About

Ravinder Reddy, PhD, is a Professor of Radiology at the University of Pennsylvania's Perelman School of Medicine. His research interests focus on developing novel multinuclear magnetic resonance imaging and spectroscopic techniques for early diagnosis and quantification of physiological and functional aberrations in pathologies such as arthritis, stroke, cancer, and Alzheimer’s disease. His work exploits quadrupolar spin-dynamics, polarization transfer, multiple quantum coherences, chemical exchange, and spin-locking T1ρ MRI to study molecular dynamics in biological tissues in vivo. Notably, his research includes mapping proteoglycan molecules in cartilage as biomarkers for early arthritis, and developing contrast techniques for various tissue types, including brain, connective tissues, and tumors. He is also involved in measuring endogenous metabolites in the brain and high-energy phosphate metabolism in the myocardium, contributing significantly to the field of biomedical imaging.

Research topics

• Biology
• Artificial Intelligence
• Computer Science
• Biochemistry
• Chemistry
• Physics
• Medicine
• Immunology
• Internal medicine
• Cell biology
• Nuclear magnetic resonance
• Neuroscience
• Cancer research

Selected publications

• Effects of nicotinamide riboside supplementation on glucose metabolism and lipid homeostasis in healthy mice

  Proceedings on CD-ROM - International Society for Magnetic Resonance in Medicine. Scientific Meeting and Exhibition/Proceedings of the International Society for Magnetic Resonance in Medicine, Scientific Meeting and Exhibition · 2025-09-16

  articleSenior author

  Motivation: The rising popularity of NAD+ precursors to alleviate metabolic stress in aging necessitates a close monitoring of tissue metabolic status. Goal(s): FINUTE and 2H-MRS are used monitor lipid homeostasis and glucose metabolism in the brains of healthy mice following supplementation of nicotinamide riboside (NR), a widely used NAD+ precursor. Approach: Mice administered saline or NR intraperitoneally for one week are imaged to assess lipid integrity. 2H-MRS is performed following administration of labeled glucose to monitor downstream metabolite labeling. Results: Mice administered NR show increased lipid integrity and improved glucose metabolism, determined through increased labeling of Glx (TCA) and lower labeling of lactate (glycolysis). Impact: Nicotinamide riboside has potential in improving cerebral glucose metabolism and lipid integrity as assessed by lipid-sensitive MRI and 2H-MR spectroscopy, necessitating further exploration of NR and other NAD+ precursors both clinically and in aging-related diseases using these methods.

  PublisherDOI

• Measurement of tryptophan relaxation times in human brain using downfield 1H MRS at 7 T

  Proceedings on CD-ROM - International Society for Magnetic Resonance in Medicine. Scientific Meeting and Exhibition/Proceedings of the International Society for Magnetic Resonance in Medicine, Scientific Meeting and Exhibition · 2025-09-16

  articleSenior author

  Motivation: Determine the tryptophan (TRP) relaxation rates from human brain 1H downfield spectrum in vivo. Goal(s): To estimate the T1 and T2 of TRP in healthy human brains at 7 T Approach: We determined TRP relaxation times using a spectrally- and slice-selective downfield MRS sequence. Results: The mean T1 and T2 estimates of TRP from in vivo human brain were 74.5±12.5ms (n=6) and 19.3±3.5ms (n=8), respectively. Impact: Reliable in vivo brain TRP relaxation measures in normal subjects could help establish reference values and also aid in utilizing it as a novel non-invasive in vivo biomarker for various aging-related and neuropsychiatric disorders.

  PublisherDOI

• Proton MRI and MRSI as a Superior Methodology to Assess Oxidative Phosphorylation

  Academic Radiology · 2025-12-16

  articleSenior author
  PublisherDOI

• BIOM-87. SODIUM (23NA) MRI AND CHEMICAL EXCHANGE SATURATION TRANSFER (CEST) IMAGING IN TYPICALLY DEVELOPING CHILDREN AND IN PEDIATRIC BRAIN TUMORS

