Carotid Artery Plaque Characterization Using CT Multienergy Imaging

Saba, Luca; Argiolas, Giovanni Maria; Siotto, Paolo; Piga, M.

doi:10.3174/ajnr.a3285

Cited by 25 publications

(17 citation statements)

References 17 publications

(21 reference statements)

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“…These results were consistent with the previous study performed by Saba et al. 28 However, we did not see this characteristic for the FN feature, as the C F-FN for all energy spectra for the CT systems were not very different. Energy bins j ¼ 2 of DT-2 were the highest as compared to other energy bins for MECT-PC in both reconstructed images.…”

Section: Simulation Resultssupporting

confidence: 83%

“…Specifically, this observer design was similar to the way that a radiologist views multiple energy windows of spectral CT images to investigate attenuation values of a tissue at multiple energy levels. In the study reported by Saba et al, 28 they showed that the HU values of each plaque type (e.g., fatty, mixed, and calcified) should be classified according to the energy level because the HU values of plaque significantly change with the selected kiloelectron volt. Our observer design was motivated by Platisa et al and Chen et al, who built and validated a sophisticated two-layered numerical observer.…”

Section: Introductionmentioning

confidence: 99%

“…Several studies have shown that material decomposition with spectral CT imaging provides better differentiation of materials for atherosclerotic plaque features. 4,12,[28][29][30][31] Nonetheless, there are limited studies of quantitative metrics for evaluating performance in terms of objective image assessment exploiting a numerical observer in spectral CT imaging. 32 The major problems may be because it is difficult to correlate the data from different energy bins, especially given the complexity of the spectral CT data, since spectral CT imaging can be considered a four-dimensional (4-D) technique to form measurements in three spatial dimensions and a unique energy dimension.…”

Section: Introductionmentioning

confidence: 99%

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Numerical observer for atherosclerotic plaque classification in spectral computed tomography

Lorsakul

Fakhri

Worstell³

et al. 2016

J. Med. Imag

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Abstract. Spectral computed tomography (SCT) generates better image quality than conventional computed tomography (CT). It has overcome several limitations for imaging atherosclerotic plaque. However, the literature evaluating the performance of SCT based on objective image assessment is very limited for the task of discriminating plaques. We developed a numerical-observer method and used it to assess performance on discrimination vulnerable-plaque features and compared the performance among multienergy CT (MECT), dualenergy CT (DECT), and conventional CT methods. Our numerical observer was designed to incorporate all spectral information and comprised two-processing stages. First, each energy-window domain was preprocessed by a set of localized channelized Hotelling observers (CHO). In this step, the spectral image in each energy bin was decorrelated using localized prewhitening and matched filtering with a set of Laguerre-Gaussian channel functions. Second, the series of the intermediate scores computed from all the CHOs were integrated by a Hotelling observer with an additional prewhitening and matched filter. The overall signal-to-noise ratio (SNR) and the area under the receiver operating characteristic curve (AUC) were obtained, yielding an overall discrimination performance metric. The performance of our new observer was evaluated for the particular binary classification task of differentiating between alternative plaque characterizations in carotid arteries. A clinically realistic model of signal variability was also included in our simulation of the discrimination tasks. The inclusion of signal variation is a key to applying the proposed observer method to spectral CT data. Hence, the task-based approaches based on the signal-known-exactly/background-known-exactly (SKE/BKE) framework and the clinical-relevant signal-known-statistically/background-known-exactly (SKS/BKE) framework were applied for analytical computation of figures of merit (FOM). Simulated data of a carotid-atherosclerosis patient were used to validate our methods. We used an extended cardiac-torso anthropomorphic digital phantom and three simulated plaque types (i.e., calcified plaque, fatty-mixed plaque, and iodine-mixed blood). The images were reconstructed using a standard filtered backprojection (FBP) algorithm for all the acquisition methods and were applied to perform two different discrimination tasks of: (1) calcified plaque versus fatty-mixed plaque and (2) calcified plaque versus iodine-mixed blood. MECT outperformed DECT and conventional CT systems for all cases of the SKE/BKE and SKS/BKE tasks (all p < 0.01). On average of signal variability, MECT yielded the SNR improvements over other acquisition methods in the range of 46.8% to 65.3% (all p < 0.01) for FBP-Ramp images and 53.2% to 67.7% (all p < 0.01) for FBP-Hanning images for both identification tasks. This proposed numerical observer combined with our signal variability framework is promising for assessing material characterization obtained through the additional energ...

