 Screening prior to at-home dosing of KI The main concern when subjects are asked to take KI on the morning prior to the study visit is the possibility that the patient is allergic to iodine and will thus have a reaction to the KI in the unobserved environment at home. The research team will identify subjects with known allergies in advance by screening the subjects medical records if available and through the health-history interview conducted via telephone by the study coordinator. Subjects who are not sure if they have an iodine allergy because they have not eaten shellfish or have never received contrast dye and, therefore, cannot say with sureness that they are not allergic will be excluded from participation. 