Upcoming Virtual Seminar Details
TBA
Previous Seminars
Thomas Kirk, Ph.D., Quantified Imaging - 12/2/25: 2:00 pm
Advances in ASL MRI and applications in monitoring Alzheimer’s therapy
Abstract: This talk will cover recent advances in ASL acquisition and analysis that enable improved measurement of physiological biomarkers on standard 3T units. The potential applications of these biomarkers will be demonstrated on a study monitoring a cohort of patients receiving amyloid therapy for Alzheimer’s disease; for which ASL shows exceptional promise as a prognostic and monitoring tool.
Stefan Posse, Ph.D., University of New Mexico - 11/17/25: 3:00 pm
Towards presurgical and intraoperative guidance in Neurosurgery
Abstract: Resting-state functional MRI (rsfMRI) is a rapidly developing task-free approach for presurgical mapping. It can complement task-based functional MRI (tfMRI) in patients who have difficulties performing tasks and efficiently map resting state networks in regions that are not typically mapped with task-based tfMRI due to time constraints, such as frontal cortex. It has the potential to provide iterative intra-operative guidance during progressive resection, enables connectome mapping in anesthetized patients, and holds promise for intra-operative guidance of minimally invasive surgery where intra-operative electrocortical mapping may not be possible. The first part of the talk will describe methodology research to characterize the physiological basis of rsfMRI in frequency bands above 0.3 Hz, advances in frequency segmented regression of nuisance signals and the development of high-speed real-time rsfMRI that approaches the sensitivity and specificity of state-of-the-art offline rsfMRI analysis pipelines. The second part of the talk will describe presurgical mapping in brain tumor patients that showed clinically acceptable concordance of real-time high-speed multi-echo rsfMRI with tfMRI, and intra-operative electrocortical stimulation (ECS). Preliminary results showing the feasibility of rsfMRI in the intraoperative settings and concurrent fMRI and EEG in patients with epilepsy will be discussed.
Brian Smith, Ph.D., Michigan State University - 5/7/25: 12:00 pm
Overcoming drug delivery barriers: New nanomedical tools for molecular imaging and theranostics in inflammatory diseases
Abstract: Many potent drugs and imaging agents face significant barriers to effective delivery, leading to suboptimal therapeutic outcomes and reduced diagnostic accuracy. Poor delivery to the intended site degrades therapeutic efficacy and can result in treatment-limiting toxicity. Two critical problems in the field of drug delivery include: 1. the lack of highly cell-specific targeting to avoid off-target side effects; and 2. the need to maintain local drug concentrations within a range of optimal efficacy, the “therapeutic window”. In this talk, I will discuss our nanoengineered solutions to both problems: Nanoimmunotheranostics: New imaging and therapeutic strategies are required to diagnose and treat atherosclerosis, a primary culprit behind cardiovascular disease - the world’s #1 killer. I will discuss our development of a new diagnostic immunoimaging strategy that leverages highly selective nanomaterial targeting to immune cells to quantify the extent of inflamed atherosclerotic plaque (the main origin of heart attacks) using photoacoustic imaging. I will show that the same nanomaterial can perform double duty as a drug delivery vehicle. In particular, l will describe our pro-efferocytic nanoimmunotherapy for atherosclerotic plaques that stimulates intraplaque macrophage consumption of dead and dying cells in the plaque core—including our results in rodent and pig models. I will describe the therapeutic properties of this therapy including a reversal in the inflammatory environment, as well as the lack of side effects due to the selectivity of the nanotherapy. Drug release monitoring: Drugs are effective only within a narrow range, i.e., the therapeutic window. However, after injection, it is unknown how much drug is available to treat disease at a given site in vivo. I will describe our development and application of nanomaterials to quantitatively measure drug release rates, and thus concentrations, at sites anywhere in the body using a new magnetic imaging modality, magnetic particle imaging. I will show how this strategy, combined with remote-controlled actuation of nanomaterials, can maintain drug concentrations within the therapeutic window to treat cancer. These nanoengineered solutions address critical challenges in drug delivery, offering improved diagnostic accuracy and therapeutic outcomes for various diseases, including cancer, atherosclerosis, and other inflammatory conditions. By leveraging the exquisite selectivity and controlled release/actuation capabilities of nanomaterials, these approaches pave the way toward safer and more effective diagnostics and therapeutics.
