***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Objective : To assess the value of spectroscopic and perfusion MRI for glioma grading and for distinguishing glioblastomas from metastases and from CNS lymphomas . Methods : The authors examined 79 consecutive patients with first detection of a brain neoplasm on nonenhanced CT scans and no therapy prior to evaluation .  Spectroscopic MRI ; arterial spin-labeling MRI for measuring cerebral blood flow ( CBF ) ; first-pass dynamic , susceptibility-weighted , contrast-enhanced MRI for measuring cerebral blood volume ; and T1-weighted dynamic contrast-enhanced MRI were performed . Receiver operating characteristic analysis was performed , and optimum thresholds for tumor classification and glioma grading were determined . Results : Perfusion MRI had a higher diagnostic performance than spectroscopic MRI . Because of a significantly higher tumor blood flow in glioblastomas compared with CNS lymphomas , a threshold value of 1.2 for CBF provided sensitivity of 97 % , specificity of 80 % , positive predictive value ( PPV ) of 94 % , and negative predictive value ( NPV ) of 89 % . Because CBF was significantly higher in peritumoral nonenhancing T2-hyperintense regions of glioblastomas compared with metastases , a threshold value of 0.5 for CBF provided sensitivity , specificity , PPV , and NPV of 100 % , 71 % , 94 % , and 100 % . Glioblastomas had the highest tumor blood flow values among all other glioma grade s. For discrimination of glioblastomas from grade 3 gliomas , sensitivity was 97 % , specificity was 50 % , PPV was 84 % , and NPV was 86 % ( CBF threshold value of 1.4 ) , and for discrimination of glioblastomas from grade 2 gliomas , sensitivity was 94 % , specificity was 78 % , PPV was 94 % , and NPV was 78 % ( CBF threshold value of 1.6 ) . Conclusion : Perfusion MRI is predictive in distinguishing glioblastomas from metastases , CNS lymphomas and other gliomas vs. MRI and magnetic resonance spectroscopy Background The treatment goal for recurrent malignant gliomas centers on disease stabilization while minimizing therapy-related side effects . Metronomic dosing of cytotoxic chemotherapy has emerged as a promising option to achieve this objective . Methods This phase I study was performed using metronomic temozolomide ( mTMZ ) at 25 or 50 mg/m2/day continuously in 42-day cycles . Correlative studies were incorporated using arterial spin labeling MRI to assess tumor blood flow , analysis of matrix metalloproteinase-2 ( MMP-2 ) and MMP-9 activities in the cerebrospinal fluid ( CSF ) as surrogates for tumor angiogenesis and invasion , as well as determination of CSF soluble interleukin-2 receptor alpha ( sIL-2Rα ) levels as a marker of immune modulation . Results Nine subjects were enrolled and toxicity consisted of primarily grade 1 or 2 hematological and gastrointestinal side effects ; only one patient had a grade 3 elevated liver enzyme level that was reversible  . Tumor blood flow was variable across subjects and time , with two experiencing a transient increase before a decrease to below baseline level while one exhibited a gradual drop in blood flow over time . MMP-2 activity correlated with overall survival but not with progression free survival , while MMP-9 activity did not correlate with either outcome parameters . Baseline CSF sIL-2Rα level was inversely correlated with time from initial diagnosis to first progression , suggesting that subjects with higher sIL-2Rα may have more aggressive disease . But they lived longer when treated with mTMZ , probably due to drug-related changes in T-cell constituency . Conclusions mTMZ possesses efficacy against recurrent malignant gliomas by altering blood flow , slowing invasion and modulating antitumor immune function BACKGROUND AND PURPOSE : The purpose of this study was to determine whether qualitative and quantitative measures obtained with pulsed arterial spin-labeling ( PASL ) and apparent diffusion coefficients ( ADC ) improve glioma grading compared with conventional MR images . MATERIAL S AND METHODS : We prospect ively performed 2 qualitative consensus review s in 33 suspected gliomas : 1 )  conventional MR images alone and 2 )  conventional MR images with PASL and ADC . To calculate the diagnostic performance parameters of PASL and ADC , we used a qualitative scoring system on the basis of the  tumor perfusion signal intensity  ( sTP ) and visual ADC scoring ( sADC ) . We then analyzed quantitative regions of interest and calculated the ratio of the maximum tumor perfusion signal intensity ( rTPmax ) and the minimum ADC value ( mADC ) . RESULTS : Two observers diagnosed accurate tumor grade s in 23 of 33 ( 70 % ) lesions in the first review and in 29 of 33 ( 88 % ) lesions in the second review . The sensitivity , specificity , positive predictive value ( PPV ) , and negative predictive value ( NPV ) for determining a glioma grading by using combined sTP and sADC scoring were 90.9 , 90.9 , 95.2 , and 83.3 % , respectively . Statistical analysis gave a threshold value of 1.24 for rTPmax and 0.98 × 10–3 mm/s2 for mADC to provide a sensitivity , specificity , PPV , and NPV of 95.5 , 81.8 , 91.3 , and 90.1 % and 90.9 , 81.8 , 90.9 , and 81.8 % , respectively . The receiver operator characteristic curve analyses showed no significant difference between the quantitative and combined qualitative parameters . CONCLUSION : PASL and ADC significantly improve the diagnostic accuracy of glioma grading compared with conventional imaging 
    Output:
    
The absolute tumour blood flow ( TBF ) values can differentiate high- grade gliomas ( HGGs ) from low- grade gliomas ( LGGs ) and grade II from grade IV tumours .
However , it lacked the capacity to differentiate grade II from grade III tumours and grade III from grade IV tumours .
In contrast , the relative TBF ( rTBF ) is effective in differentiating HGG from LGG and in glioma grading .
The maximum rTBF ( rTBFmax ) demonstrated the best results in glioma grading .
Sensitivity and specificity analysis replicate these results as well .
This meta- analysis suggests that ASL is useful for glioma grading , especially when considering the rTBFmax parameter