Purpose
To investigate the magic angle effect in three‐dimensional ultrashort echo time Cones Adiabatic T1ρ (3D UTE Cones‐AdiabT1ρ) imaging of articular cartilage at 3T.
Methods
The magic angle ...effect was investigated by repeated 3D UTE Cones‐AdiabT1ρ imaging of eight human patellar samples at five angular orientations ranging from 0° to 90° relative to the B0 field. Cones continuous wave T1ρ (Cones‐CW‐T1ρ) and Cones‐
T2∗ sequences were also applied for comparison. Cones‐AdiabT1ρ, Cones‐CW‐T1ρ and Cones‐
T2∗ values were measured for four regions of interest (ROIs) (10% superficial layer, 60% transitional layer, 30% radial layer, and a global ROI) for each sample at each orientation to evaluate their angular dependence.
Results
3D UTE Cones‐AdiabT1ρ values increased from the radial layer to the superficial layer for all angular orientations. The superficial layer showed the least angular dependence (around 4.4%), while the radial layer showed the strongest angular dependence (around 34.4%). Cones‐AdiabT1ρ values showed much reduced magic angle effect compared to Cones‐CW‐T1ρ and Cones‐
T2∗ values for all four ROIs. On average over eight patellae, Cones‐AdiabT1ρ values increased by 27.2% (4.4% for superficial, 23.8% for transitional, and 34.4% for radial layers), Cones‐CW‐T1ρ values increased by 76.9% (11.3% for superficial, 59.1% for transitional, and 117.8% for radial layers), and Cones‐
T2∗ values increased by 237.5% (87.9% for superficial, 262.9% for transitional, and 327.3% for radial layers) near the magic angle.
Conclusions
The 3D UTE Cones‐AdiabT1ρ sequence is less sensitive to the magic angle effect in the evaluation of articular cartilage compared to Cones‐
T2∗ and Cones‐CW‐T1ρ.
In the previous literature, the prevalence of right atrial (RA) clot‐in‐transit associated with pulmonary embolism is around 4–18% with an associated mortality of 80–100% in untreated cases. Surgical ...thrombo‐embolectomy has been the mainstay of treatment for stable patients but the data for percutaneous thrombo‐embolectomy is lacking in the literature. We present a series of three cases of right atrium clot‐in‐transit treated with catheter‐based therapies with Inari FlowTriever® (Inari Medical, Irvine, CA). Our three patients had different clinical profiles and presentations of right atrial clot‐in‐transit. All of the subjects had contraindications to surgical thrombo‐embolectomy and thrombolytic therapy. Catheter based embolectomy using Inari FlowTriever® was successfully performed in all the patients. As the data on this intervention is sparse, our case series highlights successful catheter based thrombo‐embolectomies in high‐risk individuals with right atrial clot in‐transit with or without pulmonary embolism.
Ultrashort echo time (UTE) MRI can quantify the major proton pool densities in cortical bone, including total (TWPD), bound (BWPD), and pore water (PWPD) proton densities, as well as the ...macromolecular proton density (MMPD), associated with the collagen content, which is calculated using macromolecular fraction (MMF) from UTE magnetization transfer (UTE-MT) modeling. This study aimed to investigate the differences in water and collagen contents in tibial cortical bone, between female osteopenia (OPe) patients, osteoporosis (OPo) patients, and young participants (Young). Being postmenopausal and above 55 years old were the inclusion criteria for OPe and OPo groups. The tibial shaft of fourteen OPe (72.5 ± 6.8 years old), thirty-one OPo (72.0 ± 6.4 years old), and thirty-one young subjects (28.0 ± 6.1 years old) were scanned using a knee coil on a clinical 3 T scanner. Basic UTE, inversion recovery UTE, and UTE-MT sequences were performed. Investigated biomarkers were compared between groups using Kruskal-Wallis test. Spearman's correlation coefficients were calculated between the total hip dual-energy x-ray absorptiometry (DXA) T-score and UTE-MRI results. MMF, BWPD, and MMPD were significantly lower in OPo patients than in the young group. Whereas T1, TWPD, and PWPD were significantly higher in OPo patients. The largest OPo/Young average percentage differences were found in MMF (41.9%), PWPD (103.5%), and MMPD (64.0%). PWPD was significantly higher (50.7%), while BWPD was significantly lower (16.4%) in OPe than the Young group on average. MMF was found to be significantly lower (27%) in OPo patients compared with OPe group. T1, MMF, TWPD, PWPD, and MMPD values significantly correlated with the total hip DXA T-scores (provided by the patients and only available for OPe and OPo patients). DXA T-score showed the highest correlations with PWPD (R = 0.55) and MMF (R = 0.56) values. TWPD, PWPD, and MMF estimated using the UTE-MRI sequences were recommended to evaluate individuals with OPe and OPo.
