NMR in Biomedicine最新文献

{"title":"Metabolic Assessment in Human Pluripotent Stem Cell-Derived Cerebral Organoids Using HR-MAS NMR Spectroscopy.","authors":"Maria Alejandra Castilla Bolanos, Vorapin Chinchalongporn, Rajshree Ghosh Biswas, Colleen Bailey, Maggie Wu, Ronald Soong, Fermisk Saleh, Andre Simpson, Carol Schuurmans, Jamie Near","doi":"10.1002/nbm.70343","DOIUrl":"10.1002/nbm.70343","url":null,"abstract":"<p><p>Brain metabolism is vital to healthy brain function and is often altered in disease; yet direct investigation in patients is challenging. Although animal models are commonly used for studying brain metabolism, their use is under increasing scrutiny due to concerns of animal welfare and model validity. Human pluripotent stem cell (hPSC)-derived cerebral organoids (COs) present a unique opportunity to model human brain developmental and neuropathological processes, allowing for detailed metabolic characterization via multiple approaches. Here, we applied high-resolution magic-angle spinning (HR-MAS) proton nuclear magnetic resonance (¹H-NMR) spectroscopy to analyze metabolite levels in hPSC-derived COs, establishing a pipeline to study neurometabolic pathways in these engineered human brain tissues. We identified and quantified 17 metabolites in hPSC-derived COs at different stages of maturity. The high spectral quality (linewidth < 4 Hz, SNR > 65) allowed detection of metabolite levels in 85- to 312-day-old hPSC-derived COs, which exhibited a metabolic profile similar to human fetal brain, with key distinguishing features relative to human adult brain, including: elevated lactate levels; approximately equimolar glutamate and glutamine levels; low N-acetylaspartate levels; and an abundance of hypotaurine. In summary, this study presents direct metabolic assessment in intact COs via HR-MAS ¹H-NMR spectroscopy. Our approach provides a platform for investigating human brain metabolism and its alteration in human brain models of neurodegeneration.</p>","PeriodicalId":19309,"journal":{"name":"NMR in Biomedicine","volume":"39 8","pages":"e70343"},"PeriodicalIF":2.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13307635/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148339545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In Vivo Assessment of Placental Structure and Perfusion in Late-Gestation Pregnancies and Their Association With Fetal Growth.","authors":"Daphna Link-Sourani, Netanell Avisdris, Xingfeng Shao, Dana Schonberger, Aviad Rabinowich, Bella Spector Fadida, Yair Wexler, Leo Joskowicz, Liat Ben Sira, Liran Hiersch, Danny J J Wang, Dafna Ben Bashat","doi":"10.1002/nbm.70346","DOIUrl":"10.1002/nbm.70346","url":null,"abstract":"<p><p>Adequate placental structure and function are crucial for fetal growth, while placental dysfunction often leads to fetal growth restriction (FGR), associated with increased perinatal morbidity and mortality. Current FGR criteria, relying on sonographic biometry and Doppler assessments, typically fall short in sensitivity for diagnosing FGR, predicting perinatal outcomes, and assessing their association with placental pathology. Advanced MRI methods offer a unique opportunity to characterize placental structure and perfusion, and to assess their relationship with fetal growth. This study aims to provide normative quantitative MRI values of placental structure and perfusion during the third trimester, to assess their interplay and association with fetal growth, and to identify differences between appropriate-for-gestational-age (AGA) and FGR-complicated pregnancies. With IRB approval, pregnant women between 30 and 37 weeks of gestation (AGA [n = 46], FGR [n = 11]) underwent prospective MRI. Placental structure (volume; umbilical-cord centricity-index [CI]), placental perfusion (placental-blood-flow [PBF] and arterial-transit-time [ATT] extracted from arterial-spin-labeling), fetal growth (estimated body weight and brain volume), and radiomics features derived from PBF and ATT maps were assessed using deep-learning and image-processing tools. Statistical analyses included Pearson correlation, analysis of covariance with gestational-age (GA) as a covariate, non-parametric tests, logistic regression, multistep