Microglia are a unique cell population in the central nervous system (CNS) and serve as its resident immune cells. They have long been recognized for their critical contributions to CNS development and the maintenance of neuronal network health, particularly in the context of neuroprotection against neurodegenerative diseases. However, the mechanisms by which microglia interact with and influence neurons have remained largely unclear. Recent advances in genetics, pharmacology, and imaging technologies have begun to unveil the mechanisms underlying microglia-neuron communication. Here, from the perspective of microglia, we review the diverse direct and indirect pathways and key molecules through which microglia interact with neurons under both physiological and pathological conditions. This rapidly expanding knowledge is reshaping our understanding of neuron-glia physiology and pathology in neurodegenerative diseases.

OBJECTIVES:This study aimed to evaluate the accuracy of non-contrast 4D-magnetic resonance angiography (4D-MRA) techniques (4D-PACK and 4D-S-PACK) in assessing collateral circulation via the Circle of Willis (CoW) in patients with internal carotid artery occlusion (ICAO), using digital subtraction angiography (DSA) as the reference standard. METHODS:In this prospective study, patients with ICAO underwent multi-contrast MRA (3D TOF-MRA, CE-MRA, 4D-PACK, and 4D-S-PACK) and DSA within 1 week. Using DSA as the reference, the diagnostic accuracy of each MRA technique was independently assessed for ICAO occlusion, CoW anatomy, and collateral pathway patterns. The 4D-MRA acquisitions included time points of 100, 200, 500, 800, 1200, 1600, and 2000 ms. Additionally, the optimal 4D-S-PACK protocol and its capacity to determine CoW flow direction were evaluated. RESULTS:A total of 19 patients with 21 ICAOs were included. Combined 4D-MRA (4D-PACK plus 4D-S-PACK) demonstrated high diagnostic accuracy for detecting ICAO (100.0%) and CoW anatomy (98.2%). In assessing collateral pathways, combined 4D-MRA (sensitivity 95.2%, specificity 100.0%, accuracy 98.2%) outperformed TOF-MRA (sensitivity 85.7%, specificity 86.1%, accuracy 86.0%) and CE-MRA (sensitivity 100.0%, specificity 86.1%, accuracy 91.2%). Using 3 time points (200, 800, and 2000 ms), 4D-S-PACK significantly reduced scan time while maintaining accurate flow direction assessment. CONCLUSIONS:Combined non-contrast 4D-PACK and 4D-S-PACK is a promising, non-invasive alternative for comprehensively evaluating ICAO, CoW morphology, and collateral circulation. ADVANCES IN KNOWLEDGE:This study establishes that a combined non-contrast 4D-MRA protocol surpasses standard MRA techniques in collateral pathway accuracy, providing a viable, non-invasive alternative to DSA.

Background : Microglia-driven inflammation is a key pathological hallmark of Alzheimer’s disease (AD). Scopoletin is a natural coumarin compound from Erycibe obtusifolia Benth with anti-inflammatory activity. However, its effects on microglial inflammatory response and cognition in AD models need to be defined. Purpose : To evaluate the pharmacological effects of scopoletin on microglial inflammatory response and cognitive improvement in 5xFAD models. Methods : Anti-inflammatory effects were assessed in LPS-stimulated BV2 and primary microglia and LPS-induced inflammation in vivo model by measuring cytokines, inflammatory markers. In 5xFAD mice, inflammation, Aβ burden, and cognitive behavior were examined. RNA sequencing, siRNA knockdown, and western blot were performed to determine inflammatory regulation pathways. Results : Scopoletin significantly reduced IL-6 and TNF-α and reversed M1/M2 polarization in LPS-stimulated BV2, suppressed microglial morphological changes in primary microglia, and attenuated LPS-induced inflammation in vivo. Scopoletin treatment alleviated inflammation and reduced Aβ deposition in the hippocampus and cortex, and improved cognitive impairment in 5xFAD mice. Furthermore, transcriptomic signature analyses suggest that scopoletin could modulate inflammatory signaling pathways in LPS-stimulated BV2 cells by elevating downstream mediators, such as Topoisomerase II Alpha (Top2A) and PP2A-NF-κB signaling. Conclusion : Scopoletin suppressed microglial inflammatory response and improved cognitive impairment in 5xFAD mice, providing new insight into new leading compound for AD modifying therapy.

