Combined Role Of Conventional And Diffusion Weighted MRI In The Differential Diagnosis Of Intracranial Rim Enhancing Lesions

Background and PurposeThe differentiation of rim enhancing abscess with atypical diffusion weightedimaging from rim enhancing high grade necrotic tumors with typical diffusionweighted imaging and vice a versa is difficult. Our purpose was to compare differentMRI findings, diffusion weighted imaging together with conventional MRI, of rimenhancing intracranial lesions to differentiate the etiologies.Methods:51patients,32male and19female，mean age of48.47years with58with rimenhancing intracranial lesions in MR, who underwent surgery in year2012, werestudied for different MR characteristics of the lesion including both conventional anddiffusion weighted imaging and pathologically correlated the observed findings.Diagnostic accuracy of statistically significant qualitative variables were tested bysensitivity, specificity, positive predictive value, negative predictive value and that ofquantitative variables were tested by area under the ROC curve.Results:Out of58rim enhancing lesions21were primary,18Abscess,14Secondary and5NCC.20lesions had restricted diffusion in center,22lesions with thin smooth rimand23lesions with low T2complete rim. Sensitivity and Specificity of restricteddiffusion at the non-enhancing center in differentiating abscess from non–abscess rimenhancing lesions are respectively88.89%and90.24%with p <0.0001. At cut offpoint of1.09, Sensitivity and specificity of core to white mater ADC ratio indifferentiating abscess from non-abscess rim enhancing lesions are88.9%and90%respectively, with p <0.0001. Sensitivity and Specificity of uniform thin smooth rimin differentiating abscess from non–abscess rim enhancing lesions are respectively83.33%and80.49%with p value <0.0001and that of hypointense T2complete rim88.89%and75.61%respectively with p value <0.0001. At cutoff point of2.17,Edema to White mater ADC ratio has sensitivity of77.8%and specificity of61.5%indifferentiating abscess from non-abscess rim enhancing lesions with p=0.004andarea under ROC curve being0.719. When combining restricted diffusion at non-enhancing center and thin smooth rim enhancement, the sensitivity and specificity of combined parameter in differentiating abscess from non-abscess rim enhancinglesions are72.22%and100%, which was highly specific.ConclusionOn studying the different MRI characteristics of Rim enhancing lesions, combinedapproach of enhanced rim characteristic with DWI is more helpful in coming to theproper diagnosis rather than relying just on DWI.