Strategic Planning

Thoraco-Abdominal Interventions Fluoroscopy and CT-Guided Kevin Cleary, PhD Associate Professor & Deputy Director Imaging Science and Information Systems (ISIS Center) Department of Radiology Georgetown University Medical Center Washington, DC http://www.caimr.georgetown.edu/ [email protected]

MICCAI 2008

Thorax (Chest) and Abdomen • Thoracic cavity – Lungs, trachea, bronchi

• Abdominal cavity – Liver – Kidney – Pancreas

• Separated by the diaphragm Wikipedia CAIMR Lab

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Georgetown University

Background • Image-guided surgery – About 20 years old – But grew out of stereotactic surgery – Initial focus on brain – Extended to spine and ENT – Always based on body landmarks and rigid body assumptions CAIMR Lab

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Thoraco-Abdominal Interventions • Application of image-guided intervention to the internal organs of the thorax and abdomen • Recent miniaturization of electromagnetic tracking has enabled the development of these systems – Ability to track inside the body

• Organs of interest – Lung, liver, kidney

• Will also discuss laproscopy CAIMR Lab

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Lung: Bronchoscopic Biopsy • Examination of airways with an optical camera • Bronchscope is a flexible instrument with several channels • Working channel can be used for biopsy • Can be difficult to tell exactly where you are relative to CT images • Image-guided systems may help with localization CAIMR Lab

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Public domain image from U.S. National Cancer Institute. Georgetown University

Bronchoscopic Biopsy First Clinical Study • Integrated electromagnetic tracking with pre-procedure CT for guidance • Based on Biosense system (locater pad under table) • First study: 8 swine (Solomon 1998) • Second study: 15 humans (Solomon 2000)

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1998 Chest Journal Solomon et al. Georgetown University

Swine Study Using Biosense

Solomon et al. (1998 Chest). CAIMR Lab

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superDimension inReach System • FDA approved • Proprietary tracking system • 1 cm thick and 47 cm by 56 cm wide localization board placed under patient • Sensor probe 1 mm in diameter and 8 mm long is integrated into flexible catheter • Cather is 1.9 mm in diameter and 130 cm long and inserted in working channel of bronchoscope • Registration is based on anatomic landmarks CAIMR Lab

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Figure courtesy of superDimension Georgetown University

Liver: TIPS procedure • Great interest in liver as “organ of choice” for abdominal interventions and deformable modeling • Many research groups worldwide working in this area • One procedure of interest is TIPS – Transjugular intrahepatic portosystemic shunt placement

http://www.med.umich.edu/ccmu/tips.htm

• Requires connection between hepatic and portal vein using a catheter-based approach CAIMR Lab

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“PIPS” • Percutaneous intrahepatic portosystemic shunt placement • Direct puncture from skin using image guidance • Puncture portal vein, hepatic vein, and inferior vena cava in a single percutaneous transabominal puncture followed by placement of an intrahepatic shut •

Reference: Levy et al. 2007

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Liver Biopsy • Electromagnetic tracking guidance in CT suite • Animal studies showed feasibility of technique • Biopsy done with image guidance only after preprocedure CT scan • View in lower left shows angle that could not seen by tilting CT gantry •

Reference: Banovac et al. 2006

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• For open liver surgery • Track surface of liver using laser range scanner • Courtesy of Pathfinder Therapeutics

Pathfinder

Liver: Biopsy Early System Ultraguide 1000 • Proprietary electromagnetic tracking system • Components • a) computer • b) field generator • c) display screen • But only tracked proximal end of needle with a clip on tracker • Reference: Howard et al. (2001) CAIMR Lab

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Kidney Biopsy Ultraguide 2000 • Kidney lesions were biopsed in 7 patients using an out-ofplane approach • Pictures • Top: system including field generator on movable arm • Middle: skin based sensor • Bottom: sensor clips onto needle • Reference: Wallace et al. (2006) CAIMR Lab

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Laproscopic Guidance

Laproscopic view (left), ultrasound (center), and image guidance (right). Top row: three still images when celiac axis is being imaged. Bottom row: superior CAIMR Labartery. Courtesy of Kirby Vosburgh, PhD, and James Georgetown University mesenteric Ellsmere, MD, Massachusetts General Hospital.

Pathfinder

Building Your Own System • System components – Tracking system – Computer – Software

• Testing – Phantom model • Consider respiratory motion

– Imaging modality CAIMR Lab

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Phantom Torso Model • Commercially available torso

• Foam liver placed on a platform that moves simulating respiratory motion

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Materials • The liver is soft foam and is amenable to needle and instrument puncture. • Small radio-opaque “tumors” are embedded in the liver • The liver also contains tubular structures that represent vena cava and hepatic veins. CAIMR Lab

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Respiratory liver motion simulator

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Graphical User Interface

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CT Scanning • Animal or model torso is scanned

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Methods: • Animal or model torso with liver brought back to angiography suite

• Registration step

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Path Planning

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Needle puncture

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Confirmation and distance measurement with fluoroscopy

