Objective: To investigate the efficacy of Signal Intensity Ratio (SIR) measurements of T2-weighted imaging (T2WI) and Apparent Diffusion Coefficient (ADC) values of ADC mapping in the differentiation of schwannomas and meningiomas originating from the CPA.
Materials and Methods: A total of 30 patients who were pathologically diagnosed (16 meningiomas, 14 VS) were included in this retrospective study. SIR was calculated by proportioning regions of interests (ROIs) measurements of solid regions of the tumor and occipital subcutaneous adipose tissue in T2WI. In ADC maps, ADCmin and ADCmean values were obtained by placing ROIs inside the solid parts of the tumor. Groups were statistically analyzed using the Mann-Whitney U test, independent-sample t-test, receiver operating characteristic (ROC) curve analyses, and Pearson correlation test.
Results: SIR, ADCmean, and ADCmin values were 0.61±0.08, 0.858±0.101x103 mm2/s, 0.815±0.099x103 mm2/s for meningioma group; and 0.80±0.12, 1.272±0.148x103 mm2/s, 1.232±0.148x103 mm2/s for VS group, respectively. These parameters were statistically lower in the meningioma group compared to the VS group (p<0.001 for all). A positive correlation was observed between SIR and ADC values among the total group (r=0.694, p<0.001 for both). ROC analysis showed that the diagnostic performance of ADC parameters was better than the SIR parameter in differentiating meningioma from VS. The cut-off values in differentiating meningioma and VS were determined as 1.027x103 mm2/s for ADCmean and 0.980x103 mm2/s for ADCmin with 100% sensitivity.
Conclusion: While both ADC and SIR values are useful in differentiating between VS and meningioma, ADC values have higher diagnostic efficacy compared to SIR.