This study employed a before-and-after design and utilized proton density fat fraction (PDFF) magnetic resonance imaging (MRI) to investigate the effects of 7 days of -6° head-down tilt bed rest (HDBR) on the lower limb muscles of healthy men. We performed multiple MRI scans of the participants’ thighs and calves during the HDBR period and collected blood and urine samples at corresponding time points to analyse biomarkers. We observed a sustained and significant reduction in thigh muscle cross-sectional area (TMCSA) and medial head of the gastrocnemius muscle cross-sectional area (MHMCSA) during HDBR (p < 0.001). The thigh subcutaneous adipose tissue area (TSAT) and the calf subcutaneous adipose tissue area (CSAT) showed a downward trend at the onset of HDBR, followed by a gradual recovery. During HDBR, both the thigh and calf muscle contractile mass index (CMI) exhibited a significant and sustained downward trend. Phosphorus (P), direct renin (DR), and red blood cells (RBC) showed significant correlations with muscle/fat parameters (p < 0.05). Our findings indicate that short-term HDBR leads to lower limb muscle atrophy and subcutaneous fat redistribution, and that these changes are dynamically associated with stress responses, metabolic indicators, and biomarkers related to bone metabolism.

Spaceflight microgravity induces complex cerebral blood flow (CBF) alterations, which may threaten neurological health including cognitive impairment and sensorimotor disturbances of astronauts. How CBF is regulated during microgravity, especially its coupling with carotid hemodynamics, remains poorly understood. This study investigated the coupling between acute hemodynamic changes in internal carotid and vertebral arteries (ICAs and VAs) and CBF, and evaluated the potential of ultrasound-derived parameters as portable predictors for CBF under simulated microgravity using –6° head-down tilt (HDT) bed rest (BR). Thirty-three male participants underwent Doppler ultrasound assessments of ICAs and VAs, and 3-dimensional pseudocontinuous arterial spin labeling (3D-pcASL) perfusion magnetic resonance imaging (MRI), at baseline and 12 h after initiation of HDT BR. Hemodynamic parameters and regional CBF values were compared and linear regression analysis was conducted to identify predictors of changes in CBF (ΔCBF), defined as the change between 12-h HDT and baseline. Ultrasound revealed no significant changes in the bilateral ICAs. In left VA, flow velocity was significantly reduced, and right VA showed decreased resistance index, pulsatility index, and systolic/diastolic ratio. CBF significantly decreased with the most pronounced reductions in posterior circulation. ΔCBF in posterior circulation regions was associated with ultrasound parameters, and anterior circulation was predominantly predicted by baseline CBF. In summary, short-term simulated microgravity reduced CBF and this reduction was closely linked to large-vessel hemodynamic alterations, especially in the posterior circulation. These findings support the potential of ultrasound as a portable and predictive tool for early CBF assessment during spaceflight.

