Magnetic Resonance Imaging Research Articles

Biodegradable Citrate‐Based Polymers Enable 5D Monitoring of Implant Evolution

AbstractBiodegradable tissue engineering scaffolds have garnered increasing interest for their role in providing mechanical support, promoting tissue regeneration, and eliminating the need for removal. However, the in vivo degradation processes remain challenging to track. Here, a novel biodegradable polymer, N‐methyldiethanolamine (MDEA) and Gadolinium(III) diethylenetriamine pentaacetate (Gd‐DTPA) modified biodegradable photoluminescent polymers (BPLPMGd), which combines near‐infrared (NIR) fluorescence and magnetic resonance (MR) dual‐modality imaging are introduced to monitor scaffold degradation in vivo. The chemical structure of BPLPMGd is characterized and its dual‐imaging properties in vitro are evaluated. Subsequently, non‐invasive dual‐modality imaging to track the degradation of implanted BPLPMGd scaffolds is performed in a rat model, comparing these results with histological data. This approach reveals that BPLPMGd enables reliable non‐invasive tracking of the degradation, where NIR fluorescence imaging offers a qualitative and quantitative analysis of scaffold mass loss, total volume and solid content changes, while magnetic resonance imaging (MRI) details structural and morphological changes, allowing for 5D monitoring of implant degradation, including 3D structure, location, mass, volume, and geometry. The combination of these imaging modalities provides a comprehensive view of scaffold degradation, where the synergistic use of both yields results greater than either modality alone, offering unprecedented 5D information of implantable devices. This innovative approach has potential applications in regenerative engineering and beyond.

Changes in the relaxivity of water-organic solvent miscible systems: Hidden forces beyond metal ions.

The relaxivity of magnetic resonance imaging (MRI) contrast agents is primarily attributed to metal ions such as gadolinium (Gd) and iron. However, the impact of organic solutes on relaxivity, particularly through alterations in water molecule dynamics, has not been thoroughly investigated. This research was aimed to explore how organic solutes affect the relaxivities of water and Gd-based contrast agents (GBCAs), potentially revealing new aspects for the development of contrast agents. To investigate the effects of different proportions of water-soluble organic solvents mixed with pure water and GBCA on T1 and T2 relaxivities. Ethanol, dimethyl sulfoxide (DMSO), 1,4-dioxane, glycerin, ethylene glycol, diethylene glycol, polyethylene glycol (PEG) 200, and PEG 400 were mixed with ultrapure water in various ratios (100:0, 90:10, 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80, 10:90, 0:100). GBCA was added to these mixtures at a concentration of 0.05 mmol/L. The mixtures underwent T1 and T2 mapping scans using a 3.0 Tesla MRI machine, and the relaxivities R1 (1/T1) and R2 (1/T2) were calculated and compared. The relaxivity R1 of ethanol, 1,4-dioxane, and DMSO mixtures with water or GBCA, as well as R2 of DMSO mixtures with GBCA, initially increased and then decreased. Conversely, R1 and R2 increased significantly with higher proportions of diethylene glycol, PEG 200, and glycerin in the mixtures with GBCA. The increase in relaxivity R1 was correlated with greater viscosity. When the proportion of DMSO and diethylene glycol exceeded 20%, minimal variability in R2 was observed as the water content decreased. Adding organic solvents to water and paramagnetic relaxation reagents could alter T1 and T2 relaxivities, suggesting potential new directions for modifying current contrast agents. Additionally, increasing the viscosity of the contrast agent was found to enhance the relaxivity.

Goal-Oriented Attentional Self-Regulation Training in Chronic Mild Traumatic Brain Injury is Linked to Microstructural Plasticity in Prefrontal White Matter.

Impaired attention is one of the most common, debilitating, and persistent consequences of traumatic brain injury (TBI), which impacts overall cognitive and executive functions in these patients. Previous neuroimaging studies, trying to understand the neural mechanism underlying attention impairment post TBI, have highlighted the role of prefrontal white matter tracts in attentional functioning in mild TBI (mTBI). Goal-Oriented Attentional Self-Regulation (GOALS) is a cognitive rehabilitation training program that targets executive control functions in participants by applying mindfulness-based attention regulation and goal management strategies. GOALS training has been demonstrated to improve attention and executive functioning in patients with chronic TBI. However, its impact on microstructural integrity of attention-associated prefrontal white matter tracts is still unclear. Here, using diffusion magnetic resonance imaging in a pilot randomized controlled trial, we investigated the effect of GOALS training on prefrontal white matter microstructure in 19 U.S. military veterans with chronic mTBI, compared with a matched control group of 14 veterans with chronic mTBI who received standard of care brain health education. We also tested for an association between microstructural white matter changes and sustained attention ability in these patients pre- and post-GOALS training. Our results show significantly better white matter microstructural integrity in left and right anterior corona radiata (ACR) in the GOALS group compared with the control group post-training. Moreover, we found a significant correlation between sustained attention ability of GOALS training participants and white matter integrity of their right ACR pre- and post-training. Finally, our findings indicated that the improved white matter integrity of the ACR in GOALS training participants was the result of increased neurite density and decreased fiber orientation dispersion within this tract.

Mapping common and distinct brain correlates among cognitive flexibility tasks: concordant evidence from meta-analyses.

