NMR in Biomedicine最新文献

{"title":"Quantitative T2* Magnetic Resonance Imaging for Iron Detection in Soft Tissue of the Fingers.","authors":"Artemis Galani, Nikolaos I Vlachogiannis, Vassilis Koutoulidis, Georgia Lymperopoulou, Petros P Sfikakis, Thomas G Maris, Lia Angela Moulopoulos","doi":"10.1002/nbm.70314","DOIUrl":"10.1002/nbm.70314","url":null,"abstract":"<p><p>T2* Magnetic Resonance Imaging (MRI) is an established method for the assessment of iron overload in multiple organs. Quantification of iron in the soft tissues of the fingers with T2* MRI could be of clinical value in conditions characterized by microvasculopathy. Herein, we examined the feasibility and repeatability of quantitative T2* MRI for the presence of iron in the soft tissues of fingers. In this prospective cohort study, 10 healthy individuals and three patients with digital microvasculopathy were subjected to hand MRI. Gradient echo (GRE) images with progressively increasing echo times (TE's) were acquired in a 1.5 T MRI system. After visual inspection of dual-colored maps of the hands, multiple regions of interest (ROIs) were placed in the soft tissues at areas that indicated increased susceptibility. Three ROIs per finger with the lowest T2* values (ms) were recorded. Mean T2* values for healthy individuals ranged from 12.5 to 16.0 ms (mean ± standard deviation [SD]: 14.0 ± 2.6 ms) except for a single ROI measurement of 8.8 ms in one individual. In contrast, multiple ROIs with T2* values below 8.8 ms were detected in the soft tissues of the three patients with digital microvasculopathy. The range of values for the three patients were (mean ± SD [range]: 7.4 ± 0.9 [5.2-8.8] ms, 7.9 ± 1.0 [5.9-10.3] ms, and 7.9 ± 1.7 [5.7-14.3] ms, respectively), suggestive of iron excess. Furthermore, 4/10 healthy individuals repeated the examination 1 year after the first MRI study. No areas with T2* below 8.8 ms were detected in the second study. In conclusion, T2* GRE is a feasible and reproducible technique for the quantification of iron in the soft tissues of the fingers.</p>","PeriodicalId":19309,"journal":{"name":"NMR in Biomedicine","volume":"39 6","pages":"e70314"},"PeriodicalIF":2.8,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147982335","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":"Multi-Shot Multi-Echo xSPEN Technique for Portable Low-Field MRI Systems.","authors":"Yueqi Qiu, Philip K Lee, Ke Dai, Suen Chen, Shiwei Yang, Changyue Wang, Haoran Bai, Zhaozhao Dang, Zhiyong Zhang","doi":"10.1002/nbm.70294","DOIUrl":"10.1002/nbm.70294","url":null,"abstract":"<p><p>In compact portable low-field MRI systems, imaging suffers from severe distortions due to significant field inhomogeneity and gradient nonlinearity. The purpose of this work was to develop and evaluate a Multi-Shot Multi-Echo cross-term Spatiotemporal Encoding (MS-ME xSPEN) sequence for highly compact, portable low-field MRI systems. This method aims to improve imaging performance while preserving the robustness of xSPEN to severe field inhomogeneities. The MS-ME xSPEN sequence was implemented using two image-domain multi-shot sampling techniques: segmented and interleaved. For subsequent evaluations, the segmented MS-ME xSPEN approach was selected and compared with conventional single-shot xSPEN. All experiments were performed on a 110-mT portable MRI system equipped with three gradient axes. A constant gradient environment was emulated by continuously activating a single gradient axis throughout the sequence. Imaging was performed on phantoms and in the human brain. MS-ME xSPEN exhibited superior resilience to in-plane distortions from field inhomogeneities and achieved higher SNR compared with the standard xSPEN. MS-ME xSPEN also enabled a wider range of T2-weighted contrasts. MS-ME xSPEN is well suited for compact portable MRI systems, offering improved SNR, flexible contrast, and robustness to field inhomogeneity.