Sarah Goodale, Ph.D., Vanderbilt University - 3/11/25: 12:00 pm
Ali Zifan, Ph.D., UC San Diego - 1/16/25: 12:00 pm
The Intersection of Radiology and AI: Enhancing Clinical Decision-Making
Abstract: In this presentation, we will explore how artificial intelligence (AI) is reshaping signal/image processing in radiology, specifically through machine learning and deep learning techniques for signal/image processing. We’ll look at how AI can be applied across a variety of imaging modalities like CT, MRI, angiography, and multi-channel time series, with a focus on data from different human organs, including the cardiovascular, pulmonary, gastrointestinal, and hepatic systems, with a special focus on Metabolic Associated Steatotic Liver Disease (MASLD). Rather than relying on generic off-the-shelf software, we’ll discuss how custom software solutions, designed specifically for these disease areas, can significantly improve image classification, segmentation, and predictive analytics. The ultimate goal is to enhance diagnostic accuracy, aid clinical decision-making, and personalize treatment.
Israt Alam, Ph.D., Stanford University - 12/18/24: 12:00 pm
Harnessing Positron Emission Tomography imaging to illuminate our understanding of the immune system
Abstract: Real-time, non-invasive monitoring of immune responses is critical to improve our management of cancer immunotherapy protocols and crucial for early prediction of therapy efficacy. Positron emission tomography (PET) is a highly sensitive and quantitative clinical molecular imaging modality, perfectly poised to provide noninvasive, whole-body mechanistic insights into immune dynamics. The current PET toolbox for detecting specific immune cells and their functional phenotypes has rapidly expanded in the last decade, with many targeting the visualization of T cells due to the central role they play in anti-cancer responses. Excitingly, several T cell imaging clinical trials are underway in immuno-oncology, transplantation, infectious diseases and autoimmunity, demonstrating the potential and need for highly specific and sensitive interrogation of these cells. This talk will focus on recent advances in PET imaging of T cells, including the broad utility of immunoPET (the use of antibody and antibody fragments) for highly specific and sensitive detection of T cell function in the context of both molecular and cellular immunotherapies. Current status of these translational efforts including challenges & new applications in immune monitoring will be discussed.
Nan Wang, Ph.D., Stanford University - 11/19/24: 2:00 pm
Hao Huang, Ph.D., University of Pennsylvania - 9/18/24: 2:00 pm
Multi-modal imaging of early developmental brain
Abstract: The human brain undergoes rapid structural and functional changes during early childhood. Multimodal MRI including arterial-spin-labeled perfusion MRI, blood–oxygen-level-dependent functional MRI, diffusion MRI and MEG offers unprecedented insight into the functional emergence, cortical microstructural changes, as well as metabolic mechanisms and structural underpinning of the functional emergence in early developmental brain. In this talk, I will introduce our efforts towards charting the 4D spatiotemporal changes of functional connectivity and cerebral blood flow in early developmental brain. Leveraging the multimodal imaging and robust statistical model, I will also demonstrate our findings for elucidating the mechanistic structure-function and function-physiology relationship in brain maturation.
Thomas Liu, Ph.D., UC San Diego - 5/3/24: 10:30 am
Multimodal Imaging and Resting-State Global Brain Activity: Controversies, Hypotheses, and Discovery
Abstract: Although measures of resting-state brain activity have been adopted by a wide range of neuroimaging studies, we still understand relatively little about the underlying mechanisms. Over the past decade, there has been a growing appreciation that global patterns of activity constitute an important component of resting-state brain signal fluctuations. There has also been considerable controversy regarding processing and analysis approaches that aim to address the presence of global activity in resting-state data. In this talk, I will review how multimodal imaging studies have contributed to our understanding of global brain activity and discuss directions for future work in this area.
Meher Juttukonda, Ph.D., Harvard University - 10/12/21: 12:00 pm
Imaging cerebral hemodynamics in typical and abnormal aging
Abstract: White matter plays a critical role in supporting human cognitive function, and white matter lesions have been implicated as a contributor to cognitive decline in Alzheimer’s disease (AD). While they are often presumed to be of vascular origin, physiological mechanisms underlying these lesions remain unclear. As the world’s population continues to age, understanding microvascular hemodynamics in typical versus abnormal aging could be critical for understanding vascular contributions to cognitive decline and for guiding the development of preventative therapies. During this talk, I will discuss 1) recent magnetic resonance imaging (MRI) approaches for characterizing gray and white matter hemodynamics in typical aging and 2) potential microvascular mechanisms that may contribute to the development of white matter lesions and consequent cognitive decline in older adults at elevated risk for AD.