Cognitive flexibility allows individuals to switch between different tasks, strategies, or ideas; an ability that is important for everyday life. The Wisconsin card sorting test (WCST) and task switching paradigm (TSP) are popular measures of cognitive flexibility. Although both tasks require switching, the TSP requires participants to memorize switching rules and retrieve them when they view a cue (rule-retrieval), whereas the classic WCST requires participants to discover the switching rule via trial-and-error (rule-discovery). Many functional magnetic resonance imaging studies have examined brain responses to these tasks. Extant meta-analyses show concordance in activation in a widespread set of areas including frontal, parietal, and cingulate cortices. Critically, past meta-analyses have not specifically examined brain correlates associated with rule derivation (i.e., rule-discovery vs. rule-retrieval) in cognitive flexibility tasks. We examine for the first time common and distinct concordance in brain responses to rule-discovery (i.e., WCST) and rule-retrieval (i.e., TSP), as well as TSP subtypes using quantitative meta-analyses. We analyzed data from 69 eligible articles with a total of 1617 young-adult participants. Conjunction results show concordance in common fronto-parietal areas predominantly in the left hemisphere. Contrast analyses show that rule-discovery required increased involvement in multiple cortical and subcortical regions such as frontopolar (Brodmann Area 10), parietal, insular cortex, thalamus and caudate nucleus predominantly in the right hemisphere. No significant differences in concordance were observed among the three, task switching paradigm sub-types. We propose a neuroanatomical model of cognitive flexibility and discuss theoretical and practical applications.

Understanding the Role of Type I Interferons in Cutaneous Lupus and Dermatomyositis: Toward Better Therapeutics.

A 29-year-old female presented to a rheumatology-dermatology clinic with a pruritic rash that began 6 months prior, after a viral illness. She had previously been diagnosed with eczema and treated with antihistamines and topical steroids without improvement. She also noted fatigue, hair loss, and severe scalp pruritus. Physical examination was notable for violaceous periorbital edema, scaly erythematous papules on the metacarpophalangeal joints of bilateral hands, dilated capillaries of the proximal nail folds, scaly plaques on bilateral elbows, and excoriated erythematous plaques on upper chest, back and hips. The patient reported no muscle weakness, and strength testing and creatinine phosphokinase were normal. Magnetic resonance imaging of the thigh showed no evidence of inflammation or edema. Antibody testing was negative. A diagnosis of clinically amyopathic dermatomyositis was made. Computed tomography scans of the chest, abdomen and pelvis, colonoscopy, and mammogram showed no evidence of cancer. The patient was initiated on methotrexate. Her cutaneous manifestations persisted with debilitating intractable pruritus, and thus, she was transitioned to mycophenolate mofetil, again with minimal improvement. Intravenous immunoglobulin was not approved by insurance given the lack of muscle involvement in her disease. This patient's case highlights a common clinical scenario in rheumatology and dermatology and raises several important issues related to the immunologic underpinnings of cutaneous lupus erythematosus (CLE) and dermatomyositis (DM): What is the role of type I interferon (IFN) in triggering skin disease in CLE and DM? What is the role of IFN in the pathogenesis of skin inflammation in CLE and DM? Can we apply what we know about IFN-targeted therapeutics in CLE and DM to develop better treatments for skin disease?

Total resection via right mini-thoracotomy for left atrial myxoma in juvenile Carney complex: a case report

Abstract Background Carney complex is a rare syndrome characterized by skin pigmentation, endocrine disorders, and myxomas. It is particularly notorious for its tendency to exhibit aggressive cardiac myxomas. Herein, we present a case of a juvenile female patient diagnosed with Carney complex who underwent a right lateral mini-thoracotomy. Case presentation A 13-year-old girl presented with sudden-onset left hemiplegia and dysarthria. Magnetic resonance imaging revealed multiple areas of restricted diffusion. Echocardiography identified a tumor in the left atrium, suspected to be related to Carney complex based on her medical history and physical examination findings. Surgery was performed via right lateral mini-thoracotomy, which minimized the risk of embolism and ensured a cosmetically favorable outcome. The left atrial wall defect was repaired with autologous pericardium. At 3 years postoperatively, follow-up echocardiography indicated no tumor recurrence and normal cardiac function. Conclusions Ongoing follow-ups are essential due to the aggressive nature of the Carney complex and its high recurrence rates. Right lateral mini-thoracotomy offers the advantage of avoiding re-sternotomy and minimizing adhesion dissection, making it the optimal choice for this case.

AMIC achieves sustained clinical improvement in isolated patellar cartilage defects over 5 years, correlating with MRI.