BACKGROUND:Unruptured intracranial aneurysms (IAs) that become symptomatic have been associated with instability. OBJECTIVE:To investigate the relationship between irregular pulsation on four-dimensional CT angiography (4D-CTA) and aneurysm wall enhancement (AWE) on vessel wall MRI (VW-MRI), and to evaluate their ability to identify symptomatic IAs. METHODS:This retrospective study included consecutive patients with IAs who underwent 4D-CTA and VW-MRI between March 2018 and May 2023. IAs were categorized as asymptomatic and symptomatic. The presence of irregular pulsation was identified on 4D-CTA video. Qualitative and quantitative AWE were evaluated. Univariate and multivariate analyses were used to identify the parameters associated with symptoms. RESULTS:192 patients with 216 aneurysms (167 asymptomatic and 49 symptomatic) were included. IAs with irregular pulsation had significantly higher wall enhancement index (WEI) than IAs without irregular pulsation (median (IQR), 0.5 (0.2-1.1) vs 0.2 (0.0-0.6), P<0.001). Symptomatic IAs had significantly higher WEI than asymptomatic IAs (median (IQR), 0.7 (0.3-1.5) vs 0.2 (0.0-0.5), P<0.001), and more irregular pulsations (79.6% vs 25.1%, P<0.001). Both irregular pulsation (OR=6.86; 95% CI 2.62 to 17.96; P<0.001) and WEI (OR=2.56; 95% CI 1.14 to 5.71; P=0.022) were independently associated with symptoms. Combination of irregular pulsation and WEI achieved the highest area under the curve of 0.86 in identifying symptomatic aneurysms compared with irregular pulsation or WEI alone (P<0.001 and P=0.002, respectively). CONCLUSION:In a large cohort of patients with unruptured IAs who underwent 4D-CTA and VW-MRI, both irregular pulsation and WEI were independently associated with symptoms. Such measures could identify IAs at higher risk of growth or rupture.

Accurate prenatal diagnosis of high-risk placenta accreta spectrum (PAS) is vital for maternal safety and can mitigate severe complications. We aimed to investigate the diagnostic value of a novel MRI sign, “increased intra-myometrial vascularity (IIMV),” and to evaluate its contribution to an optimal MRI sign combination for differentiating high-risk placenta accreta spectrum (PAS), specifically placenta increta (PI) and percreta (PP), from placenta accreta (PA) or normal placenta. This retrospective study reviewed 166 high-risk pregnant women who underwent MRI. Two radiologists independently assessed the presence of the seven established risk signs from the SAR-ESUR consensus and the novel IIMV sign. The IIMV sign was defined as continuous tubular or tortuous flow-void structures confined within the myometrium, associated with architectural distortion. Univariate logistic regression and interobserver agreement (kappa statistics) were used to select significant signs, which were then incorporated into a multivariate model to construct diagnostic combinations. AUCs were compared between combinations (with and without IIMV sign) in differentiating PI + PP group from PA + Normal groups. The novel IIMV sign demonstrated the highest specificity (0.91) and was independently associated with the differentiation between the PI + PP and Normal + PA groups. The optimal sign combination, which included IIMV, placental bulge, myometrial thinning, and bladder wall interruption, achieved an area under the curve (AUC) of 0.84. In contrast, the combination without IIMV showed a decreased AUC of 0.79 (p = 0.1203). The “increased intra-myometrial vascularity” sign is a highly specific marker for high-risk PAS. Its inclusion in an MRI-based diagnostic model improves the performance for identifying invasive placental disorders compared to combinations that do not utilize this novel sign.