Frederik Laun, Ph.D., University of Erlangen - 02/23/21: 12:00 pm
Diffusion-weighted imaging of the liver and breast – and on its inverse problem
Abstract: The successful application of diffusion-weighted imaging faces several organ-specific challenges. In this talk, these challenges and potential remedies to overcome them are discussed for liver and female breast applications. The second part of the talk will focus on the question of how much we can learn about the tissue by measuring diffusion with MR.
Moritz Zaiss, Ph.D., University of Erlangen - 01/12/21: 12:00 pm
CEST MRI – basics, tricks and applications
Abstract: Chemical exchange saturation (CEST) MRI promises novel and non-invasive molecular image contrast with correlation from pH, over metabolites, to proteins and their conformation. A basic introduction of the phenomenon is followed by standard approaches and tricks on how to obtain the small CEST signals in a reproducible manner. Also with regard to ultra-high fields, where CEST has many benefits, but several challenges. Applications in brain tumors and stroke are discussed, as well as the next steps necessary to bring this technique to broader clinical investigation at different field strengths.
Jean Chen, Ph.D., University of Toronto - 07/28/20: 10:00 -11:00 am
Mapping age effects on functional and structural connectivity in aging: Physiological considerations
Abstract: Resting-state fMRI and diffusion-tensor imaging have both been used extensively to map age-related brain-connectivity changes. In this talk, I will address two physiological considerations that could pivot the interpretation of research findings regarding brain aging: (1) the potential effect of vascular stiffening on resting-state functional connectivity in aging (2) the potential effect of increased extracellular space on diffusion-tensor based structural connectivity mapping in aging. Achieving a better understanding of such physiological biases in neuroimaging could help reduce measurement uncertainty and achieve more accurate data interpretations.
Bio: Dr. Jean Chen is Associate Professor in Medical Biophysics at the University of Toronto, director of the CRANIUM Lab at Baycrest and the Canada Research Chair in Neuroimaging of Aging. She received her MSc in Electrical Engineering from the University of Calgary (mentored by Richard Frayne) and her PhD in Biomedical Engineering from McGill University (mentored by Bruce Pike). She completed her postdoctoral work on multimodal MRI of brain aging at the Martinos Center for Biomedical Imaging (mentored by David Salat). Her current research projects are characterized by the following themes: 1) Investigating the physiological basis of resting-state fMRI; 2) The development of new brain-mapping techniques to map vascular and neuronal health; 3) Multi-modal integration of functional, vascular and structural MRI techniques to study the mechanisms of brain aging and of age-related neurodegenerative diseases.
Jia Guo, Ph.D., UC Riverside - 03/11/20: 1:00 pm
“Faster, higher, stronger”: arterial spin labeling as a non-invasive tool for perfusion mapping
Abstract: Normal brain physiology and functions are maintained and supported by sufficient blood flow. Accurate mapping of blood flow into the brain tissue can provide important information on understanding brain’s functional dynamics and responses under different physiological conditions, including diseased conditions. This talk will be focusing on arterial spin labeling (ASL), a non-invasive MR technique for quantitative mapping the blood flow in tissue (perfusion). I will give a brief introduction on different categories of ASL techniques and present examples in various applications, including understand the BOLD signal in fMRI and some clinical applications. I will then present my research work on the methodology development of ASL, making it “faster, higher, stronger” as a useful imaging tool to help solve research and clinical problems. The work includes perfusion territory mapping, venous oxygenation mapping, and other various technical development to improve the efficiency and robustness of ASL. Some of the challenges and future development in ASL will be discussed.
About the speaker: Dr. Guo received his MS in Biomedical Engineering at Peking University in 2008, and PhD in Bioengineering at UC San Diego in 2014, mentored by Dr. Eric Wong. After graduation, he joined Dr. Richard Buxton’s lab as a postdoc at UCSD, and then joined Dr. Greg Zaharchuck’s research group at Stanford University since 2016. Now he is an assistant professor in Bioengineering at UC Riverside since 2018. He was trained in MR physics, with a focus on arterial spin labeling techniques. He is interested in developing fast imaging techniques and exploring novel contrast mechanisms, and understanding the physiology and function of brain using MRI and other imaging modalities.
