PET Imaging of Proliferation with Pyrimidines

¹⁸F-FLT PET images of bone marrow of 7 AML patients grouped by clinical response. PET scans were acquired at different time points of therapy, but results were consistent within each clinical response group (complete remission and resistant disease), independent of time of assessment. Resistant disease exhibited elevated uptake, whereas complete remission displayed low uptake. (Reprinted with permission of (20).)

Transaxial views of ¹⁸F-FLT PET (top), helical CT (middle), and ¹⁸F-FDG PET (bottom) for 2 patients with DLBCL. (A) A 41-y-old man with retromandibular lymphoma showing intense ¹⁸F-FDG and ¹⁸F-FLT uptake in projection of retromandibular lymph node. This stage 1A patient revealed disease progression under therapy. (B) A 40-y-old woman (stage IVA) with histologically proven lymphoma in right iliac bone and sacrum. ¹⁸F-FDG PET shows intensely increased uptake in right ilium and sacrum. Corresponding ¹⁸F-FLT PET images allow detection of increased asymmetric uptake in right ilium and sacrum despite high physiologic ¹⁸F-FLT uptake in proliferating bone marrow. Transaxial views of helical CT display osteodestruction of right ilium. Restaging after end of therapy revealed complete response. (Reprinted from (22).)

¹⁸F-FLT PET at baseline, 2 wk, and 6 wk for responding patient (A–C, patient 25) and nonresponding patient (D–F, patient 9). (Reprinted from (34)).

PET images of patient with hypopharyngeal cancer (patient 14) before radiation therapy (A and D), 3 wk after initiation of radiation therapy (B and E), and 4 wk after end of radiation therapy (C and F). Pretreatment ¹⁸F-FLT and ¹⁸F-FDG axial PET images showed increased metabolism in primary tumor and metastatic lymph node (¹⁸F-FLT SUVs, 9.16 and 6.06, respectively; ¹⁸F-FDG SUVs, 21.81 and 13.37, respectively). ¹⁸F-FLT and ¹⁸F-FDG SUVs decreased after 30 Gy of irradiation (¹⁸F-FLT SUVs, 2.86 and 2.14, respectively; ¹⁸F-FDG SUVs, 11.44 and 6.39, respectively). ¹⁸F-FLT uptake in primary site and lymph nodes was same as in surrounding muscle (SUVs of 0.93, 0.9, and 0.9, respectively) at 4 wk after completion of treatment, whereas increased uptake of ¹⁸F-FDG persisted (SUV of 4.66 in primary lesion and 3.75 in lymph node). Patient was alive and without evidence of recurrent disease 19 mo after therapy. (Reprinted from (66).)