ABSTRACT
Objective To evaluate the diagnostic values of diffusion weighted MRI(DWI)and contrast-enhanced magnetic resonance imaging(CE-MRI)using gadolinium chelates in patients with brain abscesses.Methods Conventional TlWI,T2WI,fluid attenuated inversion recovery(FLAIR),DWI and gadolinium-enhanced MRI were performed in 49 patients with single cystic/solid brain lesions.Retrospective analysis of the DWI signals and enhancement characteristics of patients with brain abscesses(n=22)and with cystic/necrotic brain tumors(n=27)was performed; meanwhile,measurement of the ADC values of the necrotic areas was performed.DWI combined with conventional sequences (group Ⅰ),CE-MRI combined with conventional sequences(group Ⅱ),and DWI,CE-MRI and conventional sequences(group Ⅲ)were employed to calculate their sensitivity,specificity,positive predictive value,negative predictive value and accuracy; these results were compared with the pathological results.Results The high DWI signal was noted in 20 patients with brain abscesses,and low DWI signal in 24 patients with cystic/necrotic brain tumors.Evenly thin walls and a ring enhancement under enhanced scan were noted in 14 patients with abscesses and 12 patients with cystic/necrotic brain tumors.Most of the ADC values in patients with brain abscesses were significantly lower than those in patients with cystic/necrotic brain tumors(P＜0.05).The diagnostic sensitivity to brain abscess in group I,group Ⅱ and group Ⅲ were 90.9％,63.6％ and 95.5％,respectively; the difference was statistically significant between group Ⅰ and group Ⅱ(P＜0.05),and between group Ⅱ and group Ⅲ(P＜0.05),but not between group Ⅰ and group Ⅲ(P＞0.05).Conclusion DWI is more sensitive in detecting the brain abscess than CE-MRI,and the measurement of ADC values can provide valuable differential diagnostic information for patients with brain abscess and cystic/necrotic brain tumor.