Detection of Graft Versus Host Disease With [18F]F-AraG

Inclusion Criteria:

   1. Must be 21 years of age or older.

   2. Must understand and voluntarily have signed an Informed Consent after its contents
   have been fully explained.

      1. For patients highly suspected to have aGVHD and requiring systemic therapy,
      informed consent should be signed after biopsy taken to support clinical
      diagnosis.

      2. For patients at high risk for developing aGVHD, informed consent should be signed
      prior to transplant.

   3. For healthy volunteers only: Must have no known medical problems that would make
   undergoing the scan hazardous to the health of the patient or interfere with the
   results. In particular subjects should not have any cardiac or immunological disorders
   as these would likely affect the scan results. Subjects should have had a full
   physical exam within 6 months of the study. If healthy volunteers have not had a full
   medical exam within 6 months of the study, one of the nuclear medicine physicians will
   conduct the medical exam prior to any study procedures.

   4. For patients highly suspected to have aGVHD and requiring systemic therapy only:
   Taking steroid treatment for suspected aGVHD for 3 days or less.

   5. For patients at high risk for developing aGVHD only: Recipients of myeloablative or
   reduced intensity allogeneic transplants using either bone marrow or peripheral blood
   stem cells from HLA-matched or HLA-mismatched related or unrelated donors (protocols
   9142, 9022, 9924) who have not yet been placed on any therapy for acute GVHD.

Exclusion Criteria:

   1. Pregnant or nursing

   2. Individuals with known or suspected substance abuse, obtained by self-reporting.

   3. Uncontrolled infection

   4. Relapsed/persistent malignancy

   5. Currently receiving immunotherapy