Background: This investigation employed atlas-based analysis of diffusion imaging to elucidate the therapeutic effects of bilateral and unilateral forelimb movement therapy in a rat stroke middle cerebral artery occlusion (MCAO) model. Methods: Fifty-six rats were randomized into seven groups: sham, model (moderate/severe), and unilateral-treated (CIMT) (moderate/severe) and bilateraltreated (moderate/severe). Daily forelimb training began on day 7 post-surgery and continued throughout. Brain magnetic resonance imaging (MRI) and catwalk test were conducted on days 6, 14, and 28 post-MCAO. Whole-brain fractional anisotropy (FA) and mean diffusivity (MD) values based atlas evaluated the white matter integrity, complemented by gait analysis to evaluate forelimb motor therapy efficacy in forelimb functional recovery. Results: Bilateral training showed greater neuroprotection (47–53 % MRI/TTC reduction, p < 0.001) than unilateral (34–24 %)/controls; only unilateral reduced severe infarctions (20–32 %, p < 0.001). Whole-brain DTI in MCAO rats showed injury-dependent white matter reorganization post-movement therapy: Bilateral therapy boosted thalamocortical integrity in moderate injuries (13–32 % FA↑, 8–11 % MD↓, p < 0.05), while unilateral protocol (CIMT) optimized motor pathways in severe cases (6–11 % FA↑, 7–9 % MD↓, p < 0.05). Gait improvements aligned: bilateral enhanced limb contact (+6–7 %) and paw expansion (+20 %, p < 0.05), whereas unilateral accelerated recovery (step cycle↓20–40 %, swing speed↑51–55 %, p < 0.001). Conclusions: This study pioneers a diffusion atlas framework combining longitudinal DTI with voxel-wise fixel analysis, to delineate forelimb training-driven white matter reorganization patterns. Bilateral training for moderate impairment maximized structural restoration, while advocating unilateral protocols for severe cases to optimize functional recovery.

Three-dimensional magnetic resonance vessel wall imaging (3D MR-VWI) is critical for characterizing cerebrovascular pathologies, yet its clinical adoption is hindered by labor-intensive postprocessing. We developed VWI Assistant, a multi-sequence integrated deep learning platform trained on multicenter data (study cohorts 1981 patients and imaging datasets) to automate artery segmentation and reconstruction. The framework demonstrated robust performance across diverse patient populations, imaging protocols, and scanner manufacturers, achieving 92.9% qualified rate comparable to expert manual delineation. VWI Assistant reduced processing time by over 90% (10–12 min per case) compared to manual methods (p < 0.001) and improved inter-/intra-reader agreement. Real-world deployment (n = 1099 patients) demonstrated rapid clinical adoption, with utilization rates increasing from 10.8% to 100.0% within 12 months. By streamlining 3D MR-VWI workflows, VWI Assistant addresses scalability challenges in vascular imaging, offering a practical tool for routine use and large-scale research, significantly improving workflow efficiency while reducing labor and time costs.

BACKGROUND:Blood oxygenation level-dependent (BOLD) MRI can noninvasively quantify lower extremity perfusion in peripheral artery disease (PAD) patients. However, its ability to reflect perfusion change in response to lower extremity revascularization (LER) and its prognostic value for clinical outcomes are not fully understood. PURPOSE:To evaluate BOLD MRI response to LER and its predictive value for major adverse cardiovascular events (MACE) and major adverse limb events (MALE) in PAD patients. STUDY TYPE:Prospective. POPULATION:Forty-one patients (median age, 73 years; 29 men) undergoing LER for symptomatic PAD. FIELD STRENGTH/SEQUENCE:3.0 T/BOLD MRI with a multi-echo gradient-recalled echo sequence. ASSESSMENT:Pre- and post-LER BOLD MRI was performed under an ischemia-hyperemia paradigm. Normalized T2* time course curves were generated in each of 5 calf muscle compartments (anterior, lateral, deep posterior, soleus, and gastrocnemius) and times to peak (TTP), minimum/maximum values, and gradients during hyperemia (Grad) analyzed. Follow-up was every 6-12 months via hospital records and telephone interviews for MACE and MALE outcomes. Model 1 (clinical factors) and Model 2 (+BOLD MRI) were compared. STATISTICAL TESTS:Chi-square test or Fisher's exact test, Student's t-test or Wilcoxon rank-sum test, area under the receiver operating characteristic curve (AUC), Kaplan-Meier survival analysis, and Cox proportional hazards regression analysis. Significance was set at p < 0.05. RESULTS:During a median 38-month follow-up, 9 patients experienced MACE and 20 experienced MALE. Successful LER improved TTP and Grad in all muscle compartments. Grad change (ΔGradsol ) and post-LER TTP (TTPsol ) in the soleus muscle achieved the highest AUC values of 0.92 and 0.80 in predicting MACE and MALE, respectively. In multivariable Cox regression analysis, ΔGradsol and TTPsol were independent predictors of MACE (hazard ratio [HR] per standard deviation [SD] increase, 0.23) and MALE (HR per SD increase, 1.62), respectively. BOLD MRI added incremental prognostic value to clinical factors, increasing C-index by 0.06 for MACE and 0.05 for MALE. DATA CONCLUSION:BOLD MRI showed perfusion changes in skeletal muscles following revascularization and provided incremental prognostic value in PAD patients. EVIDENCE LEVEL:2. TECHNICAL EFFICACY:Stage 4.