</p>","PeriodicalId":19309,"journal":{"name":"NMR in Biomedicine","volume":"39 6","pages":"e70294"},"PeriodicalIF":2.8,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147723409","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":"Reducing Variability in Deep Gray Matter QSM Using Differential ROI Referencing: A Phantom and In Vivo Evaluation.","authors":"Tae Hyun Hwang, Gawon Lee, Myung Kyun Woo, Se-Hong Oh","doi":"10.1002/nbm.70301","DOIUrl":"10.1002/nbm.70301","url":null,"abstract":"<p><p>Quantitative susceptibility mapping (QSM) measures the intrinsic magnetic susceptibility of tissues. Because susceptibility values are inherently relative rather than absolute, referencing to a region of interest (ROI) is commonly employed to mitigate intersubject and acquisition-related variability. To validate the feasibility and robustness of a differential ROI reference method in QSM using both digital phantom and in vivo data, particularly for deep gray matter susceptibility analysis. In the digital phantom study, susceptibility values in the caudate nucleus were assessed with and without differential referencing across various simulation conditions (slab widths, brain mask erosion levels, air susceptibility). In the in vivo study, susceptibility differences between 16 patients with Parkinson's disease (PD) and 16 controls were compared across multiple deep gray matter ROIs under variable acquisition parameters. A one-way ANOVA statistical test was used in the in vivo study with multiple-comparison correction via the Benjamini-Hochberg false discovery rate (FDR-BH), with significance set at p < 0.05. In this study, \"accuracy\" refers specifically to the phantom study where ground-truth susceptibility values are known. In vivo, where such ground truth is unavailable, \"robustness\" and \"group-discrimination sensitivity\" are used as surrogate indicators of accuracy. Robustness was evaluated by the consistency of susceptibility differences across varying acquisition parameters, whereas group-discrimination sensitivity was evaluated by the ability to detect disease-related group differences between PD patients and controls. In the digital phantom study, the proposed method demonstrated stable susceptibility estimates across all conditions, with minimal deviation from true values when referencing anatomically adjacent ROIs. In the in vivo study, referenced susceptibility values (e.g., substantia nigra minus putamen) yielded consistent and significant group differences across acquisition scenarios, whereas unreferenced values were more variable. The differential ROI reference method reduces susceptibility variability associated with acquisition and processing factors. This approach may offer a practical and pathology-resilient referencing alternative for deep brain analysis in neurodegenerative diseases.</p>","PeriodicalId":19309,"journal":{"name":"NMR in Biomedicine","volume":"39 6","pages":"e70301"},"PeriodicalIF":2.8,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13150806/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147840723","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":"Elbow Flexors Muscle Fat Fraction Is a Sensitive and Relevant Outcome Measure in Nonambulant Patients With DMD.","authors":"M Michaëls, K J Naarding, M van der Holst, N Geijsen, E H Niks, H E Kan","doi":"10.1002/nbm.70306","DOIUrl":"10.1002/nbm.70306","url":null,"abstract":"<p><p>Duchenne muscular dystrophy (DMD) is an X-linked neuromuscular disease characterized by progressive muscle wasting. Objective and relevant outcome measures are needed for longitudinal follow-up and clinical trials. Quantitative MR muscle parameters in the legs are sensitive to change and related to function. However, data are limited for the upper limb, which is crucial for nonambulant DMD patients. This study investigated which MR parameters were sensitive to change over time and associated with loss of upper limb function. Muscle fat fraction (mFF) and contractile volume (CV) for elbow flexor and extensor muscles were obtained using chemical-shift-based fat-water separation scans at 3T (Philips, Ingenia) at baseline, 12, and 18 months. Standardized response means (SRM) were determined for different analysis volumes: center slice (CS), 5 (5S), 7 (7S), and all slices (AS). Parameters with SRM > 0.8 were associated with Performance of the Upper Limb, PUL2.0, using linear mixed models. Twenty nonambulant DMD patients participated. Baseline mFF ranged between 43.1% ± 12.6% for elbow extensors AS and 55.5% ± 18.9% for elbow flexors CS. SRM ranged from 0.37 for elbow flexors CV CS to 1.71 for elbow flexors AS and was consistently higher for increasing analysis volumes, longer follow-up time, and for mFF in comparison with CV. Associations with function were significant for all parameters and ranged from -0.25 to -0.34 (p < 0.001) for mFF and 0.12-0.49 (p < 0.001) for CV, except for elbow extensor CS CV (p = 0.87). Our study demonstrates that assessment of a larger part of the muscle increases the sensitivity to change over time in nonambulant DMD patients. Elbow flexor and extensor mFF 5S, 7S, and AS were sensitive to change over 12 months and related to loss of upper limb function in this population.