A New 3-D automated computational method to evaluate in-stent neointimal hyperplasia in in-vivo intravascular optical coherence tomography pullbacks

Abstract. Detection of stent struts imaged in vivo by optical coherence tomography (OCT) after percutaneous coronary interventions (PCI) and quantification of in-stent neointimal hyperplasia (NIH) are important. In this paper, we present a new computational method to facilitate the physician in this endeavor to assess and compare new (drug-eluting) stents. We developed a new algorithm for stent strut detection and utilized splines to reconstruct the lumen and stent boundaries which provide automatic measurements of NIH thickness, lumen and stent area. Our original approach is based on the detection of stent struts unique characteristics: bright reflection and shadow behind. Furthermore, we present for the first time to our knowledge a rotation correction method applied across OCT cross-section images for 3D reconstruction and visualization of reconstructed lumen and stent boundaries for further analysis in the longitudinal dimension of the coronary artery. Our experiments over OCT cross-sections taken from 7 patients presenting varying degrees of NIH after PCI illustrate a good agreement between the computer method and expert evaluations: Bland-Altmann analysis revealed a mean difference for lumen cross-section area of 0.11 ± 0.70mm2 and for the stent cross-section area of 0.10 ± 1.28mm2

Stent implant follow-up in intravascular optical coherence tomography images

The objectives of this article are (i) to utilize computer methods in detection of stent struts imaged in vivo by optical coherence tomography (OCT) during percutaneous coronary interventions (PCI); (ii) to provide measurements for the assessment and monitoring of in-stent restenosis by OCT post PCI. Thirty-nine OCT cross-sections from seven pullbacks from seven patients presenting varying degrees of neointimal hyperplasia (NIH) are selected, and stent struts are detected. Stent and lumen boundaries are reconstructed and one experienced observer analyzed the strut detection, the lumen and stent area measurements, as well as the NIH thickness in comparison to manual tracing using the reviewing software provided by the OCT manufacturer (LightLab Imaging, MA, USA). Very good agreements were found between the computer methods and the expert evaluations for lumen cross-section area (mean difference = 0.11 ± 0.70 mm2; r2 = 0.98, P\ 0.0001) and the stent cross-section area (mean difference = 0.10 ± 1.28 mm2; r2 = 0.85, P value\ 0.0001). The average number of detected struts was 10.4 ± 2.9 per crosssection when the expert identified 10.5 ± 2.8 (r2 = 0.78, P value\0.0001). For the given patient dataset: lumen cross-sectional area was on the average (6.05 ± 1.87 mm2), stent cross-sectional area was (6.26 ± 1.63 mm2), maximum angle between struts was on the average (85.96 ± 54.23), maximum, average, and minimum distance between the stent and the lumen were (0.18 ± 0.13 mm), (0.08 ± 0.06 mm), and (0.01 ± 0.02 mm), respectively, and stent eccentricity was (0.80 ± 0.08). Low variability between the expert and automatic method was observed in the computations of the most important parameters assessing the degree of neointimal tissue growth in stents imaged by OCT pullbacks. After further extensive validation, the presented methods might offer a robust automated tool that will improve the evaluation and follow-up monitoring of in-stent restenosis in patients

Shape-driven segmentation of the arterial wall in intravascular ultrasound images

Segmentation of arterial wall boundaries from intravascular images is an important problem for many applications in the study of plaque characteristics, mechanical properties of the arterial wall, its 3D reconstruction, and its measurements such as lumen size, lumen radius, and wall radius. We present a shape-driven approach to segmentation of the arterial wall from intravascular ultrasound images in the rectangular domain. In a properly built shape space using training data, we constrain the lumen and media-adventitia contours to a smooth, closed geometry, which increases the segmentation quality without any tradeoff with a regularizer term. In addition to a shape prior, we utilize an intensity prior through a non-parametric probability density based image energy, with global image measurements rather than pointwise measurements used in previous methods. Furthermore, a detection step is included to address the challenges introduced to the segmentation process by side branches and calcifications. All these features greatly enhance our segmentation method. The tests of our algorithm on a large dataset demonstrate the effectiveness of our approach

Shape-driven segmentation of the arterial wall in intravascular ultrasound images

Segmentation of arterial wall boundaries from intravascular images is an important problem for many applications in the study of plaque characteristics, mechanical properties of the arterial wall, its 3D reconstruction, and its measurements such as lumen size, lumen radius, and wall radius. We present a shape-driven approach to segmentation of the arterial wall from intravascular ultrasound images in the rectangular domain. In a properly built shape space using training data, we constrain the lumen and media-adventitia contours to a smooth, closed geometry, which increases the segmentation quality without any tradeoff with a regularizer term. In addition to a shape prior, we utilize an intensity prior through a non-parametric probability density based image energy, with global image measurements rather than pointwise measurements used in previous methods. Furthermore, a detection step is included to address the challenges introduced to the segmentation process by side branches and calcifications. All these features greatly enhance our segmentation method. The tests of our algorithm on a large dataset demonstrate the effectiveness of our approach