feature selection, and false discovery rate correction. Fetal growth parameters correlated with GA in both groups and were significantly reduced in FGR. Mean perfusion values of AGA placentas were significantly higher than previously reported at earlier GA using the same method. Placental volume correlated with ATT and total placental flow (mean PBF × placental volume/100) in AGA fetuses. Total placental flow was significantly lower in FGR compared with AGA. CI and two ATT radiomics features contributed most to differentiating AGA from FGR, with higher CI in FGR. Our findings highlight CI as a potential marker for growth restriction. Larger studies are needed to better characterize perfusion alterations in FGR.</p>","PeriodicalId":19309,"journal":{"name":"NMR in Biomedicine","volume":"39 8","pages":"e70346"},"PeriodicalIF":2.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13323874/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148369374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reproducibility of Splanchnic Blood Flow Measured Using Phase-Contrast MRI.","authors":"Lærke S Gasbjerg, Frederikke H Østergaard, Rasmus S Rasmussen, Ludvig S Langberg, Sophie W Nielsen, Lotte Alstrup, Tanne S W Larsson, Ulrik B Andersen, Henrik B W Larsson, Ali Asmar, Bryan Haddock, Mark B Vestergaard","doi":"10.1002/nbm.70348","DOIUrl":"10.1002/nbm.70348","url":null,"abstract":"<p><p>Splanchnic vessel blood flow assessment can describe physiology or pathophysiology and also has clinical relevance for patients with altered abdominal blood flow, vascular neuropathy, or atherosclerotic conditions. Reliable and practicable methods for this assessment are needed. We assessed the reproducibility of non-invasive phase-contrast MRI (PC-MRI) for measuring splanchnic blood flow and its feasibility for detecting postprandial blood flow changes. We included measurements from two groups of healthy individuals (Group A: n = 10; C: n = 10) and a group of patients with type 2 diabetes (B: n = 10) from randomized, single-blind, placebo-controlled studies, and assessed blood flow with 2D PC sequences (3 Tesla Siemens Biograph MRI and 3 Tesla Philips Achieva). Blood flow was measured in the arteria mesenterica superior, truncus coeliacus, arteria hepatica (Group A only), and vena portae hepatis over multiple days, with repeated scans each day to assess variability and reproducibility. To confirm detection of postprandial changes, nine repeated measurements were acquired during ingestion of 75-g oral glucose tolerance test compared to water ingestion. Reproducibility was assessed by coefficient of variation (CoV) and limits of agreement with the mean (LoAM) using an extended Bland-Altman analysis. Blood flow in arteria mesenterica superior, truncus coeliacus, and vena portae hepatis demonstrated low intrasubject within session CoV (7%-22%) and intrasubject between session CoV (16%-26%). Blood flow in arteria hepatica had poorer CoV for both within sessions (12%) and between sessions (32%). Glucose ingestion induced a blood flow peak increase of 88% ± 52% in arteria mesenterica superior and 68% ± 36% in vena portae hepatis, both robustly detected, while no change was observed in the arteria hepatica or truncus coeliacus. In conclusion, PC-MRI is a reproducible and feasible technique for measuring blood flow in arteria mesenterica superior, truncus coeliacus, and vena portae hepatis with the ability to detect postprandial changes. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT05391581, NCT06426823, NCT06774807.</p>","PeriodicalId":19309,"journal":{"name":"NMR in Biomedicine","volume":"39 8","pages":"e70348"},"PeriodicalIF":2.