To evaluate 5-year postoperative clinical outcomes of autologous matrix-induced chondrogenesis (AMIC) for isolated ICRS grade 3-4 patellar cartilage defects and correlate outcomes with magnetic resonance imaging (MRI). The hypothesis was that AMIC would improve clinical symptoms and induce neocartilage formation, visible on MRI, making it a safe and effective option for repairing focal patellar cartilage defects. The cohort comprised 13 focal patellar lesions in 12 patients. Pain visual analogue scale (VAS), Knee Injury and Osteoarthritis Outcome Score (KOOS), Kujala score, EuroQol-5D Health Survey questionnaire and MRI data were assessed preoperatively and at 2 and 5 years postoperatively. All MRI scans were evaluated using the Magnetic Resonance Observation of Cartilage Repair Tissue System. Descriptive statistics were calculated on all data. Inferential analysis comparing outcome scores before and after surgery employed the nonparametric Wilcoxon signed-rank test, with the nonparametric Friedman test used to detect differences across multiple test attempts. p < 0.05 was considered statistically significant. Twelve patients (23-52 years old) with patellofemoral chondral full-thickness defects (2-4 cm2) were treated. At a 5-year follow-up, eleven knees showed MRI improvement. Two were asymptomatic and nine showed clear clinical improvement. Only one knee showed no clinical improvement. MRI revealed a defect filling with newly formed cartilage characterized by a less compact and heterogeneous signal. Cartilage degradation or joint damage was observed in two knees, and bone formation within the plate was identified in four. AMIC significantly improved patients' VAS pain, KOOS, EuroQol-5D and Kujala scores compared to preoperative baseline for up to 5 years postoperatively. Satisfactory clinical outcomes and new cartilage formation, as observed by MRI, are achieved with AMIC at mid-term follow-up for ICRS grade 3-4 in small-to-medium-sized patellar defects in patients under 52 years of age, with improvements maintained for up to 5 years. Level III.

Ex vivo magnetic resonance imaging of the human fetal brain.

The fetal brain undergoes a dynamic process of development during gestation, marked by well-orchestrated events such as neuronal proliferation, migration, axonal outgrowth, and dendritic arborization, mainly elucidated through histological studies. Ex vivo magnetic resonance imaging (MRI) has emerged as a useful tool for 3D visualization of the developing fetal brain, serving as a complementary tool to traditional histology. In this review, we summarized the commonly employed ex vivo MRI techniques and their advances in fetal brain imaging, as well as a standard protocol for postmortem fetal brain specimen collection and fixation. We then provided an overview of ex vivo MRI-based studies on the fetal brain. According to our review, ex vivo T1- or T2-weighted structural MRI has contributed to the characterization of the anatomy of transient neuronal proliferative zones, the basal ganglia, and the cortex. Diffusion MRI related techniques, such as diffusion tensor imaging and tractography, have helped to investigate the microstructural patterns of fetal brain tissue, as well as the early emergence and development of neuronal migration pathways and white matter bundles. Ex vivo MRI findings have shown strong histological correlations, supporting the potential of MRI in evaluating the developmental events in the fetal brain. Postmortem MRI examinations have also demonstrated comparable, and in certain cases, superior performance to traditional autopsy in revealing fetal brain abnormalities. In conclusion, ex vivo fetal brain MRI is an invaluable tool that provides unique insights into the early stages of brain development.

Echocardiographic signs of atrial cardiopathy and MRI-detected silent brain infarcts in a middle-aged cohort: the Akershus Cardiac Examination 1950 Study

Abstract Background Atrial fibrillation (AF) is linked to clinical stroke and silent brain infarction (SBI). In the majority of AF patients, there exists a recognized form of atrial cardiopathy, and it is suggested that atrial cardiopathy, even in the absence of AF, may serve as a risk factor for stroke. However, existing evidence is limited, and it remains unclear whether atrial cardiopathy indeed poses a risk for stroke and SBI. Purpose We aimed to investigate the association between echocardiographic signs of atrial cardiopathy and the detection of SBI through magnetic resonance imaging (MRI) in a middle-aged cohort from the general population. Methods In the prospective Akershus Cardiac Examination (ACE) 1950 Study conducted within the general population in Norway, cardiovascular risk assessment including transthoracic echocardiography, was undertaken at study inclusion between 2012 and 2015. We assessed body surface area-indexed left atrial (LA) maximum and minimum volume, as well as LA reservoir and contractile strain. Subsequently, brain MRI was conducted in a subset of the cohort between 2017 and 2023. SBI was defined as presence of neuroimaging sign of infarcts, including lacunes, in individuals without a history of stroke. Logistic regression analyses were performed to explore the associations between echocardiographic measures of atrial cardiopathy and SBI on MRI, adjusting for sex, age, hypertension, and diabetes. Results A total of 397 out of 3706 (10.7%) participants in the ACE 1950 study underwent MRI examination and were included in this analysis. At the time of MRI, the mean age was 70.0±2.2 years, with 157 (40%) women, 248 (62%) with hypertension, and 36 (9%) with diabetes at study inclusion. SBI was present in 51 (13%), of which only 1 (2%) had known AF. After excluding 18 participants with pre-existing AF, no significant difference were observed in LA volumes or LA strain between participants with or without SBI (Figure 1). In unadjusted and adjusted logistic regression analyses, neither LA volume nor LA strain were associated with SBI (Table 1). Conclusion Echocardiographic signs of atrial cardiopathy were not associated with silent brain infarcts in a middle-aged cohort from the general population.

