Pituitary macroadenomas consistency affects surgical planning and may limit complete resection. Advanced MRI techniques, including virtual magnetic resonance elastography (vMRE) and synthetic MRI, may enable preoperative prediction of pituitary macroadenomas consistency. To evaluate the feasibility of vMRE and synthetic MRI for preoperative prediction of pituitary macroadenomas consistency. Prospective. Sixty-five patients with pituitary macroadenomas were prospectively enrolled (39 females; age = 49.02 ± 8.53 years). 3.0 T; Diffusion-weighted imaging (DWI), vMRE imaging based on a turbo spin-echo sequence, and synthetic MRI using the MAGiC. The tumor consistency was classified as either soft (n = 49) or hard (n = 16) by two neurosurgeons based on intraoperative findings. Apparent diffusion coefficient (ADC) values, contrast-enhanced T1 values, quantitative parameters (T1, T2, PD) derived from synthetic MRI, and vMRE stiffness values for pituitary macroadenomas were independently measured by two radiologists and were compared between two consistency groups. Intraclass correlation coefficients (ICCs) were used to evaluate the inter-reader agreement of MRI-derived quantitative parameters. Clinical and pathological characteristics and MRI-related parameters were compared between the two groups using the independent t-test or the Chi-square test. Predictive modeling was assessed using receiver-operating-characteristic (ROC) curve analysis and multivariable logistic regression, and their predictive performance was evaluated using the area under the curve (AUC). A p < 0.05 was considered statistically significant. Compared with soft groups, hard groups showed significantly lower T2 and ADC values and higher vMRE stiffness. Combined models of vMRE+ADC and ADC+T2 yielded AUCs of 0.830 and 0.797, respectively. The combination of vMRE, ADC, and T2 achieved the highest performance (AUC = 0.860). The integration of vMRE stiffness with ADC and T2 values derived from synthetic MRI demonstrated preliminary feasibility for assessing pituitary macroadenomas' consistency in this internally validated cohort, suggesting a promising multiparametric approach. 2. Stage 2. Pituitary adenomas are one kind of brain tumors. Most are soft, but about 10% are hard. Hard tumors can make surgery more difficult and increase the risk of complications and may also affect treatment outcomes. Therefore, predicting tumor consistency before surgery is important. In this study, advanced magnetic resonance imaging (MRI) was used to examine tumors before surgery and used measured values from the scans to estimate whether tumors are soft or hard. These results suggest that these MRI techniques may help predict tumor consistency. This technique may assist doctors in planning safer treatments and choosing suitable approaches.
MR elastography (MRE) has applications in breast cancer, but its optimal frequency and value in discriminating molecular subtypes remain unclear. To identify the preferable breast MRE frequency and evaluate MRE parameters in the precision diagnosis of breast cancer. Prospective. One hundred fifty-four female patients (mean age 50 ± 10.67 years) were enrolled, including five with bilateral cancer, yielding 159 lesions. 3.0 T, fast gradient-echo for DCE-MRI, single-shot EPI for DWI/ADC, SE-EPI for multifrequency MRE. The image quality of 10 frequency MRE sets was assessed (including overall image quality, diagnostic confidence, artifact impact, and signal-to-noise ratio). Stiffness (c) and viscosity (φ) were measured at the optimal frequency and compared across clinicopathological subgroups. Independent-sample t-tests or one-way analysis of variance, Mann-Whitney U or Kruskal-Wallis H tests, Friedman test, χ2 tests. Spearman's rank correlation. Univariate and multivariate analyses. Receiver operating characteristic (ROC) curves, the area under the curve (AUC). p < 0.05 was considered statistically significant. The 40-70 Hz multifrequency band demonstrated significantly superior image quality compared with all other bands. Subgroup analyses showed that c and φ differed significantly between ER-positive and ER-negative groups (c values: 2.54 (2.17-2.86) vs. 2.80 (2.37-3.30) m/s; φ values: 1.17 ± 0.21 vs. 1.24 ± 0.22 radians) and across groups with different Ki-67 expression levels (c values: 2.54 ± 0.54 vs. 2.77 ± 0.57 m/s), T stage, molecular subtypes (c values: 2.55 (2.20-2.82) vs. 2.69 (2.20-2.96) vs. 2.94 (2.52-3.33) m/s), and enhancement patterns (c values: 2.34 ± 0.41 vs. 2.73 ± 0.58 m/s). Multivariable analysis identified c [OR: 5.37 (2.13-15.54)] and age group [OR: 0.27 (0.09-0.82)] as significant independent predictors of triple-negative breast cancer, and a predictive model incorporating these variables demonstrated an AUC of 0.739 in the training set and 0.700 in the validation set. The 40-70 Hz multifrequency protocol may offer favorable image quality for breast MRE. MRE parameters, particularly stiffness, show potential for characterizing tissue biomechanical properties and could assist in distinguishing molecular subtypes. 1. Stage 2. This prospective study investigates magnetic resonance elastography, an imaging modality that measures tissue stiffness and viscosity, to identify the optimal vibration frequency for breast examination and assess its utility in distinguishing breast cancer molecular subtypes. The study includes 159 breast lesions from 154 female patients. Researchers evaluate image quality across 10 frequency sets and compare mechanical parameters across pathological subgroups. The 40–70 Hz band delivers superior image quality, and tissue stiffness shows notable differences across cancer subtypes, aiding the identification of triple‐negative breast cancer. Optimized elastography may facilitate more precise breast cancer diagnosis.