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13314320/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148352697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-Resolution Diffusion Kurtosis Imaging of Hippocampus Subfields Across the Healthy Lifespan.","authors":"Pablo Stack-Sanchez, Donald W Gross, Ali R Khan, Christian Beaulieu","doi":"10.1002/nbm.70355","DOIUrl":"10.1002/nbm.70355","url":null,"abstract":"<p><p>Diffusion kurtosis imaging (DKI) is typically applied to white matter, but it may provide insight into age-related microstructural changes in gray matter tissue like the hippocampus. The goal was to assess neurodevelopment and aging changes in hippocampal subfields using 1 mm isotropic DKI across the healthy lifespan (5-90 years). Multi-shell, 1 mm³, diffusion imaging focused on the hippocampus, was acquired at 3 T in 363 healthy participants (5-90 years, 206 females). Automatic hippocampal subfield segmentation and unfolded maps were obtained using HippUnfold. Nonlinear lifespan trajectories, sex differences, and age-corrected residual correlations with cognitive scores and other demographics were assessed for volume, mean diffusivity (MD), fractional anisotropy (FA), mean kurtosis (MK), and kurtosis FA (KFA). Whole hippocampus yielded distinct age trajectories for the volume, diffusion tensor, and diffusion kurtosis parameters: volume-quadratic fit (maximum ~35-42 years); MD-negative Gamma variate (minimum ~35 years); FA-positive Gamma variate fit (maximum ~25 years); MK-exponential fit (steep increase during development that plateaus after ~25 years); and KFA-negative linear across the lifespan. There were sex differences in age trajectories for volume and MK that were not evident with DTI metrics. Males exhibited larger volume and larger MK than females. The subfields showed similar age trajectories as whole hippocampus albeit with regional variations in the values. The subiculum showed dramatically higher MK after age 20, with males exhibiting higher values than females. MK residuals in whole hippocampus correlated positively with body mass index residuals in three age groups (young, middle age, and older). In conclusion, high-resolution 1 mm isotropic DKI of hippocampus revealed linear and nonlinear patterns with development and aging over a wide age range of 5-90 years that differ from DTI. These results suggest that DKI can provide novel insight into age-related microstructural changes at the sub-hippocampal level.</p>","PeriodicalId":19309,"journal":{"name":"NMR in Biomedicine","volume":"39 8","pages":"e70355"},"PeriodicalIF":2.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13364513/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148437417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hyperpolarized MRI Detects Increased [1-¹³C]Pyruvate Metabolism in Early Liver Regeneration.","authors":"Uffe Kjærgaard, Andrea Lund, Lotte Bonde Bertelsen, Esben Søvsø Szocska Hansen, Katrine Holm Andersen, Steffen Ringgaard, Jens Randel Nyengaard, Frank Viborg Mortensen, Christoffer Laustsen","doi":"10.1002/nbm.70340","DOIUrl":"10.1002/nbm.70340","url":null,"abstract":"<p><p>Surgical resection remains the primary curative approach for malignant liver tumors and liver regeneration is essential for patient recovery following major hepatic resection. While its molecular and cellular mechanisms have been extensively studied, the in vivo metabolic dynamics underlying early regeneration remain incompletely characterized. Hyperpolarized [1-¹³C]pyruvate MRI (HP-MRI) offers a unique, noninvasive method to assess real-time metabolic fluxes in regenerating liver tissue. Twelve male Wistar rats were randomized to either 70% partial hepatectomy (PH; n = 6) or nonsurgical controls (n = 6). On postoperative day 1, all animals underwent HP-MRI and multiparametric proton MRI. Metabolic fluxes were quantified using area-under-the-curve ratios for lactate-to-pyruvate (L/P), alanine-to-pyruvate (A/P), and lactate-to-alanine (L/A). The PH group showed significantly higher L/P (0.267 [95% CI: 0.225-0.310] vs. 0.168 [95% CI: 0.135-0.200]; p < 0.001) and A/P (0.236 [95% CI: 0.153-0.319] vs. 0.150 [95% CI: 0.128-0.172]; p = 0.028) ratios compared to controls, indicating increased exchange of pyruvate to lactate and alanine. L/A ratios remained unchanged. These findings were supported by elevated biochemical markers of hepatic injury and changes in quantitative MRI parameters, including reduced ADC and IVIM flow fraction. HP-MRI revealed increased glycolytic and transaminase activity during early liver regeneration, consistent with the metabolic demands of hepatocyte proliferation. These results demonstrate the feasibility of HP-MRI for noninvasive metabolic assessment of liver regeneration in vivo and additionally provide insights into early regenerative metabolism. This suggests HP-MRI as a promising tool for assessing postoperative recovery in patients undergoing major hepatectomy.