NUCLEUS ACCUMBENS PROJECTIONS: VALIDITY AND RELIABILITY OF FIBER RECONSTRUCTIONS BASED ON HIGHRESOLUTION DIFFUSION-WEIGHTED MRI

• Published in: Clinical neuroradiology (Munich) Vol. 29; no. S1; p. S105
• Main Authors: Rusche, Thilo, Kaufmann, Jorn, Voges, Jurgen
• Format: Journal Article
• Language: English
• Published: Springer 01.09.2019
• Subjects: Drunk driving; Magnetic resonance imaging; Medical research; Medicine, Experimental
• ISSN: 1869-1439

Background: The N. accumbens (NAc) is a key relay in the mesolimbic dopaminergic reward system. As such, it is a promising target for deep brain stimulation (DBS) in patients with psychiatric diseases. In the present study, we aimed to reconstruct the neural projections connecting the NAc with the medial prefrontal cortex (mPFC), the anterior cingulate cortex (ACC), the amygdala, the hippocampus, the dorsomedial thalamus (dmT) and the ventral tegmental area (VTA) using probabilistic fiber tractography based on diffusion-weighted MR-imaging (dMRI). Methods: MR-data (T1-MPRAGE; FLAIR; DWI: 1.6 mm isotropic resolution, 60 gradient directions) for 11 healthy subjects were acquired in seven sessions on a Siemens MAGNETOM Prisma 3T MRI-scanner. For each subject, the bilateral NAc, mPFC, ACC, amygdala, hippocampus, dmT and VTA were manually/automated segmented based on the T1 and FLAIR data and transformed to the session-specific DWI space for probabilistic fiber tractography. The results were subject to detailed visual inspection to assess their validity in terms of anatomical plausibility by comparing them with the relevant literature. To quantitatively assess the reliability of the reconstructions, exemplarily the individual fiber-tracts between the NAc and mPFC for each session and subject were clustered and transformed to a main-tract before performing an intra-subject comparison. Results: Using MRI data from 11 healthy subjects, we were able to reconstruct neural projections connecting the NAc with the mPFC (see figure 1/2), ACC, amygdala, hippocampus, dmT and VTA. Discussion: The connectivity patterns formed by the obtained fibers were in good concordance with the literature (anatomical tracer/fiber-dissection studies). Furthermore, the reliability assessment of the NAc [left and right arrow] mPFC fiber-tracts yielded to high correlations between the obtained main-tracts. Conclusion: We assessed the feasibility and reliability of the in vivo reconstruction of neural fibers connecting the human NAc with the abovementioned target regions from high-resolution dMRI data using probabilistic fiber-tractography. In clinical practice, the presented procedure may guide selective electrical stimulation of the mesolimbic fibers using directional lead technology. Compared to undirected neuromodulation of the entire NAc, this could improve for example the efficacy of DBS for the treatment of mental disorders.