Zero time-to-echo (ZTE) imaging allows for signal acquisition from tissues with extremely short T2* relaxation times, enabling the generation of computed tomography (CT)-like images through gray-scale inversion. To assess the usefulness of adding ZTE imaging to conventional MRI for the detection of hand and wrist bone erosions in rheumatoid arthritis (RA) patients, using CT as the reference method. Prospective. Fifteen patients with RA (4 male and 11 female; mean age, 61.8 ± 15.5 years) participated in this study. 3-T, T1-weighted image (fast spin echo), T2-weighted image (fast spin echo), ZTE imaging (gradient echo). Three radiologists independently evaluated bone erosions on plain radiography, conventional MRI, and ZTE imaging using a four-point scale (0 = normal; 1 = discrete erosion; 2 ≤ 50% of joint surface involvement; 3 ≥ 50%). Bone erosion was defined as a sharply delineated juxta-articular lesion with a cortical defect. A total of 25 anatomical sites per hand and wrist were assessed, including the distal radius and ulna, eight carpal bones, metacarpal bases, and proximal and distal aspects of the metacarpophalangeal joints. CT was interpreted by a musculoskeletal radiologist and served as the reference standard. Diagnostic performance (sensitivity and specificity) was compared with the McNemar test, and interobserver variability was assessed using Fleiss κ statistics. p values less than 0.01 were considered significant. The sensitivity and specificity of plain radiography, conventional MRI, and ZTE were 40.6/98.9%, 72.6/94.6%, and 95.9/97.6%, respectively. Interobserver agreement on bone erosion assessment was excellent for ZTE imaging (κ value of 0.822) but fair for plain radiography (κ value of 0.427) and good for conventional MRI (κ value of 0.711). ZTE imaging can provide reliable bone erosion assessment in RA patients. Stage 2. Accurate detection of bone erosions is important in rheumatoid arthritis (RA). In this prospective study, adding zero time‐to‐echo (ZTE) imaging significantly improved the detection of bone erosions compared with conventional MRI. When CT was used as the reference standard, ZTE demonstrated high sensitivity, specificity, and overall accuracy. ZTE also improved agreement between radiologists. These findings suggest that ZTE imaging may serve as a reliable and radiation‐free alternative to CT for evaluating bone erosions in patients with RA.
Despite known brain alterations in insomnia-particularly prevalent in older females-how it affects sleep-dependent glymphatic clearance remains understudied due to in vivo human measurement challenges. To investigate altered neurofluid dynamics in women with insomnia using indirect neuroimaging markers. Prospective. 46 healthy controls (HC; 56.3 ± 5.5 years) and 28 females with insomnia disorder (ID; 58.2 ± 4.9 years). 3.0 T, 3D T1-weighted magnetization-prepared rapid acquisition gradient echo, resting-state fMRI using gradient-echo echo-planar imaging, and multi-shell diffusion MRI using spin-echo-planar sequence. (1) Blood oxygen level dependent cerebral spinal fluid (BOLD-CSF) coupling measuring temporal coordination between neurovascular and CSF oscillations, (2) diffusion tensor image analysis along the perivascular space (DTI-ALPS) quantifying directional diffusivity in periventricular white matter, (3) choroid plexus (ChP) volume reflecting morphology of primary CSF-producing structures, and (4) nucleus basalis of Meynert (NBM) volume evaluating cholinergic system integrity potentially relevant to vascular regulation; (5) all participants completed self-reported sleep measures, including the Pittsburgh Sleep Quality Index (PSQI), Insomnia Severity Index (ISI), and Fatigue Severity Scale (FSS), and also underwent cognitive function testing. Analysis of covariance evaluated between-group differences controlling for demographic and clinical covariates. Relationships with cognitive and sleep scores were assessed using partial correlations, stratified by group only when significant interaction effects were detected. Multiple comparisons were false discovery rate corrected (p < 0.05). Classification model performance was evaluated using the area under the receiver operating characteristic curve (AUC). Model comparisons were performed using DeLong's tests (ΔAUC) and stepwise likelihood ratio tests (LRT) to assess classification gain and the independent incremental contribution of each biomarker; all tests were two-sided with α = 0.05. Compared to controls, insomnia patients showed significantly reduced BOLD-CSF coupling (-0.18 ± 0.20 vs. -0.32 ± 0.17), indicating altered temporal coordination between neurovascular and CSF dynamics. ChP volume was significantly enlarged in the insomnia group (1.72% ± 0.42% vs. 1.55% ± 0.39% of total intracranial volume), potentially reflecting compensatory CSF production upregulation, inflammatory changes, or vascular remodeling. NBM volume was significantly reduced in insomnia patients (201.75 ± 17.66 vs. 217.47 ± 21.04 mm3), suggesting cholinergic system alterations. In contrast, the DTI-ALPS index did not differ between groups (p = 0.85). BOLD-CSF coupling positively correlated with PSQI (r = 0.34), ISI (r = 0.41), and FSS (r = 0.40); ChP volume positively correlated with ISI (r = 0.32) and FSS (r = 0.35) (all FDR-corrected). A dataset consists of 74 participants (46 HC and 28 ID) were included, the four-marker classification model achieved moderate performance (AUC = 0.785, accuracy = 71.9%). Multiple indirect neuroimaging markers potentially related to neurofluid dynamics were altered in middle-aged and older women with chronic insomnia, except for DTI-ALPS. These findings include altered neurovascular-CSF coordination, ChP enlargement, and cholinergic system volume reduction. 2. Stage 2. Insomnia is common in middle‐aged and older women, but its effect on the brain's waste‐clearance system, known as glymphatic system, remains unclear. Using several magnetic resonance imaging (MRI) to compare 28 women with insomnia and 46 women who slept well. Three measures differed between the groups. Insomnia group showed weaker coordination between brain activity and cerebrospinal fluid flow, a larger choroid plexus (the tissue that makes this fluid), and a smaller nucleus basalis of Meynert (a region that helps control brain blood flow). A fourth, diffusion‐based measure did not differ. These results link insomnia to measurable changes in how the brain manages its fluids.
