A Study On The Value Of DWI, PWI And ～1H-MRS In Differentiating Brain Abscess From Necrotic Or Cystic Glioma And Metastasis

Objective To explore the value of DWI, PWI and [H-MRS in differentiation between brain abscess and necrotic or cystic glioma and metastasis.Methods The conventional MR imaging, and MR imaging with DWI, PWI and multivoxel 2D 'H-MRS were performed in 43 patients (12 patients with abscess and 26 patients with necrotic or cystic glioma and 15 patients with metastasis) before operations or treatments. DWI was performed using single shot SE-EPI sequence with two different b values (0s/mm and 1000s/mm ). PWI was performed using single shot GR-EPI sequence. Multivoxel !H-MRS was performed using PRESS sequence. The values of which measuring or calculating from DWI, PWI and 1H-MRS data were processed and then statistical analyses were performed with one way anova by using the software of SPSS 10.0.Results (1) DWI The cavities (pus) of brain abscesses showed marked hyperintensity in all 12 patients, whereas necrotic or cystic regions of gliomas and metastases demonstrated hypointensity in all 31 patients. The mean minimum ADC value of the cavities of the abscesses (0.52 ±0.12 x10-3 mm2/s) was lower than that of the necrotic or cystic regions of gliomas and metastases(2.90 ± 0.38 X 10-3 mm2/s and 2.53± 0.43X10-3 mm2/s) (P<0.01) . The mean minimum ADC value of the edema regions of the abscesses (1.75 ± 0.16 X 103 mm2/s) was lowerthan that of the peritumoral edema regions of the gliomas (1.28 ± 0.24 X 10-3mm /s) (P<0.01), but was similar with that of the peritumoral edema regions of the metastases (1.80 ± 0.16X 103 mm2/s) (P>0.05).The ADC artificial colour maps could directly reflect all the differences. (2)PWI The maximum rrCBV in the walls of the abscesses (2.55 ± 0.92) was lower than in the bodies of the gliomas and metastases (4.12 ± 0.96 and 4.32 ±1.09) (P<0.01). The maximum rrCBV in the edema regions of the abscesses (0.45 ± 0.20) was lower than in the peritumoral edema regions of gliomas (1.71±0.56) (P<0.01), but was similar with that of the peritumoral edema regions of the metastases (0.23 ± 0.09) (P>0.05). The mean maximum rrMTT was no significant difference between the walls of the abscesses (1.43 ± 0.14) and the bodies of the gliomas and metastases (1.41±0.15 and 1.65 ± 0.25 ) (P>0.05), also was it between the edema regions of the abscesses (1.37 ± 0.13) and peritumoral edema regions of the gliomas and metastases (1.41±0.14 and 1.20 ± 0.18) (P>0.05). The mean maximum rrCBF was lower in the walls of the abscesses (1.78 ± 0.49) than in the bodies of the gliomas and metastases (2.92±1.75 and 2.62±1.31 ) (P<0.01), also was it in the edema regions of the abscesses (0.33 ± 0.23) than the peritumoral edema regions of the gliomas (1.21 ± 0.37) (P<0.01), but no significant difference was found between the edema regions of the abscesses and the peritumoral edema regions of the metastases (0.19 ± 0.08) (P>0.05). The mean maximum P' was lower in the walls of the abscesses (0.47 ± 0.21) than in the bodies of the gliomas and metastases (1.55 ± 0.40 and 1.69 ± 0.57) (P<0.01), also was it in the edema regions of the abscesses (0.03 ± 0.03) than in the peritumoral edema regions of gliomas (0.51±0.17) (P<0.01), but nosignificant difference was found between the edema regions of the abscesses and the peritumoral edema regions of the metastases (0.09 ± 0.14) (P>0.05). The rCBV and rMTT artificial colour maps could directly reflect all the differences. (3)Multivoxel 2D 1H-MRS The amino acide (AA) resonances at 0.9ppm and other amino acides resonances were detected in all brain abscesses, and the succinate and or acetate resonances were also detected in some of brain abscesses, while all necrotic or cystic gliomas and metastases showed no AA resonances at 0.9ppm and other amino acides resonances and the succinate and acetate resonances except Glu resonances in fewer cases. The NAA/Cr ratio in the abscesses (2.49 ± 0.90) was higher than in the necrotic or cystic gliomas and metastases (1.03 ±0.36 and 1.70 ± 0.47) (P<0.01). No significant difference was found on the Cho/Cr ratio between the absc...