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Section: Simulation Resultssupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Numerical observer for atherosclerotic plaque classification in spectral computed tomography

Lorsakul

Fakhri

Worstell³

et al. 2016

J. Med. Imag

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“…Saba et al [106] assessed ''in vivo'' the effect of the multispectral imaging in terms of carotid artery plaque classification and found that the HU values of carotid artery plaque significantly change according to the selected keV. Results from this study demonstrated that the HU-based plaque type (fatty and mixed) classification can be improved with the use of multienergy imaging.…”

Section: Dual-energy Imagingmentioning

confidence: 71%

Imaging of the Carotid Artery Vulnerable Plaque

Saba¹,

Anzidei

Marincola

et al. 2013

Cardiovasc Intervent Radiol

111

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Atherosclerosis involving the carotid arteries has a high prevalence in the population worldwide. This condition is significant because accidents of the carotid artery plaque are associated with the development of cerebrovascular events. For this reason, carotid atherosclerotic disease needs to be diagnosed and those determinants that are associated to an increased risk of stroke need to be identified. The degree of stenosis typically has been considered the parameter of choice to determine the therapeutical approach, but several recently published investigations have demonstrated that the degree of luminal stenosis is only an indirect indicator of the atherosclerotic process and that direct assessment of the plaque structure and composition may be key to predict the development of future cerebrovascular ischemic events. The concept of ''vulnerable plaque'' was born, referring to those plaque's parameters that concur to the instability of the plaque making it more prone to the rupture and distal embolization. The purpose of this review is to describe the imaging characteristics of ''vulnerable carotid plaques.''

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“…However, the attenuation values of various types of plaques (calcified, noncalcified, or mixed) overlap as a result of contrast enhancement, motion artifact, and partial volume effect. These limitations are amplified when the tube voltage is modified (54).…”

Section: Characterization Of Plaquementioning

confidence: 99%

New and Evolving Concepts in CT for Abdominal Vascular Imaging

et al. 2014

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Computed tomographic (CT) angiography has become the standard of care, supplanting invasive angiography for comprehensive initial evaluation of acute and chronic conditions affecting the vascular system in the abdomen and elsewhere. Over the past decade, the capabilities of CT have improved substantially; simultaneously, the expectations of the referring physician and vascular surgeons have also evolved. Increasingly, CT angiography is used as an imaging biomarker for treatment selection and assessment of effectiveness. However, the growing use of CT angiography has also introduced some challenges, as potential radiation-associated and contrast media-induced risks need to be addressed. These concerns can be partly confronted by modifying scanning parameters (applying a low tube voltage) with or without using software-based solutions. Most recently, multienergy technology has endowed CT with new capabilities offering improved CT angiographic image quality and novel plaque characterization while decreasing radiation and iodine dose. In this article, we discuss current and new approaches using both conventional and multienergy CT for studying vascular disease in the abdomen. We propose various approaches to overcoming commonly encountered image quality challenges in CT angiography. In addition, we describe supplemental strategies for improving patient safety that leverage the available technology.

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Carotid Artery Plaque Characterization Using CT Multienergy Imaging

Abstract: BACKGROUND AND PURPOSE:Carotid artery plaque types can be categorized with CT according to their HU values. The purpose of this work was to analyze carotid artery plaque characteristics by using multienergy imaging.

Cited by 25 publications

References 17 publications

Numerical observer for atherosclerotic plaque classification in spectral computed tomography

Numerical observer for atherosclerotic plaque classification in spectral computed tomography

Imaging of the Carotid Artery Vulnerable Plaque

New and Evolving Concepts in CT for Abdominal Vascular Imaging

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