Diffusion magnetic resonance imaging (dMRI) is a widely used clinical imaging technique which is sensitive to changes in tissue microstructure including cellularity, perfusion, and tissue damage. DMRI has been used in whole-body imaging as well as in targeted imaging of every major anatomical region. Most clinical dMRI applications use a standard acquisition technique: the pulsed gradient spin echo (PGSE) preparation with echo planar imaging (EPI) readout. PGSE creates strong diffusion contrast while removing the effect of T2*, and EPI enables imaging of an entire 2D slice in a single shot. The PGSE-EPI method is rapid and robust; however, it is limited by low resolution and distortions typically caused by motion and susceptibility artifacts. Since the inception of dMRI, other methods have been used to sensitize diffusion and to read out the signal, which overcome different weaknesses of PGSE-EPI. These methods have largely been developed and used in the brain, but many of them have been applied to body dMRI as well. This review describes the major families of non-standard techniques used in body dMRI, covering both diffusion encoding strategies as well as image readout strategies. It then explores how these techniques have been applied in non-brain clinical applications and assesses the strengths and benefits of each method in various clinical contexts. Non-standard acquisition techniques have the potential to improve the value and efficiency of dMRI in the body, and further work to standardize and validate these sequences will enable their use in clinical contexts. Evidence Level: 3. Technical Efficacy: 2.
Progressive supranuclear palsy (PSP) is both an underdiagnosed and a frequently misdiagnosed disorder. To remedy these diagnostic limitations, MRI has been used to investigate brain morphology to differentiate PSP from Parkinson's disease (PD) and multiple system atrophy (MSA). However, while nigrostriatal degeneration and tau aggregation are prominent in PSP, and result in iron accumulation and atrophy in the region, substantia nigra (SN) atrophy remains an underexplored diagnostic marker. To investigate the diagnostic utility of QSM-derived SN parameters for PSP. Retrospective. 123 (59 Males/64 Females) PD patients, 48 (26 M/22 F) MSA patients, and 22 (11 M/11 F) PSP patients were included in the main dataset. MSA patients include 20 parkinsonian type (MSA-P) (11 M/9 F) and 18 cerebellar type (MSA-C) (9 M/9 F) of MSA with 10 undetermined subtype. The external validation set included 12 (6 M/6 F) healthy controls, 13 PD (7 M/6 F), and 10 PSP (6 M/4 F) patients. 3 T, MPRAGE T1-weighted imaging and multi-echo gradient echo imaging (mGRE) for QSM. Group level differences of SN volume, magnetic susceptibility, and susceptibility-to-volume ratio (SVR) among PSP, PD, and MSA groups, and these metrics' differentiating power are measured. Bivariate logistic regression with T1-based morphological markers alongside SN metrics is performed. Mann-Whitney U test for group comparisons. Receiver operating characteristic analysis with bootstrapping. p < 0.05 after Bonferroni correction is defined as statistically significant result. The SN SVR was significantly higher in the PSP group compared to the MSA group and the MSA-P group. Moreover, using pons measurements with SN SVR in a bivariate model resulted in the highest differentiation between the PSP and MSA groups (AUC = 0.88, 95% CI: [0.78-0.95]), particularly driven by the increased differentiation between the PSP and MSA-P groups (AUC = 0.88, 95% CI: [0.75-0.98]). External validation supported the generalizability of SN SVR, yielding 100% sensitivity and 80% specificity for differentiating PSP from HC and PD. QSM-based SN morphometry can complement T1-weighted imaging for Parkinsonism assessment. 3. Stage 2. Progressive supranuclear palsy is a rare movement disorder that is often mistaken for Parkinson's disease. Accurate diagnosis of this disease is important for correct treatment. To help with this, we investigated whether magnetic resonance imaging (MRI) measurements of the substantia nigra could improve diagnosis. We measured both tissue loss and iron accumulation in the substantia nigra and compared these findings between different movement disorders such as Parkinson's disease. The results showed that substantia nigra measurements helped distinguish progressive supranuclear palsy from similar disorders. Our findings suggest that substantia nigra imaging may provide valuable additional information for movement disorder diagnosis.
