Bidirectional iterative parcellation of diffusion weighted imaging data: Separating cortical regions connected by the arcuate fasciculus and extreme capsule

• Published in: NeuroImage (Orlando, Fla.) Fla.), 2014-11, Vol.102 (2), p.704-716
• Main Authors: Patterson, Dianne K., Van Petten, Cyma, Beeson, Pélagie M., Rapcsak, Steven Z., Plante, Elena
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Algorithms; Arcuate fasciculus; Biological and medical sciences; Brain; Cerebral Cortex - anatomy & histology; Diffusion; Diffusion Magnetic Resonance Imaging; Diffusion-weighted imaging; Extreme capsule; Female; Fundamental and applied biological sciences. Psychology; Humans; Language; Laterality; Male; Middle Aged; Nerve Net - anatomy & histology; Parcellation; Seeds; Superior longitudinal fasciculus; Vertebrates: nervous system and sense organs; Young Adult
• ISSN: 1053-8119; 1095-9572; 1095-9572
• DOI: 10.1016/j.neuroimage.2014.08.032

This paper introduces a Bidirectional Iterative Parcellation (BIP) procedure designed to identify the location and size of connected cortical regions (parcellations) at both ends of a white matter tract in diffusion weighted images. The procedure applies the FSL option “probabilistic tracking with classification targets” in a bidirectional and iterative manner. To assess the utility of BIP, we applied the procedure to the problem of parcellating a limited set of well-established gray matter seed regions associated with the dorsal (arcuate fasciculus/superior longitudinal fasciculus) and ventral (extreme capsule fiber system) white matter tracts in the language networks of 97 participants. These left hemisphere seed regions and the two white matter tracts, along with their right hemisphere homologues, provided an excellent test case for BIP because the resulting parcellations overlap and their connectivity via the arcuate fasciculi and extreme capsule fiber systems are well studied. The procedure yielded both confirmatory and novel findings. Specifically, BIP confirmed that each tract connects within the seed regions in unique, but expected ways. Novel findings included increasingly left-lateralized parcellations associated with the arcuate fasciculus/superior longitudinal fasciculus as a function of age and education. These results demonstrate that BIP is an easily implemented technique that successfully confirmed cortical connectivity patterns predicted in the literature, and has the potential to provide new insights regarding the architecture of the brain. •We present a novel procedure, bidirectional iterative parcellation (BIP).•BIP isolates cortical regions by connectivity at both ends of a tract.•BIP identified expected connectivity for the arcuate and extreme capsule.•BIP identified differences in lateralization related to demographic factors.