Review Article

The Clinical Value of PET with Amino Acid Tracers for Gliomas WHO Grade II

Table 1

Clinical applications of PET with amino acid tracers in adult low-grade gliomas (LGGs).

StudyStudy designTumor subtype1 no. of patientsResults and/or conclusion

Differential diagnosis tumor versus nontumor lesions

Herholz et al. [60]Retrospective review Consecutive suspected tumors Measures: MET ratio, histology196 patients (99 gliomas grade II)MET ratio 67% sensitivity and 72% specificity for differential diagnosis grade II gliomas versus nontumor lesions
Galldiks et al. [61]Consecutive series of children and young adults (2–21 year) with suspected tumors Measures: MET ratio, histology39 patients (6 AI, 6 AII, 4 AIII, 2 OAIII)MET ratio 83% sensitivity & 92% specificity for differential diagnosis tumor versus nontumor lesions
Pichler et al. [62]Retrospective review Consecutive tumors or other intracerebral lesions Measures: FET ratio, MRI, histology88 patients (19 gliomas grade I and grade II)FET ratio 94% sensitivity in HGG; 68% sensitivity in LGGs; 2 false positive cases (postischemic lesions) out of 10 nonbiopsy verified inflammatory lesions

Guiding stereotactic procedures and radiotherapy planning

Goldman et al. [37]Retrospective review Measures: MET ratio, FDG ratio, stereotactic guided histology14 gliomas (93 biopsies)MET ratio correlates with anaplasia; FDG ratio correlates with anaplasia; inverse correlation MET ratio and necrosis; no correlation FDG ratio and necrosis
Levivier et al. [30]Retrospective review PET-guided radiosurgery Measures: MET volume, MRI5 LGGsSpatial accuracy increased by MET volume, especially in ill-defined lesions on MRI
Nuutinen et al. [63]Prospective long-term followup Measures: MET ratio, MET volume, MRI, survival14 gliomas (13 AII and 1 AIII)MET ratio and volume: 80% sensitivity in detecting postoperative residual tumor; benefit for radiotherapy planning in 3/14 patients with inconclusive MRI
Pirotte et al. [64]Retrospective review PET-guided stereotactic biopsy Measures: MET ratio, MET volume, FDG ratio, FDG volume, histology10 LGGs (6 AII, 2 OII, 1 giant cell astrocytoma, 1 ganglioglioma)MET ratio corresponded to histology in 9 LGGs; FDG ratio corresponded to histology in 1 LGGs; MET volume superior to FDG volume, especially for cortical tumors

Evaluation of response to radiotherapy

Roelcke et al. [65]Postoperative followup of irradiated (n = 13) and nonirradiated (n = 17) patients Measures: MET ratio, FDG ratio30 AIINo differences in changes of MET and FDG ratio over time between two groups
Voges et al. [66]Followup of 125I brachytherapy Measures: FDG ratio and volume, MET ratio, and volume39 gliomas (17 AII, 2 OII, 5 OAII, 1 AI, 2 unspecified, 3 grade III, 8 GB)Minimal effect of brachytherapy on FGD ratio1 year after seed implantation, but decline of MET ratio
Würker et al. [67]Follow up of 125I brachytherapy Measures: FDG ratio, MET ratio10 LGGs (2 AI, 5 AII, 2  OAII, 1 OII)Significant decline in mean MET ratio before and 1 year after brachytherapy; no changes in mean FDG ratio; highest decline rates in tumors with high basal MET ratio

1Abbreviations: LGGs: low-grade gliomas; AI: pilocytic astrocytoma; AII: astrocytoma grade II; OII: oligodendroglioma grade II; OAII: oligoastrocytoma grade II; AIII: astrocytoma grade III; OAIII: oligoastrocytoma grade III; GB: glioblastoma.