Photodynamic microenvironment-modulating therapy (PMMT) represents a promising strategy for nasopharyngeal carcinoma (NPC). However, early assessment of therapeutic response remains challenging. To evaluate whether intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) and blood oxygen level-dependent functional MRI (BOLD-fMRI) can noninvasively detect early responses to PMMT in an NPC xenograft model. Experimental, animal model. Subcutaneous 5-8F NPC xenograft model (110 female BALB/c nude mice). 3.0 T, T2WI FSE sequence, IVIM-DWI single-shot echo-planar imaging sequence, and BOLD-fMRI SPGR sequence. Following tumor establishment, mice were randomly assigned to five treatment groups: PBS, NH2-MIL-101(Fe), PPa@NH2-MIL-101(Fe) + near-infrared (P@MIL+NIR), Doxy@NH2-MIL-101(Fe) (D@MIL), and PPa + Doxy@NH2-MIL-101(Fe) + NIR (PD@MIL+NIR). IVIM-DWI (D and f) and BOLD-fMRI (R2*) were acquired before and after treatment to assess changes in tumor microstructure, perfusion, and oxygenation. The proliferation, apoptosis, angiogenesis, and hypoxia of NPC tumor were evaluated by Ki-67 immunofluorescence staining, TUNEL immunofluorescence staining, VEGF immunohistochemical staining, and HIF-1α immunohistochemical staining. One-way ANOVA, the intraclass correlation coefficient (ICC), Pearson's correlation analysis, and the Least Significant Difference (LSD) test for post hoc pairwise comparisons, p value < 0.05 was considered significant. Good and excellent agreements between two evaluators can be seen (The range of ICCs was from 0.864 to 0.985). In P@MIL+NIR, D@MIL, and PD@MIL+NIR groups, D and f values initially decreased and then increased, while R2* values peaked at 0.5 h (63.20 ± 2.57, 61.62 ± 0.98, and 67.38 ± 1.37) and gradually declined. D, f, and R2* values were significantly correlated with the histological staining results. The combination of IVIM-DWI and BOLD-fMRI could be used in monitoring the early therapeutic responses to PD@MIL-based PMMT in NPC. 1. Stage 1. In this study, a non‐invasive method is explored for detecting early treatment responses to nasopharyngeal carcinoma. Changes in nasopharyngeal carcinoma tumor tissue and oxygen levels after photodynamic microenvironment‐modulated therapy in mouse models were tracked using multiparametric magnetic resonance imaging techniques. The results of multiparametric magnetic resonance imaging matched well with histological findings, proving these methods can tell if the therapy works at an early stage without invasive procedures.
The feasibility of multi-frequency magnetic resonance elastography (MRE) for ovarian assessment, normative stiffness values, and related influencing factors in the general population remains unclear. To evaluate ovarian MRE feasibility, preferred frequency, normative stiffness, and influencing factors in healthy individuals. Prospective. About 55 healthy female volunteers (median age: 42; median body mass index (BMI): 23). 3 T; spin-echo echo-planar imaging sequence at 40, 60, and 80 Hz. Quality-control metrics and ovarian stiffness values (left and right) were measured for all participants. Image quality was evaluated by IQS (1-4; diagnostic images ≥ 3) and confidence percentage. Intraclass correlation coefficient (ICC); ANOVA; multivariate linear regression; significance level, p < 0.05. Quality-control metrics, including fixed-ROI average phase SD [138.63 (106.17-177.74), 127.90 (97.77-186.46), and 133.70 (92.73-185.79)] and average within-ROI phase range [605.25 (468.43-777.50), 604.00 (432.83-821.50), and 607.00 (442.00-804.80)] at 40, 60, and 80 Hz, showed no significant frequency-dependent variation (both p = 0.947), confirming no substantial vibration-induced phase artifacts. Combined with good-to-excellent reproducibility (ICCs: 0.897-0.999), these data supported the feasibility of ovarian MRE. Among tested frequencies, 60 Hz showed relatively favorable image quality, the highest IQS agreement (inter-reader/intra-reader weighted κ = 0.828-0.891/0.862-0.877). Ovarian stiffness ranges were 1.56-2.91, 2.91-3.70, and 3.10-3.89 kPa in the premenopausal, perimenopausal, and postmenopausal groups, respectively. Ovarian stiffness remained stable across menstrual-cycle phases in either ovary (left/right: p = 0.250/0.358, 0.986/0.858, 0.088/0.476, 0.249/0.448, 0.633/0.185, and 0.120/0.706). Regression analysis identified age and BMI as independent predictors of ovarian stiffness; age had a larger standardized β than BMI (0.868 vs. 0.176), as did menopausal status when replacing age (0.832 vs. 0.213). About 60 Hz provided appropriate MRE images in healthy volunteers. Ovarian stiffness was influenced by menopausal status, age, and BMI. 2. Stage 1. Normal ranges of ovarian stiffness in healthy women and factors that may affect stiffness remain unclear. This study used magnetic resonance elastography (MRE), a noninvasive imaging method that measures tissue stiffness, to assess healthy ovaries. The researchers tested three vibration frequencies: 40, 60, and 80 Hz. They evaluated whether ovarian MRE was possible and reproducible, established reference ranges, and examined menstrual cycle, menopausal status, age, and body mass index. Ovarian MRE was feasible. The 60 Hz frequency performed better. Age, body mass index, and menopausal status were associated with ovarian stiffness. These findings support future ovarian MRE studies.