</p>","PeriodicalId":19309,"journal":{"name":"NMR in Biomedicine","volume":"39 6","pages":"e70306"},"PeriodicalIF":2.8,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13148194/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147840709","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 Susceptibility Mapping of the Cervical Spinal Cord at 3T and Application to Multiple Sclerosis.","authors":"Benjamin Streichenberger, Mathieu Santin, Ludovic de Rochefort, Quentin Duché, Catherine Guillemot, Samira Mchinda, Stéphane Roche, Anne Kerbrat, Elise Bannier","doi":"10.1002/nbm.70296","DOIUrl":"10.1002/nbm.70296","url":null,"abstract":"<p><p>Quantitative susceptibility mapping (QSM) is an advanced MRI technique that links phase variations to the local tissue susceptibility. In multiple sclerosis (MS), QSM has shown promise in characterizing brain lesions by assessing chronic inflammation and myelin content. However, in the spinal cord (SC), the question remains as to whether QSM can classify MS lesions as demyenilated/remyenilated and detect chronic inflammation. SC QSM poses novel challenges due to the small size, mobility and curvature of the cord, as well as magnetic field inhomogeneities caused by nearby vertebrae and physiological movement. This study compares two QSM processing methods for the SC. One method uses the IDEAL (iterative decomposition of water and fat with echo asymmetry and least-squares estimation) algorithm to account for potential fat-related signal contributions. The second assumes fat has negligible impact. Both approaches employ the PDF (projection into dipole fields) algorithm to remove the background field and the MEDI (morphology enabled dipole inversion) technique for solving the field-to-susceptibility inversion. A 2-sequence MRI protocol was developed to acquire in-phase (IP) and out-of-phase (OOP) QSM data. Eight healthy controls (HC) and twenty MS patients were scanned on a 3T Prisma scanner. We obtained the first high-resolution axial QSM maps of the cervical SC (C3-C5), clearly distinguishing gray matter (GM), white matter (WM), and MS lesions. Results showed that accounting for fat using IDEAL did not meaningfully improve the estimation of the total magnetic field or the overall quality of QSM maps. These results open up exciting possibilities for SC susceptibility imaging in MS.</p>","PeriodicalId":19309,"journal":{"name":"NMR in Biomedicine","volume":"39 6","pages":"e70296"},"PeriodicalIF":2.8,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13122293/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147777402","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":"Ferumoxytol-Enhanced Myocardial T1 Tracking Using a Hybrid 2D/3D Steady-State MRI Sequence Captures Cyclic Intramyocardial Blood Volume Dynamics.","authors":"Hazar Benan Unal, Shahriar Zeynali, Abdul Ahmed, Eric Anttila, Ronald Mastouri, Rolf P Kreutz, Rohan Dharmakumar, David C Gross, Behzad Sharif","doi":"10.1002/nbm.70308","DOIUrl":"10.1002/nbm.70308","url":null,"abstract":"<p><p>Measuring cyclic changes in intramyocardial blood volume (iMBV) from systole to diastole has been used as an imaging marker for assessing coronary microcirculation and detecting coronary artery disease (CAD) without the need for vasodilator stress. However, an MRI-based method for detecting cyclic iMBV dynamics does not exist. The aim of this study is to demonstrate the feasibility of using ferumoxytol-enhanced (FE) MRI to detect systolic-to-diastolic iMBV dynamics on clinical scanners enabled by a new myocardial \"T1 tracking\" technique. To this end, a continuous steady-state sequence was developed, combining slice/slab-selective excitation, to generate high-resolution T1-weighted images such that the myocardial signal dynamically tracks the fractional volume of blood while minimizing the influence of confounding factors such as in-flow effects, through-plane motion, and spin history. In addition to phantom studies, FE studies in swine (n = 10) were conducted to generate systolic/diastolic T1 maps from the T1-tracking data. For comparison, MOLLI T1 maps were acquired. For both the T1-tracking method and MOLLI, T1 values before/after ferumoxytol were used to calculate iMBV at end-systole (ES) and end-diastole (ED). The T1-tracking method showed a significant iMBV difference between ES and ED (ES: 6.2 ± 1.8%, ED: 7.7 ± 2.0%, p < 10^-3) as opposed to MOLLI (ES: 8.1 ± 2.9%, ED: 8.6 ± 3.1%, p = 0.4), and detected lower iMBV at ES vs. ED in all 10 studies, consistent with physiology, while MOLLI showed contradictory ES-to-ED change in 3 out of 10 studies. The proposed method showed a mean iMBV decrease of 19.1% from ED to ES, consistent with the nuclear imaging literature. In conclusion, the results show that the newly developed FE myocardial T1-tracking technique captures cyclic changes in iMBV, i.e., consistently reveals the expected drop in iMBV from diastole to systole, offering the potential to detect CAD without the need for pharmacological stress.