My lab works closely with the departments of Neurology and Neurosurgery to develop Magnetic Resonance Imaging (MRI) methods to improve neurosurgical outcomes, particularly for patients with epilepsy. We directly support clinical care by developing and providing functional MRI to localize eloquent cortex in the brain to aid in surgical planning to minimize functional and cognitive deficits post surgery. Our research focuses on mapping functional and structural brain networks in epilepsy before and after surgical treatment. Ultimately, we aim to use MRI to fully characterize the spatial and temporal impacts of seizures across the brain to optimize management of epilepsy patients. The Morgan lab has on-going research collaborations with the BIEN (Englot) Lab, the Medical Imaging Processing Laboratory (Dawant), the MASI Lab (Landman) and researchers throughout the Vanderbilt Institute of Imaging Science (VUIIS).

My interest is primarily in translational research that aims at detecting cancer, delivering targeted therapy and monitoring anti-tumor drug efficacy.  For this work, I am using a number of established mouse models of cancer to test a variety of customized activatable imaging and therapeutic agents including compounds delivered using dendrimeric scaffold nanomaterials (NDs)

We have developed 'proteolytic beacons' (PBs) that can be used to image the elevated activity of specific proteinases, such as the matrix metalloproteinases (MMPs) within the tumor microenvironment.  Our developing library of PBs exhibits selectivity for different classes of MMPs.  With various mouse models of colon, breast and lung cancers, we have demonstrated selective illumination of tumors by PBs using either optical (fluorescent) or MRI contrast.  We are currently developing new types of PBs and are exploring uses of PBs in cancer and other diseases, e.g., for measuring proteinase activation associated with tumor growth and metastasis, for assessing early response of tumors to therapy and for imaging MMP activities in non-tumor pathologies such as inflammation and wound healing.  Another endeavor is to adapt the beacon platform to generate dendrimeric nanomaterials (NDs) that not only interrogate tumors but also simultaneously target delivery of prodrugs.  These kinds of prodrugs are designed to become active after proteolytic cleavage, e.g., in the microenvironment of tumors.  Our novel bifunctional prodrug ND-PB therapeutic agents are being optimized to enhance targeted delivery of cytotoxic drugs to tumors so as improve therapeutic efficacy while reducing systemic toxicity.

My interests are diffusion tensor image analysis, functional MRI analysis and pattern recognition of anatomical features.

My current study is 'Resting state connectivity in the white matter'. The goals of this study are to investigate and evaluate recent new discoveries about the nature of temporal variations in magnetic resonance imaging signals from the human brain, acquired in a resting state, which potentially provides a completely new basis for quantifying the functional architecture of white matter.

I am interested in the evaluation of diffusion imaging and other technologies in cancer imaging.

I am interested in using computational modeling to understand the biological basis of MRI signal and quantitative measures derived from MRI. I am also interested in using numerical techniques to improve image acquisition and reconstruction.

I am currently using computational models and experiments in rat spinal cord to understand the relationship between quantitive MRI measures of myelin (myelin water fraction, magnetization transfer, and ultrashort T2 signal).

I'm interested in the development and application of imaging science in medicine and biology, and the development of imaging science as a coherent discipline for trainees.

For almost 40 years my research has spanned different areas of imaging science - from basic physics of image formation, to understanding the factors that affect the signals used to make images, to applications that derive new types of information about biological systems, to image analysis and perception. Imaging of human subjects, non-human primates and small animals provides unique information on tissue structure and function, and is being applied in a variety of different applications in neuroscience, cancer research and studies of metabolism. A general theme of interest is to understand the physical and physiological factors that affect MRI signals and to use this knowledge to devise non-invasive imaging methods that provide new types of information, as well as for developing new applications of imaging. Fundamental studies of the basis of MRI contrast mechanisms such as proton relaxation, diffusion, and the BOLD effect in fMRI help interpret images used in numerous applications. A second major theme is the development of methods for studying human brain structure and function using MRI, especially at very high fields, and for integrating fMRI data with other imaging methods such as NIR and EEG. Several novel engineering solutions are being developed to address the technical challenges of human imaging at 7 Tesla, while other research to develop robust measurements of neurotransmitters and metabolism by multinuclear MRS is also being pursued. Applications of structural and functional MRI to the brain are performed in collaboration with investigators from psychology, psychiatry and other departments. A third major theme is the use of multi-modality imaging (MRI, PET, CT, optical and ultrasound) to study small animals, especially mouse models of human cancer and other genetically modified mice. New technologies being developed include acousto-optical imaging of fluorophores. Many projects also involve the development and application of advanced image analysis methods and computer algorithms.

Our research focuses on the development, characterization, and application of MRI methods for quantifying tissue parameters, most importantly exchange between tissue water and macromolecules and metabolites. Such methods have their greatest application in imaging multiple sclerosis (MS).

We are currently working on developing and applying methods for measuring spin exchange, including developing new methods to detect tissue exchange sites (such as amides) using chemical exchange saturation transfer (CEST) and T1p. Also, we are applying quantitative magnetization transfer (qMT) methods to a rat model of multiple sclerosis in order to determine the method's sensitivity to myelin. This work may result in improved methods for research and clinical imaging.

I am interested in the relationship between diffusion magnetic resonance imaging and the distribution of axon fibers in brain white matter measured by light microscopy.

I am currently involved in the project focused on testing the ability of DTI tractograpy to investigate the cortical-cortical connectivity of the monkey brain. I will compare fiber distribution pattern calculated  by deterministic  algorithm to the histological fiber distribution determined by the stain of injected, intra-axonal tracer. 

We are interested in developing and applying MRI methods to quantitatively characterize various properties and/or compositions of tissue. To this end we develop models of NMR relaxation and water diffusion in tissue, develop and optimize MRI pulse sequences and associated technology, and experimentally investigate in vivo and ex vivo tissue models.

Current projects include: i) characterizing myelin content and thickness in normal and injured neural tissues using multi-exponential transverse relaxation, magnetization transfer, water diffusion, and ultra-short T2 methods; ii) characterizing fracture properties of cortical bone through T2-discriminated measures of bone collagen, collagen-bound water, and porosity; iii) characterizing edema and muscle fiber condition in models of skeletal muscle injury and disease using T2 and water diffusion; iv) investigating the effects of inter-compartmental water exchange on MRI measures of neural tissue, muscle, and tumors using relaxation-based exchange spectroscopy and SPECT imaging.

My research focuses on processing and analysis of magnetic resonance images, aiming at providing innovative, objective and quantitative technologies for measuring brain structure and function, and understanding structure-function relations of the neural network in human brain.