Publications by authors named "David L Thomas"

Purpose: The clinical feasibility and translation of many advanced quantitative MRI (qMRI) techniques are inhibited by their restriction to 'research mode', due to resource-intensive, offline parameter estimation. This work aimed to achieve 'clinical mode' qMRI, by real-time, inline parameter estimation with a trained neural network (NN) fully integrated into a vendor's image reconstruction environment, therefore facilitating and encouraging clinical adoption of advanced qMRI techniques.

Methods: The Siemens Image Calculation Environment (ICE) pipeline was customised to deploy trained NNs for advanced diffusion MRI parameter estimation with Open Neural Network Exchange (ONNX) Runtime.

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Introduction: Magnetic resonance imaging (MRI) is crucial for dementia diagnosis and a pre-requisite for amyloid-lowering therapies in Alzheimer's disease. Despite guidelines, many patients never undergo MRI due to limited scanner availability. Shorter scan times would reduce costs and patient burden.

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Purpose: Hepatocellular carcinoma (HCC) is common and deadly in sub-Saharan Africa, where advanced imaging techniques, such as computerized tomography and magnetic resonance imaging, are scarce. The purpose of this study was to develop a pragmatic HCC diagnostic strategy for such settings.

Methods: We evaluated standardized protocol-collected data on clinical, ultrasonographic, biochemical, and pathological criteria in a multisite study of 649 suspected HCC cases in Uganda.

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Liver disease remains a key contributor to morbidity and mortality among people with HIV. Although substantial progress has been made in terms of a cure for hepatitis C, increased life expectancy is associated with emerging issues associated with steatotic liver disease. Hepatitis B and D are still prevalent and often underrecognized as a cause of indolent liver injury leading to inflammation and fibrosis.

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The burden of hepatitis C virus (HCV) among persons who inject drugs is determined by dynamics of infection, spontaneous clearance, treatment clearance, treatment failure, and reinfection. Although analysis of HCV sequences is often used to infer the net contribution of these factors, those inferences are complicated by the quasispecies distribution and continued evolution of infection within each host. We used deep sequencing by Nanopore to study sequences of persons with and without self-reported HCV treatment.

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The cornerstone of functional cure for chronic hepatitis B (CHB) is hepatitis B surface antigen (HBsAg) loss from blood. HBsAg is encoded by covalently closed circular DNA (cccDNA) and HBV DNA integrated into the host genome (iDNA). Nucleos(t)ide analogs (NUCs), the mainstay of CHB treatment, rarely lead to HBsAg loss, which we hypothesized was due to continued iDNA transcription despite decreased cccDNA transcription.

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Arterial spin labelling (ASL) enables non-invasive quantification of regional brain perfusion using MRI. ASL was used in the Reducing Pathology in Alzheimer's Disease through Angiotensin TaRgeting (RADAR) multi-centre trial to pilot the assessment of the effects of the anti-hypertension drug losartan on cerebral blood flow (CBF). In the multi-centre setting, disparities in ASL implementation on scanners from different manufacturers lead to inherent differences in measured CBF and its associated parameters (e.

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Article Synopsis
  • The choroid plexus (CP) and blood-cerebrospinal fluid-barrier (BCSFB) play a critical role in producing and clearing cerebrospinal fluid, and their dysfunction is linked to neurodegenerative diseases like Alzheimer's disease (AD).
  • This study utilized advanced MRI techniques to measure water delivery across the BCSFB in a triple transgenic mouse model of AD, observing significant changes in CP function even before clinical symptoms appear.
  • Results indicated increased BCSFB-mediated water delivery in younger mice, with notable behavioral differences arising around 20 weeks, suggesting that CP changes could serve as early biomarkers for AD.
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Efforts to eliminate hepatitis C virus (HCV) as a public health problem must include people who inject drugs (PWID). We describe the design and baseline characteristics of the Supporting Treatment Outcomes among PWID (STOP-C) trial which evaluates whether HCV treatment outcomes in PWID can be optimized by tailoring treatment support in 7 PWID-focused integrated HIV/HCV prevention/treatment centers. The design is a 3-arm, individual-level precision-randomized trial.

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While the associations of mid-life cardiovascular risk factors with late-life white matter lesions (WMH) and cognitive decline have been established, the role of cerebral haemodynamics is unclear. We investigated the relation of late-life (69-71 years) arterial spin labelling (ASL) MRI-derived cerebral blood flow (CBF) with life-course cardiovascular risk factors (36-71 years) and late-life white matter hyperintensity (WMH) load in 282 cognitively healthy participants (52.8% female).

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Despite available curative treatments, global rates of hepatitis C virus (HCV) infection persist with significant burden in low- and middle-income countries (LMICs). Long-acting (LA) antiviral products are in development. This study explored the challenges and opportunities in LA-HCV treatment across three LMICs: Egypt, Ethiopia and India.

