Petra Schmalbrock PhD, Presenter: Nothing to Disclose

Donald W Chakeres MD, Abstract Co-Author: Nothing to Disclose

Amir Abduljalil, Abstract Co-Author: Nothing to Disclose

Peter Wassenaar MS, Abstract Co-Author: Nothing to Disclose

Michael R Thompson, Abstract Co-Author: Nothing to Disclose

Michael Vinzenz Knopp MD, PhD, Abstract Co-Author: Nothing to Disclose

To generate high-contrast, high-resolution images of the substantia nigra (SN). Histology using Calbindin staining has shown structural changes on a submillimeter scale between Parkinson’s patients and healthy controls. Our objective here was to assess brainstem contrast at 7T and the feasibility for 3D MRI to define the volume of the normal substantia nigra.

Previous ultrahigh field MRI has demonstrated that the SN can be depicted with exquisite detail on 2D susceptibility-weighted and phase reconstructed image showing similar “flame-like” appears as histology. Four healthy subjects were imaged at 7T using a transmit/receive or an 8-channel SENSE head coil. 3D images were acquired with single or dual echo Inversion Recovery Turbo Field Echo sequences using TR/TE/flip angle 13/2.2 and 11/8o and TI=1550-2800. Reconstructed voxel sizes ranged from 0.43x0.43x0.8 to 0.22x0.22x1.5mm. For comparison, 2D susceptibility weighted images were acquired with a gradient echo sequence with TR/TE/flip angle of 600/12/55o (FOV24x18cm, 1024x576 matrix, 2mm slice thickness, skip 0.2mm, reconstructed voxel 0.23x0.23x2.0).

On short TE images, the SN and red nucleus appeared bright compared to surrounding tissue. Excellent depiction of the SN as low signal structures was achieved with all long TE 3D sequences. Especially for high in-plane resolution, the spatial relation between vascular structures and the SN were depicted with exquisite detail. Whereas the SN was seen only on 2 slices with the 2D sequence, it could be seen in up to 6 slices in the 3D images. Both the transmit/receive and an 8-channel SENSE head coil had sufficient B1 homogeneity and inferior reach to allow for assessment of the brainstem.

Three-dimensional susceptibility weighted imaging of the SN is feasible at 7T, and provides more detailed structural information than 2D. Further studies are needed to explain the unexpected bright appearance, possibly a T1 effect, of the SN on the short TE images.

Three-dimensional ultrahigh MRI may become a novel tool for non-invasive assessment of Parkinson’s patients.

Schmalbrock, P, Chakeres, D, Abduljalil, A, Wassenaar, P, Thompson, M, Knopp, M, T2-weighted High Resolution 3D Imaging of the Substantia Nigra at 7T.  Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL. http://archive.rsna.org/2006/4437659.html