</p>","PeriodicalId":19309,"journal":{"name":"NMR in Biomedicine","volume":"39 8","pages":"e70340"},"PeriodicalIF":2.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13284530/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148295773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterizing Metabolic and Compositional Heterogeneity of Calf Muscle Using CEST MRI at 3 T.","authors":"Huabin Zhang, Kangli Pi, Ziyan Wang, Fan Huang, Juan Wei, Patrick Liebig, Lin Chen, Yang Zhou, Yi Zhang, Varut Vardhanabhuti, Jianpan Huang","doi":"10.1002/nbm.70341","DOIUrl":"10.1002/nbm.70341","url":null,"abstract":"<p><p>Different human calf muscles have specialized functions, leading to inherent metabolic differences. Imaging the metabolic and compositional properties of calf muscles is important for evaluating muscle health. This study aims to characterize the metabolic and compositional heterogeneity of calf muscle by chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) at 3 T. CEST MRI was performed on 14 healthy volunteers. CEST contrasts (amide, PCr, rNOE, and MT) were extracted from segmented muscles, and used for correlation analysis with age, fat content, BMI, and muscular strength. Distinct CEST signatures were observed between deep stabilizer and superficial powerhouse muscles. Significant correlations (e.g., rNOE vs. strength) revealed the impact of adiposity on muscle physiology. This study demonstrates the feasibility of CEST MRI for noninvasively characterizing muscle-specific metabolic and compositional alterations, revealing distinct signatures between functionally distinct muscle groups and significant associations with adiposity and body composition.</p>","PeriodicalId":19309,"journal":{"name":"NMR in Biomedicine","volume":"39 8","pages":"e70341"},"PeriodicalIF":2.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13292845/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148308850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"AeroCoil: Pneumatically Controlled Dual-Tunable RF Coil for Proton (¹H) and Deuterium (²H).","authors":"Chavalchart Herabut, Bryan Rangel Valle, Samantha McClendon, Dakota Ortega, Scott Beeman, Vikram Kodibagkar, Sung-Min Sohn","doi":"10.1002/nbm.70337","DOIUrl":"10.1002/nbm.70337","url":null,"abstract":"<p><p>In specific MRI applications, RF coils must operate at multiple resonance frequencies to support multinuclear imaging and spectroscopy. Designing such coils that can either resonate at or switch between multiple frequencies presents considerable technical challenges. Traditional multituned coils typically suffer from strong electromagnetic (EM) coupling due to limited physical space and the interaction between multiple resonating structures. Frequency-switchable coils offer an alternative by adjusting circuit capacitance or inductance to tune for different nuclei, typically relying on PIN diodes or similar electronic switches. However, these designs require frequency-sensitive bias circuitry, dedicated drivers, and long DC control lines, all of which are prone to RF interference within the MRI environment. Furthermore, PIN diodes introduce inherent RF leakage and nonlinearities that can significantly degrade image quality. This study introduces a pneumatically actuated frequency-switchable RF coil, termed AeroCoil, that enables resonance switching without electrical biasing. The AeroCoil design utilizes air pressure to mechanically adjust capacitance, enabling transitions between the ¹H and ²H Larmor frequencies at 9.4 T. This pneumatic mechanism eliminates the need for local electrical components near the imaging volume, thereby reducing RF noise, eliminating EM interference, and simplifying the coil's circuit architecture. The AeroCoil's performance was benchmarked against single-tuned coils, representing optimal performance at each frequency, and a PIN diode-based switchable coil. Bench measurements evaluated return losses and quality factors, whereas MRI experiments assessed SNR and image artifacts. The AeroCoil retained 88.2%-91.9% of the SNR compared with a single-tuned ¹H coil, whereas the PIN diode-based ¹H coil achieved only 68.3%-75%. At the ²H frequency, AeroCoil performance was further emphasized, retaining 71.7%-74.6% SNR, whereas the PIN diode-based design dropped sharply to 27.1%-28.8%.