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Receptor-targeted radiopharmaceuticals constitute potential agents for the diagnosis and therapy of cancer. Breast cancer is the most prevalent form of diagnosed cancer in women in the United States, and it accounts for the second highest number of cases of cancer fatalities (1). In Approximately two-thirds of the breast tumors, estrogen and progesterone steroid hormone receptors can be found. Such tumors can often be treated successfully with anti-estrogen hormone therapy (2). Hence, the ability to determine the estrogen receptor (ER) contend of the breast tumor is essential for making the most appropriate choice of treatment for the patient. Along with this diagnostic aspect, steroid-based radiopharmaceuticals with high specific activity offer an encouraging prospect for therapeutic applications: {sup 186,188}Re labeled steroids binding to receptors expressed by cancer cells appear to be potential agents for the irradiation of small to medium-sized tumors. {sup 186}Re has been regarded as an ideal radionuclide for radiotherapy due to its appropriate half-live of 90 h and {beta}-energy of 1.07 MeV. Moreover, the {gamma}-emission of 137 keV that allows in vivo imaging while in therapy is an additional bonus. {sup 188}Re is obtained from a {sup 188}W/{sup 188}Re radionuclide generator system, representing an advantage for availability at radiopharmacymore » laboratory by daily elution. In addition, {sup 188}Re emits high energy beta particles with an average energy of 769 keV, and the emission of the 155 keV allows simultaneous imaging for biodistribution evaluation in vivo. In order to avoid competitive saturation of the binding sites of the ligand receptor, Re labeled steroids with high specific activity are required, and the removal of all excess unlabeled ligands is mandatory. {sup 188}Re is eluted from a {sup 188}W/{sup 188}Re generator produced and provided by Oak Ridge National Laboratory (3). This paper outlines the solid phase-supported preparation of an n.c.a. [{sup 188}Re]Re-imido estradiol compound. The characteristic feature of the presented route is the simultaneous formation of the steroid-radioisotope linkage and release of the labeled steroid product into solution (4,5). The unlabeled ligand can then be separated by simple filtration.« less

We report NMR measurements of the nuclear relaxation rate at all copper and oxygen sites in magnetically aligned powder samples of ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$. Comparison of the oxygen and copper relaxation reveals a characteristic temperature greater than ${T}_{c}$. The copper relaxation rate is enhanced by antiferromagnetic copper spin fluctuations which are undiminished in the superconducting state. The absence of a coherence peak indicates that the superconductive pairing is not of the conventional BCS type.