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Objective: Many patients with long COVID experience neurological and psychological symptoms. Signal abnormalities on MR images in the corpus callosum have been reported. Knowledge about the metabolic profile in the splenium of the corpus callosum (CCS) may contribute to a better understanding of the pathophysiology of long COVID. Materials and methods: Eighty-one subjects underwent proton MR spectroscopy examination. The metabolic concentrations of total N-acetylaspartate (NAA), choline-containing compounds (Cho), total creatine (Cr), myo-inositol (mI), and NAA/Cho in the CCS were statistically compared in the group of patients containing 58 subjects with positive IgG COVID-19 antibodies or positive SARS-CoV-2 qPCR test at least two months before the MR and the group of healthy controls containing 23 subjects with negative IgG antibodies. Results: An age-dependent effect of SARS-CoV-2 on Cho concentrations in the CCS has been observed. Considering the subjective threshold of age = 40 years, older patients showed significantly increased Cho concentrations in the CCS than older healthy controls (p = 0.02). NAA, Cr, and mI were unchanged. All metabolite concentrations in the CCS of younger post-COVID-19 patients remained unaffected by SARS-CoV-2. Cho did not show any difference between symptomatic and asymptomatic patients (p = 0.91). Discussion: Our results suggest that SARS-CoV-2 disproportionately increases Cho concentration in the CCS among older post-COVID-19 patients compared to younger ones. The observed changes in Cho may be related to the microstructural reorganization in the CCS also reported in diffusion measurements rather than increased membrane turnover. These changes do not seem to be related to neuropsychological problems of the post-COVID-19 patients. Further metabolic studies are recommended to confirm these observations. [ABSTRACT FROM AUTHOR]

Simple Summary: IDH mutation is one of the most important prognostic biomarkers in glioma management. Noninvasive neuroimaging techniques to predict IDH mutant glioma may be valuable for guiding clinical decision-making and monitoring response to targeted therapies. The aim of our prospective study was to investigate the clinical potential of proton MR spectroscopy (1H-MRS) with an optimized TE (97 ms) in identifying IDH-mutant gliomas by detecting characteristic resonances of 2HG and its complex interplay with other clinically relevant metabolites. We confirmed that the oncometabolite 2HG was found to be significant in predicting IDH-mutant gliomas, and both single-voxel and multi-voxel 1H-MRS methods are equally efficient in detecting complex resonances of 2HG. Additionally, Glx (glutamate + glutamine) and NAA (N-acetylaspartate) were also found to be important in distinguishing IDH-mutant from wild-type gliomas. In short, 1H-MRS with an optimized TE may be helpful for noninvasively detecting the abnormally high levels of 2HG with high accuracy and comprehending its interaction with other relevant metabolites in infiltrative gliomas. Purpose: The isocitrate dehydrogenase (IDH) mutation has become one of the most important prognostic biomarkers in glioma management, indicating better treatment response and prognosis. IDH mutations confer neomorphic activity leading to the conversion of alpha-ketoglutarate (α-KG) to 2-hydroxyglutarate (2HG). The purpose of this study was to investigate the clinical potential of proton MR spectroscopy (1H-MRS) in identifying IDH-mutant gliomas by detecting characteristic resonances of 2HG and its complex interplay with other clinically relevant metabolites. Materials and Methods: Thirty-two patients with suspected infiltrative glioma underwent a single-voxel (SVS, n = 17) and/or single-slice-multivoxel (1H-MRSI, n = 15) proton MR spectroscopy (1H-MRS) sequence with an optimized echo-time (97 ms) on 3T-MRI. Spectroscopy data were analyzed using the linear combination (LC) model. Cramér–Rao lower bound (CRLB) values of <40% were considered acceptable for detecting 2HG and <20% for other metabolites. Immunohistochemical analyses for determining IDH mutational status were subsequently performed from resected tumor specimens and findings were compared with the results from spectral data. Mann–Whitney and chi-squared tests were performed to ascertain differences in metabolite levels between IDH-mutant and IDH-wild-type gliomas. Receiver operating characteristic (ROC) curve analyses were also performed. Results: Data from eight cases were excluded due to poor spectral quality or non-tumor-related etiology, and final data analyses were performed from 24 cases. Of these cases, 9/12 (75%) were correctly identified as IDH-mutant or IDH-wildtype gliomas through SVS and 10/12 (83%) through 1H-MRSI with an overall concordance rate of 79% (19/24). The sensitivity, specificity, positive predictive value, and negative predictive value were 80%, 77%, 86%, and 70%, respectively. The metabolite 2HG was found to be significant in predicting IDH-mutant gliomas through the chi-squared test (p < 0.01). The IDH-mutant gliomas also had a significantly higher NAA/Cr ratio (1.20 ± 0.09 vs. 0.75 ± 0.12 p = 0.016) and lower Glx/Cr ratio (0.86 ± 0.078 vs. 1.88 ± 0.66; p = 0.029) than those with IDH wild-type gliomas. The areas under the ROC curves for NAA/Cr and Glx/Cr were 0.808 and 0.786, respectively. Conclusions: Noninvasive optimized 1H-MRS may be useful in predicting IDH mutational status and 2HG may serve as a valuable diagnostic and prognostic biomarker in patients with gliomas [ABSTRACT FROM AUTHOR]

Objective: Many patients with long COVID experience neurological and psychological symptoms. Signal abnormalities on MR images in the corpus callosum have been reported. Knowledge about the metabolic profile in the splenium of the corpus callosum (CCS) may contribute to a better understanding of the pathophysiology of long COVID., Materials and Methods: Eighty-one subjects underwent proton MR spectroscopy examination. The metabolic concentrations of total N-acetylaspartate (NAA), choline-containing compounds (Cho), total creatine (Cr), myo-inositol (mI), and NAA/Cho in the CCS were statistically compared in the group of patients containing 58 subjects with positive IgG COVID-19 antibodies or positive SARS-CoV-2 qPCR test at least two months before the MR and the group of healthy controls containing 23 subjects with negative IgG antibodies., Results: An age-dependent effect of SARS-CoV-2 on Cho concentrations in the CCS has been observed. Considering the subjective threshold of age = 40 years, older patients showed significantly increased Cho concentrations in the CCS than older healthy controls (p = 0.02). NAA, Cr, and mI were unchanged. All metabolite concentrations in the CCS of younger post-COVID-19 patients remained unaffected by SARS-CoV-2. Cho did not show any difference between symptomatic and asymptomatic patients (p = 0.91)., Discussion: Our results suggest that SARS-CoV-2 disproportionately increases Cho concentration in the CCS among older post-COVID-19 patients compared to younger ones. The observed changes in Cho may be related to the microstructural reorganization in the CCS also reported in diffusion measurements rather than increased membrane turnover. These changes do not seem to be related to neuropsychological problems of the post-COVID-19 patients. Further metabolic studies are recommended to confirm these observations., (© 2024. The Author(s).)

