Estimation of proliferative potentiality of central neurocytoma: Correlational analysis of minimum ADC and maximum SUV with MIB-1 labeling index

Background: Central neurocytoma was initially believed to be benign tumor type, although atypical cases with more aggressive behavior have been reported. Preoperative estimation for proliferating activity of central neurocytoma is one of the most important considerations for determining tumor management. Purpose: To investigate predictive values of image characteristics and quantitative measurements of minimum apparent diffusion coefficient (ADCmin) and maximum standardized uptake value (SUVmax) for proliferative activity of central neurocytoma measured by MIB-1 labeling index (LI). Material and Methods: Twelve cases of central neurocytoma including one recurrence from January 2001 to December 2011 were included. Preoperative scans were conducted in 11, nine, and five patients for computed tomography (CT), diffusion-weighted imaging (DWI), and fluorine-18-fluorodeoxyglucose positron emission tomography (FDGPET), respectively, and ADCmin and SUVmax of the tumors were measured. Image characteristics were investigated using CT, T2-weighted (T2W) imaging and contrast-enhanced T1-weighted (T1W) imaging, and their differences were examined using the Fisher's exact test between cases with MIB-1 LI below and above 2%, which is recognized as typical and atypical central neurocytoma, respectively. Correlational analysis was conducted for ADCmin and SUVmax with MIB-1 LI. A P value <0.05 was considered significant. Results: Morphological appearances had large variety, and there was no significant correlation with MIB-1 LI except a tendency that strong enhancement was observed in central neurocytomas with higher MIB-1 LI (P=0.061). High linearity with MIB-1 LI was observed in ADCmin and SUVmax (r=-0.91 and 0.74, respectively), but only ADCmin was statistically significant (P=0.0006). Conclusion: Central neurocytoma had a wide variety of image appearance, and assessment of proliferative potential was considered difficult only by morphological aspects. ADCmin was recognized as a potential marker for differentiation of atypical central neurocytomas from the typical ones.