Background:Simulated microgravity, modeled by head-down tilt (HDT), induces cephalad fluid shifts that perturb intracranial hemodynamics and may affect cognitive function. However, the temporal adaptation of cerebral arterial blood flow (CaBF), both during simulated microgravity and throughout the recovery phase, remains incompletely understood. Methods:In this study, 38 healthy male participants underwent a 7-day -6° HDT protocol followed by a 5-day recovery phase. Four-dimensional flow magnetic resonance imaging (4D flow MRI) was performed at 8 time points [baseline, HDT 12 h, HDT 1 d, HDT 3 d, HDT 7 d, recovery (R) 1 d, R 3 d, and R 5 d] to quantify CaBF and total cerebral blood inflow (TCBI) in the basilar artery (BA), left and right internal carotid arteries (ICAL and ICAR), and left and right middle cerebral arteries (MCAL and MCAR). Systemic vitals and fasting cortisol/renin were collected, and a computerized reaching task assessed reaction time (RT), movement time (MT), and peak velocity (PV). Time effects were tested with repeated-measures analysis of variance (RM ANOVA) or the Friedman test. Predictors of ≥10% TCBI decrease during HDT and ≥10% TCBI increase during the recovery phase were assessed using logistic regression, and flow-behavior associations were examined using Spearman correlation. Results:No significant vessel lumen area changes were found after post-hoc analysis, despite an overall difference observed in the MCAR (χ²=17.40, P=0.015). However, average blood flow significantly changed in the ICAL (χ²=34.16, P<0.001), MCAL (χ²=73.11, P<0.001), and MCAR (χ²=49.02, P<0.001), while BA was stable (RM ANOVA F=0.787, P=0.599) and ICAR showed no significant pairwise effects despite an overall difference (χ²=16.35, P=0.022). TCBI progressively declined during HDT and rebounded rapidly at the onset of recovery (P<0.001). Logistic regression identified systolic blood pressure (SBP) as an independent predictor of a ≥10% TCBI reduction during HDT [P=0.044, odds ratio (OR)=3.004, 95% confidence interval (CI) 1.028-8.777], and baseline cortisol levels predicted significant TCBI decreases from baseline to HDT 7 d (P=0.047, OR=1.306, 95% CI 1.004-1.699). Cognitive-motor testing further revealed phase-dependent changes, with RT and MT generally shortening, most consistently in the no-beep condition, while PV remained stable with beep but increased without beep. Apart from an exploratory negative correlation between TCBI rebound and cued PV (r=-0.360, P=0.031), TCBI changes were largely decoupled from behavioral outcomes. Conclusions:This study demonstrates vessel-specific, lateralized adaptation of cerebral arterial inflow during 7 days of -6° HDT and 5 days of recovery, with anterior circulation more responsive to posture-induced fluid shifts and TCBI gradually decreasing then rapidly rebounding after re-ambulation. Interindividual TCBI susceptibility reflects blood pressure and endocrine status, while cognitive-motor changes remain weakly coupled, underscoring the importance of incorporating early-recovery assessments into HDT studies to better characterize cerebrovascular readaptation after re-ambulation. Clinical Trials Registry:ChiCTR2500096128.

Prolonged microgravity exposure disrupts cerebral hemodynamic homeostasis, yet longitudinal cerebral blood flow (CBF) adaptation remains poorly understood. This study investigated CBF changes under 90 days head-down bed rest (HDBR) in 36 healthy adults using pseudo-continuous arterial spin labeling (pCASL) MRI. Analyses included region-of-interest (global/regional CBF) and voxel-based whole-brain assessments, alongside physiological correlations. Results demonstrated stable global CBF after HDBR but revealed distinct microcirculatory redistribution: the vertebrobasilar (VB) territory exhibited significant perfusion increases, while voxel-based analysis identified elevated CBF in the left fusiform gyrus and reduced perfusion in the right superior frontal gyrus, middle cingulate gyrus, and Heschl's gyrus. Physiological correlations indicated negative associations between VB-CBF and diastolic blood pressure (DBP)/mean arterial pressure (MAP), with pre-HDBR heart rate as a key modulator of VB perfusion changes. A potential relationship between age and altered CBF has been found in the right superior frontal gyrus in young adults. These findings suggest that although global CBF stabilizes during simulated microgravity, posterior circulation-dominated microvascular redistribution occurs, tightly coupled with cardiovascular dynamics, offering critical insights for optimizing countermeasures in spaceflight and terrestrial cerebrovascular diseases.

Understanding how the kidney adapts to microgravity is essential for safeguarding astronaut health. Although previous studies have emphasized functional alterations, direct evidence regarding renal structural or hemodynamic changes in humans under simulated microgravity remains limited. This study aimed to evaluate the short-term effects of simulated microgravity on renal macroscopic morphology and hemodynamics using portable ultrasound during a 7-day −6° head-down tilt bed rest (HDT BR) protocol. Eighteen healthy male participants underwent continuous −6° HDT BR for 7 days. Bilateral renal structural parameters (length, anteroposterior diameter, transverse diameter, volume, parenchymal and cortical thickness) and hilar Doppler parameters, including peak systolic velocity, end-diastolic velocity, time-averaged maximum velocity, time-averaged mean velocity, resistive index, pulsatility index and systolic/diastolic ratio, were assessed before and after HDT BR. Vital signs were monitored concurrently. After 7 days of HDT BR, heart rate decreased significantly, whereas diastolic blood pressure and mean arterial pressure increased (P < 0.05). However, no significant differences were observed in any renal macrostructural or hilar Doppler parameters on either side (all P > 0.05). Despite systemic cardiovascular adjustments, renal macroscopic morphology and hilar hemodynamics remained stable after 7 days of simulated microgravity. These findings suggest short-term stability of renal macrostructural and hilar hemodynamic parameters under the specific conditions studied, without detectable changes by ultrasound. This study provides human data that contribute to the understanding of renal responses under short-term simulated microgravity conditions.