</p>","PeriodicalId":19309,"journal":{"name":"NMR in Biomedicine","volume":"39 8","pages":"e70337"},"PeriodicalIF":2.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148278212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Serum and Urine Metabolomic Profiles in Children With Growth Retardation: An Exploratory ¹H-NMR Study.","authors":"Mehtap Alim, Metin Demirel, Fatmanur Koktasoglu, Gamze Ozgürhan, Ozge Pasin, Süleyman Bas, Sahabettin Selek","doi":"10.1002/nbm.70356","DOIUrl":"10.1002/nbm.70356","url":null,"abstract":"<p><p>Growth retardation, defined by impaired anthropometric development relative to age-based population standards, may be accompanied by metabolic alterations. This study aimed to characterize serum and urine metabolomic profiles in children with growth retardation using exploratory ¹H-NMR spectroscopy. Thirty children with growth retardation and 24 controls were included in this cross-sectional study. Serum and urine samples were analyzed by ¹H-NMR spectroscopy, and annotated metabolites were evaluated using Chenomx, MetaboAnalyst, and R software. Clinical and laboratory variables were compared between groups. Metabolomic analysis included univariate comparisons, volcano plots, PCA, OPLS-DA, Spearman correlation analysis, age-adjusted regression, exploratory ROC analysis, and metabolite set enrichment analysis. The growth retardation group had lower age and BMI than controls, while serum iron and AST were higher. Volcano plot analysis showed a more distinct pattern of nominal metabolite alterations in serum than in urine. In serum, 3-hydroxybutyrate and glucuronate showed relative increases, whereas N-acetylgalactosamine, alanine, glutamate, and glucose showed relative decreases. In urine, metabolite differences were less pronounced. Multivariate analysis demonstrated a significant overall group effect in serum but not in urine. Within the growth retardation group, age was negatively correlated with serum 3-hydroxybutyrate and positively correlated with N-acetyl-L-aspartic acid, whereas several urinary metabolites showed negative correlations with age. After age adjustment, only 4-ethylbenzoic acid remained significant in serum after multiple testing correction. Exploratory ROC analysis identified N-acetylgalactosamine and 4-ethylbenzoic acid in serum and beta-alanine and creatinine in urine as the metabolites with the highest within cohort classification tendency. Children with growth retardation exhibited modest metabolic differences, with more consistent group-related alterations observed in serum than in urine. These findings mainly suggest changes related to energy metabolism, amino acid turnover, and intermediary metabolism. However, the results remain exploratory and require confirmation in larger, age-stratified and independently validated cohorts.</p>","PeriodicalId":19309,"journal":{"name":"NMR in Biomedicine","volume":"39 8","pages":"e70356"},"PeriodicalIF":2.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13366460/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148437446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantitative Guanidinium CEST-Based pH Mapping at 3 T in Healthy and Pathological Muscle.","authors":"Valentin Henriet, Pierre-Yves Baudin, Benjamin Marty, Marc Lapert, Harmen Reyngoudt","doi":"10.1002/nbm.70352","DOIUrl":"10.1002/nbm.70352","url":null,"abstract":"<p><p>Intramuscular pH has been shown to be a valuable biomarker in muscle diseases. Both ¹H and ³¹P MRS approaches are commonly used to determine pH in vivo. MRS-based pH measurements are highly sensitive and reproducible but come with limitations: single-voxel approaches and MRS imaging applications suffer from long acquisition times. High spatial resolution pH mapping can be achieved using chemical exchange saturation transfer (CEST), which is intrinsically sensitive to pH. The chemical exchange phenomenon allows for the indirect, noninvasive detection of metabolites by measuring the water