[18F]3'-deoxy-3'-fluorothymidine PET for the diagnosis and grading of brain tumors.
The aim of this study was to evaluate the feasibility of using [(18)F] 3'-deoxy-3'-fluorothymidine (FLT) positron emission tomography (PET) for the diagnosis and grading of brain tumors.


METHODS
The patient population comprised 26 patients (15 males, 11 females) with brain tumors (n=18) or nontumorous lesions (n=8). 2-[(18)F]fluoro-2-deoxy-D: -glucose (FDG) and FLT PET images were obtained using a dedicated PET scanner 1 h after the injection of 370 MBq of FDG or FLT. Uptake of FDG and FLT by the lesions was visually and semiquantitatively assessed in comparison with normal brain tissue.


RESULTS
Of 26 brain lesions, four showed increased FDG uptake compared with normal gray matter (grade 5). These four lesions showed intensely increased FLT uptake and were all high-grade tumors. Twenty-two lesions with similar (grade 4) or decreased (grades 1-3) FDG uptake compared with normal gray matter showed variable pathology. Among the 18 brain tumors, FLT PET showed increased uptake in all 12 high-grade tumors but FDG uptake was variable. In 22 brain lesions with similar or decreased uptake compared with normal gray matter on FDG PET, the sensitivity and specificity of FLT PET for the diagnosis of brain tumor were 79% (11/14) and 63% (5/8), respectively. The uptake ratios of 14 brain tumors on FLT PET were significantly higher than the lesion to gray matter ratios (p=0.012) and lesion to white matter ratios (p=0.036) of FDG uptake and differed significantly between high (5.1+/-2.6) and low (2.1+/-1.1) grade tumors (p=0.029). In nine gliomas, FLT uptake was significantly correlated with the Ki-67 proliferation index (rho=0.817, p=0.007).


CONCLUSIONS
These findings indicate that FLT PET is useful for evaluating tumor grade and cellular proliferation in brain tumors. It displayed high sensitivity and good contrast in evaluating brain lesions that showed similar or decreased uptake compared with normal gray matter on FDG PET. FLT PET, however, did not appear to be sufficiently useful for differentiating tumors from nontumorous lesions.
Choi
Seung Jin
SJ
Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, 388-1 Poongnap-dong, Songpa-gu, Seoul, 138-736, Korea.
Kim
Jae Seung
JS
Kim
Jeong Hoon
JH
Oh
Seung Jun
SJ
Lee
Jeong Gyo
JG
Kim
Chang Jin
CJ
Ra
Young Shin
YS
Yeo
Jeong Seok
JS
Ryu
Jin Sook
JS
Moon
Dae Hyuk
DH
D000293:Adolescent; D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000145:classification* / Q000000981:diagnostic imaging*; D002648:Child; D002675:Child, Preschool; D015224:Dideoxynucleosides; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D015224:Dideoxynucleosides; D019275:Radiopharmaceuticals; C002854:alovudine