Background: Pontine infarction (PI) accounts for 7% of ischemic strokes, yet motor recovery varies significantly despite comparable lesion topography. The neural mechanisms underlying this heterogeneity remain unclear. This study aimed to investigate lesion laterality-dependent functional reorganization within the motor execution network following PI through the use of region of interest (ROI)-based resting-state functional magnetic resonance imaging (rs-fMRI). Methods: A total of 31 patients with acute unilateral PI [19 with left PI (LPI) and 12 with right PI (RPI)] and 31 matched controls underwent rs-fMRI. Seed-based functional connectivity (FC) analysis of the motor execution network was performed with spherical ROIs (6-mm radius). Group differences in FC were tested with one-way analysis of variance (ANOVA) and post hoc Bonferroni correction [cluster-level family-wise error (FWE)-corrected P<0.05]. Correlations between FC, infarct volume, and National Institute of Health Stroke Scale (NIHSS) scores were assessed. Results: No significant intergroup differences were observed in age, education years, head motion parameters, or gender distribution (P>0.05). Lesion volumes during the acute phase and NIHSS scores did not differ significantly between the LPI and RPI groups (P>0.05). In patients with LPI, FC was enhanced between the right dorsolateral prefrontal cortex (DLPFC) and the thalamus/basal ganglia, between the right supplementary motor area (SMA)/precentral gyrus and ipsilateral basal ganglia, and between the thalamus and bilateral cerebellum (all cluster-level FWE-corrected P values <0.05). In contrast, FC was reduced within the ipsilateral motor cortex and between the ventral premotor cortex and sensory cortex (all cluster-level FWE-corrected P values <0.05). In patients with RPI, FC was enhanced between the posterior cingulate cortex (PCC)/precuneus and thalamus and between the left SMA and contralateral basal ganglia (all cluster-level FWE-corrected P values <0.05). Within the LPI group, the FC between the right DLPFC and thalamus correlated positively with infarct volume (r=0.575; P=0.012). However, no significant correlations were observed between FC alterations and NIHSS scores or the NIHSS motor subscores (upper and lower extremity items), respectively, in either the LPI or RPI groups (all P values >0.05). Conclusions: Motor recovery post-PI may be influenced by dynamic imbalances in multinetwork early alterations and potentially shaped by lesion laterality: left-sided lesions primarily show recruitment of contralateral prefrontal cognitive resources, whereas right-sided lesions appear to engage default mode network (DMN)-mediated spatial remapping. The thalamo-basal ganglia hub may orchestrate transhemispheric integration, and its FC alterations, such as those within the DLPFC-thalamic pathway, might reflect compensatory potential, potentially offering insights into rehabilitation strategies. However, longitudinal studies are needed to validate these preliminary findings.