  Neuro-Oncology · 2025-11-01

  articleOpen access

  Abstract In contrast to conventional 1H MRI, which primarily reveals water molecule distribution, with only indirect association with the physico-chemical microenvironment, 23Na (sodium) MRI and chemical exchange saturation transfer (CEST) have a more direct physiological interpretation, reflecting biochemical and physiologic changes in the cells of tissues, e.g. cell integrity and tissue viability allowing for direct assessment of cell membrane sodium ion channel function. Sodium concentrations are measurable by 23Na MRI and mobile proteins are measured with CEST [Amide Proton Transfer (APT) signal intensity]; when these are elevated, they have shown to be markers of tumors and proliferation. In this study, we acquired 23Na MRIs and APT in children with central nervous system (CNS) tumors and typically-developing (TD) pediatric controls. Sodium concentrations and APT signal were analyzed in regions of normal brain (brainstem, cerebellum, cerebral cortical grey matter, cerebral white matter, basal ganglia, hippocampus, thalamus) of TD controls and in pediatric brain tumors. The sodium concentration and APT in tumors were compared to homologous regions of the brains of TD controls. We hypothesized that sodium concentrations and APT signal will be greater in tumors compared to healthy brain in TD controls. We also analyzed the repeatability of subjects that received 23Na MRIs and CEST at two timepoints. Preliminary data demonstrates elevated sodium concentrations and APT signal in pediatric brain tumors (n = 5) compared to TD controls (n = 3). There was repeatability at two timepoints with consistent sodium concentrations and APT signal in TD controls (n = 3) and in pediatric brain tumors (n = 4). In conclusion, performing 23Na-MRI and CEST is feasible in pediatric patients with brain tumors. Future work will help answer the complex questions in monitoring treatment of pediatric patients with brain tumors: is there residual or recurrent tumor and differentiating tumor progression versus pseudoprogression.

  PublisherOA PDFDOI

• A Comparative Study of CrCEST and PCrCEST for Mapping of Oxidative Phosphorylation in Exercised Muscle

  Proceedings on CD-ROM - International Society for Magnetic Resonance in Medicine. Scientific Meeting and Exhibition/Proceedings of the International Society for Magnetic Resonance in Medicine, Scientific Meeting and Exhibition · 2025-09-16

  article

  Motivation: This study compares the sensitivity and specificity of two CEST-based methods for assessing oxidative phosphorylation (OXPHOS) in participants' skeletal muscle and also shows that creatine in muscle is a fast-exchanging species. Goal(s): We compare the sensitivity and specificity of creatine CEST and phosphocreatine CEST for exercised calf muscle. Approach: We acquired z-spectra at multiple saturation parameters to compare creatine CEST and phosphocreatine CEST at 3.0T and 7.0T. We also acquired creatine CEST and phosphocreatine CEST from exercised calf muscle. Results: Our findings indicate that creatine rapidly exchanges in skeletal muscle. Additionally, creatine CEST demonstrates higher sensitivity and specificity than phosphocreatine CEST. Impact: OXPHOS deficiency in skeletal muscle is associated with primary mitochondrial disorders, muscle injury, cardiovascular disease, and diabetes mellitus. This study compares the sensitivity and specificity of two CEST-based methods for assessing OXPHOS.

  PublisherDOI

• NOE Imaging of Multiple Sclerosis Subjects at 7T Detects Diffuse Contrast Changes

  Proceedings on CD-ROM - International Society for Magnetic Resonance in Medicine. Scientific Meeting and Exhibition/Proceedings of the International Society for Magnetic Resonance in Medicine, Scientific Meeting and Exhibition · 2025-09-16

  articleSenior author

  Motivation: While standard to the diagnosis of multiple sclerosis (MS), conventional structural MRI cannot provide detailed information on changes in lipid metabolism. Goal(s): To utilize NOE imaging to investigate changes between MS and healthy control subjects. Approach: NOE imaging was performed on 15 MS and 10 healthy subjects in conjunction with a multi-pool Lorentzian line fitting model to produce several contrasts including MT, APT, amine, and rNOE. Results: Statistically significant contrast decreases were observed in both the amine (15.3% in NAWM) and rNOE (11.4% in NAWM and 10.6% in NAGM) pools. Impact: This 7T NOE imaging method for patients with MS can provide complementary lipid metabolic information to standard structural imaging and can yield improved diagnostic outcomes for this patient population.

  PublisherDOI

• Lac+ Clearance Measured in Brain After Exercise with 1H-MRS

  Proceedings on CD-ROM - International Society for Magnetic Resonance in Medicine. Scientific Meeting and Exhibition/Proceedings of the International Society for Magnetic Resonance in Medicine, Scientific Meeting and Exhibition · 2025-09-16

  articleSenior author

  Motivation: Given lactate's role as an energy metabolite of the brain via the lactate shuttle hypothesis, the accumulation and clearance of lactate in brain diseases is not well understood. In this work, we show lactate elevation in the healthy human brain after intense exercise and calculate a lactate recovery time constant (ΤLac). Goal(s): To quickly detect lactate + threonine (Lac+) signal and measure its clearance post-exercise. Approach: Measure baseline and post-exercise Lac+ with 1H-MRS. Results: Lac+/Water ratios increased 2.0 - 5.1 times their baseline values with sub>ranging between 18-52 minutes across participants. Impact: Brain Lac+/Water clearance can be measured in healthy humans after intense-exercise. While the blood lactate literature suggests that larger increases in lactate correlate with faster recovery times, our results indicate that brain Lac+ recovery may be influenced by additional factors.

