Table 1.
Clinical applications of PET with amino acid tracers in adult low-grade gliomas (LGGs).
| Study | Study design | Tumor subtype1 no. of patients | Results and/or conclusion |
|---|---|---|---|
| Differential diagnosis tumor versus nontumor lesions | |||
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| |||
| Herholz et al. [60] | Retrospective review Consecutive suspected tumors Measures: MET ratio, histology | 196 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, histology | 39 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, histology | 88 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 |
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| Guiding stereotactic procedures and radiotherapy planning | |||
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| Goldman et al. [37] | Retrospective review Measures: MET ratio, FDG ratio, stereotactic guided histology | 14 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, MRI | 5 LGGs | Spatial 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, survival | 14 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, histology | 10 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 |
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| Evaluation of response to radiotherapy | |||
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| Roelcke et al. [65] | Postoperative followup of irradiated (n = 13) and nonirradiated (n = 17) patients Measures: MET ratio, FDG ratio | 30 AII | No 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 volume | 39 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 ratio | 10 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.