Valvular and myocardial fibroblast activation in aortic stenosis: a prospective positron emission tomography study

Abstract Introduction In patients with aortic stenosis, fibrosis is a common pathophysiological feature of leaflet thickening as well as left ventricular decompensation as it transitions from hypertrophy to heart failure. Valvular fibrosis can be quantified by contrast-enhanced computed tomography, and myocardial fibrosis by late gadolinium enhancement on magnetic resonance imaging, but neither can detect the activity of fibrosis and extracellular matrix remodelling. Gallium-68 Fibroblast Activation Protein Inhibitor (68Ga-FAPI) binds to activated fibroblasts, the key effector cell of fibrogenesis, and provides a measure of fibroblast activation and fibrosis activity. We aimed to measure fibrosis activity in the aortic valve and left ventricular myocardium of patients with aortic stenosis using 68Ga-FAPI uptake. Methods In a prospective observational cohort, patients with aortic stenosis and control subjects with normal aortic valves underwent transthoracic echocardiography, 68Ga-FAPI positron emission tomography, computed tomography, and magnetic resonance imaging. Valvular and myocardial 68Ga-FAPI uptake was quantified using the target-to-background ratio (TBRmax). Valvular non-calcific volume was quantified on computed tomography and replacement myocardial fibrosis was quantified by late gadolinium enhancement on magnetic resonance imaging. Results Fifty patients with aortic valve disease (9 with aortic sclerosis, and 7 with mild, 23 with moderate and 11 with severe aortic stenosis; 72±8 years, 70% male) and 4 control subjects (66±7 years, 50% male) participated. Increased 68Ga-FAPI uptake was observed in the aortic valves of patients with aortic sclerosis and stenosis and peaked in those with moderate disease (Figure 1). TBRmax of 68Ga-FAPI uptake correlated with the aortic valve non-calcific volume (r=0.354, p&amp;lt;0.05) on computed tomography. Thirty-one patients (62%) had myocardial 68Ga-FAPI uptake, of whom half (n=17; 34%) also had late gadolinium enhancement corresponding to the region of 68Ga-FAPI uptake (Figure 2). Myocardial 68Ga-FAPI uptake correlated with increased indexed left ventricular mass (r=0.333, p&amp;lt;0.05) and left ventricular wall thickness (r=0.385, p&amp;lt;0.05). Conclusions For the first time, we have identified both valvular and myocardial fibrosis activity in patients with aortic stenosis. Valvular fibroblast activation is increased in patients with aortic sclerosis and stenosis, peaking in patients with moderate disease and correlating with leaflet thickening. Myocardial fibroblast activation is seen in the majority of patients with aortic stenosis both in areas with and without established fibrosis, and is associated with indices of adverse left ventricular remodelling. Activated fibroblasts are thus an important potential treatment target in the valve and myocardium, with 68Ga-FAPI positron emission tomography holding major promise in better understanding the pathophysiology, progression and consequences of aortic stenosis.

Residual post-infarct myocardial inflammation detected by 68Ga-DOTATATE PET/MRI predicts long-term adverse cardiac remodelling

Abstract Background Maladaptive inflammatory responses are associated with adverse cardiac remodelling after myocardial infarction (MI), but clinical methods for detecting residual myocardial inflammation post-MI are lacking. Purpose To investigate somatostatin receptor subtype 2 (SST2) positron emission tomography (PET)/magnetic resonance imaging (MRI) using 68Ga-DOTATATE after MI. Methods In a prospective observational cohort study, infarct-related myocardial inflammation detected by 68Ga-DOTATATE PET at 2wk and 3mo post-MI was compared with MRI characteristics including left ventricular (LV) volumetric changes at 1yr, as well circulating immune cell phenotyping and serum proteomic markers. Patients with a prior history of MI or heart failure were excluded. Histological SST2 expression was assessed in myocardial biopsies. Results 38 participants (mean age 60 [SD 9] years; 84% male) with recent MI were enrolled, of whom 58% had an ST-segment elevation MI. Mean peak Troponin I was 16,665 (range 408 to &amp;gt;25,000) ng/L and mean post-infarct LV ejection fraction was 51 (SD 9) %. 68Ga-DOTATATE maximum standardized uptake values (SUVmax) at 10 (SD 4) days accurately localised infarcted myocardial segments defined by late-gadolinium enhancement MRI (LGE; Fig. 1); were 14.2% higher in akinetic/hypokinetic vs. normo-kinetic segments (p&amp;lt;0.0001); and were correlated both with peak segmental strain (r=0.47, p=0.003) and segmental T1 values (r=0.51, p=0.02). Mean infarct SUVmax was 19.7% lower on repeat PET/MRI after a mean 102 (SD 22) days (p&amp;lt;0.0001), and this change was in keeping with parallel reductions in T2-weighted oedema signal on MRI and serum biomarkers of cardiac injury and systemic inflammation. Residual inflammation assessed by mean infarct SUVmax at 3mo was correlated with ΔLV indexed end-diastolic volume at 369 (SD 14) days, after adjustment for baseline infarct size and other clinical variables (p=0.038). The 3mo:2wk ratio of mean infarct SUVmax was an even stronger predictor of adverse myocardial remodelling (p=0.0025). Circulating SST2+ classical monocytes were correlated with infarct 68Ga-DOTATATE signal (r=0.47, p=0.02), and SST2 was co-expressed with CD68+ macrophages in inflamed myocardial specimens of patients with recent MI and ischaemic heart failure. After statistical feature selection and multiple comparisons adjustments, among the blood markers associated with 3mo:2wk infarct SUVmax was CCL25, a chemokine involved in macrophage recruitment which has been implicated in adverse cardiac remodelling. Conclusions Here, in the first prospective clinical study of serial SST2 PET/MRI after MI, we show that 68Ga-DOTATATE can identify and track resolving infarct-related myocardial inflammation. Moreover, residual inflammation detected by 68Ga-DOTATATE is associated with long-term adverse myocardial remodelling and could provide a potential future imaging biomarker to help stratify high-risk patients for emerging immunomodulatory therapies.Figure 1.68Ga-DOTATATE PET-MRI after MI