Microglia play a pivotal role in inflammatory regulation through multifarious signaling pathways within the central nervous system, and mitigating microglial inflammation is considered a promising strategy to delay the progression of neurodegeneration. However, the role of biased receptor signaling in modulating microglial inflammation remains largely unexplored. In this study, the anti-inflammatory effects and the underlying mechanism of muscarinic receptor agonists pilocarpine and iperoxo were explored. Our results showed that pilocarpine, rather than iperoxo, inhibited the expression of TNF-α and IL-6, as well as restored ramified morphology and physiological phagocytosis of over-activated microglia. RNA-seq revealed that pilocarpine-treated BV2 exhibited transcriptional profiles more similar to the control group, with upregulation of anti-inflammatory genes. β-arrestin2 knockdown attenuated the anti-inflammatory effect of pilocarpine by reversing the expression of inflammatory factors and activation of NF-κB. Furthermore, through chemogenetic DREADDs, activation of Gαq, Gαi, or β-arrestin pathways demonstrated that β-arrestin, but neither Gαq nor Gαi, inhibited the inflammatory response in microglia. Our findings proved that pilocarpine could abate the microglial inflammatory response via biased activation of the β-arrestin2 pathway, which could be considered a promising therapeutic approach for anti-neuroinflammation.

Background The assessment of resectability after neoadjuvant chemotherapy of hepatoblastoma is dependent on Post‐Treatment EXTENT of Disease (POSTTEXT) staging and its annotation factors P (portal venous involvement) and V (hepatic venous/inferior vena cava [IVC] involvement), but MR performance in assessing them remains unclear. Purpose To assess the diagnostic performance of contrast‐enhanced MR imaging for preoperative POSTTEXT staging and diagnosing vascular involvement in terms of annotation factors P and V in pediatric hepatoblastoma following neoadjuvant chemotherapy. Study Type Retrospective. Subjects Thirty‐five consecutive patients (17 males, median age, 24 months; age range, 6–98 months) with proven hepatoblastoma underwent preoperative MR imaging following neoadjuvant chemotherapy. Field Strength/Sequence 3.0 T; T2 ‐weighted imaging ( T2WI ), T2WI with fat suppression, diffusion weighted imaging, radial stack‐of‐the‐star/Cartesian 3D Dixon T1 ‐weighted gradient echo imaging. Assessment Three radiologists independently assessed the POSTTEXT stages and annotation factors P and V based on the 2017 PRE/POSTTEXT system. The sensitivities and specificities were calculated for 1) diagnosing each POSTTEXT stage; 2) discrimination of stages III and IV (advanced) from those stages I and II (non‐advanced) hepatoblastomas; and 3) annotation factors P and V. The combination of pathologic findings and surgical records served as the reference standard. Statistical Tests Sensitivity, specificity, Fleiss kappa test. Results The sensitivity and specificity ranges for discriminating advanced from non‐advanced hepatoblastomas were 73.3%–80.0% and 80.0%–90.0%, respectively. For annotation factor P, they were 66.7%–100.0% and 90.6%, respectively. For factor V, they were 75.0% and 67.7%–83.9%, respectively. There was excellent, substantial, and moderate agreement on POSTTEXT staging (Fleiss kappa = 0.82), factors P (Fleiss kappa = 0.64), and factors V (Fleiss kappa = 0.60), respectively. Data Conclusion MR POSTTEXT provides reliable discrimination between advanced and non‐advanced tumors, and MR has moderate to excellent specificity at identifying portal venous and hepatic venous/IVC involvement. Evidence Level 3 Technical Efficacy Stage 3

