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103100

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103100

  1. 1. Progress Report for NIR Spectroscopy Studies November 7, 2000 Tania Khan Mohammed Asif, M.D. Silvio Litovsky, M.D. Morteza Naghavi, M.D.
  2. 2. 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.
  3. 3. Plaque 10/31 1 2 3 4 5 2.5 cm 1 cm
  4. 4. Data 1 2 3 4 5 0.1 mm thick pH 7.63 34.6°C0.3 mm thick pH 8.08 32.9°C 0.4 mm thick pH 7.41 32.5°C 0.6 mm thick pH 8.08 34.2°C Thrombosed/Calicified area? 0.6 x 0.5 cm 0.7 mm thick pH 8.25 32.1°C Calcified hard area
  5. 5. 4x 10x 40x HA-2-1 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 400 600 800 1000 wavelength absorbance
  6. 6. 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 absorbance 4x 10x 40x
  7. 7. 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 absorbance 4x 10x 40x
  8. 8. 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 absorbance 4x 40x Very calcified, Should have put in De-Cal Solution more than 1 hr.
  9. 9. 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 absorbance 4x 40x 10x
  10. 10. 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 absorbance 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
  11. 11. 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.
  12. 12. PRIORITIES 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, thrombus?) 5. Fix experimental setup issues 6. Start tissue pH spectroscopy of human carotid plaques study

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