105 nir spectroscopy studies
TRANSCRIPT
Progress Report for NIR Spectroscopy Studies
November 7, 2000
Tania KhanMohammed Asif, M.D.Silvio Litovsky, M.D.
Morteza Naghavi, M.D.
Progress• New probe design being worked out with Multimode to
improve NIR signal 10/31- current– Data analysis of all prior spectra required in progress– Characterize new light source in same manner (configurations,
reference standards, sampling methods)– Must send out on order before AHA next week
• Ongoing difficulties in working on a depth penetration study
• Tissue phantom study needed for pH • Experimental setup issues: time, temperature,
physiological maintenance, digital camera, etc.
Plaque 10/31
1
2
3
4
5
2.5 cm
1 cm
Data
1
2
3
4
50.1 mm thickpH 7.6334.6°C0.3 mm thick
pH 8.0832.9°C
0.4 mm thickpH 7.4132.5°C
0.6 mm thickpH 8.0834.2°CThrombosed/Calicified area? 0.6 x 0.5 cm
0.7 mm thickpH 8.2532.1°CCalcified hard area
4x
10x40x
HA-2-1
-0.4
-0.3
-0.2
-0.1
0.0
0.1
0.2
0.3
400 600 800 1000
wavelength
abso
rban
ce
HA-2-2
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
400 500 600 700 800 900 1000 1100
wavelength
abso
rban
ce
4x
10x40x
HA-2-3
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
400 500 600 700 800 900 1000 1100
wavelength
abso
rban
ce
4x
10x40x
HA-2-4
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
400 500 600 700 800 900 1000 1100
wavelength
abso
rban
ce
4x
40x
Very calcified,Should have put in De-CalSolution more than 1 hr.
HA-2-5
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
400 500 600 700 800 900 1000 1100
wavelength
abso
rban
ce
4x
40x10x
All Areas
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
400 500 600 700 800 900 1000 1100
wavelength
abso
rban
ce
VIS HA-2-5 I-M VIS HA-2-4 HA-2-3 VIS HA-2-2 HA-2-1
Fibrosis, necrosis, calcifications are all qualitativeOnly 5 points, no pH correlation can be made
Environmental condition stabilization needs to be improvedQuantify degree of surface roughness for spectra collection
CONCLUSIONS• New light source changes relative absorbance
– Light source must be characterized (configurations, reference standards, etc.)
• Tissue penetration unresolved with histology– Penetration study must be completed with new light source
• Histology and other experimental setup issues unresolved; temperature, other physiological, morphological variables
• Need quantitative measurements of histology– Cap thickness, size of necrotic core, cell density, etc.
• New probe needed to reach wavelengths above 1900 nm (lactate region) ; spectrometer OK– Currently being designed with help from Mulitmode Inc.
PRIORITIES1. Analyze data to see what would be best to
incorporate in a new probe design to get better spectra out past 1900 nm (water bands, lactate bands, cholesterol bands)
2. Characterize light source3. Conduct depth penetration study4. Conduct tissue phantom study (pH, lactate,
thrombus?)5. Fix experimental setup issues6. Start tissue pH spectroscopy of human carotid
plaques study