NIMH DIRP Molecular Imaging Branch

Robert B. Innis, M.D., Ph.D., Chief

GOALS. The Molecular Imaging Branch (MIB) was established by NIMH in 2000 and uses a variety of neuroimaging techniques to explore molecular and chemical mechanisms associated with neural function in health and disease. The overall goal of the Branch is to further elucidate pathophysiological mechanisms associated with neuropsychiatric disorders, with the expectation that such knowledge will ultimately decrease the burden of these illnesses by helping to guide the development and evalutation of improved medication therapies.

METHODOLOGIES. The primary methodologies used by investigators in this Branch are PET (positron emission tomography) and NMR (nuclear magnetic resonance). New PET radiotracers are synthesized for use as in vivo ligands to measure many different molecular targets, including membrane-bound receptors, proteins associated with intracellular signal transduction, and ones that reflect gene expression. Several NMR methods are also studied to measure molecular targets (magnetic resonance spectroscopy (MRS), local neuronal activity (functional MRI or fMRI), and structure of the brain (structural MRI).

COMPONENTS. This Branch has three sections (with a tenured scientist) and one unit (with tenured track scientist):

1) Section on PET Radiopharmaceutical Sciences: Chief, Victor Pike, PhD

2) Section on PET Neuroimaging Sciences: Robert Innis, MD, PhD

3) Section on Neuroimaging in Mood and Anxiety Disorders: Chief, Wayne Drevets, MD

4) Unit on Magnetic Resonance Spectroscopy: Chief, Jun Shen, PhD

Brief Overview

The first two Sections on Radiopharmaceuticals and Neuroimaging are almost exclusively oriented to PET, with a smaller effort in SPECT (single photon emission computed tomography). Theses two sections include a strong methodological orientation, with state-of-the-art facilities to develop, evaluate, and then apply new radiotracers for in vivo imaging. New radiotracers are synthesized and then rigorously evaluated in animals (rodents and primates) to assess their utility to localize, quantify, and measure the functional status of their targets. Promising candidate radiotracers are extended to human subjects, first in healthy subjects and then in relevant patient populations.

The Mood and Anxiety Disorders Neuroimaging Section applies both PET and NMR imaging technologies to investigate the neurobiological bases of mood and anxiety disorders. Because different imaging technologies have distinct capabilities, strengths and limitations, studies are designed so that the same subjects are iteratively studied using multiple techniques to provide complementary information about pathophysiology.

The Unit on Magnetic Resonance Spectroscopy (MRS).In vivo magnetic resonance spectroscopy is a fundamentally new method for non-invasive assessment of the homeostasis and dynamics of important endogenous metabolically active compounds and neurotransmitters in the brain. This Unit develops and applies both high-resolution and in vivo nuclear magnetic resonance spectroscopy and imaging techniques. Working with high-field magnetic resonance spectrometers this Unit develops novel NMR methods and applies them to studying neurotransmission and neurometabolism, with significant opportunities available for multi-modal collaborative imaging using MRS, MRI, and PET.