signal after a saturation at a given frequency offset. Several metabolites, such as creatine (Cr) and phosphocreatine (PCr), which are abundant in skeletal muscle, were reported to be detectable using CEST in vivo. Moreover, pH changes alter the exchange rate (k_ex,guan2.0) between guanidinium protons (of Cr and PCr) and bulk water, thereby modifying the CEST effect. In this study at 3 T, we estimate k_ex,guan2.0 based on a three-pool model, verifying the Bloch-McConnell (BM) analytical solution. The method's sensitivity was assessed in a phantom within the physiological pH range. CEST-based pH correlated strongly with the true pH measured with an analytical pH meter (R² = 0.97, p < 0.001). The method demonstrated sensitivity to subtle in vivo pH changes on the order of 0.02 pH units in leg muscles of healthy controls at rest and postexercise and in subjects with a neuromuscular disease. The CEST-based pH was significantly decreased in exercised muscle (p < 0.001) and significantly increased in pathological muscles (p < 0.05). This work demonstrates sensitive, high-resolution pH mapping of skeletal leg muscle with an ability to separate healthy from pathological tissue, highlighting its potential as a biomarker for muscle diseases.</p>","PeriodicalId":19309,"journal":{"name":"NMR in Biomedicine","volume":"39 8","pages":"e70352"},"PeriodicalIF":2.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13333537/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148391503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Task-Evoked Functional Activation and Coupling With CSF Flow Detected in the Human Brain With Ultrashort Echo Time fMRI at 7 T.","authors":"Sara Ponticorvo, Ekaterina Paasonen, Pavel Filip, Douglas L Rothman, Juha S Valjakka, Olli Gröhn, Shalom Michaeli, Silvia Mangia","doi":"10.1002/nbm.70342","DOIUrl":"10.1002/nbm.70342","url":null,"abstract":"<p><p>Ultrashort echo time (UTE) and zero echo time (ZTE) techniques have been shown to generate robust functional MRI (fMRI) contrast of hemodynamic origin from the inflow of unperturbed spins into the imaging volume under local radiofrequency transmission. As such, they are ideally suited not only to map the dynamics of cerebral blood flow (CBF) during intense neuronal activity but also the dynamics of cerebrospinal fluid (CSF). The goal of this work was to pilot the use of UTE-fMRI for human studies of brain activation and neurofluid dynamics. We thus conducted fMRI studies at 7 T with a transmit/receive head coil using a slab-selective UTE sequence on 13 human participants during a visual task. Spatio-temporally matched gradient-echo echo planar imaging (GE-EPI) data were also acquired for qualitative comparison purposes, and respiratory and cardiac signals were measured to quantify multiple physiological metrics. Functional brain activations were analyzed using a general linear model at single subject and group levels. Moreover, time-courses from the whole cortex, carotid arteries, and fourth ventricle were correlated between each other, and physiological contributions to these ROI signals were evaluated with a linear mixed model and a relative importance computation. Robust and reproducible functional activations were detected with UTE-fMRI in the visual cortex across participants. Although the functional contrast-to-noise ratio was higher with GE-EPI than with UTE, the temporal signal-to-noise ratio was lower, and group-level statistical power and activation patterns of UTE maps were similar to those obtained with GE-EPI. In addition, the UTE task-evoked signal in CSF was negatively correlated with those in the whole cortex and in the carotid arteries and was primarily driven by the stimulus paradigm. We conclude that UTE-fMRI can be used not only for functional studies of the human brain but also for assessing the relationship between hemodynamic and CSF signals, which can help elucidate brain homeostatic processes.</p>","PeriodicalId":19309,"journal":{"name":"NMR in Biomedicine","volume":"39 8","pages":"e70342"},"PeriodicalIF":2.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13284447/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148295863","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}