Cen, Steven

Abstract INTRODUCTION M0 images were missing in Siemens ASL data in Alzheimer's Disease Neuroimaging Initiative (ADNI) dataset, prohibiting cerebral blood flow (CBF) quantification. METHODS A conditional latent diffusion model was trained and evaluated on in‐house datasets, then applied to the Siemens data in ADNI‐3. Regional CBF differences by Alzheimer's disease (AD) stages, their accuracy for AD classification, and CBF trajectory slopes were compared between generated data (Siemens) and acquired data (General Electric). RESULTS The diffusion model generated M0 images with high fidelity (SSIM = 0.918 ± 0.023, PSNR = 31.361 ± 2.537) and minimal CBF bias (mean difference is 0.21 ± 1.58 mL/100 g/min). Both generated and acquired CBF showed similar spatial patterns and decreasing trends with AD progression in specific AD‐related regions. Generated CBF also improved accuracy in classifying AD stages compared to qualitative perfusion images. CONCLUSION This study shows the potential of diffusion models for imputing missing modalities in large‐scale studies exploring the use of ASL as a biomarker of AD. Highlights Using latent diffusion model, we can generate M0 image from control image in arterial spin labeling (ASL) with high fidelity. The generated M0 can be used for cerebral blood flow (CBF) quantification in Alzheimer's Disease Neuroimaging Initiative dataset. The performance of classification between Alzheimer's disease (AD) patients and cognitive normal people is better when using generated CBF maps than using non‐quantitative perfusion images. ASL CBF decreases with AD progression in key AD‐related brain regions.

The Quantitative Imaging Biomarkers Alliance Profile for dynamic susceptibility contrast (DSC) MRI and its longitudinal claims for the precision of a DSC MRI–derived quantitative imaging biomarker to assess the relative cerebral blood volume changes in gliomas are summarized.

Background Despite its approval for acute ischemic stroke >25 years ago, intravenous thrombolysis (IVT) remains underused, with inequities by age, sex, race, ethnicity, and geography. Little is known about IVT rates by insurance status. Methods and Results We assessed temporal trends from 2002 to 2015 in IVT for acute ischemic stroke in the Nationwide Inpatient Sample using adjusted, survey ‐ weighted logistic regression. We calculated odds ratios for IVT for each category in 2002 to 2008 (period 1) and 2009 to 2015 (period 2). IVT use for acute ischemic stroke increased from 1.0% in 2002 to 6.8% in 2015 (adjusted annual relative ratio, 1.15). Individuals aged ≥85 years had the most pronounced increase during 2002 to 2015 (adjusted annual relative ratio, 1.18) but were less likely to receive IVT compared with 18‐ to 44‐year‐olds in period 1 (adjusted odds ratio [aOR], 0.23) and period 2 (aOR, 0.36). Women were less likely than men to receive IVT, but the disparity narrowed over time (period 1: aOR, 0.81; period 2: aOR, 0.94). Inequities in IVT resolved for Hispanic individuals in period 2 (aOR, 0.96) but not for Black individuals (period 2: aOR, 0.81). The disparity in IVT for Medicare patients, compared with privately insured patients, lessened over time (period 1: aOR, 0.59; period 2: aOR, 0.75). Patients treated in rural hospitals remained less likely to receive IVT than in urban hospitals; a more dramatic increase in urbanity widened the inequity (period 2, urban nonteaching versus rural: aOR, 2.58, period 2, urban teaching versus rural: aOR, 3.90). Conclusions IVT for acute ischemic stroke increased among adults. Despite some encouraging trends, the remaining disparities highlight the need for intensified efforts at addressing inequities.

Background: Intravenous thrombolysis (IVT) was approved for acute ischemic stroke (AIS) 25 yrs ago, yet few AIS patients receive it, with inequities by race/ethnicity, sex, and geography. With expanding evidence-based programs, we hypothesized increases in IVT utilization and reduction in inequities. Methods: Using the Nationwide Inpatient Sample (NIS), we assessed temporal trends from 2002 to 2015 in IVT for AIS (weighted N=6,694,081) by sex, race/ethnicity, age, insurance, and hospital location/teaching status strata using survey - weighted logistic regression. Covariates included socio-demographics, comorbidities, and hospital characteristics. We calculated odds ratios for IVT by each category in 2002-2008 and 2009-2015. Results: IVT for AIS increased from 1.0% in 2002 to 6.8% in 2015, with an overall adjusted annual relative ratio (AARR) of 1.15 (CI 1.14-1.16). Individuals 18-44 yrs had the highest rate of IVT in 2015. The very elderly (≥85 yrs) had the most pronounced increase in IVT (AARR 1.18, CI 1.17-1.19). The sex disparity in IVT improved, but in 2009-2015, women were still 6% less likely to receive IVT than men (Fig 1). Individuals 18-44 yrs were ~3-fold more likely to receive IVT than the very elderly. IVT inequities for black and Hispanic stroke survivors lessened, but blacks remained ~20% less likely than whites to receive IVT. Government-insured patients were ~25% less likely to receive IVT compared to privately insured. Urban AIS patients were up to 4-fold more likely to receive IVT than rural dwellers. Conclusion: From 2002 through 2015, IVT for AIS in the U.S. increased regardless of race/ethnicity, sex, and age among ≥18 yrs, with the most pronounced increase among the very elderly. Despite encouraging trends, only 1 in 15 AIS patients received IVT and persistent inequities remain for blacks, women, government-insured, and rural stroke survivors, highlighting the need for intensifying stroke literacy and preparedness and enhancing systems of care.