Allogeneic stem cell transplantation was developed to cure many patients with hematological malignancies. It results in the development of graft versus host disease (GVHD) in 30-70% of cases. Chronic GVHD diagnosis currently uses biopsies of affected organs (skin, liver, gastrointestinal tract) and / or the observation of typical clinical signs sufficient for diagnosis. However, the anatomical sites for biopsy including the digestive tract are not clearly identified (high or low biopsy) and may present risks in their realization in particular in patients weakened by blood disease or immunosuppression.

PET-CT with 18F-FDG has already been evaluated in chronic inflammatory diseases such as Crohns disease with good sensitivity and specificity. It interest in the graft against the host was studied in acute forms of digestive and allows lesion mapping and monitoring the effectiveness of treatment.

Among patients with chronic GVHD scleroderma form, PET with 18F-FDG enabled to view musculoskeletal uptakes localized to the affected areas identified with MRI.

The investigators propose a study evaluating the sensitivity and specificity of the examination by PET-CT with 18F-FDG in the diagnosis of chronic GVHD compared to conventional diagnostic tools.

Patients will have PET/CT at day 150+/-15d post-hematopoietic stem cell transplantation (HSCT)

Inclusion Criteria:

• adult >18 years
• Signed informed consent
• subject covered by a social security system
• Absence of contraindication to PET (18F-FDG)
• Allogeneic stem cell transplantation

Exclusion Criteria:

• Adult patient under tutelage.
• Pregnant or lactating women or women of childbearing potential not currently practicing an adequate method of contraception
• Age<18 years
• Evolutive infectious disease
• glycemia >10mmol/L