Editorial [Hot Topic: Imaging Science and Technology in Drug Discovery (Guest Editor: David J. Yang)]

With progress of molecular medicine in recent years, imaging techniques are undergoing a tremendous development and improvement. They play a major role in the development of novel therapies since they generate informations about target expression as well as function, pathway activities and cell migration in the intact organism. Therefore, imaging enables the comprehensive characterization of therapeutic intervention and can be used in preclinical studies, pharmacokinetic (microdosing) studies, dose-finding studies, and proof-of-concept studies. PET and SPECT permit mapping and measuring the rate of physiological, biochemical and molecular process with the use of radiolabeled compounds and appropriate tracer kinetic models. David J. Yang, PhD., Professor of Radiochemistry at the University of Texas MD Anderson Cancer Center and Professors Hiroshi Fukuda, MD, PhD, Masatoshi Itoh, M.D. and Keizo Ishii, PhD at the Tohoku University organized the symposium on Imaging Science and Technology in Drug Discovery and Development with the long history of working and interest on various radiopharmaceuticals and PET technology to exchange ideas how to improve and promote imaging technology, especially PET and SPECT, and also to extend the investigational studies to clinical applications. The symposium was held on September 17 and 18, 2007 at the Sendai Kokusai Hotel, Sendai, Japan, sponsored by the Sendai Medical Imaging Clinic. The papers in this issue have been selected from the presentations at the symposium. Molecular imaging can accelerate several procedures in drug development and contribute to cost-reduction and also fast approval of candidate drugs. Challenges and opportunities in molecular imaging are overviewed by Yang et al. Tashiro et al. reviews the molecular imaging program at the Tohoku University with 30-year long history of basic and clinical researches using various radiopharmaceuticals, particulary neuroreceptors. Effective biomarkers have been desired both for diagnostic purpose and for the evaluation of the drug effects, and these are discussed for the proof-of-concept by Suhara and Kodaka. There are unique operational and safety requirements of PET radiotracer synthesis by the FDA, and this is presented by Sims-Mourtada et al., High resolution animal PET system using semiconductor CdTe detector is introduced by Ishii et al., Mawlawi et al. discuss multiple factors affecting quantification in PET/CT imaging to insure accuracy and reliability of PET outcome measurements. Cancer patients often manifest psychological or behavioral problems, and Tashiro et al. present a neuroimaging using PET and MRI in cancer patients. Prograssive deposition of amyloid plaque in the brain is an initiating event in the pathogenesis of Alzheimer's disease, and the PET as well as SPECT imaging of amyloid pathology in the living brain is discussed by Okamura et al. Khondkar et al. deal with the assessment of local brain metabolic responses during exercise in human with changing loads by regional changes of glucose metabolism. Overview of PET and SPECT utilization in clinical oncology is presented by Kim et al.