Diffusion tensor tractography of the temporal stem

Abstract

Objective To define the three-dimensional relationship of the uncinate fasciculus,anterior commissure, inferior occipitofrontal fasciculus, and optic radiation, to determine the positioning landmarks of these white matter tracts by using the diffusion tensor tractography (DTT). Methods The anatomy was studied in 10 adult human brain specimens (20 hemispheres). DTT of the brain was performed on 10 healthy volunteers. DTT of the white matter tracts in the temporal stem was performed by using of the simple one regions-of-interest (ROI) and muhiple-ROl based on the anatomic knowledge and conventional magnetic resonance imaging (MRI). Results The inferior limiting sulcus averaged (46.3 ± 3.1)mm in length. The shortest distance from the inferior limiting sulcus to the superior floor of the temporal horn averaged (6.5 ± 1.8)mm. The posteroinferior insular point was the anterior extremity of intersection of the Heschl's gyrus and the inferior limiting sulcns. On the inferior limiting sulcns, this point was the posterior border of the optic radiation, and the temporal stem begined at the limen insulae and ended at the posteroinferior insular point. Its length averaged (33.0 ± 2. 9) mm. The distance from the limen insulae to the tip of the temporal horn averaged(10.9 ± 1.7)mm is just one thirds of the length of the temporal stem.The uncinate fasciculus and anterior commissure made up the core of the anterior temporal stem, with the anterior commissure located psoteriorly, and they occupied the anterior one third of the temporal stem together. The inferior occipitofrontal fasciculus passed through the entire temporal stem. The most anterior extension of Meyer's loop was located between the anterior tip of the temporal horn and the limen insulea.However, Most of the optic radiation crossed the postmedian two thirds of the temporal stem. Conclusion On the inferior limiting sulcus, the posteroinferior insular point is a reliable landmark of the posterior border of the optic radiations. The limen insulae, anterior tip of the temporal horn, and posteroinferior insular point may be used to localize the white matter fibers of the temporal stem in analyzing MR imaging or during surgery. Key words: Brain; Magnetic resonance imaging; Anatomy