This workshop yielded recommendations on using hypoxia measurement to identify patients who would respond best to radiation therapy, which would improve treatment planning. This represents a narrow focus, as hypoxia measurement might also prove useful in drug development and in increasing our understanding of tumor biology.

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The new functionalized trimetallic nitride endohedral metallofullerene species Gd(3)N@C(80)[DiPEG5000(OH)(x)] is an effective proton relaxation agent, as demonstrated with in vitro relaxivity and MR imaging studies, in infusion experiments with agarose gel and in vivo rat brain studies simulating clinical conditions of direct intraparenchymal drug delivery for the treatment of brain tumors.

As addressed by the recent Food and Drug Administration Critical Path Initiative, tools are urgently needed to increase the speed, efficiency, and cost-effectiveness of drug development for cancer and other diseases. Molecular imaging probes developed based on recent scientific advances have great potential as oncologic drug development tools. Basic science studies using molecular imaging probes can help to identify and characterize disease-specific targets for oncologic drug therapy. Imaging end points, based on these disease-specific biomarkers, hold great promise to better define, stratify, and enrich study groups and to provide direct biological measures of response. Imaging-based biomarkers also have promise for speeding drug evaluation by supplementing or replacing preclinical and clinical pharmacokinetic and pharmacodynamic evaluations, including target interaction and modulation. Such analyses may be particularly valuable in early comparative studies among candidates designed to interact with the same molecular target. Finally, as response biomarkers, imaging end points that characterize tumor vitality, growth, or apoptosis can also serve as early surrogates of therapy success. This article outlines the scientific basis of oncology imaging probes and presents examples of probes that could facilitate progress. The current regulatory opportunities for new and existing probe development and testing are also reviewed, with a focus on recent Food and Drug Administration guidance to facilitate early clinical development of promising probes. Value of Imaging-Based Biomarkers in Drug DevelopmentIn the last 10 years, novel treatments have been developed that prolong survival, induce remission, and provide better quality of life for cancer patients. Among the successes are the molecularly targeted cancer treatment drugs, notably the anti-HER-2/neu antibody trastuzumab for ErbB2-expressing breast cancers (1) and the kinase inhibitor imatinib for chronic myelogenous leukemia and gastrointestinal stromal tumors (2). In addition, molecularly targeted drugs have shown efficacy in lung cancer [e.g., the epidermal growth factor receptor (EGFR) inhibitor erlotinib; ref. 3], multiple myeloma (e.g., the proteasome inhibitor bortezomib; ref. 4), advanced colorectal cancer (e.g., the EGFR antibody cetuximab; refs. 5, 6), and other breast cancer settings (e.g., the aromatase inhibitor letrozole for hormone receptor -unknown or hormone receptor -positive locally advanced or metastatic breast cancer in postmenopausal women; ref. 7). Despite their efficacy in certain settings, molecularly targeted drugs are resource-intensive to develop, with the considerable expenditures, protracted time, and numerous patients required during development resulting in high costs of the approved therapy (8). Moreover, molecular targets have been identified and characterized in relatively few oncology patients; improved phenotypic characterization of the underlying molecular lesions would expand the overall effect of targeted agents in onc...

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The risk of serious dipyridamole-induced side effects is very low and is comparable to that reported for exercise testing in a similar patient population.

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Positive rest perfusion imaging accurately identified patients at high risk for adverse cardiac outcomes, whereas negative perfusion imaging identified a low risk patient group. Early perfusion imaging allows for rapid and accurate risk stratification of emergency department patients with possible cardiac ischemia and nondiagnostic ECGs.