Because retinitis pigmentosa (RP) has been shown to cause degenerative changes in the entire visual pathway, there is an urgent need to perform longitudinal assessments of RP‐induced degeneration and identify imaging protocols to detect this degeneration as early as possible. In this study, we assessed a transgenic rat model of RP by using complementary noninvasive magnetic resonance imaging techniques, namely, proton magnetic resonance spectroscopy (1H‐MRS), to investigate the metabolic changes in RP. Our study demonstrated decreased concentrations and ratios to creatine (Cr) of N‐acetylaspartate (NAA), glutamate (Glu), γ‐aminobutyric acid (GABA), and taurine (Tau), whereas myo‐inositol (Ins) and choline (Cho) were increased in the visual cortex of Royal College of Surgeons (RCS) rats compared with control rats (p < 0.05). Furthermore, with the progression of RP, the concentrations of NAA, Glu, GABA, and Tau, and the ratios of GABA/Cr and Tau/Cr significantly decreased over time, whereas the concentrations of Ins and Cho and the ratio of Ins/Cr significantly increased over time (p < 0.05). In addition, in RCS rats, NAA/Cr decreased significantly from 3 to 4 months postnatal (p < 0.001), and Cho/Cr increased significantly from 4 to 5 months postnatal (p = 0.005). Meanwhile, the 1H‐MRS indicators in 5‐month postnatal RCS rats could be confirmed by immunohistochemical staining. In conclusion, with the progression of RP, the metabolic alterations in the visual cortex indicated progressive reprogramming with the decrease of neurons and axons, accompanied by the proliferation of gliocytes. [ABSTRACT FROM AUTHOR]

Pseudoprogression (PsP) refers to treatment‐related clinico‐radiologic changes mimicking true progression (TP) that occurs in patients with glioblastoma (GBM), predominantly within the first 6 months after the completion of surgery and concurrent chemoradiation therapy (CCRT) with temozolomide. Accurate differentiation of TP from PsP is essential for making informed decisions on appropriate therapeutic intervention as well as for prognostication of these patients. Conventional neuroimaging findings are often equivocal in distinguishing between TP and PsP and present a considerable diagnostic dilemma to oncologists and radiologists. These challenges have emphasized the need for developing alternative imaging techniques that may aid in the accurate diagnosis of TP and PsP. In this review, we encapsulate the current state of knowledge in the clinical applications of commonly used metabolic and physiologic magnetic resonance (MR) imaging techniques such as diffusion and perfusion imaging and proton spectroscopy in distinguishing TP from PsP. We also showcase the potential of promising imaging techniques, such as amide proton transfer and amino acid‐based positron emission tomography, in providing useful information about the treatment response. Additionally, we highlight the role of "radiomics", which is an emerging field of radiology that has the potential to change the way in which advanced MR techniques are utilized in assessing treatment response in GBM patients. Finally, we present our institutional experiences and discuss future perspectives on the role of multiparametric MR imaging in identifying PsP in GBM patients treated with "standard‐of‐care" CCRT as well as novel/targeted therapies. [ABSTRACT FROM AUTHOR]

Nanotechnology-based photothermal therapy (NPTT) is a new emerging modality of cancer therapy. To have the right prediction and early detection of response to NPTT, it is necessary to get rapid feedback from a tumor treated by NPTT procedure and stay informed of what happens in the tumor site. We performed this study to find if proton magnetic resonance spectroscopy (1H-MRS) can be well responsive to such an imperative requirement. We considered various treatment groups including gold nanoparticles (AuNPs), laser, and the combination of AuNPs and laser (NPTT group). Therapeutic effects on CT26 colon tumor-bearing BALB/c mice were studied by looking at alterations that happened in 1H-MRS signals and tumor size after conducting treatment procedures. In MRS studies, the alterations of choline and lipid concentrations and their ratio were investigated. Having normalized the metabolite peak to water peak, we found a significant decrease in choline concentration post-NPTT (from (1.25 ± 0.05) × 10−3 to (0.43 ± 0.04) × 10−3), while the level of lipid concentration in the tumor was slightly increased (from (2.91 ± 0.23) × 10−3 to (3.52 ± 0.31) × 10−3). As a result, the choline/lipid ratio was significantly decreased post-NPTT (from 0.41 ± 0.11 to 0.11 ± 0.02). Such alterations appeared just 1 day after NPTT. Tumor shrinkage in all groups was studied and significant changes were significantly detectable on day 7 post-NPTT procedure. In conclusion, the study of choline/lipid ratio using 1H-MRS may help us estimate what happens in a tumor treated by the NPTT method. Such an in vivo assessment is interestingly feasible as soon as just 1 day post-NPTT. This would undoubtedly help the oncologists make a more precise decision about treatment planning strategies. [ABSTRACT FROM AUTHOR]

Neurocysticercosis (NCC) is a parasitic infection caused by Cysticercus cellulosae, the metacestode of pork tapeworm (Taenia solium). NCC is one of the most common public health problems worldwide. We present a patient harboring a bilobed ring-enhancing lesion with a presumed diagnosis of brain metastasis, who returned to the USA after traveling to an endemic region. The diagnosis of NCC was established based on a characteristic resonance of succinate on proton magnetic resonance spectroscopy. Also, higher mean diffusivity and lower fractional anisotropy along with relative cerebral blood volume were observed from the lesion compared to contralateral normal brain regions. Multiparametric analysis may improve the differential diagnosis of ring-enhancing intracranial lesions such as NCC. [ABSTRACT FROM AUTHOR]

