Purpose <p>Rupture prone high-risk atheromatous plaques are characterized by large necrotic core volumes covered by thin fibrous caps which are positively remodeled; these plaques are significantly inflamed by the cells of monocyte-macrophage origin. We propose that the development of a position-sensitive positron-counting catheter, adding directionality with lead shields (sCath), would help record quantitative location-specific uptake of specifically targeted radiotracers against inflammation.</p> Methods <p>For in-vitro study, the catheter was placed on ¹⁸F point sources to measure the radioactivity counts. For ex-vivo study, the 9 aortas dissected from the rabbit model of atherosclerosis were exposed, and catheters were pulled back every 1&#xa0;cm and counts measured the for 1&#xa0;min by non-shielded catheter (nsCath), sCath-R (right side) and sCath-L (left side).</p> Results <p>In-vitro study showed linear correlation between counts and ¹⁸F point source dose until at least 100&#xa0;kBq (<i>r</i> = 0.98, <i>p</i> &lt; 0.0001). In ex-vivo study, total 100 sections were obtained from 9 aortas and counts-per-minute (cpm) from each catheter nsCath, sCath-R, -L and the average of sCath-R and -L demonstrated high correlation coefficients with quantitative %ID/g (<i>r</i> = 0.49, 0.38, and 0.48, 0.48, respectively. <i>p</i> &lt; 0.0001). They showed excellent agreement with ipsilateral macrophage numbers (sCath-R: <i>r</i> = 0.80, sCath-L: <i>r</i> = 0.73, <i>p</i> &lt; 0.0001). Although the average macrophage numbers correlated with sCath-average of both sides (<i>r</i> = 0.80, <i>p</i> &lt; 0.0001) and non-shielded Cath (nsCath) (<i>r</i> = 0.48, <i>p</i> &lt; 0.0001), the positron count rate of sCath showed stronger correlation with ipsilateral macrohpage number.</p> Conclusion <p>The directional superiority of sCath should potentially be useful in ecentric plaques for inflammation localization, compared with circumferential inflammatory load by the use of nsCath.</p>