Six-minute, in vivo MRI quantification of proximal femur trabecular bone 3D microstructure.

BACKGROUND: Assessment of proximal femur trabecular bone microstructure in vivo by magnetic resonance imaging has recently been validated for acquiring information independent of bone mineral density in osteoporotic patients. However, the requisite signal-to-noise ratio (SNR) and resolution for interrogation of the trabecular microstructure at this anatomical location prolongs the scan duration and renders the imaging protocol clinically infeasible. Parallel imaging and compressed sensing (PICS) techniques can reduce the scan duration of the imaging protocol without substantially compromising image quality. The present work investigates the limits of acceleration for a commonly used PICS technique, ℓ1-ESPIRiT, for the purpose of quantifying measures of trabecular bone microarchitecture. Based on a desired error tolerance, a six-minute, prospectively accelerated variant of the imaging protocol was developed and assessed for intersession reproducibility and agreement with the longer reference scan. PURPOSE: To investigate the limits of acceleration for MRI-based trabecular bone quantification by parallel imaging and compressed sensing reconstruction, and to develop a prototypical imaging protocol for assessing the proximal femur microstructure in a clinically practical scan time. METHODS: Healthy participants (n = 11) were scanned by a 3D balanced steady-state free precession (bSSFP) sequence satisfying the Nyquist criterion with a scan duration of about 18 min. The raw data were retrospectively undersampled and reconstructed to mimic various acceleration factors ranging from 2 to 6. Trabecular volumes-of-interest in four major femoral regions (greater trochanter, intertrochanteric region, femoral neck, and femoral head) were analyzed and six relevant measures of trabecular bone microarchitecture (bone volume fraction, surface-to-curve ratio, erosion index, elastic modulus, trabecular thickness, plates-to-rods ratio) were obtained for images of all accelerations. To assess agreement, median percent error and intraclass correlation coefficients (ICCs) were computed using the fully-sampled data as reference. Based on this analysis, a prospectively 3-fold accelerated sequence with a duration of about 6 min was developed and the analysis was repeated. RESULTS: A prospective acceleration factor of 3 demonstrated comparable performance in reproducibility and absolute agreement to the fully-sampled scan. The median CoV over all image-derived metrics was generally <6 % and ICCs >0.70. Also, measurements from prospectively 3-fold accelerated scans demonstrated in general median percent errors of <7 % and ICCs >0.70. CONCLUSION: The present work proposes a method to make in vivo quantitative assessment of proximal femur trabecular microstructure with a clinically practical scan duration of about 6 min.

Cannabis Use Is Associated With Depression Severity and Suicidality in the National Comorbidity Survey-Adolescent Supplement.

Objective: To investigate the association of cannabis use with major depression and suicidal behavior in adolescence. Method: Data are from the National Comorbidity Survey-Adolescent Supplement N=10,123, a nationally representative survey of adolescents aged 13 to 18 years. Weighted logistic regression and ordinal regression analyses of major depression and suicidal behavior outcomes were conducted on cannabis variables, incorporating sociodemographic characteristics. Results: Adolescents with lifetime cannabis use have 2.07 times higher odds of mild/moderate (adjusted odds ratio [aOR]; 95% CI=1.69, 2.53) and 3.32 times higher odds of severe major depressive disorder (MDD; aOR; 95% CI=2.31, 4.75). Cannabis use (aOR 6.90, 95% CI=4.67,10.19), mild/moderate MDD (aOR 4.10, 95% CI=2.82, 5.98), and severe MDD (aOR 13.97, 95% CI = 7.59, 25.70) were associated with higher odds of suicide attempt. Past 12-month cannabis use (aOR 3.70, 95% CI = 2.16, 6.32), mild/moderate major depressive episodes (MDE) (aOR 7.85, 95% CI=3.59, 17.17), and severe MDE (aOR 36.36, 95% CI=13.68,96.64) were associated with higher odds of suicide attempt. The frequency of past 12-month cannabis use was associated with higher odds of suicide attempt and with MDE severity, with higher odds among individuals who use cannabis 3 or more days than among individuals who use cannabis less frequently, suggesting a dose effect. Among cannabis users, older age of onset of cannabis use was associated with lower odds of suicidal behaviors. Conclusion: Cannabis use is associated with higher odds of depression and depression severity in adolescence. Furthermore, depression and cannabis use are independently associated with higher odds of suicide attempt. Diversity & Inclusion Statement: We worked to ensure sex and gender balance in the recruitment of human participants. We worked to ensure race, ethnic, and/or other types of diversity in the recruitment of human participants. The author list of this paper includes contributors from the location and/or community where the research was conducted who participated in the data collection, design, analysis, and/or interpretation of the work. One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented racial and/or ethnic groups in science. We actively worked to promote sex and gender balance in our author group. We actively worked to promote inclusion of historically underrepresented racial and/or ethnic groups in science in our author group.

