Diagnosis of Thin-Capped Fibroatheromas in Intravascular Optical Coherence Tomography Images: Effects of Light Scattering

BACKGROUND—Intravascular optical coherence tomography (IVOCT) images are recorded by detecting light backscattered within coronary arteries. We hypothesize that non–thin-capped fibroatheroma (TCFA) causes may scatter light to create the false appearance of IVOCT TCFA. METHODS AND RESULTS—Ten human cadaver hearts were imaged with IVOCT (n=14 coronary arteries). IVOCT and histological TCFA images were coregistered and compared. Of 21 IVOCT TCFAs (fibrous cap 1 quadrant), only 8 were true histological TCFA. Foam cell infiltration was responsible for 70% of false IVOCT TCFA and caused both thick-capped fibroatheromas to appear as TCFA, and the appearance of TCFAs when no lipid core was present. Other false IVOCT TCFA causes included smooth muscle cell–rich fibrous tissue (12%) and loose connective tissue (9%). If the lipid arc >1 quadrant (obtuse) criterion was disregarded, 45 IVOCT TCFAs were identified, and sensitivity of IVOCT TCFA detection increased from 63% to 87%, and specificity remained high at 92%. CONCLUSIONS—We demonstrate that IVOCT can exhibit 87% (95% CI, 75%–93%) sensitivity and 92% specificity (95% CI, 86%–96%) to detect all lipid arcs (both obtuse and acute, 1 quadrant requirement enhances the ability of IVOCT to detect TCFA.