A catheter-based radiation detector for endovascular detection of atheromatous plaques

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. 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 18F point sources, and then the radioactivity was measured as the probe was pulled out stepwise. The sensitivity for 18F 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 18F point sources were set on the ball's surface. Even though 298 MBq of 18F-fluorodeoxyglucose was injected into the ball, the point sources located every 10 mm on the ball's surface were detectable separately. 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. (orig.)