• MELAS patients exhibited metabolite abnormalities in acute SLLs. • Lactate level in acute SLLs was positively correlated with focal rCBF in MELAS patients. • Combination of 1H-MRS and ASL can help to reveal the pathogenesis of acute SLEs. Our purpose is to detect the metabolic alterations in acute stroke-like lesions (SLLs) and further investigate the correlations between metabolic concentrations and focal cerebral blood flow in patients with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) using proton MR spectroscopy (1H-MRS) and arterial spin labeling (ASL). A total of 23 patients with MELAS at acute stage of stroke-like episodes (SLEs) and 20 normal controls (NC) were recruited in this study, respectively. All subjects underwent conventional MRI and1H-MRS. In addition, ASL was performed in each patient. The measurements of creatine (Cr), choline (Cho), N-acetyl aspartate (NAA), lactate (Lac), glutamine/glutamate (Glx) levels and the ratios of Cho/Cr, NAA/Cr, Lac/Cr and Glx/Cr in acute SLLs for MELAS patients and left parietal and occipital lobes for NC were measured using LC-model software. Furthermore, in MELAS group, the associations between relative cerebral blood flow (rCBF) and metabolite concentrations in acute SLLs were also assessed. In MELAS group, acute SLLs were identified with metabolic abnormalities and increased rCBF. Specifically, compared with controls, MELAS patients exhibited significantly higher Lac, Cho levels and Lac/Cr, Cho/Cr ratios, and lower NAA, Glx levels and NAA/Cr and Glx/Cr ratios. Moreover, for MELAS patients, Lac concentration in acute SLLs was positively correlated with focal rCBF. This study exhibited the neural injury with increasing lactate and cerebral blood flow in the acute SLEs. It might shed light on the underlying biochemical mechanism of mitochondrial cytopathy and angiopathy in MELAS. [ABSTRACT FROM AUTHOR]

Abstract Background The aim of our study was to determine the value of single-voxel proton MR spectroscopy (1HMRS) in distinguishing benign from malignant focal bone lesions in the peripheral skeleton. MRI and 1HMRS was performed in 50 focal lesions (> 1 cm size) detected on radiographs of peripheral skeleton.1HMRS was performed at 1.5 T with TE of 144 ms with automatic shimming and water suppression. Qualitative analysis for a discrete choline peak at 3.2 ppm was done. Significance of the presence of choline peak on 1HMRS in distinguishing benign from malignant lesions was calculated using histopathology as a gold standard. Chi-square test was used and p value

To investigate normal quantitative proton magnetic resonance spectroscopy (MRS) features of the cisternal segment of the trigeminal nerve and evaluate possible metabolite concentration differences in the affected and unaffected nerves of trigeminal neuralgia patients. A total of 33 consecutive patients who underwent a MR study of the internal auditory canal/posterior fossa and dedicated trigeminal nerve multivoxel MRS were enrolled. Measurements of N -acetyl aspartate (NAA), creatine (Cr), choline (Cho), myoinositol (mI), glutamate-glutamine (Glx) concentrations, and ratios of NAA-to-Cr, Cho-to-Cr, and Cho-to-NAA were automatically calculated by the dedicated software. Vascular conflicts were also recorded. The mean Cr concentration was significantly higher on the affected sides in all parts of the nerve (p < 0.05), while the mean NAA concentration was significantly higher in only the distal portion (p = 0.04). Mean mI concentration was significantly higher in the middle and distal parts (p < 0.05). NAA-to-Cr ratio was significantly higher in the proximal and middle parts (p < 0.05), while Cho-to-Cr ratio was significantly higher only in the middle portion (p = 0.028). Finally, the Cho-to-NAA ratio was significantly higher only in the distal portion (p = 0.04). Vascular conflicts were observed in 24 patients (72.7%), and in 20 of them (60.6%) the conflict was on the same side as the neuralgia symptoms. Although the detected statistical relationships were variable in the spectroscopic measurements, metabolite concentrations and ratios were successfully exhibited in all patients. Features of a normal trigeminal nerve were able to determine by MRS. All calculated metabolite concentrations were higher in the affected nerves; however, only some of them were statistically significant. No statistically significant relationships were found between the MRS measurements and nerves with and without vascular compression. • High-quality MR spectroscopy images can be obtained from trigeminal nerve by using a dedicated software at 3.0 Tesla system. • Automatically calculated concentrations were higher in the affected nerves; but, only some showed statistical significance. • The calculated metabolite ratios were variable in the affected and unaffected trigeminal nerves. • No significant difference was found regarding MR spectroscopic measurements in nerves with and without vascular compression. [ABSTRACT FROM AUTHOR]

Background: Areal bone mineral density (BMD) of the lumbar spine by DXA is greater in Black compared to White adolescents. Bone strength is determined not only by BMD but also its microenvironment, and marrow adipose tissue (MAT) has been shown to be an important determinant of skeletal integrity, independent of BMD. Racial differences in volumetric BMD (vBMD) and MAT in adolescents and young adults with obesity are unknown. Objective: To assess racial differences in lumbar vBMD and MAT in Black and White adolescents and young adults with obesity and to assess body composition determinants of bone parameters. We hypothesized that Blacks will have higher vBMD and lower MAT of the lumbar spine compared to Whites. Methods: The study group comprised 77 adolescents/young adults, 25 Black and 52 White, (mean age 18.2 ± 2.5 years, range 13 to 24 years) with moderate to severe obesity (mean body mass index (BMI) 46.2 ± 7.3 kg/m2, range 35.5 to 69.7 kg/m2). Groups were similar in age, BMI, and sex distribution (p > 0.84). Subjects underwent QCT of the lumbar spine (L1−L2) for assessment of vBMD with the use of a calibration phantom and 1H-MRS/MRI for quantification of lumbar MAT content (L1-L2) and abdominal fat and thigh muscle mass. Groups were compared by Student's t-test or Wilcoxon test. Correlation analysis was performed to assess associations between bone parameters and body composition. Results: Black adolescents/young adults with obesity had higher vBMD compared to Whites (p 0.1). Conclusion: There are racial differences in lumbar vBMD in adolescents and young adults with moderate to severe obesity, with Blacks having higher vBMD than Whites, while there were no differences in MAT content. The known inverse association between BMD and MAT was only observed in Whites but not in Blacks, suggesting possible racial differences in stem cell differentiation into the bone and fat lineages.

