G. Johnson

Overview:

Dr. Johnson is the Charles E. Putman University Professor of Radiology, Professor of Physics, and Biomedical Engineering, and Director of the Duke Center for In Vivo Microscopy (CIVM). The CIVM is an NIH/NIBIB national Biomedical Technology Resource Center with a mission to develop novel technologies for preclinical imaging (basic sciences) and apply the technologies to critical biomedical questions. Dr. Johnson was one of the first researchers to bring Paul Lauterbur's vision of magnetic resonance (MR) microscopy to practice as described in his paper, "Nuclear magnetic resonance imaging at microscopic resolution" (J Magn Reson 68:129-137, 1986). Dr. Johnson is involved in both the engineering physics required to extend the resolution of MR imaging and in a broad range of applications in the basic sciences.

Positions:

Charles E. Putman University Distinguished Professor of Radiology

Radiology
School of Medicine

Professor of Radiology

Radiology
School of Medicine

Professor in the Department of Physics

Physics
Trinity College of Arts & Sciences

Member of the Duke Cancer Institute

Duke Cancer Institute
School of Medicine

Education:

Ph.D. 1974

Duke University

Grants:

Small Animal Imaging Resource Program

Administered By
Radiology
Awarded By
National Institutes of Health
Role
Principal Investigator
Start Date
End Date

The Duke University Molecular Imaging Center

Administered By
Radiology
Awarded By
National Institutes of Health
Role
Principal Investigator
Start Date
End Date

Ultra-resolution imaging of brain circuitry and its development in mental health

Administered By
Duke-UNC Center for Brain Imaging and Analysis
Awarded By
National Institutes of Health
Role
Co Investigator
Start Date
End Date

Whole brain multimodal microscopy of an apoptosis reporter mouse

Administered By
Psychiatry & Behavioral Sciences, Translational Neuroscience
Awarded By
National Institutes of Health
Role
Collaborator
Start Date
End Date

Waxholm Space for Rodent Neuroinformatics

Administered By
Radiology
Awarded By
University of Pennsylvania
Role
Principal Investigator
Start Date
End Date

Publications:

Cytoarchitecture of the mouse brain by high resolution diffusion magnetic resonance imaging.

MRI has been widely used to probe the neuroanatomy of the mouse brain, directly correlating MRI findings to histology is still challenging due to the limited spatial resolution and various image contrasts derived from water relaxation or diffusion properties. Magnetic resonance histology has the potential to become an indispensable research tool to mitigate such challenges. In the present study, we acquired high spatial resolution MRI datasets, including diffusion MRI (dMRI) at 25 ​μm isotropic resolution and quantitative susceptibility mapping (QSM) at 21.5 ​μm isotropic resolution to validate with conventional mouse brain histology. Diffusion weighted images (DWIs) show better delineation of cortical layers and glomeruli in the olfactory bulb than fractional anisotropy (FA) maps. However, among all the image contrasts, including quantitative susceptibility mapping (QSM), T1/T2∗ images and DTI metrics, FA maps highlight unique laminar architecture in sub-regions of the hippocampus, including the strata of the dentate gyrus and CA fields of the hippocampus. The mean diffusivity (MD) and axial diffusivity (AD) yield higher correlation with DAPI (0.62 and 0.71) and NeuN (0.78 and 0.74) than with NF-160 (-0.34 and -0.49). The correlations between FA and DAPI, NeuN, and NF-160 are 0.31, -0.01, and -0.49, respectively. Our findings demonstrate that MRI at microscopic resolution deliver a three-dimensional, non-invasive and non-destructive platform for characterization of fine structural detail in both gray matter and white matter of the mouse brain.
Authors
Wang, N; White, LE; Qi, Y; Cofer, G; Johnson, GA
MLA Citation
Wang, Nian, et al. “Cytoarchitecture of the mouse brain by high resolution diffusion magnetic resonance imaging.Neuroimage, vol. 216, Apr. 2020, p. 116876. Pubmed, doi:10.1016/j.neuroimage.2020.116876.
URI
https://scholars.duke.edu/individual/pub1439889
PMID
32344062
Source
pubmed
Published In
Neuroimage
Volume
216
Published Date
Start Page
116876
DOI
10.1016/j.neuroimage.2020.116876

MRI tools for assessment of microstructure and nephron function of the kidney.