Extra-cellular volume fraction analysis on cardiac CT is useful for predicting the prognosis of hypertrophic cardiomyopathy

Abstract Introduction Extra-cellular volume (ECV) fraction on magnetic resonance imaging (MRI) can evaluate the degree of myocardial fibrosis and has been reported to help diagnose and evaluate the prognosis of cardiomyopathy. In hypertrophic cardiomyopathy (HCM), ECV analysis on MRI is reported to help predict ventricular arrhythmias. However, the performance of cardiac MRI takes time, and there are also several contraindications. Cardiac computed tomography (CT) is more versatile than cardiac MRI and is also useful in screening coronary artery disease. ECV analysis on CT is now available, and a good correlation with ECV on MRI has been reported. We hypothesized that ECV on CT, a new fibrosis indicator, would be useful in predicting prognosis in HCM patients. Purpose To determine the utility of ECV analysis on CT to predict the prognosis in patients with HCM. Methods One hundred and three HCM patients (68 males, 66 ± 11 years old) who underwent cardiac CT using 320-row detector CT or 256-row detector CT, from 2008 to 2021 at our two hospitals were analyzed. We measured left ventricular (LV) ECV (LV-ECV) on CT and collected patient characteristics, transthoracic echocardiographic, and other CT findings. We investigated the relationship between these findings and the major adverse cardiac events (MACEs) (cardiac death, fatal arrhythmia, and heart failure hospitalization) after CT. Results All patients were followed for 64 ± 54 months after cardiac CT, and 15 patients (14.6%) had MACEs (ten heart failure hospitalization cases, two ventricular fibrillation cases, two sustained ventricular tachycardia cases, and one sudden cardiac death case). The patients with MACEs had a significantly higher LV-ECV, sudden cardiac death (SCD) risk score and lower LV ejection fraction (LVEF) than those without MACEs（42.0 ± 8.3% vs. 33.7 ± 6.1%, P &amp;lt; 0.001, 2.4 ± 0.39 vs 1.95 ± 0.16, P= 0.047, and 57.7 ± 11.9% vs. 66.7 ± 6.9%, P = 0.004). The percentage of dilated phase HCM was significantly higher in the patients with MACEs than those without MACEs (21% vs 0%, p=0.002). LV-ECV was the only significant predictor of MACEs based on the multivariate analysis by Cox proportional hazard model (hazard ratio 1.23, 95% confidence interval 1.09-1.41, P&amp;lt;0.001). The optimal threshold of LV-ECV to predict MACEs was 37.6% based on the receiver operating characteristic analysis. The sensitivity and specificity of LV-ECV to predict MACEs were 73% and 78% at the best cut-off, and the area under the curve was 0.79 (Figure A). The patients with LV-ECV ≥ 37.6% (30 patients) had significantly higher MACEs than those with LV-ECV &amp;lt; 37.6% during the follow-up periods (P &amp;lt; 0.001) (Figure B). Conclusion LV-ECV on CT of 37.6% is a good prognostic indicator in HCM cases. ECV analysis on CT helped predict MACEs in HCM cases.

Altered cerebral oxygen extraction and metabolism in preterm neonates and the relationship to anemia: A noncontrast MRI study

AbstractObjectiveThe preterm brain is susceptible to structural injuries, which may be related to an imbalance between blood supply and oxygen metabolism. However, the effect of preterm birth on cerebral oxygen metabolism and its underlying mechanism have not been fully elucidated. The present study measured cerebral oxygen extraction and metabolism using noncontrast magnetic resonance imaging (MRI) methods in preterm neonates and examined its relationship with anemia of prematurity.MethodsFifty neonates with a gestational age of 28–42 weeks were enrolled. Cerebral oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO2) were measured with T2‐relaxation‐under‐spin‐tagging (TRUST) MRI, together with cerebral blood flow (CBF).ResultsWe showed that CBF (p = 0.00021) and CMRO2 (p &lt; 0.0001) increased with gestational age while OEF increased with postnatal age (p = 0.0013). Higher OEF was also associated with a higher Apgar score at birth (p = 0.039). Furthermore, hematocrit significantly mediates the increase of OEF with postnatal age (p &lt; 0.001). Structural equation modeling analysis suggested a bidirectional relationship between CBF and CMRO2; both contributed to the changes in OEF.InterpretationThese findings demonstrated an altered cerebral oxygen metabolism in preterm brain, suggesting a potential role of MRI–based oxygenation measurement in the assessment of transfusion and intervention for preterm neonates.