Purpose
To investigate tricomponent analysis of human cortical bone using a multipeak fat signal model with 3D ultrashort TE Cones sequences on a clinical 3T scanner.
Methods
Tricomponent fitting of ...bound water, pore water, and fat content using a multipeak fat spectra model was proposed for 3D ultrashort TE imaging of cortical bone. Three‐dimensional ultrashort TE Cones acquisitions combined with tricomponent analysis were used to investigate bound and pore water T2∗ and fractions, as well as fat T2∗ and fraction in cortical bone. Feasibility studies were performed on 9 human cortical bone specimens with regions of interest selected from the endosteum to the periosteum in 4 circumferential regions. Microcomputed tomography studies were performed to measure bone porosity and bone mineral density for comparison and validation of the bound and pore water analyses.
Results
The oscillation of the signal decay was well‐fitted with the proposed tricomponent model. The sum of the pore water and fat fractions from tricomponent analysis showed a high correlation with microcomputed tomography porosity (R = 0.74, P < 0.01). Estimated bound‐water fraction also demonstrated a high correlation with bone mineral density (R = 0.70, P < 0.01).
Conclusion
Tricomponent analysis significantly improves the estimation of bound‐water and pore‐water fractions in human cortical bone.
Objectives:
The co-occurrence of different classes of population-level stressors, such as social unrest and public health crises, is common in contemporary societies. Yet, few studies explored their ...combined mental health impact. The aim of this study was to examine the impact of repeated exposure to social unrest-related traumatic events (TEs), coronavirus disease 2019 (COVID-19) pandemic-related events (PEs), and stressful life events (SLEs) on post-traumatic stress disorder (PTSD) and depressive symptoms, and the potential mediating role of event-based rumination (rumination of TEs-related anger, injustice, guilt, and insecurity) between TEs and PTSD symptoms.
Methods:
Community members in Hong Kong who had utilized a screening tool for PTSD and depressive symptoms were invited to complete a survey on exposure to stressful events and event-based rumination.
Results:
A total of 10,110 individuals completed the survey. Hierarchical regression analysis showed that rumination, TEs, and SLEs were among the significant predictors for PTSD symptoms (all P < 0.001), accounting for 32% of the variance. For depression, rumination, SLEs, and PEs were among the significant predictors (all P < 0.001), explaining 24.9% of the variance. Two-way analysis of variance of different recent and prior TEs showed significant dose-effect relationships. The effect of recent TEs on PTSD symptoms was potentiated by prior TEs (P = 0.005). COVID-19 PEs and prior TEs additively contributed to PTSD symptoms, with no significant interaction (P = 0.94). Meanwhile, recent TEs were also potentiated by SLEs (P = 0.002). The effects of TEs on PTSD symptoms were mediated by rumination (β = 0.38, standard error = 0.01, 95% confidence interval: 0.36 to 0.41), with 40.4% of the total effect explained. All 4 rumination subtypes were significant mediators.
