Design of a Hadamard Transform Spectral Imaging System
for Brain Tumor Resection Guidance
Paul Holcomb, Tasha Nalywajko, Melissa Walden
Advisors: Anita Mahadevan-Jansen, Ph.D.; Paul King, Ph.D.; Steven Gebhart
Problem Definition
Design Objective
Current 3D imaging
systems for brain
surgery are too slow
and possess too low of
a resolution to be
effective in an
operating room setting
Construct imaging
system using digital
micro-mirror device
and Hadamard
transform for use with
operating microscope
in a clinical setting
Design Criteria
Light Source & Test Image
• Must produce an image quickly
• Must accurately reproduce area of interest in the brain
• Must distinguish healthy versus tumor tissue
• Must be small enough to be usable in an operating room
setting
• Must interface with operating microscope
Benign tumor
• Over 18,000 people diagnosed with brain
tumors every year; 71% mortality rate
• Correlation between complete resectioning of
tumors and improved prognosis
• Complete resectioning requires knowing the
location of the tumor, especially tumor
margins
• Imaging in a clinical setting should be fast
Primary malignant
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• Camera lens (28mm focal
length) collects diffuse reflectance
from flat at a distance of 8”
(203.2mm)
Inverse Hadamard Transform
Digital Micro-mirror Device
Hadamard Matrix Example
• SNR with Hadamard: √n
• SNR with S-Matrix: (√n)/2
• Black flat installed around
camera lens to block stray
reflected light from test source
Secondary malignant
Left: Camera lens from Stage 1 (left) integrated
into light source & test image setup
• Costs:
– OR cost: $10K - $15K per surgery
(depending on length)
– ICU: $2152/24 hrs
– Floor: $1360/24 hrs
– Time spent in surgery
– Time spent recovering:
• 1 week in hospital
• 4-8 weeks rest before resuming full
activities
•Patient benefits:
–Increased prognosis
–Shorter surgery time
–Less time in hospital (ICU or floor)
–Less post-surgical treatment required
Wuttig and Riesenburg, “Sensitive Hadamard Transform Imaging Spectrometer”
System Diagram
Comparison of prognosis based on
percentage of tumor resection from low
grade GBM patients
• Digital micro-mirror device integrated into
the main system after Stage 1 to apply the
Hadamard matrix (or S-matrix)
LaCroix et al. “A multivariate analysis of 416 patients with
glioblastoma multiforme: prognosis, extent of resection, and
survival”, J. Neurosurg. Vol. 95 (2001); pp. 190-198.
• New CCD camera on order, spectrograph
currently being refit to accommodate system
requirements and CCD camera in Stage 3
(Stage 1)
Operating
Room
2.91 hr $14,550 2.25 hr $11,250
ICU bed
2 days $4,304 2 days $4,304
Floor bed 3 days $4,080 2 days $2,720
Totals
6 days $22,934 5 days $18,274
Difference
$4,660
1
Apply Hadamard matrix
(or S Matrix) using DMD
Comparison of tumor resection costs with
and without Hadamard transform
spectral imaging
Compress image to 160um x
8.2mm line
(Stage 2)
Disperse light spectrally using
spectrograph and collect
image using CCD camera
(Stage 3)
X
Spectrum
Lin et al. “In vivo brain tumor demarcation using optical
spectroscopy”, J Photochemistry and Photobiology, Vol. 73
(2001); pp. 396-402.
• Stage 2 image compression system initially
designed to function with collimated light, and
is currently being redesigned
Collect reflected light,
demagnify to less than 10mm
square, and focus on DMD
With two pathology With no pathology
testings and old
testings and new
system
system
Time
Cost
Time
Cost
Apply inverse Hadamard
transform using computer
•50mm focal length achromatic
doublet lens focuses collected
light from the camera lens onto
the DMD
DMD & Stages 2/3 Design
Illuminate sample with
white light
Y
Demarcation of healthy brain tissue and tumor
margins in vivo using point source
measurement of diffuse reflectance
Right: Stage 1 setup including camera lens (left),
focusing lens (middle) and DMD (right)
Comparison of Fourier (left) and Hadamard imaging of a satellite photo.
•Spectral difference between tumor tissue and
healthy tissue
•Point source measurements taken in vitro and
in vivo
•Five sites measured by diffuse reflectance and
confirmed by pathology as cancerous were
missed by MRI
Light box (left) containing white light source
and lens for focusing light on optical flat with
test image (red circle, right)
Stage 1 Design
Cost/Benefit Analysis
Proof of Principle
• Light box with 100mm focal length
lens aperture used to focus white light
and remove stray light interference from
white light source
• Initial test image for focusing is a 3mm
x 10mm line drawn on white optical flat
Hadamard Transform and DMD
Why is this important?
• Diffuse white light source used to
illuminate sample
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1
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1
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Digital micro-mirror device and
control circuitry for computer
interface
Future Directions
• Compression stage needs to be redesigned due to the diffuse nature of the
image source
• CCD camera needs to be replaced
• Spectrograph needs to be modified to collect the desired wavelength range
and to interface with new CCD camera
• System needs to be reduced in size for use in operating room
Acknowledgements
We would like to thank Dr. Anita Mahadevan-Jansen, Steve Gebhart, and Dr.
Paul King for their support in this endeavor.
This project was made possible by the ___ grant.