Quantification of Low-Attenuation Plaque Burden from Coronary CT Angiography: A Head-to-Head Comparison with Near-Infrared Spectroscopy Intravascular US

Phenotyping atherosclerotic plaque and perivascular adipose tissue: signalling pathways and clinical biomarkers in atherosclerosis

Computed tomography coronary angiography provides a non-invasive evaluation of coronary artery disease that includes phenotyping of atherosclerotic plaques and the surrounding perivascular adipose tissue (PVAT). Image analysis techniques have been developed to quantify atherosclerotic plaque burden and morphology as well as the associated PVAT attenuation, and emerging radiomic approaches can add further contextual information. PVAT attenuation might provide a novel measure of vascular health that could be indicative of the pathogenetic processes implicated in atherosclerosis such as inflammation, fibrosis or increased vascularity. Bidirectional signalling between the coronary artery and adjacent PVAT has been hypothesized to contribute to coronary artery disease progression and provide a potential novel measure of the risk of future cardiovascular events. However, despite the development of more advanced radiomic and artificial intelligence-based algorithms, studies involving large datasets suggest that the measurement of PVAT attenuation contributes only modest additional predictive discrimination to standard cardiovascular risk scores. In this Review, we explore the pathobiology of coronary atherosclerotic plaques and PVAT, describe their phenotyping with computed tomography coronary angiography, and discuss potential future applications in clinical risk prediction and patient management.

Predictive value of change in percent calcified plaque burden based on serial coronary computed tomographic angiography for cardiovascular events

Background

Plaque progression is an independent risk factor for major adverse cardiovascular events (MACE), and change in the total plaque burden (PB) is a common indicator of plaque progression. However, the type of component (calcification or non-calcification) and the magnitude of changes cannot be determined. We aimed to analyze the capability of the percent calcified PB (PCPB) in reflecting the total and its noncalcified and calcified component PB change, and the predictive value of PCPB for MACE.

Methods

Patients who received two or more coronary computed tomographic angiography (CCTA) examinations were included and were divided into MACE and non-MACE groups. The volumes of total plaque, subcomponents and vessel were measured in the serial CCTA. The segmental stenosis score (SSS), high-risk plaque (HRP), total and subcomponent PB, and their annual changes (△PB/year) were calculated. PCPB was calculated as (calcified PB/total PB) × 100%.

Results

Totally 116 patients were enrolled in this study, including 26 (22.4%) patients with MACE. The △PCPB/year showed negative correlation with △total PB/year (r=-0.353, P<0.001), ∆noncalcified PB/year (r=-0.591, P<0.001), while positively correlated with △calcified PB/year (r=0.400, P<0.001). If the △PCPB/year covariate was not added, the baseline HRP, Framingham risk score (FRS), and △total PB/year were independent predictors of MACE. Otherwise, the HRPbaseline, FRSbaseline, and △PCPB/year became independent risk factors of MACE. The area under the curve (AUC) of HRPbaseline + FRSbaseline + △PCPB/year was higher than that of HRPbaseline + FRSbaseline + △total PB/year (AUC: 0.894 vs. 0.820, P=0.016).

Conclusions

The △PCPB/year index simultaneously reflects changes of the total and its internal compositions PB. Moreover, our study shows the potential of △PCPB/year to predict MACE independently from the annual change of total PB.

Computed tomography versus near-infrared spectroscopy for the assessment of coronary atherosclerosis

BACKGROUND

Coronary computed tomography angiography (CCTA) has been proposed as an alternative to intravascular imaging for assessing plaque pathology.

AIMS

We aimed to assess the efficacy of CCTA against near-infrared spectroscopy-intravascular ultrasound (NIRS-IVUS) in evaluating atheroma burden and composition and for guiding coronary interventions.

METHODS

Seventy patients with a chronic coronary syndrome were recruited and underwent CCTA and NIRS-IVUS. The imaging data were matched, and the estimations of lumen, vessel wall and plaque dimensions and composition of the two modalities were compared. The primary endpoint of the study was the efficacy of CCTA in detecting lipid-rich plaques identified by NIRS-IVUS. Secondary endpoints included the performance of CCTA in evaluating coronary artery pathology in the studied segments and its value in stent sizing, using NIRS-IVUS as the reference standard.

RESULTS

In total, 186 vessels were analysed. The attenuated plaque volume on CCTA had weak accuracy in detecting lipid-rich plaques (58%; p=0.029). Compared to NIRS-IVUS, CCTA underestimated the lumen volume (309.2 mm3 vs 420.4 mm3; p=0.001) and plaque dimensions (total atheroma volume 116.1 mm3 vs 292.8 mm3; p<0.001 and percentage atheroma volume 27.67% vs 41.06%; p<0.001) and overestimated the lipid component (lipid core burden index 48.6 vs 33.8; p=0.007). In the 86 lesions considered for revascularisation, CCTA underestimated the reference vessel area (8.16 mm2 vs 12.30 mm2; p<0.001) and overestimated the lesion length (23.5 mm vs 19.0 mm; p=0.029) compared to NIRS-IVUS.

