Meltem IzzetogluOptical Brain Imaging Team

School of Biomedical Engineering, Science & Health Systems, Drexel University

Philadelphia, PA

Joint Studies with Britton Chance and His Team

Adult and Pediatric Applications of Optical Brain Imaging

June 3 & 4, 2011Philadelphia PA, USA

Britton Chance: Life, Times, & Legacy

Symposium and Workshop

Outline

Early joint studies with Dr. Chance and Optical Brain Imaging team at Drexel University Signal processing algorithm developments and various applications First prototype pediatric system development, testing and

applications

Influence of the early studies in the current algorithm developments, system designs and applications Algorithms for motion artifact removal and applications Evolution of the pediatric system to current wireless version and

applications Evolution of the phantom model and tests conducted

Algorithm developments and applications

Single trial evoked hemodynamic response extraction (Izzetoglu et al, 2005)

Anagram Protocol (a linguistic problem solving study of graded difficulty)

Model Fitting for Single Trial Hemodynamic Response Detectiono Oxygenation data (Oxy) is modeled as the summation of each single trial hemodynamic

functions (HF) related to stimulus:

o Each hemodynamic function is represented by a gamma function :

o Unknown parameters of HFs are found by minimizing the mean square error between Oxy data and the model by using least mean squares curve fitting:

N

iihfOxy

1

i i iti i ihf At e

AmplitudeFWHM

Time to Peak

2

1,,)(min

,

N

iiBA

hfOxyiiii

fNIR Sensor

Algorithm developments and applications Single trial evoked hemodynamic response extraction Results on 14 subject Anagram data collected at Dr. Chance’s Laboratory

Oxygenation rise times follow the same pattern as the behavioral response times (Pearson’s r = 0.92).

The rise time and maximum amplitude of oxygenation increase as the difficulty level of the anagram solutions increase

Av e rage d Re sponse and Rise Time s of the Sing le Tr ia l

He mo dyn amic Re spon se Estimate s

0.000

1.000

2.000

3.000

4.000

5.000

6.000

7.000

8.000

3L-1st Set 4L-1st Set 5L 4L-2nd Set 3L-2nd Set

Ave Resp TAve RiseT

Av e ra g e d M a x im u m Am p litu d e o f th e S in g le Tir a l H e m o d yn a m ic R e s p o n s e Es tim ate s

0 .0 0 0

0 .0 5 0

0 .1 0 0

0 .1 5 0

0 .2 0 0

0 .2 5 0

0 .3 0 0

0 .3 5 0

0 .4 0 0

0 .4 5 0

3L -1 s t Se t 4 L -1 s t Se t 5 L 4L -2 nd Se t 3 L -2n d Se t

All Anagram Data: Correlation Coefficient=0.92; Slope=1.17

0.0001.0002.0003.0004.0005.0006.0007.0008.0009.000

10.000

0.000 1.000 2.000 3.000 4.000 5.000 6.000 7.000 8.000Response Time

Rise

Tim

e

Algorithm developments and applications Arithmetic and Geometric Mathematical Problem Solving Study

Higher bilateral oxygenation is observed during tasks with higher difficulty compared to control tasks with less difficulty.

fNIR findings of are inline with fMRI literature that indicates higher prefrontal cortex activation during problem solving

fNIR Sensor

Geometric Control Tangram Puzzle

Arithmetic Control Arithmetic Tasks

First prototype pediatric system developmentOne light source (with two built in LEDs at 730 and 850nm wavelengths) two detector wired pediatric system (Alper Bozkurt, Master’s thesis,2004)

Testing on phantoms and pediatric applicationsTesting on liquid phantom in Dr. Chance’s Laboratory (Bozkurt et al, 2005)

Pediatric Application - Hearing test (Rosen et al, 2005) NIRS measurements were obtained for 1 minute before, during, and 1 minutes

after NJ State mandated hearing screen evaluation from two healthy newborns.

Influence of the early studies in algorithm developments, system designs

and applications

Evolution of Signal Processing Algorithms and Applications

Motion Artifact Removal Adaptive, Wiener and Kalman Filters (Izzetoglu et al. 2005, 2010)

ICA/PCA based algorithm used in the operating room (Kurtulus Izzetoglu, Ph.D. thesis, 2008)

S-MAR used in BCI Settings and FAA Applications (Hasan Ayaz, Ph.D. thesis, 2010)

16-channel fNIR sensor

Evolution of the pediatric system to current wireless version with application to pediatric pain assessment

Wireless pediatric system

Pediatric pain assessment (Izzetoglu et al, 2010)

5 healthy term infants

2 heel-stick blood draws, 2 intra-muscular vaccination, 1 circumcision and vaccination.

HbO2 Hb

Texas Instrument’s ZigBee cc2430 System-on-Chip

60 feet wireless communication in open space 30 feet wireless communication in lab

environment Battery performance of 3 continuous hours

Evolution of the phantom model

Multi Layer Dynamic Liquid Phantom adult human head model with skin, skull, CSF and brain layers Dynamic changes in Hb and HbO2 can be established Allows measurement from skin and brain sides Targets can be placed within the brain layer

Tests conducted effects of superficial layers at different source detector separations

Hematoma and edema tests

1700 1800 1900 2000 2100 2200 2300 2400 2500 2600

-10

-5

0

5

10

15

20Hematoma Test using new probe with 960nm

time (sec)

HbHbO2WaterBV

Deoxygenation Oxygenation

Hematoma

Hematoma

Thank You________________________________________________________

Meltem Izzetoglu

3141 Chestnut StPhiladelphia PA 19104Tel: 215-895-1988Fax: 215-895-4983Email: meltem@cbis.ece.drexel.edu

www.biomed.drexel.edu/fnir