MRI can provide excellent detail of renal structure and function. Recently, novel MR contrast mechanisms and imaging tools have been developed to evaluate microscopic kidney structures including the tubules and glomeruli. Quantitative MRI can assess local tubular function and is able to determine the concentrating mechanism of the kidney noninvasively in real time. Measuring single nephron function is now a near possibility. In parallel to advancing imaging techniques for kidney microstructure is a need to carefully understand the relationship between the local source of MRI contrast and the underlying physiological change. The development of these imaging markers can impact the accurate diagnosis and treatment of kidney disease. This study reviews the novel tools to examine kidney microstructure and local function and demonstrates the application of these methods in renal pathophysiology.
Authors
Xie, L; Bennett, KM; Liu, C; Johnson, GA; Zhang, JL; Lee, VS
MLA Citation
Xie, Luke, et al. “MRI tools for assessment of microstructure and nephron function of the kidney.Am J Physiol Renal Physiol, vol. 311, no. 6, Dec. 2016, pp. F1109–24. Pubmed, doi:10.1152/ajprenal.00134.2016.
URI
https://scholars.duke.edu/individual/pub1145655
PMID
27630064
Source
pubmed
Published In
Am J Physiol Renal Physiol
Volume
311
Published Date
Start Page
F1109
End Page
F1124
DOI
10.1152/ajprenal.00134.2016

Addendum to “Waxholm Space atlas of the Sprague Dawley rat brain” [NeuroImage 97 (2014) 374-386].

The main focus of our original article was to describe the anatomical delineations constituting the first version of the WHS Sprague Dawley atlas, apply the Waxholm Space coordinate system, and publish the associated MRI/DTI template and segmentation volume in their original format. To increase usability of the dataset, we have recently shared an updated version of the volumetric image material (v1.01). The aims of this addendum are to inform about the improvements in the updated dataset, in particular related to navigation in the WHS coordinate system, and provide guidance for transforming coordinates acquired in the first version of the atlas.
Authors
Papp, EA; Leergaard, TB; Calabrese, E; Johnson, GA; Bjaalie, JG
MLA Citation
Papp, Eszter A., et al. “Addendum to “Waxholm Space atlas of the Sprague Dawley rat brain” [NeuroImage 97 (2014) 374-386].Neuroimage, vol. 105, Jan. 2015, pp. 561–62. Pubmed, doi:10.1016/j.neuroimage.2014.10.017.
URI
https://scholars.duke.edu/individual/pub1071273
PMID
25635280
Source
pubmed
Published In
Neuroimage
Volume
105
Published Date
Start Page
561
End Page
562
DOI
10.1016/j.neuroimage.2014.10.017

Robust material decomposition for spectral CT

There is ongoing interest in extending CT from anatomical to functional imaging. Recent successes with dual energy CT, the introduction of energy discriminating x-ray detectors, and novel, target-specific, nanoparticle contrast agents enable functional imaging capabilities via spectral CT. However, many challenges related to radiation dose, photon flux, and sensitivity still must be overcome. Here, we introduce a post-reconstruction algorithm called spectral diffusion that performs a robust material decomposition of spectral CT data in the presence of photon noise to address these challenges. Specifically, we use spectrally joint, piece-wise constant kernel regression and the split Bregman method to iteratively solve for a material decomposition which is gradient sparse, quantitatively accurate, and minimally biased relative to the source data. Spectral diffusion integrates structural information from multiple spectral channels and their corresponding material decompositions within the framework of diffusion-like denoising algorithms. Using a 3D, digital bar phantom and a material sensitivity matrix calibrated for use with a polychromatic x-ray source, we quantify the limits of detectability (CNR = 5) afforded by spectral diffusion in the triple-energy material decomposition of iodine (3.1 mg/mL), gold (0.9 mg/mL), and gadolinium (2.9 mg/mL) concentrations. © 2014 SPIE.
Authors
MLA Citation
Clark, D. P., et al. “Robust material decomposition for spectral CT.” Progress in Biomedical Optics and Imaging  Proceedings of Spie, vol. 9038, 2014. Scopus, doi:10.1117/12.2042546.
URI
https://scholars.duke.edu/individual/pub1033329
Source
scopus
Published In
Progress in Biomedical Optics and Imaging Proceedings of Spie
Volume
9038
Published Date
DOI
10.1117/12.2042546

Dual-energy computed tomography imaging of atherosclerotic plaques in a mouse model using a liposomal-iodine nanoparticle contrast agent.

BACKGROUND: The accumulation of macrophages in inflamed atherosclerotic plaques has long been recognized. In an attempt to develop an imaging agent for detection of vulnerable plaques, we evaluated the feasibility of a liposomal-iodine nanoparticle contrast agent for computed tomography imaging of macrophage-rich atherosclerotic plaques in a mouse model. METHODS AND RESULTS: Liposomal-iodine formulations varying in particle size and polyethylene glycol coating were fabricated and shown to stably encapsulate the iodine compound. In vitro uptake studies using optical and computed tomography imaging in the RAW 264.7 macrophage cell line identified the formulation that promoted maximal uptake. Dual-energy computed tomography imaging using this formulation in apolipoprotein E-deficient (ApoE(-/-)) mice (n=8) and control C57BL/6 mice (n=6) followed by spectral decomposition of the dual-energy images enabled imaging of the liposomes localized in the plaque. Imaging cytometry confirmed the presence of liposomes in the plaque and their colocalization with a small fraction (≈2%) of the macrophages in the plaque. CONCLUSIONS: The results demonstrate the feasibility of imaging macrophage-rich atherosclerotic plaques using a liposomal-iodine nanoparticle contrast agent and dual-energy computed tomography.
Authors
Bhavane, R; Badea, C; Ghaghada, KB; Clark, D; Vela, D; Moturu, A; Annapragada, A; Johnson, GA; Willerson, JT; Annapragada, A
MLA Citation
Bhavane, Rohan, et al. “Dual-energy computed tomography imaging of atherosclerotic plaques in a mouse model using a liposomal-iodine nanoparticle contrast agent.Circ Cardiovasc Imaging, vol. 6, no. 2, Mar. 2013, pp. 285–94. Pubmed, doi:10.1161/CIRCIMAGING.112.000119.
URI
https://scholars.duke.edu/individual/pub953148
PMID
23349231
Source
pubmed
Published In
Circ Cardiovasc Imaging
Volume
6
Published Date
Start Page
285
End Page
294
DOI
10.1161/CIRCIMAGING.112.000119

