Positron Emission Tomography - Computed Tomography (PET-CT) Scanning in Chronic Graft Versus Host Disease (cGvHD)

Graft versus Host Disease (GvHD), in both its acute and chronic forms, is the major intrinsic complication of allogeneic hematopoeitic stem cell transplant (allo-HSCT). Moreover, chronic GvHD may be regarded as a "late effect" of cancer therapy, and the severity of chronic GvHD is the chief determinant of long-term survival following allo-HSCT. Unfortunately, the investigators understanding (and thus management) of chronic GvHD is not optimal; a recent NIH Consensus Conference has defined inadequacies in virtually all facets of chronic GvHD management. Notably for this study, the lack of suitable biomarkers compromises diagnosis, staging and therapeutic response evaluation of chronic GvHD - and also hinders better understanding of the biology of this process. In particular, the activity of chronic GvHD is often difficult to discern, potentially causing either undertreatment, with the risk of morbidity and/or mortality due to uncontrolled chronic GvHD, or possibly overtreatment, with potent ISTs causing unnecessary toxicity. Obviously, the development of reliable biomarkers of chronic GvHD activity would be a very useful advance in addressing this problem, as well as other facets of management not addressed due to certain limitations, as detailed herein. Potentially, certain imaging technologies could address this problem. To date, imaging technology has been used only sporadically in chronic GvHD and is not an integral part of routine assessments. However, and despite its nonspecific nature, certain "inflammatory" features of some chronic GvHD cases, plus clinical similarity to certain autoimmune diseases in which functional imaging has been tested in research trials - (and perhaps notably), a limited experience in acute GvHD - the investigators postulate that Positron emission tomography - computed tomography (PET-CT) scans may be useful as a biomarker of disease activity in chronic GvHD. This protocol is an initial effort to that end.