A new technique for assessing arterial pressure wave forms and central pressure with tissue Doppler

BACKGROUND: Non-invasive assessment of arterial pressure wave forms using applanation tonometry of the radial or carotid arteries can be technically challenging and has not found wide clinical application. 2D imaging of the common carotid arteries is routinely used and we sought to determine whether arterial waveform measurements could be derived from tissue Doppler imaging (TDI) of the carotid artery. METHODS: We studied 91 subjects (52 men, age 52 ± 14 years) with and without cardiovascular disease. Tonometry was performed on the carotid artery simultaneously with pulsed wave Doppler of the LVOT and acquired digitally. Longitudinal 2D images of the common carotid artery with and without TDI were also acquired digitally and both TDI and tonometry were calibrated using mean and diastolic cuff pressure and analysed off line. RESULTS: Correlation between central pressure by TDI and tonometry was excellent for maximum pressure (r = 0.97, p < 0.0001). The mean differences between central pressures derived by TDI and tonometry were minimal (systolic 5.36 ± 5.5 mmHg; diastolic 1.2 ± 1.2 mmHg). CONCLUSION: Imaging of the common carotid artery motion with tissue Doppler may permit acquisition of a waveform analogous to that from tonometry. This method may simplify estimation of central arterial pressure and calculation of total arterial compliance

Synergistic Effect of Cardiovascular Risk Factors on Necrotic Core in Coronary Arteries A Report From the Global Intravascular Radiofrequency Data Analysis Registry

ObjectivesThis study explored whether an individual or a cluster of risk factors affects the extent of necrotic core (NC) assessed by intravascular ultrasound (IVUS) radiofrequency data (RFD) analysis.BackgroundSeveral systemic diseases contribute to the development of coronary artery disease.MethodsThe Global Intravascular Radiofrequency Data Analysis Registry was a prospective, multicenter, nonrandomized database that enrolled 990 patients with coronary artery disease in whom 1 major coronary artery was imaged by IVUS-RFD. For the multivariable analysis, the population was divided into 4 classes: young women, young men (both ≤62 years), old women, and old men (>62 years). Mean NC area was categorized as 1: top quartile (≥0.62 mm2) or as 0: lower 3 quartiles.ResultsYoung patients had less NC compared with older patients (0.40 ± 0.36 mm2 of NC vs. 0.50 ± 0.46 mm2 in old patients, p = 0.0007). Nondiabetic patients had less NC than diabetic patients (0.43 ± 0.41 mm2 of NC vs. 0.51 ± 0.44 mm2 in diabetic patients, p = 0.02). The NC area was lower in normotensive patients (0.40 ± 0.36 mm2) than in hypertensive patients (0.48 ± 0.44 mm2) (p = 0.02). In the bivariate analysis, age, hypertension, diabetes, and prior coronary artery bypass graft were statistically significant, however in logistic regression analysis, only age (odds ratio [OR]: 1.023, 95% confidence interval [CI]: 1.009 to 1.037, p = 0.001) and diabetes (OR: 1.636, 95% CI: 1.174 to 2.279, p = 0.004) remained statistically significant. In a per-class logistic regression analyses including only diabetes as covariate, the OR in young women was 2.1 (95% CI: 0.77 to 6.0, p = 0.14), in young men the OR was 1.6 (95% CI: 0.90 to 2.7, p = 0.11), in old women the OR was 2.3 (95% CI: 1.09 to 4.9, p = 0.03), and in old men the OR was 1.6 (95% CI: 0.96 to 2.7, p = 0.07). Further, when only patients with diabetes and hypertension were included, young men (OR: 2.0, p = 0.041), old women (OR: 3.04, p = 0.046), and old men (OR: 2.2, p = 0.025) were significant.ConclusionsIndividually and collectively, age and diabetes mellitus are associated with an increase in NC by IVUS-RFD analysis

In-vivo optical coherence tomography image analysis

Optical Coherence Tomography (OCT) is a recent modality, which measures the intensity of back-reflected infrared light. The main advantage of OCT is its high resolution at the cost of a decreased penetration depth. OCT can differentiate between typical constituents of atherosclerotic plaques, such as lipid, calcium, and fibrous tissue better than intravascular ultrasound as shown by recent studies, also related to plaque vulnerability. Moreover, it has been shown that OCT provides monitoring of stents imaged in-vivo after percutaneous coronary interventions, which is important for quantification of in-stent neointimal hyperplasia. Image analysis problems using intra-coronary OCT pullbacks will be presented for study of atherosclerotic plaque composition and mainly follow-up of in-stent restenosis using in-vivo OCT images

Measurement of arterial distensibility and compliance to assess prognosis

Background and aim: Total arterial compliance (TAC) reflects arterial function in the entire systemic circulation while distensibility coefficient (DC) is an estimate of local arterial compliance obtained from large elastic arteries. There are few studies relating TAC or DC to outcome. We sought whether DC or TAC predicted outcome in a primary prevention cohort with a spectrum of cardiovascular risk