BACKGROUND:Ultra-high-field 5 T MRI systems offers potential advantages in signal-to-noise ratio(SNR) for visualizing fine anatomical structures. This prospective study aimed to assess the feasibility of parotid gland imaging in patients with Sjögren's syndrome (SS) at 5 T MRI and to compare image quality and fat fraction (FF) with between 5 T and 3 T MRI. METHODS:Thirty-one patients with SS underwent MRI examinations on both 3 T and 5 T scanners from October 2024 to August 2025. The sequences included transverse T1-weighted (T1W) sequence, transverse T2-weighted (T2W) fat-only, transverse T2-weighted (T2W) water-only, 3D MR sialography(MRS), and sequences for FF quantification: Iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL-IQ) at 3 T/Fat Analysis & Calculation Technique (FACT3d) at 5 T. Image quality was assessed subjectively using a five-point Likert scale and objectively by calculating signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and the contrast ratio (CR). MRS sialography staging and parotid gland FF measurements were also performed. Statistical comparisons were made using paired t-tests, Wilcoxon signed-rank tests, Bland-Altman analysis, Pearson Correlation analysis and intraclass correlation coefficient (ICC). RESULTS:Compared with 3 T MRI, 5 T MRI demonstrated significantly superior subjective image quality scores, SNR, and CNR across all anatomical sequences (all p < 0.05), with the most pronounced improvement on T2WI. 5 T MRS showed a tendency to detect more advanced ductal changes and achieved significantly higher ductal CNR (all p < 0.05). FF measurements between 5 T and 3 T showed excellent agreement and a strong positive correlation (r = 0.981, p < 0.01). CONCLUSIONS:5 T MRI provides markedly improved image quality for parotid gland assessment in SS while maintaining excellent consistency in FF quantification and sialography staging compared with 3 T MRI, highlighting its potential for detecting early-stage glandular changes.

This study aimed to investigate cervical vessel hemodynamics during 7 days of −6° head-down tilt (HDT) bed rest (BR) and 5 days of recovery in 40 healthy males, focusing on bilateral analysis and dynamic temporal monitoring. Diameter, flow velocity, and blood flow volume (BFV) of bilateral common (CCAs), internal (ICAs), external carotid arteries and vertebral arteries (VAs) were measured at eight time points using ultrasound. Cervical vessels exhibited heterogeneous and lateralized responses. Left VA exhibited the most pronounced BFV and velocity fluctuations, with significant reductions during HDT and recovery to baseline post-HDT, while right VA remained stable. CCAs and ICAs had dynamic diameter and velocity changes, but stable BFVs. Left VA BFV reduction was significantly associated with right VA dominance, elevated heart rate, and increased mean arterial pressure at HDT 3 d. Despite stable total BFV, left VA BFV declined during BR, warranting further monitoring.

Purpose: Dobutamine, a sympathomimetic agent, is widely used clinically, influencing cardiac output, heart rate (HR), and blood pressure (BP), which may impact cerebral blood flow (CBF), critical for brain metabolism. However, the effects of dobutamine on CBF and internal carotid artery (ICA) blood flow remain unclear, with contradictory reported in both clinical and animal studies. It is necessary to investigate the effects of dobutamine on cervical and cerebral hemodynamics. This study aimed to evaluate the effects of dobutamine infusion on ICA blood flow and CBF, explore their relationship, and identify factors influencing CBF to facilitate timely monitoring in clinical practice. Methods: Forty-eight healthy volunteers underwent physiological assessment, ICA ultrasound, and brain magnetic resonance imaging (MRI) data before and after the administration of dobutamine. Paired t and Wilcoxon signed-rank tests were used to analyze changes, while logistic regression explored associations between hemodynamic factors and CBF. Results: Dobutamine infusion significantly increased HR, respiration rate, systolic BP (SBP), diastolic BP (DBP), and mean arterial pressure, while blood oxygen remained stable. Compared with those in the resting state, the peak systolic velocity (Vs), resistance index, pulsatility index, and systolic/diastolic ratio (S/D) increased, whereas end-diastolic velocity (Vd) decreased. ICA diameter and mean velocity showed no significant changes. CBF significantly decreased in the anterior and middle cerebral arteries. Logistic regression identified SBP, DBP, and S/D difference as key factors associated with CBF reduction. Conclusions: Dobutamine altered ICA hemodynamics and reduced CBF in anterior and middle cerebral arteries. Real-time ICA ultrasound monitoring provides valuable guidance during clinical use.