Slice encoding for metal artifact correction (SEMAC) is used in MRI for total hip arthroplasties for metal artifact reduction. However, ripple artifacts often arise near the implant, impairing diagnosis in affected regions. Applying a wavelet domain filter (WD-Filter) might reduce ripple artifacts and improve image quality. Retrospective. 100 patients with primary total hip arthroplasty (female: 51, mean age: (64 ± 13) years; male: 49, mean age: (65 ± 13) years) who underwent clinically indicated MRI using compressed sensing SEMAC. 1.5 T; compressed sensing-accelerated turbo spin-echo (TSE)-based SEMAC sequence. Three readers rated 250 ripple artifacts before and after applying the WD-filter. 4-point Likert scales were used for the intensity of ripple artifacts (Likert-RA, "none": 1, "mild": 2, "moderate": 3, "severe": 4) and the image quality (Likert-IQ, "poor": 1, "moderate": 2, "good": 3, "excellent": 4). The relative reduction of the signal intensity standard deviation ( Δ S D ROI $$ \Delta S{D}_{ROI} $$ ) was measured in a region of interest (ROI) containing the ripple artifact. Inter-reader agreement was assessed with Fleiss' kappa, with 95% confidence intervals. Differences between pre- and post-filter ratings (Likert-RA and Likert-IQ) were evaluated using the Wilcoxon signed-rank test, while Δ S D ROI $$ \Delta S{D}_{ROI} $$ was compared using a two-sided paired t-test. A p value of less than 0.05 indicated statistical significance. Prior to WD-Filter application, 122 ± 2 $$ \left(122\pm 2\right) $$ ripple artifacts were rated as "severe", 95 ± 3 $$ \left(95\pm 3\right) $$ as "moderate", and 32 ± 1 $$ \left(32\pm 1\right) $$ as "mild". After filtering, 168 ± 4 $$ \left(168\pm 4\right) $$ artifacts were rated as "none", and 82 ± 4 $$ \left(82\pm 4\right) $$ as "mild". Upon filter application, Likert-RA and Likert-IQ significantly improved from 3.4 ± 0.7 $$ \left(3.4\pm 0.7\right) $$ to 1.3 ± 0.5 $$ \left(1.3\pm 0.5\right) $$ and 1.4 ± 0.5 $$ \left(1.4\pm 0.5\right) $$ to 3.4 ± 0.6 $$ \left(3.4\pm 0.6\right) $$ , respectively, with a large effect size (r > 0.89) and "almost perfect" inter-rater agreement (kappa range: 0.86-0.96). The filtered images showed a significantly reduced Δ SD ROI $$ \Delta {\mathrm{SD}}_{\mathrm{ROI}} $$ compared to the unfiltered images (relative change: 19 % ± 10 % $$ \left(19\%\pm 10\%\right) $$ ). The WD-Filter effectively reduced ripple artifacts in MRI of total hip arthroplasty and improved image quality. 3. Stage 3. MRI of patients with metal hip implants often produces wave‐like image distortions called ripple artifacts, which can interfere with the visualization of surrounding tissues and impair diagnosis. The proposed wavelet domain filter (WD‐Filter) removes these artifacts from the images after the scan, without requiring additional imaging time. In a study of 100 patients with hip replacements, three radiologists independently confirmed that the filter significantly reduced ripple artifacts and improved image quality. No cases showed worsened image quality after filtering. This post‐processing approach offers a practical tool to enhance image quality in MRI of patients with metal hip implants.
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E-cigarettes contribute to endothelial dysfunction, a known cause of systemic atherosclerotic disease that cannot be adequately characterized by a single physiological parameter measured at a single vascular bed. Quantify and compare acute effects of smoking or vaping with tobacco cigarettes (t-cigs), nicotinized e-cigarettes (e-cigs+), non-nicotinized e-cigarettes (e-cigs-) on the vascular system via quantitative MRI. Prospective. Forty one smokers/vapers (mean age 29.8 ± 7.6 years), 17 non-smokers/non-vapers (mean age 26.5 ± 3.9 years). 3 T/oximetry, blood flow velocimetry. Smokers/vapers were scanned pre- and post- three challenges (ecig+, ecig, tcig). Each challenge was on a separate day. Blood flow velocity waveform in the femoral artery was measured at rest and in response to cuff occlusion, yielding parameters characterizing hyperemia (arterial peak velocity, time to peak, time of forward flow (TFF, duration of monophasic forward flow), hyperemic index, peripheral flow reserve, (PFR, peak over baseline velocity)). The dynamics of venous oxygen saturation (SvO2) in the superficial femoral vein were quantified in terms of washout time of oxygen-depleted blood, upslope (rate of resaturation), and overshoot (peak SvO2). Aortic pulse wave velocity was evaluated. Cerebrovascular reactivity and cerebral metabolic rate of oxygen consumption were assessed at the superior sagittal sinus. Neurovascular compliance was assessed at the common carotid arteries. Paired t-tests, Wilcoxon rank sum tests, linear mixed-effects models, Bonferonni corrections. p < 0.05 indicated statistical significance. At the femoral vein and artery, across users, post-challenge, the following decreased significantly: baseline SvO2 (e-cig+: -12%; e-cig-: -14%; t-cig: -9%); baseline velocity (e-cig+: -23%; e-cig-: -22%; t-cig: -18%); TFF (e-cig+: -17%; e-cig-: -12%). The following significantly increased: upslope (e-cig+: +22%; e-cig-: +23%; t-cig: +19%); overshoot (e-cig+: +19%; e-cig-: +23%); PFR (e-cig-: +32%; t-cig: +31%). Accounting for user type, the mixed model showed TFF to decrease significantly post-challenge for all interventions: -15, -17, -23% for smokers, vapers, and dual users. e-cig+, e-cig-, t-cig exposure resulted in strong, significant acute effects on vascular function markers. 1. Stage 1. E‐cigarettes contribute to endothelial dysfunction, an early step in atherogenesis. This study used MRI to quantify and compare the acute vascular effects of tobacco cigarette smoking, nicotinized e‐cigarette vaping, and non‐nicotinized e‐cigarette vaping in cigarette smokers and e‐cigarette users. Participants underwent MRI examinations before and after smoking or vaping challenges. Both smoking and vaping significantly reduced resting femoral vein oxygen saturation and femoral artery blood velocity. These findings demonstrate the acute deleterious effects of smoking and vaping on MRI markers of vascular function.