Purpose: To develop localization sequences for in vivo MR spectroscopy (MRS) on clinical scanners of 3 T to record spectra that are not influenced by magnetization transfer from water. Methods: Image‐selected in vivo spectroscopy (ISIS) localization and chemical‐shift‐selective excitation (termed I‐CSE) was combined in two ways: first, full ISIS localization plus a frequency‐selective spin‐echo and second, two‐dimensional (2D) ISIS plus a frequency‐selective excitation and slice‐selective refocusing. The techniques were evaluated at 3 T in phantoms and human subjects in comparison to standard techniques with water presaturation or metabolite‐cycling. ISIS included gradient‐modulated offset‐independent adiabatic (GOIA)‐type adiabatic inversion pulses; echo times were 8‐10 ms. Results: The novel 2D and 3D I‐CSE methods yield upfield spectra that are comparable to those from standard MRS, except for shorter echo times and a limited frequency range. On the downfield/high‐frequency side, they yield much more signal for exchangeable protons when compared to MRS with water presaturation or metabolite‐cycling and longer echo times. Conclusion: Novel non‐water‐excitation MRS sequences offer substantial benefits for the detection of metabolite signals that are otherwise suppressed by saturation transfer from water. Avoiding water saturation and using very short echo times allows direct observation of faster exchanging moieties than was previously possible at 3 T and additionally makes the methods less susceptible to fast T2 relaxation. [ABSTRACT FROM AUTHOR]

Context: Sleeve gastrectomy (SG), the most common metabolic and bariatric surgery in adolescents, is associated with bone loss. Marrow adipose tissue (MAT) is a dynamic endocrine organ that responds to changes in nutrition and might serve as a novel biomarker for bone health. Two types of MAT have been described, which differ in anatomic location-proximal regulated MAT vs distal constitutive MAT.Objective: To determine the effects of SG on volumetric bone mineral density (vBMD) and MAT in adolescents with obesity. We hypothesized that SG would lead to a decrease in vBMD and differential changes in MAT.Design: 12-month prospective study in 52 adolescents with moderate-to-severe obesity (38 female; mean age:17.5 ± 2.2 years; mean BMI 45.2 ± 7.0 kg/m2), comprising 26 subjects before and after SG and 26 nonsurgical controls.Main Outcome Measures: Lumbar vBMD by quantitative computed tomography; MAT of the lumbar spine, femur and tibia by proton magnetic resonance spectroscopy; abdominal fat and thigh muscle by magnetic resonance imaging.Results: Adolescents lost 34.1 ± 13.1 kg after SG vs 0.3 ± 8.4 kg in the control group (P < 0.001). Lumbar vBMD decreased in the SG group (P = 0.04) and this change was associated with a reduction in weight and muscle area (P < 0.05) and an increase in lumbar MAT (P = 0.0002). MAT of the femur and tibia decreased after SG vs controls (P < 0.05); however, the differences were no longer significant after controlling for change in weight.Conclusion: SG in adolescents decreased lumbar vBMD associated with an increase in lumbar MAT and decrease in extremity MAT. This demonstrates differential changes of regulated MAT in the lumbar spine and constitutive MAT in the distal skeleton in adolescents in response to SG. [ABSTRACT FROM AUTHOR]

Glioblastoma is the most common and most malignant primary brain tumor. Despite aggressive multimodal treatment, its prognosis remains poor. Even with continuous developments in MRI, which has provided us with newer insights into the diagnosis and understanding of tumor biology, response assessment in the posttherapy setting remains challenging. We believe that the integration of additional information from advanced neuroimaging techniques can further improve the diagnostic accuracy of conventional MRI. In this article, we review the utility of advanced neuroimaging techniques such as diffusion-weighted imaging, diffusion tensor imaging, perfusion-weighted imaging, proton magnetic resonance spectroscopy, and chemical exchange saturation transfer in characterizing and evaluating treatment response in patients with glioblastoma. We will also discuss the existing challenges and limitations of using these techniques in clinical settings and possible solutions to avoiding pitfalls in study design, data acquisition, and analysis for future studies. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY STAGE: 3 J. Magn. Reson. Imaging 2020;52:978-997. [ABSTRACT FROM AUTHOR]

Proton magnetic resonance spectroscopy (MRS) is a promising noninvasive diagnostic technique for investigation of breast cancer metabolism. Spectroscopic imaging data may be obtained following contrast-enhanced MRI by applying the point-resolved spectroscopy sequence (PRESS) or the stimulated echo acquisition mode (STEAM) sequence from the MR voxel encompassing the breast lesion. Total choline signal (tCho) measured in vivo using either a qualitative or quantitative approach has been used as a diagnostic test in the workup of malignant breast lesions. In addition to tCho metabolites, other relevant metabolites, including multiple lipids, can be detected and monitored. MRS has been heavily investigated as an adjunct to morphologic and dynamic MRI to improve diagnostic accuracy in breast cancer, obviating unnecessary benign biopsies. Besides its use in the staging of breast cancer, other promising applications have been recently investigated, including the assessment of treatment response and therapy monitoring. This review provides guidance on spectroscopic acquisition and quantification methods and highlights current and evolving clinical applications of proton MRS. Level of Evidence 5 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2019. [ABSTRACT FROM AUTHOR]

Background Meningeal melanoma is a rare tumor of the central nervous system, whose amelanotic variant is called "amelanotic meningeal melanoma" (AMM). AMM does not produce melanin and therefore does not exhibit typical short T1 and short T2 signal on magnetic resonance imaging and thus can be easily misdiagnosed and be inappropriately managed. To date, only 4 AMM cases have been reported in the English literature. Here, we report the fifth case. Case Description A 26-year-old female patient presented with a 4-month history of progressive headache and nausea, the conventional magnetic resonance imaging demonstrated a posterior fossa mass accompanied by diffuse leptomeningeal dissemination. Repeated cerebrospinal fluid cytology screening showed negative results. The functional magnetic resonance examinations, including diffusion-weighted imaging, proton magnetic resonance spectroscopy, and dynamic susceptibility contrast perfusion-weighted imaging, provided complementary information. The final diagnosis of AMM was made by immunohistochemistry. Despite gross total excision of the tumor, the disease progressed, and the patient died 10 months after diagnosis. Conclusions Our experience with this case demonstrated that meningeal melanoma should be included in the differential diagnosis when an intracranial mass is accompanied by leptomeningeal dissemination, and especially when proton magnetic resonance spectroscopy and dynamic susceptibility contrast perfusion-weighted imaging indicate a malignant tumor whereas diffusion-weighted imaging does not. And the loss of a typical melanin signal should not server as an excluding criterion for meningeal melanoma. [ABSTRACT FROM AUTHOR]