Dobutamine, an inotropic agent, is known to enhance cardiac function. However, its concurrent effects on cervical artery hemodynamics and cerebral microcirculation, along with their potential correlation, remain unclear. This study aimed to investigate these relationships in healthy volunteers under dobutamine stress. In this self-controlled study, cervical artery hemodynamic parameters, including vessel diameters, peak systolic velocity, end-diastolic velocity (EDV), mean flow velocity (MV), resistance index and pulsatility index of cervical arteries parameters of 20 healthy volunteers were obtained via ultrasound. Whole-brain cerebral blood flow (wCBF_ASL) and cerebral blood flow in regions of interest (CBF_ROI) were obtained by magnetic resonance imaging using arterial spin labeling before and during the dobutamine stress test. Blood flow (BF) in the cervical arteries were calculated from the MV and the vessel diameter. Ultrasound-derived cerebral blood flow (CBF_US) was defined as the sum of the BF from the left and right internal carotid arteries (ICA) and the vertebrobasilar artery. Overall cerebral blood flow, measured by both CBF_US and wCBF_ASL, remained unchanged during dobutamine stress (P > 0.05). However, dobutamine induced significant reductions in CBF_ROI in specific regions, including the right middle temporal pole, left middle temporal pole, and left cerebellum (P < 0.05). Notably, linear regression analysis revealed that the change in EDV of the right internal carotid artery (ICA-R) was a significant positive predictor of the CBF change in the right middle temporal pole (B = 0.32, p = 0.042). Dobutamine administration can induce regional cerebral hypoperfusion despite stable global cerebral blood flow. Alterations in ICA hemodynamic parameters are correlated with these regional perfusion deficits. These findings suggest that monitoring cervical artery hemodynamics during dobutamine administration may offer insights into regional cerebral perfusion changes, and could potentially be explored as a complementary tool for risk stratification in patients undergoing dobutamine stress tests.

To assess the stability of liver perfusion quantification using arterial spin labeling MRI (ASL-MRI) in healthy subjects. The arterial and portal venous liver perfusion were measured with two pseudo-continuous ASL acquisitions at a 3.0-Tesla MRI system. To assess the short-term repeatability of ASL-MRI, twelve healthy subjects underwent three consecutive ASL examinations in the fasting state. Following meal ingestion, the postprandial liver perfusion was measured. Changes in liver perfusion measured by ASL before and after meal ingestion, and their correspondence with portal vein hemodynamic variations assessed by Doppler ultrasonography (US), were analyzed to evaluate the stability of ASL in detecting postprandial perfusion alterations. The arterial and portal venous liver perfusions in healthy volunteers under the fasting condition were 59.3 ± 17.8 and 237.6 ± 71.9 mL/100 g/min, respectively. Both the arterial and portal venous liver perfusion results demonstrated excellent short-term repeatability (ICCs, 0.97, 0.96; CVs, 6.43

Background:The microgravity-induced cephalad fluid shift is thought to contribute to neuro-ophthalmological changes such as optic disc edema, globe flattening, and hyperopic shift. However, the effects of prolonged simulated microgravity on ophthalmic alterations and their potential relationship with functional reorganization in the visual cortex remain unclear. This study aimed to address these knowledge gaps. Methods:A total of 36 participants underwent a 90-day -6° head-down tilt bed rest (HDTBR), a well-established ground-based model for simulating microgravity. Ophthalmic and neuroimaging assessments were performed at three time points: baseline, 1-3 days post-HDTBR, and after a 28-day recovery period. The evaluations included visual function tests such as near visual acuity (NVA), distance visual acuity, best-corrected visual acuity (BCVA), contrast sensitivity, and stereopsis, along with ocular blood flow (OBF) measurements using three-dimensional pseudo-continuous arterial spin labeling (3D-pcASL) and functional connectivity (FC) analysis of the visual cortex via functional magnetic resonance imaging (fMRI). Results:OBF, NVA, and BCVA exhibited a consistent and significant decrease following 90-day HDTBR (all P<0.05). Meanwhile, FC within the primary visual cortex (V1) and the left parietal area F, part M (PFm), as well as between V1 and the visual area 3 (V3), showed a significant increase (voxel level P<0.001, cluster level P<0.025, false discovery rate corrected). Additionally, changes in OBF were positively correlated with alterations in BCVA (r=0.3981, P=0.0162), whereas increased FC between V1 and V3 was associated with a decline in BCVA (r=-0.3394, P=0.0429). Notably, our findings suggest that more than 1 month of recovery may be required to fully counteract these ocular and neural adaptations. Conclusions:OBF may be a key risk factor for decreased visual acuity in stimulated microgravity, potentially driving functional network reorganization of the visual cortex by modifying visual function. These insights contribute to a new insight for ophthalmic health risks associated with human spaceflight.

