The goal of this study is to estimate micro-architectural parameters of cortical porosity such as pore diameter (ϕ), pore density (ρ) and porosity (ν) of cortical bone from ultrasound frequency dependent attenuation using an artificial neural network (ANN). First, heterogeneous structures with controlled pore diameters and pore densities (mono-disperse) were generated, to mimic simplified structure of cortical bone. Then, more realistic structures were obtained from high resolution CT scans of human cortical bone. 2-D dimensional finite-difference time-domain simulations were conducted to calculate the frequencydependent attenuation in the 1-8MHz range. An ANN was then trained with the ultrasonic attenuation at different frequencies as the input feature vectors while the output was set as the micro-architectural parameters (pore diameter, pore density and porosity). The ANN is composed of three fully connected dense layers with 24, 12 and 6 neurons, connected to the output layer. The dataset was trained over 6000 epochs with a batch size of 16. The trained ANN exhibits the ability to predict the micro-architectural parameters with high accuracy and low losses. ANN approaches could potentially be used as a tool to help inform physics-based modelling of ultrasound propagation in complex media such as cortical bone. This will lead to the solution of inverse-problems to retrieve bone micro-architectural parameters from ultrasound measurements for the non-invasive diagnosis and monitoring osteoporosis.

OBJECTIVE: To implement a standardized universal substance use screening process in an outpatient prenatal clinic at an urban tertiary care hospital. METHODS: Using a quality-improvement framework that involved process modeling, stakeholder analyses, and plan-do-study-act cycles, we implemented universal substance use screening for prenatal patients using a modified 5Ps screening tool (Parents, Peers, Partner, Past, Present). Implementation included an operational workflow based on the SBIRT (Screening, Brief Intervention, Referral to Treatment) model. The primary outcome measure was percentage of patients who were screened for substance use, with a goal of 90% screened. Secondary outcome measures were percentage who screened positive and percentage of the time a positive screen resulted in documentation of a brief intervention by a health care practitioner. RESULTS: Over a 19-month implementation period, 733 patient encounters were sampled. A substance use screen was completed in 618 (84%). We exceeded our goal of screening 90% of eligible patients for the final 6 months of data collection. Of the 618 completed screens, 124 (20%) screened positive. Health care practitioner documentation of brief interventions for patients with a positive screen reached 80% in the final phase of implementation, but then declined to 50% by the completion of the study period. CONCLUSION: A sustainable and generalizable process to carry out substance use screening within a large prenatal practice is feasible, and assisted with identification of patients not known to be at risk. Further efforts are needed to evaluate how to sustain health care practitioner documentation of intervention in response to positive screens.