The Apparent Diffusion Coefficient in Glial Tumors

Abstract

Background: Diffusion-Weighted Imaging (DWI) is one of the fast developing techniques in the field of MRI. This method uses the random diffusion motion of water molecule depending on physiological and anatomical characteristics of living organisms. Aim: To calculate the apparent diffusion coefficient and diffusion values in order to determine the degree in the glial tumors. Patients and methods: In the study, cases were selected among those who presented with a diagnosis of intracranial mass to Neurosurgery Department of Erciyes University, Medicine School. Overall, 20 patients were included to the study: 7 patients with Glioblastoma Multiforme (GBM), 4 patients with anaplastic astrocytoma (AA), 4 patients with diffuse astrocytoma, 3 patients with ependymoma and 2 patients with low-grade astrocytoma. The apparent diffusion coefficient (ADC) images were acquired from echo-planar diffusion-weighted images (DWIs). For each tumor, the mean ADC values and the mean diffusion value were measured at a large region of interest (ROI) defined within tumor and at symmetrical normal brain tissue. Statistical analyses were performed by using SPSS 15.0 Statistical Package Program. Results: We calculated mean ADC values (2.91 × 10-3 mm2/s, 0.69 × 10-3 mm2/s, 3.13 × 10-3 mm2/s, 2.41 × 10-3 mm2/s and 0.70 × 10-3 mm2/s) and mean diffusion values (0.11 × 10-3 mm2/s, 1.6 × 10-3 mm2/s, 0.10 × 10-3 mm2/s, 1.58 × 10-3 mm2/s, 0.90 × 10-3 mm2/s) for GBM, AA, diffuse astrocytoma, low degree astrocytoma and ependymoma, respectively. The diffusion value of normal brain was calculated to be 0.85 × 10-3 mm2/s. A P-value <0.05 was considered statistically significant. We estimated a significant difference between GBM and AA (p=0.001). Although there were marked differences among diffuse astrocytomas, low degree astrocytoma and ependymoma, the difference did not reach statistical significance. Conclusion: The mean ADC value, the mean diffusion value and intensity region may provide additional information in determining tumor degree in malignant glial tumors.