Objective: To investigate the effects of 7-day −6° head-down bed rest (HDBR) on lower limb muscle volume, fat, and muscle strength in healthy males. Materials and Methods: In this prospective study, thigh and calf proton density fat fraction (PDFF) magnetic resonance imaging (MRI) was performed on 34 (thigh-measured) and 32 (calf-measured) healthy male participants. These participants were subjected to the HDBR trial between July 2024 and September 2024 at five time points: baseline (PRE), bed rest day 3 (BR3), day 7 (BR7), and recovery days 3 (R3) and 5 (R5). Muscle volume, subcutaneous fat volume, muscle PDFF, and subcutaneous fat PDFF were quantified. Blood and urine samples were collected to measure biomarkers. Analysis of dynamic changes in indicators of thigh and calf parameters and their correlation with biomarkers. Results: A total of 34 healthy male participants underwent HDBR. 34 (mean age, 28.03 ± 6.74 [SD]) had thigh measurements, and 32 (mean age, 27.47 ± 5.79 [SD]) had calf measurements. Bilateral thigh muscle cross-sectional area (MCSA) and bilateral medial head of gastrocnemius muscle cross-sectional area (MHMCSA) decreased consistently and significantly during HDBR (p<0.001). Thigh subcutaneous adipose tissue (SAT) and calf subcutaneous adipose tissue (CSAT) areas initially decreased, then gradually increased during HDBR, with inflection points at BR3. Left thigh subcutaneous adipose tissue fat fractions (SATL-FF) and left calf subcutaneous adipose tissue fat fractions (CSATL-FF) increased consistently and significantly during HDBR (p<0.001). The right medial head of the gastrocnemius muscle intramuscular fat fraction (MHIMFR-FF) increased significantly during HDBR (p=0.035). Significant correlations (p<0.05) were observed between urinary cortisol, cortisol, red blood cells, and calcium with muscle/fat parameters. Conclusion: Short-term HDBR induces lower limb muscle atrophy and subcutaneous fat redistribution, which are dynamically correlated with stress, metabolic, and bone metabolism-related biomarkers.

Objective To evaluate the effect of stent implantation for vertebrobasilar artery stenosis，by using 3D arterial spin labeling (3D ASL) technique. Methods A retrospective analysis was conducted on the clinical and 3D ASL data of 48 patients who underwent vertebral-basilar artery stenting. Post-labeling delay times (PLD) of 1.5 s and 2.5 s were chosen, and the average regional cerebral blood flow (rCBF) values were measured in nine brain regions of the posterior circulation: bilateral thalamus, bilateral occipital lobes, bilateral cerebellar hemispheres, midbrain, pons, and medulla. The 48 patients were divided into two groups based on the presence or absence of acute ischemic stroke in the posterior cerebral circulation region detected by diffusion-weighted imaging (DWI). The preoperative and postoperative rCBF results were statistically analyzed. Results In the infarct group, there were significant increases in rCBF values of all nine brain regions at both PLD = 1.5 s and 2.5 s postoperatively compared to preoperatively. At PLD = 1.5 s, statistically significant differences in rCBF values between the preoperative and postoperative periods were found in the right thalamus, left cerebellum, midbrain, and pons regions (P < 0.05). At PLD = 2.5 s, statistically significant differences in rCBF values between the preoperative and postoperative periods were observed in the left occipital lobe, right cerebellum, midbrain, and pons regions (P < 0.05). When analyzing the rCBF values of the brain regions with recent infarcts in the infarct group, there was a significant increase in postoperative rCBF values compared to preoperative values (P < 0.05). After excluding the data from brain regions with recent infarcts, the CBF values in the remaining brain regions were also increased postoperatively, and some brain regions showed statistically significant differences in rCBF values between the preoperative and postoperative periods (P < 0.05). In the non-infarct group, there were no statistically significant differences in the preoperative and postoperative rCBF values in all brain regions at both PLD = 1.5 s and 2.5 s (P > 0.05). Conclusion The application of 3D ASL technology shows significant value in assessing the surgical efficacy of vertebral-basilar artery stenting, especially in patients with acute posterior circulation infarction.