Abstract Bone strength is affected not only by bone mineral density (BMD) and bone microarchitecture but also its microenvironment. Recent studies have focused on the role of marrow adipose tissue (MAT) in the pathogenesis of bone loss. Osteoblasts and adipocytes arise from a common mesenchymal stem cell within bone marrow and many osteoporotic states, including aging, medication use, immobility, over – and undernutrition are associated with increased marrow adiposity. Advancements in imaging technology allow the non-invasive quantification of MAT. This article will review magnetic resonance imaging (MRI)- and computed tomography (CT)-based imaging technologies to assess the amount and composition of MAT. The techniques that will be discussed are anatomic T1-weighted MRI, water-fat imaging, proton MR spectroscopy, single energy CT and dual energy CT. Clinical applications of MRI and CT techniques to determine the role of MAT in patients with obesity, anorexia nervosa, and type 2 diabetes will be reviewed. Highlights • Marrow adipose tissue can be assessed non-invasively using MRI- and CT-based imaging technologies. • Proton MR spectroscopy can determine the quantity and composition of marrow adipose tissue. • Water-fat imaging allows marrow adipose tissue assessment of different skeletal regions in a single examination. • Dual-energy CT can assess both bone mineral density and marrow adipose tissue in the same examination. [ABSTRACT FROM AUTHOR]

Abstract Marrow adipose tissue (MAT) in humans is distributed differentially across age and skeletal site. We have shown impaired microarchitecture and reduced bone strength at appendicular sites in conditions associated with high MAT of the axial skeleton in adults (including conditions of over- and undernutrition). Data are lacking regarding differences in MAT content of the appendicular versus the axial skeleton, and its relationship with bone microarchitecture and strength. Furthermore, data are conspicuously lacking in adolescents, a time when hematopoietic marrow is progressively converted to fatty marrow. The purpose of our study was to examine differential associations between appendicular (distal tibia) and axial (lumbar spine) MAT and bone microarchitecture and strength estimates of the distal tibia in adolescents with obesity. We hypothesized that compared to MAT of the axial skeleton (lumbar spine), MAT of the appendicular skeleton (distal tibia) would show stronger associations with bone microarchitecture and strength estimates of the appendicular skeleton (distal tibia). We evaluated 32 adolescents and young adults (27 females) with obesity; with a mean age of 17.8 ± 2.1 years and median body mass index (BMI) of 41.34 kg/m2, who underwent dual energy X-ray absorptiometry (DXA) for total fat mass, proton MR spectroscopy (1H-MRS) of the distal tibia and 4th lumbar vertebra for MAT, high resolution peripheral quantitative computed tomography (HR-pQCT) of the distal tibia for volumetric bone mineral density (vBMD) and microarchitecture, and micro finite element analysis (FEA) for distal tibial strength estimates. Linear correlations between bone parameters and MAT were determined using the Spearman or Pearson methods, depending on data distribution. Lumbar spine MAT was inversely associated with age (r = −0.36; p = 0.037). Total and trabecular vBMD and trabecular number at the distal tibia were inversely associated with MAT at the distal tibia (r = −0.39, p = 0.025; r = −0.51, p = 0.003; r = −0.42, p = 0.015 respectively) but not with lumbar spine MAT (r = −0.19, p = 0.27; r = −0.18, p = 0.3; r = 0.005, p = 0.97 respectively). In adolescents and young adults with obesity, the associations between MAT and appendicular bone parameters differ depending on the site of MAT assessment i.e. axial vs. appendicular. Studies evaluating these endpoints in adolescents and young adults with obesity should take the site of MAT assessment into consideration. Highlights • Marrow Adipose Tissue (MAT) content varies by age and skeletal site. • Associations differ between axial vs appendicular MAT and appendicular bone parameters. • BMD and microarchitecture at distal tibia have stronger associations with MAT content at distal tibia than lumbar spine MAT. [ABSTRACT FROM AUTHOR]

Abstract: Vascular cognitive impairment and dementia (VCID) is a major public health concern because of the increased incidence of vascular disease in the aging population and the impact of vascular disease on Alzheimer's disease. VCID is a heterogeneous group of diseases for which there are no proven treatments. Biomarkers can be used to select more homogeneous populations. Small vessel disease is the most prevalent form of VCID and is the optimal form for treatment trials because there is a progressive course with characteristic pathological changes. Subcortical ischemic vascular disease of the Binswanger type (SIVD‐BD) has a characteristic set of features that can be used both to identify patients and to follow treatment. SIVD‐BD patients have clinical, neuropsychological, cerebrospinal fluid (CSF) and imaging features that can be used as biomarkers. No one feature is diagnostic, but a multimodal approach defines the SIVD‐BD spectrum disorder. The most important features are large white matter lesions with axonal damage, blood–brain barrier disruption as shown by magnetic resonance imaging and CSF, and neuropsychological evidence of executive dysfunction. We have used these features to create a Binswanger Disease Scale and a probability of SIVD‐BD, using a machine‐learning algorithm. The patients discussed in this review are derived from published studies. Biomarkers not only aid in early diagnosis before the disease process has progressed too far for treatment, but also can indicate response to treatment. Refining the use of biomarkers will allow dementia treatment to enter the era of precision medicine. This article is part of the Special Issue “Vascular Dementia”. [ABSTRACT FROM AUTHOR]

Choline and lipid lactate peaks elevated in a number of intracranial space occupying lesions, in endemic area tuberculosis should be considered. Choline peak along with lipid lactate elevation is non-specific and can be seen in a number of other conditions like high-grade gliomas, Metastases, lymphomas and demyelinating disorders. We present a case of 45 year old gentle man known case chest tuberculosis on treatment default presenting with multiple intracranial lesions showing lipid–choline elevation.