</p>","PeriodicalId":19309,"journal":{"name":"NMR in Biomedicine","volume":"39 6","pages":"e70308"},"PeriodicalIF":2.8,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13184369/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147974121","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":"Reducing Noise Induced by Cardiac Pulsatility in Brain Maps of R₂* and Magnetic Susceptibility Using Tailored k-space Sampling.","authors":"Quentin Raynaud, Thomas Dardano, Rita Oliveira, Giulia Di Domenicantonio, Tobias Kober, Christopher W Roy, Ruud B van Heeswijk, Antoine Lutti","doi":"10.1002/nbm.70305","DOIUrl":"10.1002/nbm.70305","url":null,"abstract":"<p><p>Maps of the transverse relaxation rate R₂* and magnetic susceptibility (χ) are computed from gradient-echo data and are sensitive to signal instabilities induced by cardiac pulsation. Here, we introduce two k-space sampling strategies that aim to mitigate the impact of cardiac-induced noise in brain maps of R₂* and χ. The proposed strategies are based on the higher level of cardiac-induced noise near the k-space centre compared to the periphery. Using CArtesian trajectory with Spiral PRofile (CASPR), the first strategy allows for the acquisition of a specific number of averages at each k-space location, derived from the local level of cardiac-induced noise. The second strategy uses cardiac triggering to synchronize the acquisition near the k-space centre with the cardiac cycle in real time. We compared the variability across four repetitions of R₂* and χ maps computed from data acquired using both strategies and with a standard linear trajectory. Data were acquired in 10 healthy volunteers. Compared to linear trajectory, CASPR reduced the variability of R₂* and χ maps across repetitions by 22% and 16% across the whole brain, reaching over 30% in inferior brain regions, for a 14% increase in scan time. CASPR also reduced the level of aliasing artefacts from pulsating blood vessels. Cardiac triggering did not reduce the variability of R₂* or χ maps. CASPR can be designed to mitigate cardiac-induced noise in brain maps of the MRI parameters R₂* and χ. Synchronization of data acquisition with the cardiac cycle did not reduce the level of cardiac-induced noise.</p>","PeriodicalId":19309,"journal":{"name":"NMR in Biomedicine","volume":"39 6","pages":"e70305"},"PeriodicalIF":2.8,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13158452/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147869159","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":"Hierarchical Bayesian Modelling Improves Microstructural Parameter Mapping in Diffusion and Exchange MRI Data.","authors":"Elizabeth Powell, Mark Maskery, Hedley C A Emsley, Laura M Parkes, Geoff J M Parker, Paddy J Slator","doi":"10.1002/nbm.70277","DOIUrl":"10.1002/nbm.70277","url":null,"abstract":"<p><p>Microstructure modelling quantifies subvoxel tissue features by combining an MRI acquisition with a mathematical model, which is typically fitted voxel-by-voxel with least-squares (LSQ) minimisation to give voxelwise maps of microstructural quantities such as diffusivity and compartmental fractions. Such approaches are susceptible to voxelwise noise, which can lead to erroneous values in parameter maps. Hierarchical Bayesian modelling (HBM) can address this limitation but has only been demonstrated for simple models. We previously derived an HBM approach for an arbitrary microstructure model with flexible parameter constraints, utilising a Markov chain Monte Carlo algorithm for parameter estimation; here, the method is demonstrated and evaluated using simulated and human data for two previously unexplored diffusion MRI techniques, namely, diffusion kurtosis imaging and blood-brain barrier filter exchange imaging. When compared with LSQ minimisation, HBM increased the accuracy, precision, contrast-to-noise ratio and parameter map quality in both simulated and human data. HBM was also able to resolve local parameter variations associated with white matter lesions in a small sample of cerebral small vessel disease subjects, which were obscured by high noise levels in the LSQ-derived parameter maps. Finally, a noise sensitivity assessment in simulations showed that HBM improved the contrast-to-noise ratio and parameter map quality even at low signal-to-noise ratios. This generalised HBM framework can improve parameter estimation for more complex diffusion MRI microstructural models that extend beyond linear combinations of exponentials.