DOI: 10.1161/circ.146.suppl_1.13674 ISSN: 0009-7322

Abstract 13674: Optimal Hounsfield Threshold for Lipid-Rich Plaque by Artificial Intelligence-Enabled Quantitative CT Using Near-Infrared Spectroscopy

Hiroyuki Omori, Hitoshi Matsuo, James Earls, Yoshihiro Sobue, Shinichiro Fujimoto, Yui Nozaki, Gaku Nakazawa, Kuniaki Takahashi, Kazuhiro Osawa, Ryo Okubo, Umihiko Kaneko, Hideyuki Sato, Takashi Kajiya, Toru Miyoshi, Keishi Ichikawa, Mitsunori Abe, Toshiro Kitagawa, Hiroki Ikenaga, Mike Saji, Nobuo Iguchi, Takeshi Ijichi, Hiroshi Mikamo, Akira Kurata, Masao Moroi, raisuke iijima, Tami Crabtree, James K Min, Rine Nakanishi
  • Physiology (medical)
  • Cardiology and Cardiovascular Medicine
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Introduction: By near-infrared spectroscopy (NIRS), plaques with 4-mm maximum lipid-core burden index (maxLCBI4 mm ) ≥ 400 are lipid-rich plaque. By CCTA, the optimal Hounsfield threshold (HU) for lipid-rich plaques defined by presence of low-density non-calcified plaque (LD-NCP) is still unclear.

Hypothesis: Artificial intelligence-enabled quantitative CT (AI-QCT) will enable identification of HU for lipid-rich plaques when compared to NIRS reference standard.

Methods: 128 atherosclerotic plaques from 47 patients were enrolled prospectively. MaxLCBI 4mm (cutoff was defined as 400) and LD-NCP derived from AI-QCT (Cleerly LABS, Denver CO) were compared. LD-NCP using 3 different thresholds (<30, <50, and <70 HU) were analyzed by sensitivity, specificity, positive and negative predictive value, accuracy, and area Under the Curve (AUC).

Results: Amongst 128 atherosclerotic plaques evaluated, 26 (20.3%) met NIRS criteria for lipid rich plaque (maxLCBI 4mm ≥400). The volume of LD-NCP was measure using three different thresholds, <30, <50, and <70 HU as well as criteria of PR > 1.1 and LD-NCP volume >1.8 mm 3 (LD-NCP volume threshold identified from AUC). This yielded a sensitivity, specificity, positive and negative predictive value, accuracy, and AUC of 92%, 88%, 67%, 98%, 89%, and 0.944 at <30HU, 96%, 79%, 53%,99% 82%, 0.921 at <50HU, and 96% 72%, 46%, 99%, 77%, and 0.907 respectively at <70HU (30 vs. 50 HU: p=0.008; 30 vs. 70HU: p=0.002 (Figure 1).

Conclusions: A <30 HU threshold for definition of LD-NCP on AI-QCT correlates optimally with NIRS proven lipid-rich plaques.

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