Research Areas:

Age Factors
Aging
Alzheimer Disease
Angiography, Digital Subtraction
Animals
Anisotropy
Aorta
Artifacts
Atlases as Topic
Bayes Theorem
Biological Markers
Blast Injuries
Blood Flow Velocity
Blood-Brain Barrier
Brain
Brain Diseases
Brain Injuries
Brain Mapping
Cardiac-Gated Imaging Techniques
Cardiovascular System
Cell Line, Tumor
Central Nervous System
Cerebellar Nuclei
Cerebral Cortex
Computer Graphics
Computer Simulation
Computer Systems
Computers
Contrast Media
Coronary Vessels
Databases, Factual
Diagnostic Imaging
Diffusion
Diffusion Tensor Imaging
Disease Models, Animal
Disease Susceptibility
Dose-Response Relationship, Drug
Drug Evaluation, Preclinical
Echo-Planar Imaging
Electromagnetic Fields
Electromagnetic Phenomena
Embryo, Mammalian
Equipment Design
Female
Fetal Alcohol Syndrome
Fiber Optic Technology
Fibrosis
Four-Dimensional Computed Tomography
Fourier Analysis
Gadolinium
Gadolinium DTPA
Genotype
Heart
Heart Rate
Helium
Histological Techniques
Histology
Humans
Image Enhancement
Image Interpretation, Computer-Assisted
Image Processing, Computer-Assisted
Imaging
Imaging, Three-Dimensional
Immunohistochemistry
Infarction, Middle Cerebral Artery
Informatics
Information Dissemination
Intubation
Iodine
Kidney
Kidney Cortex
Kidney Diseases
Kidney Glomerulus
Kidney Medulla
Least-Squares Analysis
Liposomes
Liver
Magnetic Resonance Angiography
Magnetic Resonance Imaging
Magnetic Resonance Spectroscopy
Magnetic susceptibility
Magnetics
Magnetite Nanoparticles
Manganese
Manganese Compounds
Methods
Mice
Mice, Inbred BALB C
Mice, Inbred C57BL
Mice, Inbred Strains
Mice, Knockout
Mice, Neurologic Mutants
Mice, Nude
Microbubbles
Microcirculation
Microscopy
Microscopy, Confocal
Microscopy, Electron, Scanning
Models, Anatomic
Models, Animal
Models, Biological
Models, Cardiovascular
Models, Neurological
Models, Statistical
Molecular Imaging
Monitoring, Physiologic
Multiple Sclerosis
Myocardial Contraction
Myocardial Infarction
Nanoparticles
Nervous System
Neural Pathways
Noble Gases
Nuclear magnetic resonance
Optical Imaging
Pathology
Perfusion
Perfusion Imaging
Phantoms, Imaging
Phenotype
Protons
Pulmonary Artery
Pulmonary Circulation
Pulmonary Diffusing Capacity
Pulmonary Fibrosis
Pulmonary Gas Exchange
Putamen
Radiation Dosage
Radiation Injuries, Experimental
Radiographic Image Enhancement
Radiographic Image Interpretation, Computer-Assisted
Radiography, Thoracic
Rats
Rats, Inbred F344
Rats, Sprague-Dawley
Reference Standards
Respiration
Respiratory Mechanics
Retrospective Studies
Rubidium
Signal Processing, Computer-Assisted
Software
Spatio-Temporal Analysis
Specimen Handling
Spectrometry, Fluorescence
Staining and Labeling
Stereotaxic Techniques
Substantia Nigra
Subtraction Technique
Technology, Radiologic
Tissue Fixation
Tomography
Tomography Scanners, X-Ray Computed
Tomography, Emission-Computed, Single-Photon
Tomography, Optical
Tomography, X-Ray Computed
Toxicology
Tumor Burden
Tumor Microenvironment
Ultrasonics
Ultrasonography, Doppler, Transcranial
Ventilation-Perfusion Ratio
Ventilators, Mechanical
Ventricular Function, Left
X-Ray Microtomography
X-Rays
Xenon Isotopes
Xenon Radioisotopes