Conclusions:
Prior and ongoing TEs, PEs, and SLEs cumulatively exacerbated PTSD and depressive symptoms. The role of event-based rumination and their interventions should be prioritized for future research.
Purpose
To develop a 3D adiabatic T1ρ prepared ultrashort echo time cones (3D AdiabT1ρ UTE‐Cones) sequence for whole knee imaging on a clinical 3T scanner.
Methods
A train of adiabatic full passage ...pulses were used for spin locking, followed by time‐efficient multispoke UTE acquisition to detect signals from both short and long T2 tissues in the whole knee joint. A modified signal model was proposed for multispoke UTE data fitting. The feasibility of this 3D AdiabT1ρ UTE‐Cones technique was demonstrated through numerical simulation, phantom, and ex vivo knee sample studies. The 3D AdiabT1ρ UTE‐Cones technique was then applied to 6 in vivo knee joints of healthy volunteers to measure T1ρ values of quadriceps tendon, patellar tendon, anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), meniscus, patellar cartilage, and muscle.
Results
Numerical simulation, phantom and ex vivo knee sample studies demonstrated the feasibility of whole knee imaging using the proposed multispoke 3D AdiabT1ρ UTE‐Cones sequence. The healthy volunteer knee study demonstrated an averaged T1ρ of 13.9 ± 0.7 ms for the quadriceps tendon, 9.7 ± 0.8 ms for the patellar tendon, 34.9 ± 2.8 ms for the ACL, 21.6 ± 1.4 ms for the PCL, 22.5 ± 1.9 ms for the meniscus, 44.5 ± 2.4 ms for the patellar cartilage, and 43.2 ± 1.1 ms for the muscle.
Conclusion
The 3D AdiabT1ρ UTE‐Cones sequence allows volumetric T1ρ assessment of both short and long T2 tissues in the knee joint on a clinical 3T scanner.
Ultrashort echo time magnetic resonance imaging (UTE-MRI) techniques have been increasingly used to assess cortical bone microstructure. High resolution micro computed tomography (μCT) is routinely ...employed for validating the MRI-based assessments. However, water protons in cortical bone may reside in micropores smaller than the detectable size ranges by μCT. The goal of this study was to evaluate the upper limit of UTE-MRI and compare its efficacy to μCT at determining bone porosity ex vivo. This study investigated the correlations between UTE-MRI based quantifications and histomorphometric measures of bone porosity that cover all pores larger than 1 μm. Anterior tibial midshaft specimens from eleven donors (51 ± 16 years old, 6 males, 5 females) were scanned on a clinical 3 T-MRI using UTE magnetization transfer (UTE-MT, three power levels and five frequency offsets) and UTE-T2* sequences. Two-pool MT modeling and bi-component exponential T2* fitting were performed on the MRI datasets. Specimens were then scanned by μCT at 9 μm voxel size. Histomorphometry was performed on hematoxylin and eosin (H&E) stained slides imaged at submicron resolution. Macromolecular fraction from MT modeling, bi-component T2* fractions, and short component T2* showed strong correlations (R > 0.7, p < 0.01) with histomorphometric total and large-pores (>40 μm) porosities as well as with μCT-based porosity. UTE-MRI could also assess small pores variations with moderate correlations (R > 0.5, p < 0.01). The UTE-MRI techniques can detect variations of bone porosity comprised of pores below the range detectable by μCT. Such fine pore variations can contribute differently to the development of bone diseases or to the bone remodeling process, however, this needs to be investigated. In scanned specimens, major porosity changes were from large pores, therefore the μCT employment was likely adequate to validate UTE-MRI biomarkers.
•Two common UTE-MRI techniques were investigated for their capability of cortical bone porosity assessment.•MMF as well as short-component fraction and T2* showed strong correlations with histomorphometric and μCT porosity.•UTE-MRI was able also to detect small pores variation with moderate correlation, that are below the detectable range by μCT.
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