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On the 20th anniversary of the Alzheimer's Disease Neuroimaging Initiative (ADNI), this paper provides a comprehensive overview of the role of arterial spin labeling (ASL) magnetic resonance imaging (MRI) in understanding perfusion changes in the aging brain and the relationship with Alzheimer's disease (AD) pathophysiology and its comorbid conditions. We summarize previously used acquisition protocols, available data, and the motivation for adopting a multi-post-labeling delay (PLD) acquisition scheme in the latest ADNI MRI protocol (ADNI 4). We also detail the process of setting up this scheme on different scanners, emphasizing the potential of ASL imaging in future AD research.

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Article Synopsis
  • Metagenomic next generation sequencing (mNGS) effectively identified novel and rare pathogens in patients with unexplained acute febrile illness in Uganda, surpassing traditional clinical microbiology methods.
  • The study involved 42 participants, aged around 28, who exhibited symptoms suggestive of viral infections, with 10 of them (23.8%) showing significant viral, bacterial, or fungal signals.
  • This research confirmed the presence of Rickettsia conorii, causing Mediterranean Spotted Fever, marking the first documented case in sub-Saharan Africa, highlighting the potential of mNGS for future disease surveillance.
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Magnetic resonance imaging (MRI) is the standard tool to image the human brain In this domain, digital brain atlases are essential for subject-specific segmentation of anatomical regions of interest (ROIs) and spatial comparison of neuroanatomy from different subjects in a common coordinate frame. High-resolution, digital atlases derived from histology (e.g.

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Background: Efforts are underway to support the development of novel mucosal coronavirus disease 2019 (COVID-19) vaccines. However, there is limited consensus about the complementary role of mucosal immunity in disease progression and how to evaluate immunogenicity of mucosal vaccines. This study investigated the role of oral mucosal antibody responses in viral clearance and COVID-19 symptom duration.

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The magnetic resonance imaging (MRI) Core has been operating since Alzheimer's Disease Neuroimaging Initiative's (ADNI) inception, providing 20 years of data including reliable, multi-platform standardized protocols, carefully curated image data, and quantitative measures provided by expert investigators. The overarching purposes of the MRI Core include: (1) optimizing and standardizing MRI acquisition methods, which have been adopted by many multicenter studies and trials worldwide and (2) providing curated images and numeric summary values from relevant MRI sequences/contrasts to the scientific community. Over time, ADNI MRI has become increasingly complex.

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Water exchange rate (Kw) across the blood-brain barrier (BBB) is an important physiological parameter that may provide new insight into ageing and neurodegenerative disease. Recently, two non-invasive arterial spin labelling (ASL) MRI methods have been developed to measure Kw, but results from the different methods have not been directly compared. Furthermore, the association of Kw with age for each method has not been investigated in a single cohort.

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Hepatitis C virus (HCV) causes substantial morbidity and mortality, particularly among people who inject drugs (PWID). While elimination of HCV as a public health problem may be possible through treatment-as-prevention, reinfection can attenuate the impact of treatment scale-up. There is a need to better understand the distribution and temporal trends in HCV infection risk, including among HCV-seropositive individuals who will be eligible for treatment and at risk for subsequent reinfection.

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Phase four of the Alzheimer's Disease Neuroimaging Initiative (ADNI4) magnetic resonance imaging (MRI) protocols aim to maintain longitudinal consistency across two decades of data acquisition, while adopting new technologies. Here we describe and justify the study's design and targeted biomarkers. The ADNI4 MRI protocol includes nine MRI sequences.

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Background: People with HIV (PWH) who are coinfected with hepatitis B virus (HBV) have a higher risk of mortality compared with PWH alone. Populations such as people who inject drugs (PWID) and men who have sex with men (MSM) are particularly at high risk for HBV acquisition; yet, limited epidemiological data from these populations exist on HBV prevalence from low- and middle-income country settings (LMICs).

Methods: We characterized the prevalence and correlates of HBV serological markers in a sample of PWID and MSM with HIV recruited across 15 Indian cities using hepatitis B surface antigen (HBsAg), hepatitis B core antibody (anti-HBc), and hepatitis B surface antibody (anti-HBs).

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Article Synopsis
  • Metagenomic next-generation sequencing (mNGS) often struggles to detect low-level viral presence and is biased toward linear viruses, which limits the understanding of certain viral infections, particularly those from the anellovirus family.
  • The study introduces a new sequencing protocol using rolling circle amplification (RCA) with the long-read Oxford Nanopore technology, specifically designed for circular single-stranded DNA viruses found in human samples.
  • The protocol demonstrates effective detection of anelloviruses in diverse sample populations, overcoming challenges associated with circular genomes and enabling improved characterization of the human virome.
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After recovery from a hepatitis B virus (HBV) infection, reactivation can occur with immunosuppression; thus, it is assumed that replication competent HBV persists in the liver. We sought to detect persistent HBV from 13 people with spontaneous recovery. We quantified HBV DNA and RNA in core liver biopsy specimens (median, 1.

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In the United States, modelling studies suggest a high prevalence of hepatitis C virus (HCV) infection in incarcerated populations. However, limited HCV testing has been conducted in prisons. Through the Louisiana Hepatitis C Elimination Plan, persons incarcerated in the eight state prisons were offered HCV testing from 20 September 2019 to 14 July 2022, and facility entry/exit HCV testing was introduced.

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