Jiang Du, Ph.D., UC San Diego - 03/03/20: 12:00 pm
Ultrashort Echo Time Magnetic Resonance Imaging of Myelin
Abstract: Conventional magnetic resonance imaging (MRI) techniques have been employed to image and quantify white matter of the brain, mostly focused on various water components which have long T2 relaxation times. Myelin in white matter of the brain has extremely short T2 relaxation (T2 << 1 ms), and is invisible with conventional clinical MR sequences. MR relaxation properties, including longitudinal relaxation time (T1) and transverse relaxation time (T2 or T2*) as well as myelin proton density are virtually unknown. We have developed two-dimensional (2D) and 3D Ultrashort Echo Time (UTE) sequences with minimum nominal TEs of 8 µs that is about 100~1000 times shorter than conventional TEs of several milliseconds or longer, and this makes it possible to detect proton signal from myelin protons. In this talk a series of contrast mechanisms will be introduced for high resolution morphological imaging of myelin in vitro and in vivo. Quantitative imaging techniques to measure MR and tissue properties (such as T1, T2*, phase, myelin proton density, etc.) of myelin in white matter of the brain will be introduced. The applications in multiple sclerosis and traumatic brain injury will also be discussed.
Martin Sereno, Ph.D., UC San Diego - 02/18/20: 12:00 pm
DNA and Language: Origin vs. Evolution of Symbol-Using Systems
Abstract: Two of the most significant transitions on Earth were the origin of life and then the origin of human language and thought. Both are underpinned by naturally-occurring symbol-using systems. By constructing a detailed analogy between the objects and relations within each system, we can gain insights in both directions. Since the second system rides around upon the first, many have attempted to devise evolutionary explanations for language. Examination of the Darwinian evolution of vocal learning in other animals suggests that the initial fixation of a key prerequisite to language into the human genome may have actually required initially side-stepping not only iconicity, but the urge to mean itself. At the heart of each system is a Janus-like structure capable of serving either as symbol or meaning, which may give us additional clues as to how these remarkable systems might have been booted.
Selda Yildiz, Ph.D., Oregon Health and Science University - 02/07/20: 12:00 pm
Yogic Breathing, Sleep, and Non-Invasive MRI-Based Measures of Cerebrospinal Fluid Circulation
Abstract: CSF, a clear colorless fluid secreted by the choroid plexuses, moves by bulk flow around the central nervous system, and ensures the health of the central nervous system. CSF is regularly driven by arterial pulsation and respiration. Proper CSF circulation has wide-ranging impact on neurological functions, and impairment in CSF circulation has been associated with neurodegeneration. Recent studies have defined a brain-wide glial-vascular physiology, termed as ‘glymphatic function’, which supports the interchange of CSF and interstitial fluid along perivascular pathways and facilitates the clearance of solutes and metabolic wastes from the brain interstitium - mainly during sleep compared to wakefulness. Dr. Yildiz’s recent research efforts focused on developing non-invasive imaging approaches to better understand the mechanisms regulating CSF circulation (bulk flow and glymphatic function), and utilizing these imaging approaches to investigate if yogic breathing can be used as a potential therapy for regulating and improving CSF circulation and sleep.
Rick Buxton, Ph.D., UC San Diego - 01/14/20: 12:00 pm
The thermodynamics of thinking: connections between neural activity, energy metabolism and blood flow
Abstract: Functional magnetic resonance imaging (fMRI) and other current functional neuroimaging methods are sensitive to cerebral metabolism and cerebral blood flow (CBF) rather than the underlying neural activity itself. Current studies have shown that the connections between metabolism, flow and neural activity are complex and somewhat counterintuitive: CBF and glycolysis increase more than seems to be needed to provide oxygen and pyruvate for oxidative metabolism in the mitochondria; the oxygen extraction fraction is relatively low in the brain and decreases when oxygen metabolism increases; and it appears that inhibitory neural activity is an important driver of CBF, even though such activity is likely to have less of an energy cost in terms of ATP consumption compared with excitatory activity. This work lays a foundation for the idea that this unexpected pattern of physiological changes is consistent with basic thermodynamic considerations related to metabolism. In the context of this thermodynamic framework, the apparent mismatches in metabolic rates and CBF are related to preserving the entropy change of oxidative metabolism, specifically the O2/CO2 ratio in the mitochondria. However, the mechanism supporting this CBF response is likely not due to feedback from a hypothetical O2 sensor in tissue, but rather is consistent with feed-forward control by signals from both excitatory and inhibitory neural activity. Quantitative predictions of the thermodynamic framework, based on models of O2 and CO2 transport and possible neural drivers of CBF control, are in good agreement with a wide range of experimental data, including responses to neural activation, hypercapnia, hypoxia and high altitude acclimatization.