Posterior circulation ischemic stroke (PCIS) possesses unique features. However, previous studies have primarily or exclusively relied on anterior circulation stroke cases to build machine learning (ML) models for predicting onset time. To date, there is no research reporting the effectiveness and stability of ML in identifying PCIS onset time. We aimed to build diffusion-weighted imaging-based ML models to identify the onset time of PCIS patients. Consecutive PCIS patients within 24 h of definite symptom onset were included (112 in the training set and 49 in the independent test set). Images were processed as follows: volume of interest segmentation, image feature extraction, and feature selection. Five ML models, naïve Bayes, logistic regression, tree ensemble, k-nearest neighbor, and random forest, were built based on the training set to estimate the stroke onset time (binary classification: ≤ 4.5 h or > 4.5 h). Relative standard deviations (RSD), receiver operating characteristic (ROC) curves, and the calibration plot was performed to evaluate the stability and performance of the five models. The random forest model had the best performance in the test set, with the highest area under the curve (AUC, 0.840; 95

目的:探讨噬血细胞综合征(HLH)患者桥脑病变MRI特征及病因.资料与方法:回顾性分析2019年6月—2022年6月北京友谊医院18例HLH患者桥脑病变的MRI特征及临床资料,MRI分析包括病变位置、平扫及增强信号特征、是否有桥脑外病灶、复查变化,并与临床症状、血液生化结果、脑脊液生化结果进行对照分析.结果:18例患者中16例无中枢神经系统症状;15例(83.3％)病变检出前曾发生电解质紊乱(低钠或低钾),14例行脑脊液检查者3例(21.4％)合并脑脊液生化异常;MRI表现为桥脑中央部病灶,T1WI低信号,T2WI及FLAIR高信号,12例(66.7％)表现为DWI高信号但ADC值不低,3例(16.7％)表现为DWI高信号且ADC值减低,6例(33.3％)检出桥脑外病灶;电解质紊乱纠正及鞘内注射化疗药物后,桥脑病变变化不一,与临床预后无确切关联.结论:当HLH患者发生桥脑中央病变时,可能的原因为桥脑中央髓鞘溶解(CPM)或HLH中枢神经系统(CNS-HLH)受累,临床上需关注电解质变化情况,警惕CPM的发生及进展,同时结合脑脊液生化检查判断有无CNS-HLH并进行针对性的治疗.

