The technical utilization of radioactive isotopes for diagnostic procedures has followed a somewhat different line of development at Harper Hospital (Detroit) from that in many other institutions. While numerous details have been reported and some of them have been demonstrated before this Society previously, we would like at this time to present the entire procedure, and with certain illustrative cases try to show the advantages that this technic offers in the diagnosis and evaluation of cases of thyroid cancer. Some parts of the technical procedure have been widely utilized elsewhere, and some radiologists who were trained at Harper Hospital are making use of the entire procedure in their own institutions throughout the country. In general, however, there has been a tendency to try to shorten the procedure and eliminate technical detail and professional labor. These efforts at simplification are very necessary, and any development which will reduce the cost and labor of the procedure, without sacrificin...