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Experiments • Liver phantom (model torso) - 84 targeting passes • Swine - 36 targeting passes • Two experienced operators (faculty) • Two inexperienced operators (residents) • Measured parameters: – Planning time – Accuracy – Total procedure time

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Results Model liver (n=82)

Swine (n=36)

Registration error

1.4 mm (SD 0.3)

1.9 mm (SD 0.4)

Average Planning time (s)

30

63

Average Puncture time (s)

33

43

5.8 (SD 3.4)

8.6 (SD 6.4)

Median distance from center of target (mm)

• No statistical difference in planning time, needle puncture time, or accuracy of placement between experienced and inexperienced operators CAIMR Lab

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Conclusions: • The novel electromagnetic navigation system allows probe delivery into hepatic tumors of a physiologic liver model and live anesthetized swine • less experienced = experienced in this study

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Image Guided Surgical Toolkit (IGSTK) Open Source Software Package • Basic components for an image-guided system – Tracker – Registration – Visualization

• Initial release at SPIE Medical Imaging 2006 in February • Available at igstk.org • Can be used in commercial products • Overview article in IEEE Computer April 2006 • Recent article in Journal of Digital Imaging CAIMR

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IGSTK Basics • Based on open source standards and BSD style licensing • Built on – The Visualization Toolkit – The Insight Segmentation and Registration Toolkit (ITK) – GUI Toolkit • The Fast Light Toolkit (FLTK) • Qt

Layered Architecture IGS - APPLICATION GUI: FLTK / Qt / MFC

IGSTK ITK VNL

GDCM

VTK Threads, XML,…

OpenGL

Software Components • High level components – 2D and 3D visualization – Registration modules – Tracker interfaces

• Low level components – Error handling – Logging

• Application programming interfaces

Architecture

State Machine Architecture • Every component defined by a state machine • State of a component is explicit and always known • All transitions between states are valid and meaningful • State machine: set of states, a set of inputs, and a set of directed transitions

State Machine Component Example

Clinical Workflow • Place fiducials on patient • Pre-procedure CT (later rotation angio) • Registration step – Fiducials in CT space – Fiducials in magnetic space

• Provide image overlay and respiratory tracking during procedure • Confirming image upon completion CAIMR

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First patient: April 2008

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Assisting Staff

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Registration Step & Respiratory Tracking Needle

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Marking the Target in the Lesion

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Planning the Path

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Off-axial View Shows Clear Path

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Final Position

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Summary Slide I • Image-guided systems for thoraco-abdominal interventions have been developed for several different organs and several different procedures • All systems to date still rely on rigid body assumptions, and none of them handle respiratory motion (except for gating techniques) or deformation in any robust manner CAIMR Lab

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Summary Slide II • Clinical adoption is still very slow and we are in the early stages of work in this field, although some commercial systems do exist • Electromagnetic tracking technology will continue to improve and will lead to improvements in these systems • Progress can be made by building prototype systems in a partnership between engineers and clinicians • These systems will ultimately benefit patient care CAIMR Lab

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References I • Banovac, F., E. Wilson, et al. (2006). "Needle biopsy of anatomically unfavorable liver lesions with an electromagnetic navigation assist device in a computed tomography environment." J Vasc Interv Radiol 17(10): 1671-5. • Ellsmere, J., J. Stoll, et al. (2004). "A new visualization technique for laparoscopic ultrasonography." Surgery 136(1): 84-92. • Howard, M. H., R. C. Nelson, et al. (2001). "An electronic device for needle placement during sonographically guided percutaneous intervention." Radiology 218(3): 905-11. • Levy, E. B., H. Zhang, et al. (2007). "Electromagnetic trackingguided percutaneous intrahepatic portosystemic shunt creation in a swine model." J Vasc Interv Radiol 18(2): 303-7. CAIMR Lab

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References II • Solomon, S. B., P. White, Jr., et al. (1998). "Real-time bronchoscope tip localization enables three-dimensional CT image guidance for transbronchial needle aspiration in swine." Chest 114(5): 1405-10. • Solomon, S. B., P. White, Jr., et al. (2000). "Three-dimensional CT-guided bronchoscopy with a real-time electromagnetic position sensor: a comparison of two image registration methods." Chest 118(6): 1783-7. • Wallace, M. J., S. Gupta, et al. (2006). "Out-of-plane computedtomography-guided biopsy using a magnetic-field-based navigation system." Cardiovasc Intervent Radiol 29(1): 108-13.

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Acknowledgments • Clinicians

– Filip Banovac, MD – Vance Watson, MD – Elliot Levy, MD

• Scientists / Researchers – – – – –

David Lindisch, RT Patrick Cheng, MS Ziv Yaniv, PhD Emmanuel Wilson, MS Seong K. Mun, PhD

• Collaborators

– Brad Wood, MD, NIH Radiology

• Funding

– US Army Medical Research and Materiel Command grant W81XWH-04-1-007 – NIH / NIBIB R01 EB007195

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