Images display a 71-year-old male patient presenting with stable angina pectoris. (A) XCA revealed 3-vessel coronary artery disease with subtotal stenosis of proximal and mid left anterior descending artery (red arrows), gadobutrol enhanced [18F]fluoride-PET/MR demonstrated (B) enrichment of gadobutrol (red arrows) and (C) increased [18F]fluoride uptake (red arrows, reddish colour) in the plaque region. (D) MR-CNR values correlated with XCA determined degree of stenosis (P < 0.005). (E) Corresponding coronary-segment assigned PET-TBR values significantly correlated with degree of stenosis (P < 0.001) foremost below a TBR threshold of 1.28 (P = 0.003). (F) In segments with a TBR >1.25, the OCT-presence of a plaque lipid core was more frequently detected (plaque Types 3–6; P < 0.001). High-risk plaques (Types 5 and 6)—mainly calcified TCFAs—were predominantly located in segments with a TBR >1.28 (P = 0.012). Plaque types: (0) no plaque, (II) fibrocalcific plaque, (III) fibroatheroma, (IV) calcified fibroatheroma, (V) non-calcified TCFA, and (VI) calcified TCFA. CNR, contrast-to-noise ratio; OCT, optical coherence tomography; TBR, tissue-to-background ratio; TCFA, thin-cap fibroatheroma; XCA, invasive X-ray coronary angiography.