Objectives: The goal of our study was to assess diffusion-weighted (DW) imaging and proton magnetic resonance (MR) spectroscopy findings in osteosarcoma versus normal muscle at 3 Tesla (3 T) MR system. Patients and Methods: Nineteen patients highly suspicious for osteosarcoma and 12 normal young healthy adults were enrolled in this study. Two patients were excluded from the study due to incompatible histopathologic results. DW imaging and multivoxel proton MR spectroscopy at 3 T were performed for all participants. Surgical biopsy and histopathological examination were done for every patient after imaging. SPSS 20 was used for statistical analysis. Results: The minimum apparent diffusion coefficient (ADC) value of osteosarcoma (0.88 ± 0.28) in this study confirms the significant restriction of this tumor against the dark background of normal muscle in high b-value images. Fourteen (82%) of the available 17 patients had ADC values ≤ 1 x 10-3 mm²/s. The maximum choline/creatine (Cho/Cr) ratio of osteosarcoma (1.94 ± 1.12) was statistically higher than the normal muscle (1.34 ± 0.11). Receiver operating curve (ROC) analysis (the area under the curve = 0.7) indicated a maximum Cho/Cr ratio of 1.37 as the cut point between the normal muscle and osteosarcoma, with a sensitivity, specificity and accuracy of 58.8%, 83.3%, and 69%, respectively. All patients with Cho/Cr ratios more than the cut point had ADC values ≤ 1 x 10-3 mm²/s and all patients with ADC values higher than 1 x 10-3 mm²/s had Cho/Cr ratios ≤ 1.37. Conclusion: It was concluded that DW imaging and proton MR spectroscopy are two effective noninvasive techniques in the evaluation of osteosarcoma. [ABSTRACT FROM AUTHOR]

The study was aimed to the analysis of correlations between anatomic brain parameters and characteristics of neurophysiological and metabolic supportive mechanisms of cognitive functions in the patients with ultra-high risk of schizophrenia. The study comprised 30 young male patients and 30 age- and sexmatched mentally healthy subjects. We used the methods of diffusion-weighted tomography, single voxel proton MR spectroscopy, and oddball ERP recording. The statistically significant intergroup differences in the structural connectivity were confirmed in the anterior thalamic radiation of the left hemisphere. The diffusion abnormalities in this area were correlated with P300 latencies and the level of γ-aminobutyric acid (GABA). [ABSTRACT FROM AUTHOR]

Purpose To characterize the downfield spectrum at 5-10 ppm in the human brain at a high magnetic field of 7 T. Knowledge of relaxation parameters is of interest for spectroscopy as well as chemical exchange-dependent saturation transfer experiments. Methods Water-suppressed spectra were recorded as echo time and inversion time series in healthy volunteers to investigate T2 and T1 values of downfield peaks in gray matter at 7T. The spectra were fitted in a two-dimensional fashion to a heuristic model of a series of Voigt lines, and the relaxation times were obtained for 12 peaks of interest. Results The mean T2 values averaged over the volunteers ranged from 24 to 158 ms, whereas the mean T1 values ranged from 0.22 to 2.40 s. Spectra of specific inversion and echo times revealed superposition of the amide peaks of N-acetylaspartate with short T2 and an inhomogeneously broadened component with longer T2. Conclusions T2 values were shorter than expected for most peaks, whereas T1 values had a very wide range; shorter relaxation times for some peaks suggests the presence of macromolecules. Most of the larger peaks seemed to be composed of overlapping components, because the Gaussian widths in the Voigt line shape descriptions were larger than expected based on field inhomogeneities. Magn Reson Med 78:11-19, 2016. © 2017 International Society for Magnetic Resonance in Medicine [ABSTRACT FROM AUTHOR]

Obesity and its possible association with diseases including diabetes and cardiovascular diseases have been studied for decades for its impact on healthcare. Recent studies clearly indicate the need for developing accurate and reproducible methodologies for assessing body fat content and distribution. Body fat distribution plays a significant role in developing an insight in the underlying mechanisms in which adipose tissue is linked with various diseases. Among imaging technologies including computerized axial tomography (CAT or CT), magnetic resonance imaging (MRI), and magnetic resonance spectroscopy (MRS), MRI and MRS seem to be the best emerging techniques and together are being considered as the gold standard for body fat content and distribution. This paper reviews studies up to the present time involving different methodologies of these two emerging technologies and presents the basic concepts of MRI and MRS with required novel image analysis techniques in accurate, quantitative, and direct assessment of body fat content and distribution. This article is part of a Special Issue entitled: Oxidative Stress and Mitochondrial Quality in Diabetes/Obesity and Critical Illness Spectrum of Diseases — edited by P. Hemachandra Reddy. [ABSTRACT FROM AUTHOR]

Bariatric surgery is associated with bone loss but skeletal consequences may differ between Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG), the two most commonly performed bariatric procedures. Furthermore, severe weight loss is associated with high marrow adipose tissue (MAT); however, MAT is also increased in visceral adiposity. The purpose of our study was to determine the effects of RYGB and SG on BMD and MAT. We hypothesized that both bariatric procedures would lead to a decrease in BMD and MAT. We studied 21 adults with morbid obesity (mean BMI 44.1 ± 5.1 kg/m 2 ) prior to and 12 months after RYGB ( n = 11) and SG ( n = 10). All subjects underwent DXA and QCT of the lumbar spine and hip to assess aBMD and vBMD. Visceral (VAT) and subcutaneous (SAT) adipose tissue was quantified at L1–L2. MAT of the lumbar spine and femur was assessed by 1H-MR spectroscopy. Calcitropic hormones and bone turnover markers were determined. At 12 months after surgery, mean weight and abdominal fat loss was similar between the RYGB and SG groups. Mean serum calcium, 25(OH)-vitamin D, and PTH levels were unchanged after surgery and within the normal range in both groups. Bone turnover markers P1NP and CTX increased within both groups and P1NP increased to a greater extent in the RYGB group ( p = 0.03). There were significant declines from baseline in spine aBMD and vBMD within the RYGB and SG groups, although the changes were not significantly different between groups ( p = 0.3). Total hip and femoral neck aBMD by DXA decreased to a greater extent in the RYGB than the SG group ( p < 0.04) although the change in femoral vBMD by QCT was not significantly different between groups ( p > 0.2). MAT content of the lumbar spine and femoral diaphysis did not change from baseline in the RYGB group but increased after SG ( p = 0.03). Within the SG group, 12-month change in weight and VAT were positively associated with 12-month change in MAT ( p < 0.04), suggesting that subjects with less weight and VAT loss had higher MAT. In conclusion, RYGB and SG are associated with declines in lumbar spine BMD, however, the changes are not significantly different between the groups. RYGB may be associated with greater decline of aBMD at the total hip and femoral neck compared to SG. MAT content increased after SG and this was associated with lower weight and VAT loss. [ABSTRACT FROM AUTHOR]