BACKGROUND AND PURPOSE: Intracranial plaque enhancement (IPE) identified by contrast-enhanced vessel wall MR imaging (VW-MR imaging) is an emerging marker of plaque instability related to stroke risk, but there was no standardized timing for postcontrast acquisition. We aim to explore the optimal postcontrast timing by using multiphase contrast-enhanced VW-MR imaging and to test its performance in differentiating culprit and nonculprit lesions. MATERIALS AND METHODS: Patients with acute ischemic stroke due to intracranial plaque were prospectively recruited to undergo VW-MR imaging with 1 precontrast phase and 4 consecutive postcontrast phases (9 minutes and 13 seconds for each phase). The signal intensity (SI) values of the CSF and intracranial plaque were measured on 1 precontrast and 4 postcontrast phases to determine the intracranial plaque enhancement index (PEI). The dynamic changes of the PEI were compared between culprit and nonculprit plaques on the postcontrast acquisitions. RESULTS: Thirty patients with acute stroke (aged 59 +/- 10 years, 18 [60%] men) with 113 intracranial plaques were included. The average PEI of all intracranial plaques significantly increased (up to 14%) over the 4 phases. There was significantly increased PEI over the 4 phases for culprit plaques (an average increase of 23%), but this was not observed for nonculprit plaques. For differentiating culprit and nonculprit plaques, we observed that the performance of IPE in the second postcontrast phase (cutoff = 0.83, AUC = 0.829 [0.746-0.893]) exhibited superior accuracy when compared with PEI in the first postcontrast phase (cutoff = 0.48; AUC = 0.768 [0.680-0.843]) (P = .022). CONCLUSIONS: A 9-minute delay of postcontrast acquisition can maximize plaque enhancement and better differentiate between culprit and nonculprit plaques. In addition, culprit and nonculprit plaques have different enhancement temporal patterns, which should be evaluated in future studies.

The present study aimed to investigate the incremental prognostic value of the right ventricular fractal dimension (FD), a novel marker of myocardial trabecular complexity by cardiac magnetic resonance (CMR) in patients with arrhythmogenic cardiomyopathy (ACM). Consecutive patients with ACM undergoing CMR were followed up for major cardiac events, including sudden cardiac death, aborted cardiac arrest, and appropriate implantable cardioverter defibrillator intervention. Prognosis prediction was compared by Cox regression analysis. We established a multivariable model supplemented with RV FD and evaluated its discrimination by Harrell’s C-statistic. We compared the category-free, continuous net reclassification improvement (cNRI) and integrated discrimination index (IDI) before and after the addition of FD. A total of 105 patients were prospectively included from three centers and followed up for a median of 60 (48, 66) months; experienced 36 major cardiac events were recorded. Trabecular FD displayed a strong unadjusted association with major cardiac events (p < 0.05). In the multivariable Cox regression analysis, RV maximal apical FD maintained an independent association with major cardiac events (hazard ratio, 1.31 (1.11–1.55), p < 0.002). The Hosmer–Lemeshow goodness of fit test displayed good fit (X2 = 0.68, p = 0.99). Diagnostic performance was significantly improved after the addition of RV maximal apical FD to the multivariable baseline model, and the continuous net reclassification improvement increased 21

BACKGROUND:Left atrial (LA) dysfunction is involved in idiopathic inflammatory myopathy (IIM). Multiparametric cardiovascular magnetic resonance (CMR) strain imaging is a feasible and reproducible tool for examining global and regional LA functions, as well as left ventricular (LV) function in IIM patients. AIM:The aim of this study was to evaluate the feasibility and reproducibility of LA strain occurrence and strain rate for LA function assessment using CMR in IIM cases. MATERIALS AND METHODS:A total of 36 IIM and 42 healthy control cases were included. Baseline ventricular function was comparatively assessed in both groups. LA strain occurrence and strain rate were examined by cine cardiac magnetic resonance imaging [MRI] utilizing an in-house semiautomated technique. LA global function indexes were quantitated, including reservoir, conduit, and booster-pump functions. RESULTS:A total of 78 participants were enrolled in this study. There was no significant difference in left/right ventricular routine functions between IIM patients and control individuals (p>0.05); the same results (p>0.05) was also observed between patients with high hs-cTnI and normal. However, LV mass index had significant difference (p1=0.003, p2<0.01). Compared with IIM patients and control individuals, only total strain (εs) (p4=0.046) and passive strain (εe) (p4=0.002) showed significant difference, and in cases with high hs-cTnI and normal hs-cTnI, there are differences for εs (p3=0.012) and εe (p4=0.047). The strongest association was found between εe and LV ejection fraction (LVEF) (r=0.581, p<0.01). CONCLUSION:IIM cases have altered LA reservoir and conduit functions, and LA strain could reflect LA function.