  PublisherDOI

• Metasurface Enabled In Vivo Cervical Spine Imaging at 7T

  Proceedings on CD-ROM - International Society for Magnetic Resonance in Medicine. Scientific Meeting and Exhibition/Proceedings of the International Society for Magnetic Resonance in Medicine, Scientific Meeting and Exhibition · 2025-09-16

  articleSenior author

  Motivation: Cervical spine imaging at 7T is only feasible using dedicated RF coils that do not allow for simultaneous imaging of both brain and cervical spine, while also being prohibitively expensive. Goal(s): To utilize metasurfaces to extend the field of view on a widely utilized RF coil to improve c-spine image quality. Approach: Metasurfaces were placed on either side of the head/neck partially outside of the single channel transmit / 32-channel receive head coil of five healthy subjects. Results: Substantial improvements in GRE and MPRAGE image contrast were observed where portions of the cervical spine were completely recovered. Impact: By utilizing a pair of inexpensive metasurfaces higher quality c-spine imaging can be accomplished at 7T without the need for dedicated RF coils.

  PublisherDOI

• Optimization of Lipid Inversion with Hyperbolic Secant Adiabatic Pulses in Transient NOE at 7T

  Proceedings on CD-ROM - International Society for Magnetic Resonance in Medicine. Scientific Meeting and Exhibition/Proceedings of the International Society for Magnetic Resonance in Medicine, Scientific Meeting and Exhibition · 2025-09-16

  articleSenior author

  Motivation: In vivo lipid quantification in brain tissue is challenging due to limited uniform spin inversion with conventional adiabatic pulses, affecting transient NOE (tNOE) reliability. Goal(s): Optimize B1 amplitude of hyperbolic secant (HS) adiabatic pulses in tNOE to reduce magnetization transfer (MT) effects and improve lipid quantification repeatability. Approach: Validated optimized pulse parameters on a water phantom, then acquired repeatable tNOE maps in vivo, assessing white and gray matter contrast. Results: Optimized scanner voltage (305 V) produced high-quality tNOE contrast with minimal MT interference, showing CoVs of 1% for white and 3% for gray matter. Impact: This approach may improve lipid degeneration monitoring in neurodegenerative diseases like MS and Alzheimer's.

  PublisherDOI

• Cannabis Use and Glutamate across the Psychosis Spectrum: In Vivo Evidence from 7T Proton Magnetic Resonance Spectroscopy

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-10-09

  preprintOpen access

  Abstract Cannabis use is linked to elevated psychosis risk, yet the neurobiological mechanisms that couple use to symptom expression remain unclear. Because glutamatergic dysregulation has been implicated in both cannabis effects and psychosis vulnerability, we examined whether brain glutamate relates to dimensional symptoms as a function of cannabis use across the psychosis spectrum. Seventy-nine participants—typically developing controls, clinical high-risk individuals, and patients with psychosis—completed dimensional clinical assessments, detailed cannabis surveys, urine toxicology, and ultra-high-field 7T 1 HMRS quantification of anterior cingulate cortex (ACC) glutamate levels. Linear models assessed the main and interactive effects of ACC glutamate and cannabis use on positive and negative symptoms. Self-reported cannabis use showed strong concordance with urine toxicology. Cannabis use was associated with higher positive and negative symptoms. Independently, higher ACC glutamate predicted greater positive and negative symptoms. Notably, lower glutamate levels were associated with higher positive symptoms in cannabis users. Exploratory analyses suggested interactions for depressive and manic symptoms, indicating that glutamatergic abnormalities may amplify the overall severity of cannabis-related symptoms. Sensitivity analyses revealed lower ACC glutamate in psychosis patients—especially cannabis users—highlighting diagnostic group differences and reinforcing the link between cannabis exposure and glutamatergic dysfunction. These findings implicate ACC glutamatergic dysfunction as a transdiagnostic correlate of symptom burden, particularly in those with psychosis who are cannabis users. Glutamate-targeted interventions and longitudinal designs will be needed to examine causal pathways linking cannabis exposure to psychosis-relevant outcomes.

  PublisherOA PDFDOI

Recent grants

• NIH Grant R21DA032256

  NIH · $400k · 2013

• NIH Grant R01AR045404

  NIH · $2.6M · 2011

• NIH Grant R01AR045242

  NIH · $1.8M · 2007

• In vivo Mapping of Muscle Specific Metabolism

  NIH · $3.1M · 2022–2026

• NIH Grant R03MH047002

  NIH · $143k · 1994

Frequent coauthors

• J. S. Leigh

  183 shared

• Sridhar R. Charagundla

  120 shared

• Alan H. Stolpen

  University of Iowa Health Care

  107 shared

• Arijitt Borthakur

  California University of Pennsylvania

  106 shared

• J.H. Duyn

  National Institute of Neurological Disorders and Stroke

  100 shared

• Richard S. Dunn

  100 shared

• Jürgen Hennig

  Humboldt-Universität zu Berlin

  100 shared

• R. Allen Waggoner

  RIKEN Center for Brain Science

  100 shared

Labs

• Stellar-Chance LaboratoriesPI

Education

• PhD, Chemistry

  Indian Institute of Technology Kanpur

  1989