Real-time Parathyroid Visualization System for use in Endocrine Surgery

Oral Presentation 3Feb 16, 2010

BME 273 Senior DesignGroup 1Isaac Pence

Advisors:Dean ParasDr. Mahadevan-Jansen

37,000 new cases of Thyroid cancer in U.S. every year:~78% Papillary and/or papillary-follicular mixed~17% Follicular and/or Hurthle cell~4% Medullary~1% Anaplastic

100,000 new cases of Hyperparathyroidism in U.S. every year:95.5% one enlarged gland<1% cancer of parathyroid

-Osteoporosis, gastric ulcers, pancreatitis, kidney stones and bone fractures

Just the basic facts…

Significance

• Parathyroid operation typically takes 2 to 6 hours to complete (depending on case and skill of surgeon)

• 5-15% of patients not cured after the operation. – Increased cost and pain from recurrence, persistence of disease or surgical error

• Up to 4% of patients experience a serious complication depending on surgeon's experience.

• Expected hospital stay of 1 to 3 nights

• $10,288 for in-patient stay– entire system should total less than cost of single repeat case with in-patient stay

Inadvertent removal of parathyroid glands during endocrine surgery

Iatrogenic injury common after procedures

Resultant conditions of hypoparathyroidism and hypocalcemia can cause major health concerns

Success primarily dependent upon surgeon experience

No methods for visual distinction between similar tissues

Problem:

• Optics lab have determined higher parathyroid autofluorescence compared to other neck tissues

• Previous work undertaken to develop system for visualization system

• Design Criteria:• System must be easy to use, requiring

little to no training• Function in real-time, with intuitive

information output• Easily integrated into surgical setting• Reduce time and error-rates of current

surgical practices

Develop a real-time visualization system:

Objective:

Idea:

Employ relative thyroid and parathyroid auto-fluorescence to develop a real-time imaging system for use in endocrine surgery

Find-R-Scope from previous Senior design project

Drawbacks:

Poor Image quality (low quality lenses)

Surgical Considerations

Unwieldy Configuration

Limited penetration depth

Solution: IR Viewer Modification

Method:

- Diode laser (785nm) to emit excitation wavelength

- Improve existing detector interface:

- Alter handle configuration to allow reliable support

(better integrate in surgical setting)

- Add adapter to interface C-mount lenses

- Determine optimal coupling of image into CCD

- Write LabView VI to compile information

- Employ false color for simple user interface

- Test with sample tissue and in surgery

Considerations

Imaging system must be able to clearly focus on entire surgical cut, approximately 6 inch diameter

Sterile field surrounds patient: ~3 feet

Surgeon needs visual indicator of parathyroid margin (focus <1 inch) within context of surgical field

Imaging to be done no closer than 1 foot from patient

Initial considerations are subject to change, input obtained from Dr. Phay and Dr. Broome of VUMC Endocrine surgery

Preliminary Results

Preliminary Results

Preliminary Results

By removing front end of casing, further testing of lenses can be conducted

Preliminary Results

At 3 feet from target, Navitar lens couple straight into imaging tube. Far (left) and near (right) focus

images

Preliminary Results

Goals:

- Determine if fixed zoom lens will provide higher resolution

- Determine necessary excitation parameters

- Improve necessary program interface

- Find appropriate fluorescence standard for threshold creation

- Verify system in vitro

Performance Indicators:

Percentage of accurate identifications made when compared to histology and surgeon determination

Time required for surgical procedure

Cost of implementing system

Continuing Work:

Redesign of lens coupling interface is underway (physical design of viewer)

Researching fixed zoom lenses capable of video imaging necessary scale

Upcoming:

Developing software for fluorescence quantification

Determine optimal filter configuration for desired image

Determine Fluorescence standards or phantom creation