</p>","PeriodicalId":19309,"journal":{"name":"NMR in Biomedicine","volume":"39 6","pages":"e70277"},"PeriodicalIF":2.8,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13160881/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147875102","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":"Q-MRS: Quantitative Magnetic Resonance Spectral Analysis Using Deep Learning.","authors":"Christopher J Wu, Lawrence S Kegeles, Douglas L Rothman, Jia Guo","doi":"10.1002/nbm.70279","DOIUrl":"10.1002/nbm.70279","url":null,"abstract":"<p><p>Quantification of magnetic resonance spectroscopy (MRS) data using linear combination modeling (LCM) is challenging, partly due to the large number of spectral parameters to be estimated. Popular conventional LCM approaches often place soft constraints on signal amplitude ratios to improve fitting stability, at the cost of introducing bias. Meanwhile, existing deep learning (DL) methods tend to oversimplify the problem by omitting important spectral parameters, limiting their real-world utility. With these considerations in mind, we developed Q-MRS, a DL framework based on a Convolutional vision Transformer (CvT) that combines the strengths of a convolutional neural network (CNN) and a Transformer. The model was trained on a large dataset of simulated spectra and evaluated on high-quality 3T GABA-edited MEGA-PRESS data acquired from health adults in the medial parietal lobe. On simulated data with known ground-truth metabolite levels, the CvT outperformed two baseline models, a simple CNN and an Inception network. When applied to the in vivo data, Q-MRS produced fit quality and concentration estimates comparable with those of two established LCM methods, LCModel and Osprey, without imposing constraints on metabolite amplitude ratios. These results suggest that the proposed method is a promising approach for MRS analysis.</p>","PeriodicalId":19309,"journal":{"name":"NMR in Biomedicine","volume":"39 5","pages":"e70279"},"PeriodicalIF":2.8,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147633318","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":"Noninvasive Mapping of Creatine Kinase Metabolism in Human Muscle Using pH-Insensitive PCrCEST MRI at 3 and 5 T.","authors":"Xinran Chen, Xi Xu, Chongxue Bie, Peter van Zijl, Nirbhay Yadav, Jiadi Xu, Qizhi Yang, Tao Wang, Zhong Chen, Lin Chen, Yang Zhou","doi":"10.1002/nbm.70280","DOIUrl":"10.1002/nbm.70280","url":null,"abstract":"<p><p>Phosphocreatine (PCr) recovery after exercise reflects creatine kinase (CK) metabolism and is a key marker of muscle energetics. However, current chemical exchange saturation transfer (CEST)-based PCr imaging (PCrCEST) remains limited by pH-dependent contrast. Here, we present a pH-insensitive PCrCEST strategy that minimizes pH-related signal variability, enabling more reliable in vivo quantification during exercise, when tissue pH may change. Theoretical derivation, simulations, and phantom studies confirmed that PCrCEST signals varied by less than 20% across the physiological pH range when the saturation radial frequency (γB₁) matches the guanidinium proton exchange rate. Under this optimized B₁ condition, kinetic simulations further show that the PCrCEST-derived recovery time constant (τ_PCr) closely follows expected behavior even during dynamic pH changes. The pH-insensitive strategy was implemented at both 3 and 5 T and assessed in human calf muscle during plantar flexion exercise. These results demonstrate that pH-insensitive PCrCEST enabled robust mapping of muscle CK metabolism. The availability of pH-insensitive CEST mapping improves the potential of CEST not only for exercise measurements but also for broader clinical translation.</p>","PeriodicalId":19309,"journal":{"name":"NMR in Biomedicine","volume":"39 5","pages":"e70280"},"PeriodicalIF":2.8,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147632711","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}