Intravascular Characterization of Atheroscleotic Lesions with 18FFDG

1
Intravascular Characterization of Atheroscleotic
Lesions with 18F-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

Introduction

• An intravascular method is needed to detect
  vulnerable plaques (VP).
• VP contain abundant inflammatory cells, which in
  turn accumulate 18F-Fluorodeoxyglucose (FDG).

3
Objective

• To test the hypothesis that a catheter-mounted
  scintillation detector can detect experimental
  atherosclerotic lesions after injection of FDG.

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
Intra-Vascular Beta Probe

• More sensitive to positron emissions than ? 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
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
Results

• Sensitivity of the probe was 85011 cps/microCi
• Catheter-determined activity correlated with well
  counting measurements

8
Results Beta Probe Counts
15
(Plt0.001)
n9
10
Beta Probe Counts (cps)
5
n15
Plaque
Non-plaque
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
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
Contacts

• Ahmed Tawakol, M.D.
• Mass. General Hospital, Boston, MA
• atawakol_at_partners.org
• Farhad Daghighian, PhD
• IntraMedical Imaging Inc. LA, CA
• fd_at_intra-medical.com