18F-THK5351 PET Can Evaluate Tumor Extension in Intravascular Large B-Cell Lymphoma

A 79-year-old man presenting with gait disturbance and cognitive decline was diagnosed with intravascular large B-cell lymphoma (IVLBCL) by random skin biopsy. Some IVLBCL lesions were identified by PET examinations using 11 C-methionine, 18 F-FDG, and 18 F-THK5351. 11 C-methionine and 18 F-FDG uptake, which likely reflects the presence of the lymphoma cells themselves, increased clearly in the left putamen but weakly in the left deep white matter. 18 F-THK5351 uptake increased in all lesions, likely reflecting perivascular astrogliosis caused by IVLBCL. Hence, 18 F-THK5351 PET can evaluate tumor extension in IVLBCL lesions where 11 C-methionine and 18 F-FDG PET may fail in its visualization.