[11C]-l-Methionine positron emission tomography in the management of children and young adults with brain tumors

Only a few Methyl-[11C]-l-methionine (MET) positron emission tomography (PET) studies have focused on children and young adults with brain neoplasm. Due to radiation exposure, long scan acquisition time, and the need for sedation in young children MET-PET studies should be restricted to this group of patients when a decision for further therapy is not possible from routine diagnostic procedures alone, e.g., structural imaging. We investigated the diagnostic accuracy of MET-PET for the differentiation between tumorous and non-tumorous lesions in this group of patients. Forty eight MET-PET scans from 39 patients aged from 2 to 21 years (mean 15 ± 5.0 years) were analyzed. The MET tumor-uptake relative to a corresponding control region was calculated. A receiver operating characteristic (ROC) was performed to determine the MET-uptake value that best distinguishes tumorous from non-tumorous brain lesions. A differentiation between tumorous (n = 39) and non-tumorous brain lesions (n = 9) was possible at a threshold of 1.48 of relative MET-uptake with a sensitivity of 83% and a specificity of 92%, respectively. A differentiation between high grade malignant lesions (mean MET-uptake = 2.00 ± 0.46) and low grade tumors (mean MET-uptake = 1.84 ± 0.31) was not possible. There was a significant difference in MET-uptake between the histologically homogeneous subgroups of astrocytoma WHO grade II and anaplastic astrocytoma WHO grade III (P = 0.02). MET-PET might be a useful tool to differentiate tumorous from non-tumorous lesions in children and young adults when a decision for further therapy is difficult or impossible from routine structural imaging procedures alone

Optimizing the application method of entomopathogenic nematode suspension for biological control of large pine weevil Hylobius abietis

Entomopathogenic nematodes (EPNs) are effective against the immature stages of the large pine weevil Hylobius abietis. In three field trials we compared the efficacy of the application method of EPN for weevil suppression below the suggested threshold of 20 weevils per stump: applying the EPN suspension in the top edges of the stumps (‘top’) vs. drenching the soil around stumps (‘standard’). For Steinernema carpocapsae, weevil suppression was below the targeted threshold only when suspension was applied in the standard way (two of the three sites). On the other hand, weevil suppression was provided in all three cases of ‘top’ application of Heterorhabditis downesi suspension, whereas suppression in ‘standard’ application was observed in one site. Percentage parasitism of developing weevils in relation to depth and distance help explain EPN movement post-application. Weevil suppression relative to suggested thresholds can be improved by altering the method of EPN application depending on the nematode species