Anatomic and FunctionalGuidance of Neurosurgery.

Robert L. Galloway Jr.Associate Professor of Biomedical

Engineering and NeurosurgeryDirector, Center for Technology-

Guided Therapy

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Technology-Guided Therapy

The use of technology to improve the spatial and temporal specificity of the

delivery of therapy

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Technology -Guided Therapy• Pre-therapeutic data (images, population

data, therapy plan…)

• Registration methodology (matching pre-therapeutic data to specific patient in specific position)

• Intraoperative guidance and data collection.

• Display of position, plan, anatomy, function and disease.

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History of Image-Guided Therapy

• 1896 J.H. Clayton. X-Ray use in surgery

• 1904 Horsley and Clarke. Stereotactic frame

• 1946 Spiegel and Wycis. Stereotactic frame using xrays.

• 1940’s~1950s: Leksell, Riechert-Mundinger, Talairach, Cooper...

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Problems with X-Ray film Stereotaxy

• Target must be clearly visible in both images

• Lack of apparent relationship between arc settings and position.

• Best for electrophysiology-based ablation

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Problems with Frame-Based Stereotaxy

• Still point-based

• Frame obstructs surgical field

• Arc-based approach obscures relationship between target points and arc settings.

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Registration

When the mathematical relationship between a point in one space and the homologous point in another space is known, the spaces are considered registered. If that relationship can be reduced to a single common translation and rotation, the registration is considered rigid,

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Translate

Rotate

Rigid Registration

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Point Based Registration

• Fiducial point (landmarks)

• Intrinsic Fiducials (anatomic landmarks)

• Extrinsic Fiducials (markers)

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Marker -Based Registration

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New Methods of Registration

Surface-Based Registration

• Image to Physical Space Registration

• Use the outer surface of the skull

• Segmentation in CT forms a surface

• Measure points on the outer surface of the skull with ultrasound

Surface-based registration of physical space with CT images using A-mode ultrasound localization of the skull

• Advantages – No separate surgical procedure – No additional imaging scans

• Disadvantages– Residual Error is less predictive of actual error– More time consuming in the OR

Comparison with Fiducial Markers

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OptotrakInterfac e Card

Serial Port

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Tomographic Images

• Can show anatomy

• Can show function (PET and functional MR)

• Can show extent of disease.

All of the above are qualified statements

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Surface Normal Uncertainty

Surface

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Tomographic Angiography

Surgically Appropriate MIPs

1) Threshold image, make binary image2) Calculate center of mass from binary image3) Fit center of mass points from each slice to a line4) Extend plane from the line perpendicular to MIP trajectory

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Depth-Buffer Based Targeting

Depth-Buffer Based Targeting

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Originals

Globaltransformation

Localtransformation

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Implantation of Thalamic Stimulators

Population Data

• Goal - to provide information from multiple subjects during surgery

• Create a functional Atlas (MR or CT)

Tglobal

Tlocal

Tlocal + Tglobal

Optical Flow

• Differences between images considered as motion from one time frame to the next

• This motion is observed as a change in intensity, represented as a field of velocity vectors called the optical flow

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Atlas

Atlas Patient

Patient

3D Visualization Display

Intraoperative Tracking and Data Collection

Interactive, Image Guided Endoscopic Surgery

Tomographic Volume Endoscopic View

Image to Physical Space Registration

• Endoscopic image space (u,v) was registered with physical space (x,y,z).

• If distortions are minimized, registration from physical space points to image space points can be described by the direct linear transformation (DLT):

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y

x

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Integration of Intraoperative Imaging

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Tracked Ultrasound

Preliminary Experiments• Vertebral surface point extraction using tracked

U/S on phantom spine

• Spinal CT surface extraction• Point-to-surface registration• Qualitative assessment of registration accuracy

Visual Results: Phantom Ultrasound Points

New Software Design

Video

Tomogram

Rotational

2-D Images

DisplayOptotrak

Polaris

Art. Arms

Magnetic

Localizer

Render

Biopsy

Preop Plan

Transparency

GraphicA-Mode US

Electrophys.

Biomechanical

Optical Biopsy

IO

Quaternion

SVD

HTM

ICP

Registration

Deformation

Functional

Correction

ORION

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What’s Next?• Functional Mapping

• Deformable Models

• In-Vivo Tissue Identification

• Image-Guided Delivery of FEL Beam

• Direct Injection Chemotherapy

• Guided Gene Therapy Delivery

• Brachytherapy seed placement

The Center For Technology-Guided Therapy

• Robert L. Galloway BME&Neurosurgery• Cynthia B. Paschal BME &Radiology• Anita Mahadevan-Jansen BME• E. Duco Jansen BME• J. Michael Fitzpatrick EECS&Radiology

&Neurosurgery• Benoit M. Dawant EECS

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The Center For Technology-Guided Therapy

• William C. Chapman, MD Surgery

• Anthony Cmelak, MD Radiation Oncology

• Charles Coffey, PhD Radiation Oncology

• Dennis Duggan, PhD Radiation Oncology

• Dennis Hallahan, MD Radiation Oncology & BME

• Robert M. Kessler, MD Radiology

• Peter E. Konrad, MD, PhD Neurosurgery & BME

• Steven Toms, MD, MPH Neurosurgery TGT

The Center For Technology-Guided Therapy

Andy BassJim Stefansic

Diane MuratoreSteve Hartmann

David CashTuhin Sinha

Steve Gebhart

BME

Jeannette HerringJay West

Duane YoderRui Li

Yi Quiao

EECS

Alan Herline, MD

Surgery

Blake Arrington Gwen Banks Ryan Beasley Caryl Brzymialkiewicz Calley Hardin Elaine Isom Tammy McCreary Kristjan Onu

Danielle Pinson Stacey Scheib Chee Xiong

REU