Background and purpose To assess the sensitivity of non-localized, whole-head 1 H-MRS to an individual's serial changes in total-brain NAA, Glx, Cr and Cho concentrations — metabolite metrics often used as surrogate markers in neurological pathologies. Materials and methods In this prospective study, four back-to-back (single imaging session) and three serial (successive sessions) non-localizing, ~3 min 1 H-MRS ( TE / TR / TI = 5/10 4 /940 ms) scans were performed on 18 healthy young volunteers: 9 women, 9 men: 29.9 ± 7.6 [mean ± standard deviation (SD)] years old. These were analyzed by calculating a within-subject coefficient of variation (CV = SD/mean) to assess intra - and inter -scan repeatability and prediction intervals. This study was Health Insurance Portability and Accountability Act compliant. All subjects gave institutional review board-approved written, informed consent. Results The intra -scan CVs for the NAA, Glx, Cr and Cho were: 3.9 ± 1.8%, 7.3 ± 4.6%, 4.0 ± 3.4% and 2.5 ± 1.6%, and the corresponding inter -scan (longitudinal) values were: 7.0 ± 3.1%, 10.6 ± 5.6%, 7.6 ± 3.5% and 7.0 ± 3.9%. This method is shown to have 80% power to detect changes of 14%, 27%, 26% and 19% between two serial measurements in a given individual. Conclusions Subject to the assumption that in neurological disorders NAA, Glx, Cr and Cho changes represent brain-only pathology and not muscles, bone marrow, adipose tissue or epithelial cells, this approach enables us to quantify them, thereby adding specificity to the assessment of the total disease load. This will facilitate monitoring diffuse pathologies with faster measurement, more extensive (~90% of the brain) spatial coverage and sensitivity than localized 1 H-MRS. [ABSTRACT FROM AUTHOR]

Introduction: We examined the effect of maturation on the regional distribution of brain metabolite concentrations using multivoxel chemical shift imaging. Methods: From our pool of pediatric MRI examinations, we retrospectively selected patients showing a normal cerebral MRI scan or no pathologic signal abnormalities at the level of the two-dimensional 1H MRS-CSI sequence and an age-appropriate global neurological development, except for focal neurological deficits. Seventy-one patients (4.5 months-20 years) were identified. Using LC Model, spectra were evaluated from voxels in the white matter, caudate head, and corpus callosum. Results: The concentration of total N-acetylaspartate increased in all regions during infancy and childhood except in the right caudate head where it remained constant. The concentration of total creatine decreased in the caudate nucleus and splenium and minimally in the frontal white matter and genu. It remained largely constant in the parietal white matter. The concentration of choline-containing compounds had the tendency to decrease in all regions except in the parietal white matter where it remained constant. The concentration of myoinositol decreased slightly in the splenium and right frontal white matter, remained constant on the left side and in the caudate nucleus, and rose slightly in the parietal white matter and genu. Conclusion: CSI determined metabolite concentrations in multiple cerebral regions during routine MRI. The obtained data will be helpful in future pediatric CSI measurements deciding whether the ratios of the main metabolites are within the range of normal values or have to be considered as probably pathologic. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Leukoaraiosis (LA), is a radiological finding with bilateral, either patchy or diffuse areas of the cerebral white matter.We aimed to determine proton MRS findings of LA and compare to those with chronic ischemic infarcts and control subjects, in order to understand the metabolic changes in LA. METHODS: We compared 25 patients with LA, 10 patients with chronic ischemic infarct and 9 control subjects without LA. Ratios for n-acetyl aspartate (NAA)/creatine (Cr) and myoinositol (MI)/Cr were obtained from leukoaraiotic area, chronic ischemic infarct and normal white matter. For the cognitive impairment Minimental Status Examination (MMSE) was applied to all individuals. RESULTS: Between LA and normal white matter, NAA/Cr values were shown no statistically significant difference. MI/Cr value of LA was significantly increased when compared with normal white matter (0.72±0.22 to 0.59±0.15; p

Magnetic resonance imaging (MRI) of the breast gained a role in clinical practice thanks to the optimal sensitivity of contrast-enhanced (CE) protocols. This approach, first proposed 30 years ago and further developed as bilateral highly spatially resolved dynamic study, is currently considered superior for cancer detection to any other technique. However, other directions than CE imaging have been explored. Apart from morphologic features on unenhanced T2-weighted images, two different non-contrast molecular approaches were mainly run in vivo: proton MR spectroscopy (1H-MRS) and diffusion-weighted imaging (DWI). Both approaches have shown aspects of breast cancer (BC) hidden to CE-MRI: 1H-MRS allowed for evaluating the total choline peak (tCho) as a biomarker of malignancy; DWI showed that restricted diffusivity is correlated with high cellularity and tumor aggressiveness. Secondary evidence on the two approaches is now available from systematic reviews and meta-analyses, mainly considered in this article: pooled sensitivity ranged 71-74% for 1H-MRS and 84-91% for DWI; specificity 78-88% and 75-84%, respectively. Interesting research perspectives are opened for both techniques, including multivoxel MRS and statistical strategies for classification of MR spectra as well as diffusion tensor imaging and intravoxel incoherent motion for DWI. However, when looking at a clinical perspective, while MRS remained a research tool with important limitations, such as relatively long acquisition times, frequent low quality spectra, difficult standardization, and quantification of tCho tissue concentration, DWI has been integrated in the standard clinical protocols of breast MRI and several studies showed its potential value as a stand-alone approach for BC detection. [ABSTRACT FROM AUTHOR]

