DTI Research Projects in Image-Guided Therapy

Lauren O’Donnell

SFN Chicago Oct. 09 Defining Spatial Relationships Between fMRI and Fiber Tracts

Neurosurgical Planning for White Matter

• Tumor mass effect displaces– Gray matter (GM)– White matter (WM)

• Tracts are not visible during surgery– Electrocortical stimulation for GM not WM

• Healthy WM and tumor may have same “jello-like” consistency

• To preserve function– Avoid crucial tracts– Incision and trajectory planning

• Challenges in DTI Tractography for IGT– Displacement complicates tract

selection/identification– Edema may interrupt tract tracing– Anatomy not completely traced by single tensor

Fiducial Tractography: Slicer• Fiducial:

– Movable seed point

• Interactive Probing of Fiber Bundles– Peritumoral

Fibers

• fMRI Display in Context with Structural and Diffusion Volumes

Image by JJ. Lemaire. Fiducial Tractography by A. Yarmarkovitch

Slide courtesy R. Kikinis

Open IGT Link: Slicer3 in OR• December 2007: Concept• January 2008: Prototype and

Name• July 2008: BrainLab VVLink

with Yale (Papademetrios)• December 2008: Real Time

MR Control• February 11, 2009: Initial

Clinical Application with Dr. Alex Golby

• Multi-Site Collaboration coordinated by NCIGT (Jolesz, Hata et al)

Golby, Hata, Liu, Tokada, Ibanez, Papademetrios

Slide courtesy R. Kikinis

2-Tensor Tractography• Crossing fibers exist

– i.e. Corpus callosum connects to frontal/temporal/parietal/occipital

• Peled’s model: 2 tensors in a plane– Resolving crossings in the corticospinal tract

by two-tensor streamline tractography: Method and clinical assessment using fMRI. Arish A. Qazi, Alireza Radmanesh, Lauren O'Donnell, Gordon Kindlmann, Sharon Peled, Stephen Whalen, Carl-Fredrik Westin and Alexandra J. Golby. NeuroImage 47(supplement 2):T98-T106, 2009

• Kalman filtered tractography– James Malcolm and

Yogesh Rathi (BWH)– Python implementation

project this week

O’Donnell et. al. Defining Spatial Relationships Between fMRI and Fiber Tracts. MICCAI Diffusion Workshop 2009

DTI+fMRI Atlas Project: Identify displaced tracts

• Proposed model• fMRI-fiber distances

O’Donnell et. al. Defining Spatial Relationships Between fMRI and Fiber Tracts. MICCAI Diffusion Workshop 2009

DTI+fMRI Atlas Project: Leave-One-Out Model Predictions