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For preoperative cervical assessment, both CT and MRI are often required for bony and soft-tissue evaluation, yet CT entails radiation and MRI poorly depicts cortical bone. ZTE offers CT-like contrast in one examination, but whether it correlates with CT for quantitative morphometry remains still uncertain. To quantify ZTE-CT agreement for cervical osseous morphometry and to compare ZTE with conventional MRI for depicting degenerative osseous features. Prospective. 38 consecutive surgical patients (21 men, mean age 54.3 ± 11.7 years). 3.0 T MRI; sagittal T1 and T2; 3D ZTE; CT. Nine categories of cervical morphometric parameters (80 measurements per patient) were assessed using standardized anatomical landmarks; the mean and minimum of all level-specific values were derived per patient for each parameter. Two radiologists independently performed quantitative measurements; three radiologists independently assigned the degenerative osseous feature best depicted on ZTE relative to conventional MRI from four predefined categories. Intraclass correlation coefficients (ICC) and Bland-Altman analysis for quantitative measurements, and Fleiss' κ for qualitative comparison; post hoc exploratory analyses investigated unanticipated findings. A two-sided p < 0.05 was considered statistically significant. Interobserver agreement was excellent for all parameters (ICC > 0.98). For mean measurements, ZTE showed good-to-excellent agreement with CT for vertebral body height, disc height, and neuroforaminal dimensions (ICC 0.85-0.94). Minimum measurements showed moderate agreement overall; pedicle dimensions demonstrated low agreement with CT (ICC < 0.60), driven by overestimation of anatomically narrow pedicles. ZTE improved delineation of degenerative osseous features versus conventional MRI in 35 of 38 patients (92.1%; Fleiss' κ = 0.86). ZTE MRI shows strong agreement with CT for key cervical spine morphometric parameters and improves depiction of degenerative osseous changes compared with conventional MRI. However, CT may remain necessary when precise pedicle evaluation is required for surgical planning. 1. Stage 2. Preoperative planning for cervical spine surgery typically requires both CT and MRI: CT for bone evaluation and MRI for soft tissues. This study tested whether zero echo time (ZTE) MRI, a technique that generates bone‐like images during a routine MRI scan, could replace CT in 38 patients before surgery. Most ZTE measurements agreed well with CT, and ZTE showed bone changes more clearly than conventional MRI. However, ZTE was less accurate for severely narrowed pedicles—the bony channels that guide surgical screws. ZTE may reduce the need for CT in many cases, but CT remains necessary when precise pedicle measurement is required.
Assessment of amyloid-β (Aβ) burden and associated iron deposition and neurodegeneration is important for Alzheimer's disease (AD) management. Although quantitative susceptibility mapping (QSM) detects iron and myelin changes, conventional metrics suffer from signal cancelation between paramagnetic and diamagnetic components. Consequently, spatial interactions between these independent susceptibility sources and Aβ burden remain unestablished. To investigate spatial associations between regional Aβ burden and independent paramagnetic and diamagnetic susceptibility sources using χ-separation. Prospective. A total of 77 participants with mild cognitive impairment or dementia (mean age, 74 years; women, 50) examined using QSM and amyloid positron emission tomography (PET) (18F-flutemetamol or 18F-florbetapir). 3 T/QSM (3-dimensional multi-echo gradient-echo sequence). χ-separation decomposed QSM data into paramagnetic (χ-para) and diamagnetic (χ-dia) components. Centiloid-scale maps standardized PET quantification for voxel-wise analysis. The spatial relationship between Aβ load and susceptibility metrics was analyzed using voxel-wise correlations within AD-signature cortical regions. Voxel-wise spatial associations between Centiloid values and QSM metrics were evaluated using Pearson's coefficients. Spatial association was considered statistically significant if the 99% confidence interval (CI) did not cross zero. Conventional QSM showed near-zero cortical susceptibility and obscured pathological details owing to physiological cancelation. χ-separation unmasked susceptibility sources. Local Aβ deposition was consistently associated with reduced absolute χ-dia across cortical regions (mean r range: -0.267 to -0.098; all 99% CIs did not cross zero), consistent with alterations in net diamagnetic susceptibility sources, potentially involving myelin-related components. χ-para showed weaker and regionally heterogeneous associations with Aβ burden, with a positive association most evident in the precuneus (mean r = 0.072, 99% CI: 0.052-0.092). χ-separation reveals region-specific cortical alteration associated with regional Aβ pathology. By separating these susceptibility sources, this method may provide complementary information to conventional QSM, offering a refined, noninvasive approach for characterizing amyloid-associated tissue changes in AD. 2. Stage 2. This study investigated complex brain tissue changes in individuals assessed for Alzheimer's disease by combining an advanced magnetic resonance imaging technique, susceptibility source separation, with amyloid positron emission tomography. This method separates mixed susceptibility signals in the brain into paramagnetic and diamagnetic susceptibility sources, which may reflect different tissue components. The analysis examined how these separated sources relate spatially to amyloid deposition. The results showed that amyloid‐related susceptibility alterations were mainly associated with diamagnetic source changes, whereas paramagnetic associations were weaker and regionally heterogeneous. This noninvasive approach may help characterize amyloid‐associated tissue changes beyond conventional susceptibility imaging.
