Heart/Mediastinal Ratio Study for Potential Equivalence of Heart/Mediastinal Ratios at One and Two Hours to the Traditional Heart/Mediastinal Ratio Obtained at Four Hours

The purpose of this study is to determine if the measurement (with a standard nuclear camera) of radioactivity normally present in the nervous system of your heart at four hours after the injection of radioactive drug for your diagnostic I-123 MIBG scan is any different than radioactivity measured in your heart at one and/or two hours after your diagnostic scan injection. If equivalent information to the conventional 4 hr H/M ratio could be collected by obtaining H/M ratios at 1 or 2 hour windows, it would greatly facilitate patient acceptance of the procedure since the requirements for obtaining a valid H/M ratio would be considerably less time-consuming. One hour before being injected with the drug (I-123 MIBG) for your MIBG scan, you will be given a standard dose of non-radioactive iodine (Lugol's solution) to block your thyroid from receiving the small amount of radiation that is a normal part of the MIBG scan. You will then be injected with MIBG, and you will have 10 minute pictures of your chest at 15 minutes, 1 hour, 2 hours, and 4 hours in addition to the standard 24 hour pictures. These pictures will be taken in the Nuclear Medicine Section, Department of Radiology at Ochsner Medical Center-Kenner. The experimental (research) part of this study is having the extra 10-minute pictures of your chest at 15 minutes, 1 hour, 2 hours, and 4 hours. Normally, pictures are only taken 24 hours after the injection. Therefore the research is limited to the four extra pictures taken, and involve no additional injections or I-123 drug beyond that you will be receiving regardless of whether you are part of this research.