Assessment of meniscal extrusion with ultrasonography: a systematic review and meta-analysis

BackgroundMagnetic resonance imaging (MRI) is the imaging of choice for meniscal extrusion (ME). However, they may underappreciate the load-dependent changes of the meniscus. There is growing evidence that weight-bearing ultrasound (WB US) is more suitable, particularly in revealing occult extrusion. We therefore perform a systematic review and meta-analysis on the validity and reliability of US in diagnosing extrusion. Furthermore, we explored whether it detects differences in extrusion between loaded and unloaded positions and those with pathological (osteoarthritis and meniscal injury) and healthy knees.MethodsThe Cochrane Controlled Register of Trials, PubMed, Medline, and Embase were used to perform a systematic review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. Data pertaining to intra- and interrater reliability of US in measuring meniscal extrusion (ME), its correlation with magnetic resonance imaging (MRI), and head-to-head comparison of potential factors to influence ME were included [loading versus unloading position; osteoarthritis (OA) or pathological menisci (PM) versus healthy knees; mild versus moderate–severe knee OA]. Pooled data were analyzed by random or fixed-effects models.ResultsA total of 31 studies were included. Intraclass correlation coefficients (ICC) for intra- and interrater reliability were minimum 0.94 and 0.91, respectively. The correlation between US and MRI was (r = 0.76). US detected ME to be greater in the loaded position in all knees (healthy, p < 0.00001; OA, p < 0.00001; PM, p = 0.02). In all positions, US detected greater extrusion in OA (p < 0.0003) and PM knees (p = 0.006) compared with healthy controls. Furthermore, US revealed greater extrusion in moderate–severe OA knees (p < 0.00001).ConclusionsThis systematic review suggests ultrasonography can play an important role in the measurement of meniscal extrusion, with results comparable to that of MRI. However, to what extent it can differentiate between physiological and pathological extrusion requires further investigation, with an absolute cutoff value yet to be determined. Nevertheless, it is an appropriate investigation to track the progression of disease in those with meniscal pathologies or osteoarthritis. Furthermore, it is a feasible investigation to evaluate the meniscal function following surgery.Level of evidence: IV, Systematic review of level III–IV evidence.

Extra cellular volume by computed tomography is useful for prediction of prognosis in cardiac sarcoidosis

Abstract Background Extracellular volume (ECV) fraction on magnetic resonance imaging (MRI) has been useful in evaluating the degree of myocardial fibrosis and has been reported to help diagnose and evaluate the prognosis of cardiomyopathy. However, there are also several contraindications in the cardiac MRI, and the performance of it takes time. Computed tomography (CT) helps screen for coronary artery disease, is more versatile than cardiac MRI, and is also useful in screening for coronary artery disease. Myocardial extracellular volume (ECV) analysis on CT has been recently eligible and has shown a good correlation with ECV on MRI. We hypothesized that ECV on CT, a new fibrosis indicator, would be useful in predicting prognosis in patients with cardiac sarcoidosis (CS). Purpose The purpose of this study is to evaluate the utility of ECV analysis on CT for predicting major adverse cardiac events (MACEs) in cases with cardiac sarcoidosis (CS). Methods As a single-center study, 48 patients (18 males, 67 ± 11 years old) diagnosed with CS based on the 2016 Japanese Circulation Society criteria and who underwent cardiac CT using 320-row detector CT or 256-row detector CT, and including late-phase images from December 2008 to January 2024 were analyzed retrospectively. We evaluated the ECV of left ventricular myocardium (LVM) using commercially available software (Figure A). The primary endpoint was MACEs, a composite of all-cause death, heart failure hospitalization, and fatal ventricular arrhythmia. Results Among all 48 patients, 14 combined events (10 fatal ventricular arrhythmias, three heart failure hospitalizations, and one all-cause death) were observed during a follow-up of 56 ± 57 months. ECV of LVM on CT was significantly higher in patients with MACEs than the others (37 ± 5.6% vs 33 ± 4.6%, P = 0.0087). The best cut-off value of ECV of LVM on CT for prediction of MACEs was 34.97%, and the sensitivity and specificity of LV-ECV to predict MACEs were 71% and 76% at the best cut-off, and the area under the curve was 0.73 based on the receiver operating characteristics curve analysis (P = 0.009) (Figure B). The cases with ECV ≥ 34.97% (n = 18) had significantly higher MACEs than the cases with ECV &amp;lt; 34.97% based on the Kaplan-Meier analysis (P = 0.0031) (Figure C). In the multivariate Cox proportional hazard model, ECV on LVM (Hazard ratio 1.11, 95% confidence interval 1.00-1.21, p=0.0493) and history of VT ablation (Hazard ratio 27.7, 95% confidence interval 4.27-180, p=0.0011) were the significant predictors of MACEs. Conclusion Adverse events mainly caused by fatal ventricular arrhythmia are relatively common in CS. Evaluation of ECV by CT may be useful for the prediction of MACEs in cases with CS.

