Progress Report for NIR
November 7, 2000
Mohammed Asif, M.D.
Silvio Litovsky, M.D.
Morteza Naghavi, M.D.
• 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
• Tissue phantom study needed for pH
• Experimental setup issues: time, temperature,
physiological maintenance, digital camera, etc.
0.1 mm thick
34.6°C0.3 mm thick
0.4 mm thick
0.6 mm thick
area? 0.6 x 0.5 cm
0.7 mm thick
Calcified hard area
400 500 600 700 800 900 1000 1100
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 qualitative
Only 5 points, no pH correlation can be made
Environmental condition stabilization needs to be improved
Quantify degree of surface roughness for spectra collection
• New light source changes relative absorbance
– Light source must be characterized (configurations, reference
• Tissue penetration unresolved with histology
– Penetration study must be completed with new light source
• Histology and other experimental setup issues
unresolved; temperature, other physiological,
• 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.
1. 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 source
3. Conduct depth penetration study
4. Conduct tissue phantom study (pH, lactate,
5. Fix experimental setup issues
6. Start tissue pH spectroscopy of human carotid