Volumetric Characterization of Human Coronary Calcification by Frequency-Domain Optical Coherence Tomography

Abstract

Background Coronary artery calcification (CAC) presents unique challenges for percutaneous coronary intervention. Calcium appears as a signal-poor region with well-defined borders by FD-OCT, which might enable full quantification of CAC. The objective of this study was to demonstrate the accuracy of intravascular frequency-domain optical coherence tomography (FD-OCT) to determine distribution of CAC. Methods and Results Cadaveric coronary arteries were imaged using FD-OCT at 100Dm frame interval. Arteries were subsequently frozen, sectioned and imaged in their entire length at 20Dm intervals using the Case Cryo-Imaging automated system™. Full volumetric co-registration between FD-OCT and cryo-images was performed. Calcium area, distance from lumen and angle were traced on every cross-section and volumetric quantification was performed offline using a dedicated algorithm. Thirty left anterior descending (LAD) arteries were imaged by both FD-OCT and cryo-imaging. Of these, 13 vessels had a total of 55 plaques with calcification by cryo-imaging and FD-OCT identified 47 (85%) of these plaques. Quantitative analyses of 1285 cryo-images were compared with corresponding co-registered 257 FD-OCT images. Calcium distribution, represented by the calcium-lumen distance (depth) and the mean calcium angle, was similar with excellent correlation between FD-OCT and cryo-imaging respectively (calcium-lumen distance: 0.25±0.09mm vs. 0.26±0.12mm, p=0.742; R=0.90), (mean calcium angle: 35.33±21.86° vs. 39.68±26.61°, p=0.207; R=0.88). Volumetric quantification of CAC was possible by OCT; calcium volume was underestimated in large calcifications in which the abluminal plaque border could not be well visualized (3.11±2.14mm3 vs. 4.58±3.39mm3, p=0.001) in OCT vs. cryo respectively. Conclusion Intravascular FD-OCT can accurately characterize CAC distribution. OCT can quantify absolute calcium volume, but may underestimate calcium burden in large plaques with poorly defined abluminal borders.

Impact of Target Lesion Coronary Calcification on Stent Expansion

“…Recently, volumetric OCT analysis of coronary calcium content was proposed to be accurate. 23 The effect of calcium volume on total stent expansion (ie, actual stent volume/expected stent volume) needs to be investigated.…”

Relationship Between Thickness of Calcium on Optical Coherence Tomography and Crack Formation After Balloon Dilatation in Calcified Plaque Requiring Rotational Atherectomy

“…Optical coherence tomography (OCT) is an optical analogue of IVUS that can visualize calcium components with less signal attenuation, 15 enabling full delineation of superficial calcium components in the arterial wall. 16 The aim of this study was to clarify the relationship between lesion characterization after RA and the mechanisms of lumen enlargement after adjunctive balloon angioplasty followed by stent implantation in complex calcified coronary plaque evaluated using sequential frequency domain-OCT (FD-OCT).…”

Clinical Utility and Significance of Intravascular Ultrasound and Optical Coherence Tomography in Guiding Percutaneous Coronary Interventions

“…OCT can visualize superficial calcium with less signal attenuation, enabling full delineation of calcium components in the superficial arterial wall. 31 In addition, OCT provides clear images of calcium cracks after balloon angioplasty. Kume et al 32 evaluated 91 coronary segments from 33 consecutive human cadavers by both IVUS and OCT.…”