Background The prognostic value of left ventricular segmental strain (SS) in ST‐elevation myocardial infarction (STEMI) remains unclear. Hypothesis To assess the prognostic value and application of SS. Study Type Retrospective analysis of a prospective registry. Population Five hundred and forty‐four patients after STEMI (500 in Cohort 1, 44 in Cohort 2). Field Strength/Sequence 3 T, balanced steady‐state free precession, gradient echo, and gradient echo contrast‐enhanced images. Assessment Participants underwent cardiac MR during the acute phase after STEMI. Infarct‐related artery (IRA) strain was determined based on SS obtained from cine images. The primary endpoint was the composite of major adverse cardiovascular events (MACEs) after 8 years of follow‐up. In Cohort 2, SS stability was assessed by MR twice within 8 days. Contrast and non‐contrast risk models based on SS were established, leading to the development of an algorithm. Statistical Test Student's t ‐test, Mann–Whitney U ‐test, Cox and logistic regression, Kaplan–Meier analysis, net reclassification index (NRI). P < 0.05 was considered significant. Results During a median follow‐up of 5.2 years, 83 patients from Cohort 1 experienced a MACE. Among SS, IRA peak circumferential strain (IRA‐CS) was an independent factor for MACEs (adjusted hazard ratio 1.099), providing incremental prognostic value (NRI 0.180, P = 0.10). Patients with worse IRA‐CS (>−8.64%) demonstrated a heightened susceptibility to MACE. Additionally, IRA‐CS was significantly associated with microvascular obstruction (MVO) (adjusted odds ratio 1.084) and infarct size ( r = 0.395). IRA‐CS showed comparable prognostic effectiveness to global peak circumferential strain (NRI 0.100, P = 0.39), also counterbalancing contrast and non‐contrast risk models (NRI 0.205, P = 0.05). In Cohort 2, IRA‐CS demonstrated stability between two time points ( P = 0.10). Based on risk models incorporating IRA‐CS, algorithm “HJKL” was preliminarily proposed for stratification. Data Conclusions IRA‐CS is an important prognostic factor, and an algorithm based on it is proposed for stratification. Level of Evidence 4 Technical Efficacy Stage 2

Neuroinflammation is a critical factor that contributes to neurological impairment and is closely associated with the onset and progression of neurodegenerative diseases. In the central nervous system (CNS), microglia play a pivotal role in the regulation of inflammation through various signaling pathways. Therefore, mitigating microglial inflammation is considered a promising strategy for restraining neuroinflammation. Muscarinic acetylcholine receptors (mAChRs) are widely expressed in the CNS and exhibit clear neuroprotective effects in various disease models. However, whether the activation of mAChRs can harness benefits in neuroinflammation remains largely unexplored. In this study, the anti-inflammatory effects of mAChRs were found in a neuroinflammation mouse model. The expression of various cytokines and chemokines was regulated in the brains and spinal cords after the administration of mAChR agonists. Microglia were the primary target cells through which mAChRs exerted their anti-inflammatory effects. The results showed that the activation of mAChRs decreased the pro-inflammatory phenotypes of microglia, including the expression of inflammatory cytokines, morphological characteristics, and distribution density. Such anti-inflammatory modulation further exerted neuroprotection, which was found to be even more significant by the direct activation of neuronal mAChRs. This study elucidates the dual mechanisms through which mAChRs exert neuroprotective effects in central inflammatory responses, providing evidence for their application in inflammation-related neurological disorders.

