Diffusion tensor MR imaging of cerebral gliomas: evaluating fractional anisotropy characteristics

FA correlation to glioma tumor grade has been mixed if not disappointing. There are several potential underlying fundamental issues that have contributed to these results. In an attempt to overcome these past shortfalls, we evaluated characteristics of FA of the solid tissue components of gliomas, including whether high-grade gliomas have a greater variation of FA than low-grade gliomas.

Thirty-four patients with gliomas (9 grade II, 8 grade III, and 17 grade IV) underwent diffusion tensor imaging at 3T. Mean FA, maximum FA, and minimum FA values were measured within the solid tissue components of the tumors. The variations of FA were evaluated by determining the range of FA values and the maximum SDs of FA. The variations of FA values among different tumor grades were compared statistically. We also correlated FA variations with minimum FA and maximum FA.

The maximum FA, FA range, and maximum SD for grade II tumors were significantly lower than those for grade III and IV tumors (P < .0001 ∼ P = .0164). A very good correlation of maximum FA to FA range (r = 0.931) and maximum SD (r = 0.889) was observed.

The FA range and maximum SD appear useful for differentiating low- and high-grade gliomas. This analysis added value to the findings on conventional MR imaging. In addition, focal maximum FA is a key factor contributing to the larger FA variation within high-grade gliomas.