Automated, calibration-free quantification of cortical bone porosity and geometry in postmenopausal osteoporosis from ultrashort echo time MRI and deep learning.

BACKGROUND: Assessment of cortical bone porosity and geometry by imaging in vivo can provide useful information about bone quality that is independent of bone mineral density (BMD). Ultrashort echo time (UTE) MRI techniques of measuring cortical bone porosity and geometry have been extensively validated in preclinical studies and have recently been shown to detect impaired bone quality in vivo in patients with osteoporosis. However, these techniques rely on laborious image segmentation, which is clinically impractical. Additionally, UTE MRI porosity techniques typically require long scan times or external calibration samples and elaborate physics processing, which limit their translatability. To this end, the UTE MRI-derived Suppression Ratio has been proposed as a simple-to-calculate, reference-free biomarker of porosity which can be acquired in clinically feasible acquisition times. PURPOSE: To explore whether a deep learning method can automate cortical bone segmentation and the corresponding analysis of cortical bone imaging biomarkers, and to investigate the Suppression Ratio as a fast, simple, and reference-free biomarker of cortical bone porosity. METHODS: In this retrospective study, a deep learning 2D U-Net was trained to segment the tibial cortex from 48 individual image sets comprised of 46 slices each, corresponding to 2208 training slices. Network performance was validated through an external test dataset comprised of 28 scans from 3 groups: (1) 10 healthy, young participants, (2) 9 postmenopausal, non-osteoporotic women, and (3) 9 postmenopausal, osteoporotic women. The accuracy of automated porosity and geometry quantifications were assessed with the coefficient of determination and the intraclass correlation coefficient (ICC). Furthermore, automated MRI biomarkers were compared between groups and to dual energy X-ray absorptiometry (DXA)- and peripheral quantitative CT (pQCT)-derived BMD. Additionally, the Suppression Ratio was compared to UTE porosity techniques based on calibration samples. RESULTS: The deep learning model provided accurate labeling (Dice score 0.93, intersection-over-union 0.88) and similar results to manual segmentation in quantifying cortical porosity (R2 ≥ 0.97, ICC ≥ 0.98) and geometry (R2 ≥ 0.82, ICC ≥ 0.75) parameters in vivo. Furthermore, the Suppression Ratio was validated compared to established porosity protocols (R2 ≥ 0.78). Automated parameters detected age- and osteoporosis-related impairments in cortical bone porosity (P ≤ .002) and geometry (P values ranging from <0.001 to 0.08). Finally, automated porosity markers showed strong, inverse Pearson's correlations with BMD measured by pQCT (|R| ≥ 0.88) and DXA (|R| ≥ 0.76) in postmenopausal women, confirming that lower mineral density corresponds to greater porosity. CONCLUSION: This study demonstrated feasibility of a simple, automated, and ionizing-radiation-free protocol for quantifying cortical bone porosity and geometry in vivo from UTE MRI and deep learning.

A Case Report of Neuropathic Pain and Unilateral Lower Extremity Weakness Following a Cardiac Arrest.

Femoral nerve palsy is a rare, but significant complication following percutaneous coronary intervention (PCI) for conditions such as myocardial infarction. We present a case of a 61-year-old male patient who presented for cardiac rehabilitation following an emergent PCI procedure for cardiac arrest secondary to ST-elevation myocardial infarction. He later developed right lower extremity weakness and severe neuropathic pain on arrival to the acute rehabilitation unit. After physical examination and electrodiagnostic studies, he was determined to have a right femoral nerve neuropathy. This case report highlights the clinical course, physical examination/electrodiagnostic findings, and subsequent pain management of femoral nerve palsies.

Severe Diesel Injection Injury to the Face, Neck and Orbit: Surgical Management and Critical Care Considerations.

The purpose of this report is to discuss high-pressure injection injuries involving the face and orbit and discuss factors affecting prognosis and management as these injuries are rare and uniquely challenging to manage given the complex anatomy and extensive damage that may occur. In this case, we present severe injury to the left orbit, maxillofacial region, and neck of a 29-year-old male who suffered a high-pressure diesel injection injury requiring several surgical debridements, intensive care unit (ICU) level care, and ultimately sub-total exenteration. Initial management involved systemic antibiotics, steroids, and surgical debridement; however, our patient experienced subsequent rapid deterioration resulting in admission for more aggressive subspecialty intervention. Decision-making was guided by serial CT of the face and orbits, and C-reactive protein (CRP) levels in addition to the physical examination. His course was complicated by progressive extensive soft tissue necrosis requiring 8 surgical debridements and optic nerve tenting despite orbital decompression resulting in loss of the OS. Ultimately, definitive treatment required sub-total exenteration and negative wound pressure therapy over the orbit followed by eyelid reconstruction as an outpatient. We conclude that without prompt recognition and meticulous debridement, the resultant injury from high-pressure injection injuries can be devastating and lead to permanent vision loss, loss of an eye, loss of facial function, and airway compromise depending on the location of the injury. A multi-disciplinary team involving oculoplastics, otolaryngology, infectious disease, and ICU should be assembled based on the complexity of this injury and its sequela. CRP can be useful to monitor patient recovery and the need for further surgical intervention. When debridement results in complex wounds over the orbit and face, negative pressure wound therapy should be considered.

