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Tawakol

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Tawakol

  1. 1. Intravascular Characterization of Atheroscleotic Lesions with 18 F-FDG & A Novel Intravascular Beta Probe A. Tawakol*, D. Elmaleh*, H. Gewirtz*, J. Muller*, A. J. Fischman*, & F. Daghighian† *Harvard Medical School and *Massachusetts General Hospital, Boston, MA † IntraMedical Imaging Inc., Los Angeles, CA.
  2. 2. • An intravascular method is needed to detect vulnerable plaques (VP). • VP contain abundant inflammatory cells, which in turn accumulate 18 F- Fluorodeoxyglucose (FDG). Introduction:
  3. 3. Objective: To test the hypothesis that a catheter- mounted scintillation detector can detect experimental atherosclerotic lesions after injection of FDG.
  4. 4. Methods: • Atherosclerotic Animal Model: – New Zealand rabbits – Balloon injury of the infradiaphragmatic aorta – High cholesterol diet for 10 weeks. • At 10 weeks, 1 mCi/kg FDG was administered to atherosclerotic and control rabbits. • 3-4 hours after FDG, rabbits were sacrificed, and aortas removed as a single segment.
  5. 5. Intra-Vascular Beta Probe • More sensitive to positron emissions than γ rays • A 1 mm diameter, 2 mm-long plastic scintillator was optically coupled to a PMT via a 40 cm long fiber. • Over-all diameter of probe is 1.6 mm. IntraMedical Imaging Inc. LA, CA
  6. 6. Measurement in Animals: • The flexible beta probe was inserted into the abdomino-thoracic aortae. • Measurements made : – At sites of grossly visible plaque, – At non-injured sites in the cholesterol fed rabbits, – In corresponding areas in control aorta, – Each, in triplicate, (at 2 sec/measurement), • The queried aortic segments were then excised and examined using standard well counting.
  7. 7. Results: • Sensitivity of the probe was 850±11 cps/microCi • Catheter-determined activity correlated with well counting measurements:
  8. 8. Results: Beta Probe Counts Plaque Non-plaque 5 10 BetaProbeCounts(cps) n=9 n=15 (P<0.001) 15
  9. 9. Conclusions: • Atherosclerotic plaques can be readily distinguished from non-injured regions by the beta probe. • This newly developed intravascular detector, together with FDG, has promise for the in vivo detection of vulnerable plaques
  10. 10. Discussion • Thinner, more sensitive beta probes are being developed at IntraMedical. • Combination of detection and therapy may enhance the clinical applicability of this technique.
  11. 11. Contacts Ahmed Tawakol, M.D. Mass. General Hospital, Boston, MA atawakol@partners.org Farhad Daghighian, PhD IntraMedical Imaging Inc. LA, CA fd@intra-medical.com

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