Study Using Fluorine-18-Labeled Fluoro-Misonidazole Positron Emission Tomography to Detect Hypoxia in Locally Advanced (T3-T4 and./or N1)Primary Rectal Cancer Patients

You will be scanned 2 to 3 times on the same day, but you will only be administered one dose of the FMISO tracer. The first scan will last about 30 minutes. Then you will have 1 to 3 hours to wait before you are scanned again. Some patients will undergo a second scan approximately one-and-a-half hours after the start of the first scan. This scan will last about 10 minutes. The final scan will occur between 2-4 hours after the start of the first scan. This final scan will also last about 10 minutes. During the PET scan, you may have a separate i.v. line put into your other arm so that we can take 2 to 3 blood samples. These samples will be less than half a teaspoon each. We are taking these blood samples to see how quickly FMISO leaves your blood stream. The first sample will be taken between 2 and 40 minutes after the FMISO is injected. The other two blood samples will be taken with each subsequent scan.