Systemic Determinants of Peripapillary Vessel Density in Healthy African Americans: The African American Eye Disease Study.

PURPOSE: To determine the relationship between systemic factors and radial peripapillary capillary (RPC) vessel density (VD) in healthy African American (AA) participants of the African American Eye Disease Study. DESIGN: A population-based, cross-sectional study. METHODS: A total of 4135 eyes from 2127 AA participants aged 40 years and older in Inglewood, California, were imaged for 6×6-mm optic disc scans on a spectral-domain optical coherence tomography angiography (OCTA) device. Of these, 1029 eyes from 1029 participants who met the inclusion and exclusion criteria were analyzed, including only 1 eye per participant. Custom software was used to quantify RPC VD. Multivariate linear regression was used to identify systemic factors associated with RPC VD with a significance level set at 0.05. The contribution of each variable to the final model was estimated with the magnitude of standardized regression coefficients (SRCs). The fit of the final model was measured by R2. RESULTS: The average RPC VD was 0.346±0.045. Controlling for signal strength, the systemic variables in the final multivariate model associated with reduced RPC VD were older age (ß = -0.0123 per decade; SRC = -0.2733; P < .0001), male sex (ß = -0.0067; SRC = -0.0716; P = .0060), and longer diabetes duration (ß = -0.0022 per 5 years; SRC = -0.0527; P = .0427). The model R2 was 0.3689. CONCLUSIONS: Age, sex, and systemic influences, such as diabetes duration, need to be considered when assessing changes in RPC VD in glaucoma and other ocular diseases. Longitudinal studies are needed to investigate whether reduced RPC VD and the factors that affect it are associated with an increased risk of developing glaucomatous nerve damage.

Ocular Determinants of Peripapillary Vessel Density in Healthy African Americans: The African American Eye Disease Study.

Purpose: The African American (AA) population has unique ocular anatomic characteristics and a disproportionately high incidence of glaucoma, which is associated with lower peripapillary vessel density (VD). This study aimed to identify ocular determinants of peripapillary VD in healthy AAs. Methods: This was a cross-sectional, population-based study of 1029 AAs, ages 40 and older. Participants underwent examination to obtain axial length (AL), IOP, central corneal thickness (CCT), mean retinal nerve fiber layer (RNFL) thickness, visual field mean deviation (MD), and 6 × 6-mm optical coherence tomography angiography scans of the optic nerve. Participants with glaucoma, vision-threatening diabetic retinopathy, or other relevant ocular disease were excluded. Prototype software was used to quantify VD. A multivariable regression model, controlling for age and signal strength, identified the ocular variables that predicted peripapillary VD. The contribution of each variable was assessed with the magnitude of standardized regression coefficients (SRC). Results: Based on univariate regressions, AL, RNFL thickness, and MD had significant associations with peripapillary VD (all P < 0.001). In the final multivariate model, lower mean RNFL thickness (ß = 0.0022, P < 0.001, SRC = 0.542) and longer AL (ß = -0.0055, P < 0.001, SRC = -0.118) were associated with lower peripapillary VD, controlling for age and signal strength, with model R2 of 0.69. Conclusions: Thinner RNFL and longer AL were the most influential ocular determinants of lower peripapillary perfusion in healthy AA eyes. Additional research is needed to clarify whether longer AL increases risk of glaucoma by affecting capillary perfusion.

A multi-scale model for hair follicles reveals heterogeneous domains driving rapid spatiotemporal hair growth patterning.

The control principles behind robust cyclic regeneration of hair follicles (HFs) remain unclear. Using multi-scale modeling, we show that coupling inhibitors and activators with physical growth of HFs is sufficient to drive periodicity and excitability of hair regeneration. Model simulations and experimental data reveal that mouse skin behaves as a heterogeneous regenerative field, composed of anatomical domains where HFs have distinct cycling dynamics. Interactions between fast-cycling chin and ventral HFs and slow-cycling dorsal HFs produce bilaterally symmetric patterns. Ear skin behaves as a hyper-refractory domain with HFs in extended rest phase. Such hyper-refractivity relates to high levels of BMP ligands and WNT antagonists, in part expressed by ear-specific cartilage and muscle. Hair growth stops at the boundaries with hyper-refractory ears and anatomically discontinuous eyelids, generating wave-breaking effects. We posit that similar mechanisms for coupled regeneration with dominant activator, hyper-refractory, and wave-breaker regions can operate in other actively renewing organs.