Background It is unclear whether dobutamine, commonly used clinically in echocardiography and short-term congestive heart failure treatment for promoting increased myocardial contractility, affects brain microcirculatory behavior. Cerebral microcirculation plays an important role in ensuring adequate oxygen transport. Therefore, we investigated the effects of dobutamine on cerebral hemodynamics. Methods Forty-eight healthy volunteers without cardiovascular or cerebrovascular disease underwent MRI to obtain cerebral blood flow (CBF) maps using 3D pseudocontinuous arterial spin labeling before and during the dobutamine stress test. Additionally, cerebrovascular morphology was obtained based on 3D-time-off-light (3D-TOF) magnetic resonance angiography (MRA). Electrocardiogram, heart rate (HR), respiration rate (RR), blood pressure, and blood oxygen were simultaneously recorded before and during dobutamine injection and during recovery (not during MRI). The anatomic features of the circle of Willis and the basilar artery (BA) diameter were assessed on MRA images by two radiologists with extensive neuroimaging experience. Binary logistic regression was used to test for the independent determinants of CBF changes. Results HR, RR, systolic (SBP), and diastolic blood pressure (DBP) significantly increased after dobutamine infusion. Blood oxygen levels remained similar. Compared to the CBF in the resting state, the CBF values exhibited significantly lower CBF levels in both grey matter and white matter. Furthermore, compared with the CBF in the resting state, that in the stress state was decreased in the anterior circulation, mainly in the frontal lobe (voxel level P < 0.001, pixel level P < 0.05). Logistic regression showed that body mass index (BMI; odds ratio [OR] 5.80, 95% confidence interval [CI] 1.60–21.01, P = 0.008], resting SBP (OR 0.64, 95% CI 0.45–0.92, P = 0.014), and BA diameter (OR 11.04, 95% CI 1.05–116.53, P = 0.046) were significantly associated with frontal lobe CBF changes. Conclusions Dobutamine-induced stress significantly decreased CBF in the frontal lobe anterior circulation. Individuals with a high BMI and low SBP during the dobutamine stress test are more likely to have a stress-induced CBF decrease. Thus, attention should be paid to blood pressure, BMI, and cerebrovascular morphology of patients undergoing dobutamine stress echocardiography or those receiving intensive care or anesthesia.

Introduction There is a growing interest in exploring brain-heart interactions. However, few studies have investigated the brain-heart interactions in healthy populations, especially in healthy young adults. The aim of this study was to explore the association between cardiovascular and spontaneous brain activities during dobutamine infusion in healthy young adults. Methods Forty-eight right-handed healthy participants (43 males and 5 females, range: 22–34 years) underwent vital signs monitoring, cognitive function assessment and brain MRI scans. Cardiovascular function was evaluated using blood pressure and heart rate, while two resting-state functional magnetic resonance imaging (rs-fMRI) methods—regional homogeneity (ReHo) and amplitude of low-frequency fluctuation (ALFF)—were used together to reflect the local neural activity of the brain. Logistic regression was used to model the association between brain and heart. Results Results showed that blood pressure and heart rate significantly increased after dobutamine infusion, and the performance in brain functional activity was the decrease in ReHo in the left gyrus rectus and in ALFF in the left frontal superior orbital. The results of logistic regression showed that the difference of diastolic blood pressure (DBP) had significant positive relationship with the degree of change of ReHo, while the difference of systolic blood pressure (SBP) had significant negative impact on the degree of change in ALFF. Discussion These findings suggest that the brain-heart interactions exist in healthy young adults under acute cardiovascular alterations, and more attention should be paid to blood pressure changes in young adults and assessment of frontal lobe function to provide them with more effective health protection management.

BACKGROUND:Acute cerebrovascular accidents, long-term hypoperfusion, and/or remote neuronal degeneration may lead to structural alterations in patients with moyamoya disease (MMD). This study sought to comprehensively investigate the distribution characteristics of subcortical gray matter volume and their correlations with angiographic changes in the intracranial artery in patients with MMD.METHOD:One hundred forty-two patients with MMD and 142 age- and sex-matched healthy controls underwent 3-dimensional high-resolution structural magnetic resonance imaging. Volumes of subcortical gray matter and subregions of the hippocampus and amygdala were calculated, and the degree of stenosis/occlusion of intracranial arteries in patients with MMD was evaluated on MR angiography.RESULTS:Volume reductions in the thalamus, caudate, putamen, hippocampus, amygdala, pallidum, and nucleus accumbens were found in patients with MMD. Hippocampal subfields and amygdala subnuclei in patients with MMD showed distinct vulnerability, and morphological alterations in specific subregions were more obvious than in the whole hippocampus/amygdala. Volume loss in several subcortical areas was related to disease duration and intracranial arterial changes.CONCLUSIONS:Our findings revealed structural alteration patterns of subcortical gray matter in MMD. The specific atrophy in subregions of the hippocampus and the amygdala suggested potential cognitive and affective impairments in MMD, which warrants further investigation. Chronic cerebral hemodynamic alterations in MMD may play a pivotal role in morphological changes in subcortical areas.