Purpose: To gain a deeper understanding of the influence of skeletal muscle fiber orientation on metabolite visibility, magnetization transfer from water, and water proton relaxation rates in ¹H MR spectra. Methods: Non-water-suppressed MR spectroscopy was performed in tibialis anterior muscle (TA) of 10 healthy adults, with the TA oriented either parallel or at the magic angle to the 3T field. Spectra were acquired with metabolite-cycled PRESS, and water inversion from 50 to 2510 ms before excitation. Water proton T2 relaxation was sampled with STEAM with echo times from 12 to 272 ms. Results: Apparent concentrations of total creatine (tCr), taurine, and trimethylammonium compounds were reduced by 29% to 67% when TA was parallel to B0. Both tCr peak areas were strongly correlated to the methylene peak splitting. Magnetization transfer rates from water to tCr CH3 were not significantly different between orientations. Water T1s were similar between orientations, but T2s were statistically significantly shorter by 1 ms in the parallel orientation (P = 0.002). Conclusion: Muscle metabolite visibilities in MR spectroscopy and water T2 times depend substantially on muscle fiber orientation relative to B0. In contrast, magnetization transfer rates appear to depend on muscle composition, rather than fiber orientation. [ABSTRACT FROM AUTHOR]

Objective: To assess short- and long-term reproducibility of marrow adipose tissue (MAT) quantification by 1H-MR spectroscopy.Materials and Methods: Our study was IRB-approved and HIPAA compliant. Written informed consent was obtained. We studied 20 overweight/obese but otherwise healthy subjects (12 female, 8 male) with a mean age of 37 ± 6 years. All subjects underwent proton magnetic resonance spectroscopy (1H-MRS) of the fourth lumbar vertebral body using a single-voxel point-resolved spatially localized spectroscopy sequence without water suppression at 3 T. Measurements were repeated after 6 weeks and 6 months using identical scanning protocols. The following clinical parameters were collected, weight, BMI, exercise status, and trabecular bone mineral density (BMD), by quantitative computed tomography. Short- (baseline, 6 weeks) and long-term (baseline, 6 months) reproducibility of MAT was assessed by the coefficient of variance (CV), standard deviation (SD), and interclass correlation coefficients (ICCs). Short- and long-term changes in clinical parameters were assessed by paired t-test.Results: For short-term reproducibility between baseline and 6-week scans, the CV was 9.9 %, SD was 0.08, and ICC was 0.97 (95 % CI 0.94-099). For long-term reproducibility between baseline and 6-month scans, the CV was 12.0 %, SD was 0.10, and ICC was 0.95 (95 % CI 0.88 to 0.98). There was no significant short- or long-term change in clinical parameters (weight, BMI, exercise status, BMD) (p > 0.2).Conclusion: 1H-MRS is a reproducible method for short- and long-term quantification of MAT. Our results can guide sample size calculations for interventional and longitudinal studies. [ABSTRACT FROM AUTHOR]

Background: To improve the extent over which whole brain quantitative three-dimensional (3D) magnetic resonance spectroscopic imaging (MRSI) maps can be obtained and be used to explore brain metabolism in a population of healthy volunteers. Methods: Two short echo time (20 ms) acquisitions of 3D echo planar spectroscopic imaging at two orientations, one in the anterior commissure-posterior commissure (AC-PC) plane and the second tilted in the AC-PC +15° plane were obtained at 3 Tesla in a group of 10 healthy volunteers. B1 (+) , B1 (-) , and B0 correction procedures and normalization of metabolite signals with quantitative water proton density measurements were performed. A combination of the two spatially normalized 3D-MRSI, using a weighted mean based on the pixel wise standard deviation metabolic maps of each orientation obtained from the whole group, provided metabolite maps for each subject allowing regional metabolic profiles of all parcels of the automated anatomical labeling (AAL) atlas to be obtained. Results: The combined metabolite maps derived from the two acquisitions reduced the regional intersubject variance. The numbers of AAL regions showing N-acetyl aspartate (NAA) SD/Mean ratios lower than 30% increased from 17 in the AC-PC orientation and 41 in the AC-PC+15° orientation, to a value of 76 regions of 116 for the combined NAA maps. Quantitatively, regional differences in absolute metabolite concentrations (mM) over the whole brain were depicted such as in the GM of frontal lobes (cNAA = 10.03 + 1.71; cCho = 1.78 ± 0.55; cCr = 7.29 ± 1.69; cmIns = 5.30 ± 2.67) and in cerebellum (cNAA = 5.28 ± 1.77; cCho = 1.60 ± 0.41; cCr = 6.95 ± 2.15; cmIns = 3.60 ± 0.74). Conclusion: A double-angulation acquisition enables improved metabolic characterization over a wide volume of the brain. [ABSTRACT FROM AUTHOR]

Aim: Findings from clinical studies in postmenopausal women with late initiation of hormone replacement therapy (HRT) that test whether HRT protects cognitive functions in women are inconsistent. The aim of this study was to investigate the effects of HRT on brain metabolite ratios when initiated in the early postmenopausal period (critical window). Materials and methods: Proton magnetic resonance spectrometry (1H MRS) was performed in 4 brain regions of 47 healthy postmenopausal women (21 received HRT, 26 did not). The subjects were aged between 45 and 65 years. The duration of HRT ranged from 1 to 12 years (mean: 6.3 years). The duration of menopause was 2-12 years (mean: 6.1 years) for HRT users and 1-20 years (mean: 7.8 years) for non-HRT users. Metabolite ratios [N-acetyl aspartate/choline (NAA/Cho), NAA/creatine (Cr), and Cho/Cr] were evaluated. Results: Cho/Cr ratios were significantly increased and NAA/Cho ratios significantly decreased in all 4 regions in the HRT user group compared to the other group after elimination of the effects of age and menopause duration. Regression analysis revealed an association only between NAA/Cho and duration of menopause. Conclusion: HRT-related changes in metabolite ratios are found in all brain regions. Decreased NAA/Cho and increased Cho/Cr levels do not support the neuroprotective role of HRT in the critical window. [ABSTRACT FROM AUTHOR]