Environmental conditions established at facility design, construction, updates, and/or procurement of specialized equipment are the foundation of safe MR practice. Establishing an institutional MR safety program must take into consideration the conditions of the MR environment, and staff training should be tailored to its features. To identify the concordance on conditions for a safe MR environment among a variety of widely known national guidance documents. Analysis of guidance documents. Not applicable. Not specific to field strength. Information was extracted from national MR safety guidance documents about the expected conditions in a safe MR environment, and categorized among (1) facility design, (2) MR equipment selection, and (3) peripheral equipment. Commonalities and differences were identified. Descriptive statistics. Six publicly available national guidance documents for MR safety were obtained, from countries with relatively high density of MR systems (between 9 and 38 MR systems per million inhabitants): Australia, New Zealand, Sweden, Switzerland, UK, and USA. Full or partial concordance was observed among many measures related to facility design (21/25 conditions), MR equipment features (7/9 conditions), and peripheral equipment (10/13 conditions). This work identified the common and divergent recommendations on facilities and equipment from a variety of guidance documents from national sources. Highlighting common (and uncommon) features recommended by guidance can help users identify weaknesses in their MR environment. This could inform jurisdictions/countries without official guidance and serve in the development of future guidance documents or MR safety training materials. 5. 1. Human magnetic resonance imaging presents hazards to both patients and staff due to the use of magnetic fields to image the human body. The risks associated with these hazards are reduced through careful device engineering, facility design, staff expertise, institutional policies, and clinical procedures. Healthcare institutions rely on expert guidance to inform the necessary safety measures. In this work, six recognized national‐level guidance documents were analyzed to extract and compare the information related to facility design and equipment selection that establish the environment for safe practice of in vivo magnetic resonance.
The optimal velocity encoding limit (VENC) in phase contrast MRI is subject-specific because it depends on peak flow rate and the presence of flow jets. Currently, VENC is set manually with limited prior knowledge of the peak velocity. Setting the correct VENC might improve measurement precision or shorten scan times. To evaluate a workflow for autonomous selection of the optimal VENC without technologist interaction. Prospective and retrospective. The retrospective cohort included 254 scans from 113 patients (47 ± 14 years, 58 female) and 18 healthy volunteers (34 ± 15 years, 10 female). The prospective cohort included 5 patients with abnormal flow (47 ± 19 years, 2 female) and 10 healthy volunteers (28 ± 7 years, 6 female). 1.5 T, 0.55 T; Cartesian gradient echo phase-contrast sequence. A workflow has been designed to autonomously estimate and prescribe the optimal VENC. A 30s free-breathing calibration scan was followed by automatic estimation of the maximum velocity (Vmax) in < 6 s. The calculated optimal VENC was then automatically applied in the subsequent flow measurement without operator intervention. The target VENC:Vmax ratio was 1.1-1.25 according to consensus statements. Shapiro-Wilk test, nonparametric two-sided bootstrap with 90% confidence intervals, Wilcoxon signed-rank test, paired t-test. Holm correction was applied to prespecified pairwise comparisons. p < 0.05 was considered significant. Retrospective analysis demonstrated sub-optimal VENC setting in 96.5% of examinations with a VENC:Vmax ratio [2.03, 2.13] (two-sided bootstrap 90% confidence interval). In the prospective cohort, autonomous inline VENC selection yielded a mean VENC:Vmax ratio of 1.19 ± 0.10, significantly lower than subject-invariant VENC settings (VENC150:Vmax = 1.49 ± 0.31, VENC200:Vmax = 1.99 ± 0.41). Optimized VENC improved measurement precision, reducing velocity standard deviation by 41.9% ± 8.0%, and enabling shorter scan time to approximately 1/3 compared with default VENC 200 cm/s while maintaining equivalent velocity-to-noise performance. Inline autonomous VENC selection improved flow-measurement precision, simplified the acquisition workflow, and reduced scan time at 0.55 T. 2. 1. Accurate blood flow measurement with phase‐contrast MRI depends on selecting an appropriate velocity encoding value (VENC) for each individual. The VENC parameter is commonly chosen manually or preset for general coverage across subjects, resulting in reduced measurement precision. An autonomous workflow was developed to set the optimal VENC during the examination. The method produced optimal VENC values in healthy volunteers and a small cohort of patients. This approach may improve the precision and ease of use of quantitative cardiac MRI and could help standardize blood flow imaging in clinical practice.
Nasopharyngeal carcinoma (NPC) can be detected early on MRI, but adoption for screening is limited by a shortage of experienced specialists. MRI artificial intelligence (AI) algorithms for diagnosing NPC in the literature may address this, but most studies focus on routine clinical care, and their applicability in screening requires close examination. To (i) evaluate the diagnostic performance of AI for NPC detection, (ii) analyze the impact of study protocols, and (iii) assess the applicability of existing studies to NPC screening. Systematic review. Thirty-eight studies were included, including a total of 23,398 patients (20,693 NPC and 2705 non-NPC). 1.5 T to 3.0 T. Following PRISMA guidelines, PubMed, Scopus, and Embase records from January 1, 2009 to August 16, 2025 were screened by two independent reviewers for studies on NPC detection, localization, and/or diagnosis using MRI. Included studies were reviewed for applicability and risk of bias. Lesion-localization performance (Dice similarity score [DSC]) and NPC vs. non-NPC discrimination (sensitivity/specificity) were extracted and summarized. Subgroup analyses assessed the impact of intravenous contrast on AI performance. Meta-analysis used standard random-effects univariate restricted maximum likelihood model and hierarchical summary receiver operator characteristics for performance pooling and subgroup analysis, taking p value < 0.05 as significance. Pooled performance from 30 localization and 6 discrimination studies was DSC = 0.80 (CI: 0.78-0.82) and sensitivity/specificity = 97.1% (CI: 88.0%-99.3%)/87.8% (CI: 78.9%-93.2%), respectively. Intravenous contrast did not significantly affect AI performance for either task (p > 0.05). Only seven studies were fully applicable to screening. AI-driven NPC screening using MRI is feasible at high sensitivity. Using non-contrast MRI did not significantly impact AIs' performance. However, applicability and the suboptimal ratio of NPC: non-NPC patients remain the weaknesses of existing studies, warranting further investigation with cohorts that better reflect the screening scenario. The systematic review protocol of this system is registered with the Inplasy registry (Ref. INPLASY202570076).
