Purpose: Although various radiopharmaceuticals have been developed for the detection of atheromas, external imaging techniques have limitations when it comes to the detection of small plaques. In this study, we developed a charged particle-sensitive detector for the endovascular detection of small plaques.
Methods: The device consists of a probe, an automatic pullback unit and a controller. The probe, which consists of a plastic scintillator and flexible optical fibres, is 1.0 mm in diameter. The probe was inserted into a catheter placed on (18)F point sources, and then the radioactivity was measured as the probe was pulled out stepwise.
Results: The sensitivity for (18)F was 9.3 cps/kBq, and there was a close linear correlation between the peak counts and source dose until at least 0.8 MBq. Furthermore, this device showed low background counts (<0.1 cps) and a low detection limit (0.21 kBq). To investigate the effect of background radioactivity on the measurement at the point sources, a ball phantom was prepared and five (18)F point sources were set on the ball's surface. Even though 298 MBq of (18)F-fluorodeoxyglucose was injected into the ball, the point sources located every 10 mm on the ball's surface were detectable separately.
Conclusion: The data gathered suggest that a catheter-based radiation detector in combination with charged particle-emitting radiopharmaceuticals is useful for the endovascular detection of small lesions such as coronary plaques.