Quantitative and reproducibility study of four tractography algorithms used in clinical routine

Abstract

Purpose: To evaluate fiber tracking strategy in terms of acquisition schemes in conjunction with four algorithms used in clinical routine, we studied one of the major tracts, anatomically well known, and which should be preserved as much as possible during neurosurgery: the corticospinal tract. Materials and Methods: Two identical exams, composed of three DTI acquisition schemes (6, 15, and 32 gradient directions), were performed on 12 healthy subjects during two different sessions. For each subject, intra-operator, and inter-exam reproducibility was quantitatively calculated from different fiber tracking algorithms: three deterministic and a probabilistic one. Inter-exam reproducibility was evaluated comparing fiber tracking results from the repetition of the same acquisition one month apart and variation of the fiber density distribution percentile. Results: For each fiber tracking algorithm, the best reproducibility result is obtained in case of 50% of fiber density and for the number of directions equal to 32. The reproducibility is improved using the probabilistic algorithm. Conclusion: This study highlights increased reliability of reproducibility results based on the number of directions used during the acquisition. The method of tractography used and the choice of adequate density fiber tract greatly improve the results. © 2011 Wiley-Liss, Inc.