and lipid signals decay rapidly in the time domain, the major part of the background signal is in the very first points of the signal.…”

Section: Background Separately Accommodatedmentioning

confidence: 99%

Time-domain quantitation of 1 H short echo-time signals: background accommodation

Ratiney

Coenradie

Cavassila

et al. 2004

MAGMA Magnetic Resonance Materials in Physics, Biology and Medi

153

167

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Quantitation of 1H short echo-time signals is often hampered by a background signal originating mainly from macromolecules and lipids. While the model function of the metabolite signal is known, that of the macromolecules is only partially known. We present time-domain semi-parametric estimation approaches based on the QUEST quantitation algorithm (QUantitation based on QUantum ESTimation) and encompassing Cramér-Rao bounds that handle the influence of 'nuisance' parameters related to the background. Three novel methods for background accommodation are presented. They are based on the fast decay of the background signal in the time domain. After automatic estimation, the background signal can be automatically (1) subtracted from the raw data, (2) included in the basis set as multiple components, or (3) included in the basis set as a single entity. The performances of these methods combined with QUEST are evaluated through extensive Monte Carlo studies. They are compared in terms of bias-variance trade-off. Because error bars on the amplitudes are of paramount importance for diagnostic reliability, Cramér-Rao bounds accounting for the uncertainty caused by the background are proposed. Quantitation with QUEST of in vivo short echo-time (1)H human brain with estimation of the background is demonstrated.

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“…S2). This leads to a complicated, multipeak 31 P MR spectrum (including a broad membrane peak and narrow metabolite peaks), which would ordinarily be a poor choice for high-resolution MRI (27). However, our quadratic echo pulse block (Fig.…”

Section: Resultsmentioning

confidence: 99%

Phosphorus-31 MRI of hard and soft solids using quadratic echo line-narrowing

Frey

Michaud

VanHouten

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Magnetic resonance imaging (MRI) of solids is rarely attempted. One of the main reasons is that the broader MR linewidths, compared to the narrow resonance of the hydrogen ( 1 H) in free water, limit both the attainable spatial resolution and the signal-to-noise ratio. Basic physics research, stimulated by the quest to build a quantum computer, gave rise to a unique MR pulse sequence that offers a solution to this long-standing problem. The "quadratic echo" significantly narrows the broad MR spectrum of solids. Applying field gradients in sync with this line-narrowing sequence offers a fresh approach to carry out MRI of hard and soft solids with high spatial resolution and with a wide range of potential uses. Here we demonstrate that this method can be used to carry out three-dimensional MRI of the phosphorus ( 31 P) in ex vivo bone and soft tissue samples.bone mineral | cell membranes M agnetic resonance imaging (MRI) has become an invaluable tool for clinical medicine, fundamental biomedical research, the physical sciences, and engineering (1). Typically, MRI detects only the signal from free water, using just a single nuclear isotope ( 1 H). Extending the reach of MRI to the study of other elements, and to hard or soft solids, opens new frontiers of discovery. One example is phosphorus ( 31 P), which is abundant in both bone mineral and cell membranes, so 31 P MRI of tissues is, in principle, possible. In practice, however, the slower motion of 31 P in those environments (compared to 1 H in water) results in much broader MR spectra (Fig. S1), limiting both the attainable spatial resolution and the signal-to-noise ratio (2). In this paper, we describe the use of a pulse sequence to narrow the 31 P MR spectrum of solids to that of a liquid (3), making high-resolution imaging possible. This line-narrowing MR sequence was discovered in the course of basic research (3-6) initiated by Kane's proposal (7) to build a quantum computer using phosphorus spins in silicon. Applying field gradients in synch with this sequence, we have obtained high-resolution 3D MR images of the 31 P in a variety of ex vivo animal bone samples. This is a unique probe of a key element in bone mineral, which complements existing assessments of bone quality. Using the same approach, we have obtained 3D MR images of 31 P in several ex vivo soft tissues.Bone is a composite material (8), containing approximately 45% bone mineral by volume (9). Bone mineral is similar to calcium hydroxyapatite (i.e., Ca 10 ðOHÞ 2 ðPO 4 Þ 6 Þ, but it is less crystalline, and it has a unique stoichiometry (10). The spatial distribution, composition, and quantity of bone mineral are primarily responsible for the compressive strength and stiffness of bone (8-10). While a few 31 P MRI studies have successfully targeted in vivo (10-12) and ex vivo (10, 13, 14, 15) bone, the broad MR spectra have limited the achievable spatial resolution to no better than 0.5 mm (15) and more typically in the range of 2 mm. There is currently a great need to probe the internal compositi...

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Postprocessing method to segregate and quantify the broad components underlying the phosphodiester spectral region of in vivo31P brain spectra

Cited by 37 publications

References 37 publications

Prefrontal membrane phospholipid metabolism of child and adolescent offspring at risk for schizophrenia or schizoaffective disorder: an in vivo 31P MRS study

Prefrontal membrane phospholipid metabolism of child and adolescent offspring at risk for schizophrenia or schizoaffective disorder: an in vivo 31P MRS study

Time-domain quantitation of 1 H short echo-time signals: background accommodation

Phosphorus-31 MRI of hard and soft solids using quadratic echo line-narrowing

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