Grading of supratentorial astrocytic tumors by using the difference of ADC value

To investigate the application value of diffusion-weighted imaging (DWI), the difference of apparent diffusion coefficient (ADC(difference)) value calculated from ADC(difference) map was used, in evaluating the pathologic grade of astrocytic tumors. 33 patients with histopathologically proven supratentorial astrocytic tumors were included in this prospective study. All of them received conventional magnetic resonance imaging (MRI), DWI with diffusion factor of 0 and 50 s/mm(2) and of 0 and 3,000 s/mm(2), and perfusion-weighted imaging (PWI) examinations. Pseudo-color ADC(difference) maps were obtained by means of using ADC map with low b value (0 and 50 s/mm(2)) minus ADC map with high b value (0 and 3,000 s/mm(2)). The highest ADC(difference) value of grades I-II, grade III, and grade IV was (0.91 +/- 0.07) x 10(-3), (1.81 +/- 0.38) x 10(-3), and (2.36 +/- 0.32) x 10(-3) mm(2)/s, respectively, and there was statistical difference among them (p < 0.001). The highest ADC(difference) value between low-grade (grades I-II) and high-grade (grades III-IV) astrocytic tumors showed statistical difference as well (p < 0.001). The highest ADC(difference) value of astrocytic tumors correlated positively with the pathologic grade of tumor (r = 0.853, p < 0.001). Positive correlation was found between the highest ADC(difference) value and maximum relative cerebral blood volume (rCBV) value (r = 0.829, p < 0.001) in high-grade astrocytic tumors; however, the highest ADC(difference) value and maximum rCBV value had no significant correlation in low-grade astrocytic tumors (r = 0.259, p = 0.536). Quantitative analysis of highest ADC(difference) value of supratentorial astrocytic tumors may provide valuable information of tumor microcirculation and perfusion, thus allowing a promising new method for preoperatively assessing the pathologic grade of tumor.