Repeat PET/CT Imaging of Patients With Amyloid 124I-AT-01 to Measure Changes in Organ-specific Amyloid Load

Inclusion Criteria: * Must have given written informed consent (signed and dated) and any authorizations required by local law and be able to comply with all study requirements. * Must have a diagnosis of systemic amyloidosis based on the patient's medical record. * Must have undergone PET/CT imaging with 124I-AT-01 as part of the AMY1001 study (IND #132282) with visually positive uptake of radiotracer in at least one abdominothoracic organ. * Must have been imaged with 124I-AT-01 as part of the AMY1001 study (IND #132282) more than 12 months prior to repeat imaging. * Females: must be non-pregnant and non-lactating and either: surgically sterile (e.g., tubal occlusion, hysterectomy, bilateral salpingectomy, bilateral oophorectomy); post-menopausal (defined as 12 months of spontaneous amenorrhea in females \> 55 years of age or, in females ≤ 55 years, 12 months of spontaneous amenorrhea without an alternative medical cause and follicle-stimulating hormone (FSH) levels in the post-menopausal range for the laboratory involved). Exclusion Criteria: * Disabling dementia or other mental or behavioral disease. * Patients on dialysis. * Inability or unwillingness to comply with the study requirements. * Patients taking heparin, or heparin derivatives (e.g. low molecular weight heparins) for anticoagulation. * Other reason that would make the subject inappropriate for entry into this study. * Inability to lie still for 60 minutes on the PET/CT scanner. * History of iodine (potassium iodide) allergy. * Positive ADA finding defined as significantly higher than normal human serum mean values AND with a mean value at least five times greater than the mean value of the normal human serum control.