Validation of fat mass metrics in pediatric obesity

Introduction Hudda-Index is a prediction model for fat mass (FM) based on simple anthropometric measures., FM is a crucial factor in the development of comorbidities, i.e., type 2 diabetes. Hence, Hudda-Index is a promising tool to facilitate identification of children at risk for metabolic comorbidities. It has been validated against deuterium dilution assessments, however, independent validation against the gold-standard for body composition analysis, magnetic resonance imaging (MRI), is lacking. The aim of this study is to validate FM calculated by Hudda-Index against FM measured by MRI. The secondary aim is to compare Hudda-Index to other anthropometric measures including body mass index (BMI), BMI-standard deviation score (BMI-SDS), waist/hip-ratio, waist circumference (WC) and skinfold thickness. Methods The study cohort consists of 115 individuals between the age of 9 and 15 years, recruited at Paracelsus Medical University Hospital in Salzburg (Austria) and Uppsala University Children's Hospital (Sweden). Anthropometry, blood samples, and oral glucose tolerance tests followed standard procedures. MRI examinations were performed to determine visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT). Results BMI and WC showed slightly stronger associations with the reference standard VAT (r=0.72 and 0.70, p&lt;0.01, respectively) than Hudda-Index (r= 0.67, p&lt;0.01). There is an almost perfect linear association between BMI and Hudda-Index. Accordingly, BMI and Hudda-Index both showed an acceptable association with cardiometabolic parameters. VAT was strongly associated with markers of liver status (LFF r=0.59, p&lt;0.01) and insulin resistance (HOMA-IR r=0.71, p&lt;0.01) and predicted metabolic dysfunction-associated steatotic liver disease (MASLD). Conclusion BMI, although an imperfect measure, remains the most reliable tool and estimates cardiometabolic risk more reliably than other anthropometry-based measures.

High physical activity relates to higher risk of incident carotid plaque components

Abstract Background The rupture of carotid atherosclerotic plaque, primarily driven by plaque components, is among the leading causes of ischemic stroke. Although physical activity (PA) stands as a major modifiable target for prevention of atherosclerotic diseases, recent studies suggested a potential adverse impact of high-volume PA on atherosclerotic plaque burden in athletes. Data remains scarce from the community-dwelling population regarding to the impact of PA on the longitudinal change of carotid plaque components. Objectives To assess the association between PA and the incidence of carotid plaque components and explore whether the association of PA with stroke and all-cause mortality differs by the presence of plaque components. Methods Between 2007 and 2012, in a community- dwelling cohort in Netherlands, 1327 stroke-free persons (mean ± standard deviation age 72 ± 9 years, 45% women) with carotid atherosclerosis (carotid intima-media thickness &amp;gt; 2.5 mm) were invited for magnetic resonance imaging (MRI) to assess carotid plaque components. From these, 696 persons (1267 carotid arteries) underwent a follow-up MRI between 2014 and 2017 (median between-scan interval 6 years). Carotid plaque components included calcification, intraplaque hemorrhage (IPH), and lipid-rich necrotic core (LRNC). The volume of moderate, vigorous and total PA (unit: metabolic equivalent task hour, MET-h) was assessed using LASA Physical Activity Questionnaires around the time of the first MRI scan. Participants were followed for the occurrence of stroke or all-cause mortality until December 31, 2019. Generalized estimation equation and Cox regression models were used in the analyses, with adjustments for plaque size and other cardiovascular risk factors. Results Compared to lowest quintile PA group, participants in the highest quintile total PA group had a higher risk of new onset of plaque components, odds ratio (95%CI) 2.69 (1.21; 5.94) for calcification, 1.35 (0.82; 2.24) for LRNC and 1.93 (1.12; 3.34) for IPH (Figure 1). Similar associations were observed for vigorous PA but not for moderate PA. Over a median follow-up of 9.5 years, 118 persons suffered a stroke and 298 died. As shown in table 1, baseline IPH, rather than LRNC or calcification, modulated the associations of PA with stroke and all-cause mortality (P-interaction &amp;lt;0.05): higher total PA was associated with a lower risk of stroke among IPH-free persons, with the hazard ratio (95% CI) of 0.929 (0.867; 0.996) per 10 MET-h/week increase; no associations between PA and stroke were found among those with IPH. Similar associations were found between vigorous PA and all-cause mortality. Conclusions Among the middle-aged and elderly with subclinical atherosclerosis, high level PA, especially high vigorous PA, may lead to an unstable carotid plaque. The beneficial effect of PA on stroke and all-cause mortality is only among persons with a stable carotid plaque profile, especially without IPH.

Basal inferior-septal segment is highly susceptible to deformation in the clinical spectrum of transthyretin-derived cardiomyopathy

Abstract Background The prevalence of transthyretin-derived cardiomyopathy (ATTR-CM) is increasing; however, understanding the morphological and functional manifestations within the left ventricle (LV) across the spectrum of heart failure (HF) remain limited. Purpose This study aims to assess the longitudinal strain (LS) using 2D speckle-tracking echocardiography in ATTR-CM patients and compared them with the features of magnetic resonance imaging (MRI). Methods 2D speckle-tracking echocardiography evaluated LS in 63 histology-confirmed ATTR-CM patients (median age: 78 years; male: 94%), with and without developing HF. Additionally, native T1 and extracellular volume (ECV) measured using MRI were compared with LS in 18-segments depicted on a Bull’s eye plot. Results Patients were grouped based on HF status: Group 1 (no HF symptoms, n=10), Group 2 (HF with preserved LV ejection fraction (LVEF), n=17), and Group 3 (reduced LVEF, n=36). Group 3 exhibited higher levels of brain natriuretic peptide and troponin T, and lower estimated glomerular filtration rate, compared with Group 1 and 2. Echocardiography revealed heightened LV thickness and decreased LVEF in Group 3. LS analysis revealed susceptibility to deformation in the basal inferior-septal segment, persisting even in Group 1. MRI revealed a high average native T1 level with minimal standard deviation (indicative of tissue homogeneity). However, this level increased as distance from the inferior-septal segment grew in the basal and mid-ventricular slices. Contrast images displayed maximal ECV in the basal and mid-ventricular inferior-septum, a phenomenon persisting in Group 1. Segmental LS decline, as assessed by echocardiography, correlated with ECV expansion but not with native T1 values. Conclusion 2D speckle-tracking echocardiography can identify segmental LS impairment in ATTR-CM patients, potentially reflecting amyloid burden and fibrosis extent. Our data suggest that amyloid deposition might be widespread from the basal inferior-septal segment to other areas.

