TABLE 1.
Summary of selected studies on imaging approaches for distinguishing brain tumors from neuroinflammation
| Technique | Main findings | References |
|---|---|---|
| Proton MR spectroscopic imaging | Higher levels of choline are associated with GBM tumor progression or recurrence, whereas low levels of choline indicate necrotic tissue | [31, 42] |
| The analysis of increased ratios of choline content in relation to other chemicals can separate tumors from necrosis with an accuracy of up to 97% | ||
| Conventional MRI with the T1/T2 mismatch criterion | Differentiates tumors from neuroinflammation with a specificity of 75% and a sensitivity of 44% | [45] |
| PET scan | Differentiates tumors from neuroinflammation with a specificity of 69% and a sensitivity of 92% and is superior to NMR spectroscopy for choline/N‐acetylaspartate and choline/creatine ratios across different thresholds | [45] |
| T2*‐weighted dynamic susceptibility‐weighted contrast material‐enhanced MRI | Mean, maximum and minimum relative peak height and relative cerebral blood volume were significantly higher in GBM compared to radiation‐induced necrosis in a retrospective study (n = 57 patients) | [46] |
| Mean, maximum and minimum relative percentage of signal intensity recovery values were significantly lower in recurrent GBM compared to radiation necrosis | ||
| Proton MR spectroscopy | Increase in choline levels in patients with necrosis (4 of 9 cases) | [47] |
| Proton MR spectroscopy | Increased lactate/creatine and phosphocreatine ratio and decreased choline /phosphocreatine ratio compared, or reductions in all major metabolites, to recurrent GBM patients (n = 11) with radiation necrosis | [48] |
| MR spectroscopy and MR perfusion using choline/N‐acetylaspartate and choline/phosphocreatine ratios and rCBV | Enhanced ability to differentiate necrosis from recurrent GBM in meta‐analysis of 13 studies involving 397 patients | [49] |
| 11C‐choline PET | Good ability to differentiate GBM relapse from radiation necrosis in meta‐analysis of 6 studies involving 118 patients | [50] |
| MRI, F18‐fluorodeoxyglucose and 11C‐choline PET/CT | 11C‐choline PET/CT is superior in differentiating GBM recurrence from necrosis (n = 55) | [51] |
| (11)C‐methionine‐PET was superior to both (11)C‐choline and F18‐fluorodeoxyglucose‐PET | (11)C‐methionine‐PET is superior to (11)C‐choline or F18‐fluorodeoxyglucose‐PET for distinguishing GBM recurrence from necrosis (n = 50) | [52] |
| F18‐fluorodeoxyglucose and [18F]fluoro‐ethyl‐tyrosine PET | PET were effective in discriminating GBM from radiation necrosis, with F18‐fluorodeoxyglucose delayed PET is particularly useful in discriminating GBM tumors from radiation necrosis in an orthotopic rat model of GBM | [34] |
| [18F]‐2‐fluoroethyl‐L‐phenylalanine PET | LAT1 tumor‐specific PET tracer 2‐[18F]‐2‐fluoroethyl‐L‐phenylalanine PET is able to differentiate GBM from radiation necrosis and shows less contamination by inflammation compared to F18‐fluorodeoxyglucose signals | [35] |
Abbreviations: MR = magnetic resonance; GBM = glioblastoma; MRI = magnetic resonance imaging; PET = positron emission tomography; NMR = nuclear magnetic resonance; rCBV = relative cerebral blood volume; CT = computerized tomography; LAT1 = L‐type amino acid transporter 1.