A previous single-case study has demonstrated that a modified time-spatial labeling inversion pulse (Time-SLIP) technique, specifically Deep Abdominal Breathing-induced CSF Flow Imaging with Time-SLIP (DAB Time-SLIP), successfully visualized dynamic cerebrospinal fluid (CSF) flow during deep breathing with superior contrast compared to conventional Time-SLIP. However, it is unclear whether this occurs consistently across healthy individuals. To investigate CSF flow dynamics during deep breathing in healthy volunteers with the DAB Time-SLIP. Prospective. 10 healthy participants (7 men; mean age, 29.5 years). 1.5-Tesla, Time-SLIP. Midsagittal Time-SLIP imaging was performed using a 9 s repetition interval. A labeling pulse was applied at four vertebral levels (Th11-L1-L3-L5 or Th12-L2-L4-S1), and images were acquired after a 2 s delay. Separate imaging sessions were conducted during shallow breathing and during a structured 8 s deep abdominal breathing cycle. During deep-abdominal-breathing, an intentional phase shift between the 9 s imaging interval and the 8 s respiratory cycle enabled visualization of CSF movement across the entire cycle within 72 s. This protocol for CSF dynamics during deep-breathing was designated as DAB Time-SLIP. Images acquired under these two breathing conditions were compared with the reference label images obtained during breath-holding, and CSF flow velocity and displacement range were quantified based on the resulting positional changes. Wilcoxon signed-rank test and simple linear regression analysis. A p < 0.05 was considered significant. Cranial flow occurred during inhalation, whereas caudal flow was observed during exhalation. Both the magnitude and the displacement range of CSF flow velocity and CSF movement of range progressively decreased toward the caudal direction (rS = -0.9479). Compared with free breathing, the range of CSF movement using DAB Time-SLIP was significantly greater. DAB Time-SLIP demonstrated cranial CSF flow during deep inspiration and caudal CSF flow during deep expiration. Stage 1. Deep Abdominal Breathing‐induced CSF Flow Imaging with Time‐SLIP (DAB Time‐SLIP) enables visualization of lumbar spinal CSF flow. In the lumbar region, spinal CSF flow velocity tends to be lower in the caudal direction and higher in the cranial direction. In addition, it exhibits greater displacement during deep breathing than during free breathing. This approach may be applicable to spinal disorders, such as lumbar spinal stenosis, warranting further investigation.
Access to MRI is limited by lengthy exam times and inefficient utilization. Focused protocols can reduce exam times, but workflow variability and inefficient room turnaround contribute to conservative scheduling with long exam slots. To develop and evaluate a high-throughput clinical MRI suite architecture and workflow, using an AI-prescribed free-breathing chemical shift-encoded (CSE) MRI exam to quantify liver proton density fat fraction (PDFF) in under 5 min of total MRI room time. Prospective. 24 healthy volunteers in two cohorts: 12 research staff (7 women/5 men; age 26.8 ± 5.8 years) and 12 community volunteers (6 women/6 men; age 41.3 ± 13.5 years). 1.5 T; free-breathing 2D multi-echo gradient echo CSE-MRI. Each participant underwent three nonconsecutive CSE-MRI exams in a continuously queued workflow to characterize timing and PDFF repeatability. Workflow intervals were recorded from timestamped video review and image metadata. Staff cohort exams included two CSE-MRI acquisitions to assess within-exam repeatability, while community cohort exams included one to simulate clinical practice. Three radiologists (8/13/14 years of experience) independently evaluated AI-automated prescriptions for complete liver coverage and rated CSE-MRI image quality (five-point Likert scale). Student's t-tests; Gwet's AC2; repeatability coefficients (RCs) with bootstrap 95% confidence intervals; Bland-Altman analysis. p < 0.05 was significant. Diagnostic image quality was achieved in all 72 exams (median PDFF Likert score 5/5, inter-rater AC2 ≥ 0.86). Total MRI room times averaged 4:09 ± 0:14 min (staff) and 3:35 ± 0:34 min (community). Turnaround times averaged under 2 min, enabling throughput of 16.1 exams per hour in the community cohort. Automated prescription achieved complete liver coverage in all exams. PDFF RCs were 0.78% (staff within-exam), 0.99% (staff between-exam), and 1.21% (community between-exam) absolute PDFF. The proposed high-throughput MRI workflow achieved over 16 exams per hour with highly repeatable liver fat quantification, demonstrating a framework for improving MRI utilization and access. 1. 2. Liver disease affects over two billion people globally, and magnetic resonance imaging (MRI) can detect liver fat buildup that signals early disease. Liver MRI exams frequently take 30–60 min per patient, limiting access. This study tested a faster workflow combining three innovations: a redesigned MRI suite with movable tables that enable simultaneous patient preparation and imaging; software that automatically positions imaging volumes over the liver; and an imaging method that does not require breath‐holding, which slows conventional liver MRI. With this approach, over 16 patients could be imaged per hour while keeping fat measurements accurate and reliable.