Purpose The temporal evolution of ventricular trabecular complexity and its correlation with major adverse cardiovascular events (MACE) remain indeterminate in patients presenting with acute ST elevation myocardial infarction (STEMI). Methods This retrospective analysis enrolled patients undergoing primary percutaneous coronary intervention (pPCI) for acute STEMI, possessing cardiac magnetic resonance (CMR) data in the acute (within 7 days), subacute (1 month after pPCI), and chronic phases (6 months after pPCI) from January 2015 to January 2020 at the three participating sites. Fractal dimensions (FD) were measured for the global, infarct, and remote regions of left ventricular trabeculae during each phase. The potential association of FD with MACE was analyzed using multivariate Cox regression. Results Among the 200 analyzed patients (182 men; median age, 61 years; age range, 50–66 years), 37 (18.5%) encountered MACE during a median follow-up of 31.2 months. FD exhibited a gradual decrement (global FD at acute, subacute, and chronic phases: 1.253 ± 0.049, 1.239 ± 0.046, 1.230 ± 0.045, p < 0.0001), with a more pronounced decrease observed in patients subsequently experiencing MACE ( p < 0.001). The global FD at the subacute phase correlated with MACE (hazard ratio 0.89 (0.82, 0.97), p = 0.01), and a global FD value below 1.26 was associated with a heightened risk. Conclusion In patients post-STEMI, the global FD, serving as an indicator of left ventricular trabeculae complexity, independently demonstrated an association with subsequent major adverse cardiovascular events, beyond factors encompassing left ventricular ejection fraction, indexed left ventricular end-diastolic volume, infarct size, heart rate, NYHA class, and post-pPCI TIMI flow. Critical relevance statement In patients who have had an ST-segment elevation myocardial infarction, global fractal dimension, as a measure of left ventricular trabeculae complexity, provided independent association with subsequent major adverse cardiovascular event. Key points • Global and regional FD decreased after STEMI, and more so in patients with subsequent MACE. • Lower global FD at the subacute phase and Δglobal FD from acute to subacute phase were associated with subsequent MACE besides clinical and CMR factors. • Global FD at the subacute phase independently correlated with MACE and global FD value below 1.26 was associated with higher risk. Graphical Abstract

Objectives To differentiate high-grade from low-grade clear cell renal cell carcinoma (ccRCC) using diffusion-relaxation correlation spectroscopic imaging (DR-CSI) spectra in an equal separating analysis. Methods Eighty patients with 86 pathologically confirmed ccRCCs who underwent DR-CSI were enrolled. Two radiologists delineated the region of interest. The spectrum was derived based on DR-CSI and was further segmented into multiple equal subregions from 2*2 to 9*9. The agreement between the 2 radiologists was assessed by the intraclass correlation coefficient (ICC). Logistic regression was used to establish the regression model for differentiation, and 5-fold cross-validation was used to evaluate its accuracy. McNemar’s test was used to compare the diagnostic performance between equipartition models and the traditional parameters, including the apparent diffusion coefficient (ADC) and T2 value. Results The inter-reader agreement decreased as the divisions in the equipartition model increased (overall ICC ranged from 0.859 to 0.920). The accuracy increased from the 2*2 to 9*9 equipartition model (0.68 for 2*2, 0.69 for 3*3 and 4*4, 0.70 for 5*5, 0.71 for 6*6, 0.78 for 7*7, and 0.75 for 8*8 and 9*9). The equipartition models with divisions >7*7 were significantly better than ADC and T2 (vs ADC: P = .002-.008; vs T2: P = .001-.004). Conclusions The equipartition method has the potential to analyse the DR-CSI spectrum and discriminate between low-grade and high-grade ccRCC. Advances in knowledge The evaluation of DR-CSI relies on prior knowledge, and how to assess the spectrum derived from DR-CSI without prior knowledge has not been well studied.

Aneurysm wall enhancement (AWE) on high-resolution contrast-enhanced vessel wall MRI (VWMRI) is an emerging biomarker for intracranial aneurysms (IAs) stability. Quantification methods of AWE in the literature, however, are variable. We aimed to determine the optimal post-contrast timing to quantify AWE in both saccular and fusiform IAs. Consecutive patients with unruptured IAs were prospectively recruited. VWMRI was acquired on 1 pre-contrast and 4 consecutive post-contrast phases (each phase was 9 min). Signal intensity values of cerebrospinal fluid (CSF) and aneurysm wall on pre- and 4 post-contrast phases were measured to determine the aneurysm wall enhancement index (WEI). AWE was also qualitatively analyzed on post-contrast images using previous grading criteria. The dynamic changes of AWE grade and WEI were analyzed for both saccular and fusiform IAs. Thirty-four patients with 42 IAs (27 saccular IAs and 15 fusiform IAs) were included. The changes in AWE grade occurred in 8 (30