The purpose of the study was to evaluate the value of PET using 11C-methionine (PET-Met) for distinction between true @entity11 progression and pseudoprogression (PsPr). 72 @entity1 with treated @entity13 investigated by PET-Met were identified from prospective database. Entry criteria included new or progressive MR imaging enhancing lesions within first 6 months after irradiation and definite final diagnosis on the basis of the pathological study (n=17) or clinical-radiological follow-up on an average 16 months. PET examinations were assessed by visual inspection and calculating 11C-methionine uptake index (UI). Results. Pseudoprogression was defined as early radiological progression with subsequent regress or stabilization, without salvage therapy. 42 @entity1 were considered to exhibit PsPr and 30 @entity1 had true @entity11 progression. In PsPr group PET scans were either negative (n=6) or slightly increased tracer uptake (UI range 1.2-2.14) was seen in the site of contrast-enhanced lesion. The UI was 1.48  0.39 (mean  SD). In comparison with pretreatment PET 15 @entity1 showed decrease 11C-methionine uptake on an average by 26%. In recurrence group PET-Met showed abnormal high focal 11C-methionine uptake in the lesion. The UI was 2.54  0.84 (range 1.54-5.4). An UI threshold value of greater than 1.9 optimized differentiation between @entity11 progression and PsPr with sensitivity of 83.5% and specificity of 97.0%. Conclusion. Metabolic characteristics of PsPr included negative tracer accumulation or slightly increased 11C-methionine uptake in the contrast-enhancing lesion with UI less than 1.9.

[PET using 11C-methionine in recognition of pseudoprogression in XXXX after combined treatment].

@entity11 :: ('MESH:D005910', 'Disease') :: ['glioma'] @entity1 :: ('9606', 'Species') :: ['patients'] @entity13 :: ('MESH:C564230', 'Disease') :: ['cerebral glioma']
@entity13 :: (MESH:C564230,Disease) :: ['cerebral glioma']