Initial results of the Hyperion IIDPET insert for simultaneous PET-MRI applied to atherosclerotic plaque imaging in New-Zealand white rabbits.

In preclinical research, in vivo imaging of mice and rats is more&#xD;common than any other animal species, since their physiopathology is very well-&#xD;known and many genetically altered disease models exist. Animal studies based on&#xD;small rodents are usually performed using dedicated preclinical imaging systems&#xD;with high spatial resolution. For studies that require animal models such as mini-&#xD;pigs or New-Zealand White (NZW) rabbits, imaging systems with larger bore&#xD;sizes are required. In case of hybrid imaging using Positron Emission Tomography&#xD;(PET) and Magnetic Resonance Imaging (MRI), clinical systems have to be used,&#xD;as these animal models do not typically fi t in preclinical simultaneous PET-MRI&#xD;scanners.&#xD;Approach. In this paper, we present initial imaging results obtained with the&#xD;Hyperion IID PET insert which can accommodate NZW rabbits when combined&#xD;with a large volume MRI RF coil. First, we developed a rabbit-sized image&#xD;quality phantom of comparable size to a NZW rabbit in order to evaluate the&#xD;PET imaging performance of the insert under high count rates. For this phantom,&#xD;radioactive spheres with inner diameters between 3.95 and 7.86 mm were visible&#xD;in a warm background with a tracer activity ratio of 4.1 to 1 and with a total&#xD;18-F activity in the phantom of 58MBq at measurement start. Second, we performed&#xD;simultaneous PET-MR imaging of atherosclerotic plaques in a rabbit in vivo using&#xD;a single injection containing 18-F-FDG for detection of infl ammatory activity,&#xD;and Gd-ESMA for visualization of the aortic vessel wall and plaques with MRI.&#xD;Main results. The fused PET-MR images reveal 18-F-FDG uptake within an&#xD;active plaques with plaque thicknesses in the sub-millimeter range. Histology&#xD;showed colocalization of 18-F-FDG uptake with macrophages in the aortic vessel wall lesions. &#xD;Significance. Our initial results demonstrate that this PET insert&#xD;is a promising system for simultaneous high-resolution PET-MR atherosclerotic&#xD;plaque imaging studies in NZW rabbits.

Identification of new instances of white matter hyperintensities in patients following TAVI (from the CAPITA study)

Abstract A third of patients diagnosed with symptomatic severe aortic valve stenosis and scheduled for transcatheter aortic valve implantation (TAVI) exhibit some level of cognitive impairment. The prospective CAPITA study aimed to systematically evaluate the impact of TAVI on cerebral and cognitive outcomes in patients undergoing the procedure. In this report, we focus on the identification of new incidence of white matter hyperintensities (WMH) and the correlation with changes in cognitive functioning. The CAPITA (CArdiac OutPut, Cerebral Blood Flow and Cognition In Patients With Severe Aortic Valve Stenosis Undergoing Transcatheter Aortic Valve Implantation) study is a prospective study of cerebral and cognitive outcomes following TAVI. Patients underwent magnetic resonance imaging (MRI) and extensive neuropsychological testing at baseline and three month follow-up. New cerebral infarcts were defined according to NeuroARC criteria. We examined the incidence of new WMH in terms of volume (Δ mL) and number on FLAIR MRI, and explored the correlation between new WMH and cognitive functioning. A total of 148 patients were included who underwent TAVI between August 2020 and October 2022. Mean age was 80.5±5.7 years, of whom 43% female with a median STS-PROM of 2.0% (IQR 1.4%-2.9%). Median baseline WMH comprised 127 (IQR 32-216) lesions, with a total volume of 13.1 (IQR 7.0-24.6) mL. At 3 months follow-up, the number of lesions increased to 164 (IQR 121-301) lesions, with a total volume of 13.3 (IQR 5.8-21.5) mL. Median WMH volume increase was 0.1 (IQR 0.0-0.3) ml (p=0.02). A total of 9 patients (9.5%) had an increase of 1 mL of WMH or more. At follow-up, 12% of patients exhibited cognitive decline of &amp;gt;0.5SD. These patient tended to have a greater increase in white matter hyperintensity volume (1.26±2.96 ml), compared to the 53% of patients with stable cognition (0.29±0.45 ml) and the 36% of patients with improved cognition (0.31±0.91 ml), (p=0.06). WMH lesions did not exhibit distribution patterns across various locations within the groups characterized by declined, stable, or improved cognition (Figure 1). WMH volumes were higher in patients who experienced postprocedural delirium than in patients without delirium (27.1±14.0 vs 15.0±12.5 mL, p&amp;lt;0.001). In this study, patients with severe symptomatic aortic valve stenosis undergoing TAVI, there was an overall increase of white matter hyperintensity volume between baseline and 3-month follow-up. Up to 12% of patients had cognitive decline, which was associated with new white matter hyperintensities on MRI.