Christine Fennema-Notestine, Ph.D., UC San Diego - 12/3/19: 12:00 pm
Multi-channel structural MRI measures of white matter disease: Associations with immune recovery, inflammation, hypertension, and cognition in HIV and Aging
Abstract: White matter disease results from ischemia, vascular disease, de-myelination, gliosis, and other inflammatory processes, and it is evident in HIV disease, normal aging, hypertension, and other conditions. Our multi-channel structural MRI approach provides sensitive measures of these white matter abnormalities. Additional insight into underlying causes of white matter abnormalities may be provided by single-voxel proton MR spectroscopy which estimates chemical metabolites, including those thought to reflect neuronal integrity and neuroinflammation. Following a methodological overview, white matter abnormalities will be discussed within the contexts of HIV disease and aging. In HIV, these abnormalities are associated with variables such as immune recovery, CSF biomarkers of inflammation, and cognitive impairment. White matter disease, however, also increases with normal aging, as well as within a number of comorbid conditions such as hypertension and smoking, providing challenging statistical modelling to assess disease specific effects. White matter abnormalities are highly heritable in middle age, and these abnormalities are strongly associated with hypertension, driven both by genetic and unique environmental influences. These abnormalities are also associated with alcohol use as well as episodic and working memory performance in middle age. Our current work explores regional measures of white matter abnormalities, using the spatial distribution of abnormalities to drive a watershed-based approach. Preliminary studies support meaningful neuroanatomical parcellations, and localized inferior superior corona radiata associations with hypertension. These regional parcellations may allow for better discrimination among mechanisms of underlying white matter disease.
Gadi Goelman, Ph.D., The Hebrew University of Jerusalem - 10/21/19: 4:00 pm
Multivariate functional connectivity analysis to obtain directed pathways of multiple-nodes
Abstract: I will describe our new multivariate functional connectivity analysis that uses nonlinear coherence in wavelet space to infer how information is transferred within the cortex. To demonstrate the method ability to study dynamic processes, I will describe its application with hyperscanning fMRI data of joint attention interaction. The analysis inferred that this interaction is bidirectional, each with a different mechanism. To demonstrate the analysis strength with resting-state fcMRI data, I will describe its application with Parkinson’s disease data aiming to explore the cortical representations of akinesia, rigidity and tremor. Results provide a comprehensive view of cortical representations associated with motor symptoms and pointing to the critical importance of hemispheric symmetry and frequency of activity.
Eric Wong, Ph.D., UC San Diego - 11/12/19: 12:00 pm
Example-based Hebbian learning: from prediction to complex thought
Abstract:The brain has recently been described as a prediction machine, driven to minimize prediction error, but it is unclear what mechanisms might implement learning in support of prediction. Hebbian Learning as implemented by spike timing dependent plasticity (STDP) is a well-recognized mechanism for synaptic plasticity. We argue here that STDP supports learning of prediction in a very simple and direct manner, and that evolution of this basic learning motif can support higher level learning. For a network that is presented with a series of stimuli [A, B, …], if any connections exist between neurons excited by A and those excited by B, then those synapses will be strengthened by STDP, and in the future, stimulus A will excite or potentiate B. This implements direct online conversion of observations to predictions. In higher animals that can exhibit conscious control of actions, a sequence of controlled actions can be strung together by this same Hebbian mechanism to form an automatic (learned) sequence. With the advent of abstraction, as enabled by language, arbitrary associations between abstractions can be communicated by others, and learned by the same mechanism. We hypothesize that the STDP mechanism initially evolved as a prediction engine, but with the advent of conscious thought was co-opted to support higher learning and the gradual increase of human intelligence across generations. This allowed for the development of complex thought which was used in addition to prediction in support of survival.