Bradley Neil Delman MD, Presenter: Nothing to Disclose

Cheuk Ying Tang PhD, Abstract Co-Author: Nothing to Disclose

Girish Manohar Fatterpekar MBBS, Abstract Co-Author: Nothing to Disclose

Meng Law MD, Abstract Co-Author: Nothing to Disclose

Thomas P. Naidich MD, Abstract Co-Author: Nothing to Disclose

Many significant brainstem structures are difficult to identify using conventional magnetic resonance (MR) imaging. Earlier work showed that 9.4T MR microscopy (MRM) with intermediate-weighted sequences depicts fine white matter tracts, cranial nerve nuclei, and reticular nuclei (REFs). We hypothesized that use of sequential 9.4T MR microscopy and micro diffusion tensor imaging (MicroDTI) would permit display of the locations and trajectories of fine structures of the brainstem, including the intra-axial segments of cranial nerve fascicles from nuclei to cisterns, and fine fasciculi within the stem.

Six formalin-fixed normal adult human brainstems were scanned on a 9.4T superconducting magnet with 89mm bore and 30mm birdcage coil (Brüker Avance, Brüker Analytik, Rheinstetten, Germany). High-resolution anatomic images were obtained in 3 orthogonal planes (voxel size of 78x78x500µm). DTI was performed in matched planes using a multi-shot echo sequence in 6 directions. Data were processed with DTI Studio v2 (Johns Hopkins Univ., Baltimore, MD) to generate fractional anisotropy, diffusivity, and fiber tract direction-encoded color maps.

Sequential use of MRM and MicroDTI does display the location and direction of very fine white matter structures, beyond what is visualized on routine clinical scanning, including the intra-axial fascicles of cranial nerves III-VIII and IX-XI complex (from their nuclei into cisterns); and fine intrinsic tracts of the bases and tegmentum, such as medial longitudinal fasciculus, medial and lateral lemnisci, and solitary tracts. MicroDTI confirms structure location and provides directional data as fractional anisotropy maps. The hypothesis is proved correct.

MRM and MicroDTI at 9.4T provide anatomic and structural detail of the brain that surpasses conventional MRI techniques. Results may be used to learn high-resolution anatomy of the stem in anticipation of advances in resolution of clinical scanning, ultimately aiding in diagnosis and treatment.

The ability to identify specific tract or nuclei involvement may ultimately aid in diagnosis, and planning of surgical or radiation therapy of patients with brainstem lesions.

Delman, B, Tang, C, Fatterpekar, G, Law, M, Naidich, T, High Resolution MR Microscopy and Micro Diffusion Tensor Imaging of the Human Brainstem at 9.4T: A Postmortem Study..  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5013663.html