CONCLUSIONS

CCTA has limited efficacy in assessing plaque composition and quantifying lumen and plaque dimensions and tissue types, which may potentially impact revascularisation planning.

Cardiac CT, MRI, and PET in 2023: Exploration of Key Articles across Imaging and Multidisciplinary Journals

In this review, the authors examine recent advancements in noninvasive cardiac imaging, focusing on cardiac CT, MRI, and PET, reviewing key publications from imaging and multidisciplinary journals from 2023. The authors discuss the increasing adoption of photon-counting CT and its applications in coronary and structural imaging, and explore various aspects of plaque and functional assessment, emphasizing their clinical implications. Radiation exposure analysis from the SCOT-HEART (Scottish Computed Tomography of the Heart) trial is also discussed. The authors highlight the integration of artificial intelligence applications in cardiac imaging. Three-year follow-up data from the ADVANCE Registry are described, showcasing the potential of using artificial intelligence to improve diagnostic accuracy and patient outcomes in cardiovascular care. The authors explore the latest studies evaluating different cardiomyopathies using cardiac MRI. Radiologists' growing understanding of the brain-heart axis is presented through discussion of several studies. The authors also discuss the prognostic advantages of MRI over PET in patients with cardiac sarcoidosis. Finally, the authors outline society statements and guidelines from 2023 that are pertinent to cardiac imaging, offering a comprehensive review of current trends and applications in noninvasive imaging modalities.

Computed Tomography Angiography Identified High-Risk Coronary Plaques: From Diagnosis to Prognosis and Future Management

CT angiography has become, in recent years, a main evaluating modality for patients with coronary artery disease (CAD). Recent advancements in the field have allowed us to identity not only the presence of obstructive disease but also the characteristics of identified lesions. High-risk coronary atherosclerotic plaques are identified in CT angiographies via a number of specific characteristics and may provide prognostic and therapeutic implications, aiming to prevent future ischemic events via optimizing medical treatment or providing coronary interventions. In light of new evidence evaluating the safety and efficacy of intervening in high-risk plaques, even in non-flow-limiting disease, we aim to provide a comprehensive review of the diagnostic algorithms and implications of plaque vulnerability in CT angiography, identify any differences with invasive imaging, analyze prognostic factors and potential future therapeutic options in such patients, as well as discuss new frontiers, including intervening in non-flow-limiting stenoses and the role of CT angiography in patient stratification.

Coronary Plaque Characterization with T1-weighted MRI and Near-Infrared Spectroscopy to Predict Periprocedural Myocardial Injury

Purpose To clarify the predominant causative plaque constituent for periprocedural myocardial injury (PMI) following percutaneous coronary intervention: (a) erythrocyte-derived materials, indicated by a high plaque-to-myocardium signal intensity ratio (PMR) at coronary atherosclerosis T1-weighted characterization (CATCH) MRI, or (b) lipids, represented by a high maximum 4-mm lipid core burden index (maxLCBI4 mm) at near-infrared spectroscopy intravascular US (NIRS-IVUS). Materials and Methods This retrospective study included consecutive patients who underwent CATCH MRI before elective NIRS-IVUS-guided percutaneous coronary intervention at two facilities. PMI was defined as post-percutaneous coronary intervention troponin T values greater than five times the upper reference limit. Multivariable analysis was performed to identify predictors of PMI. Finally, the predictive capabilities of MRI, NIRS-IVUS, and their combination were compared. Results A total of 103 lesions from 103 patients (median age, 72 years [IQR, 64-78]; 78 male patients) were included. PMI occurred in 36 lesions. In multivariable analysis, PMR emerged as the strongest predictor (P = .001), whereas maxLCBI4 mm was not a significant predictor (P = .07). When PMR was excluded from the analysis, maxLCBI4 mm emerged as the sole independent predictor (P = .02). The combination of MRI and NIRS-IVUS yielded the largest area under the receiver operating curve (0.86 [95% CI: 0.64, 0.83]), surpassing that of NIRS-IVUS alone (0.75 [95% CI: 0.64, 0.83]; P = .02) or MRI alone (0.80 [95% CI: 0.68, 0.88]; P = .30). Conclusion Erythrocyte-derived materials in plaques, represented by a high PMR at CATCH MRI, were strongly associated with PMI independent of lipids. MRI may play a crucial role in predicting PMI by offering unique pathologic insights into plaques, distinct from those provided by NIRS. Keywords: Coronary Plaque, Periprocedural Myocardial Injury, MRI, Near-Infrared Spectroscopy Intravascular US Supplemental material is available for this article. © RSNA, 2024.

Radiology: Cardiothoracic Imaging Highlights 2023

Radiology: Cardiothoracic Imaging publishes novel research and technical developments in cardiac, thoracic, and vascular imaging. The journal published many innovative studies during 2023 and achieved an impact factor for the first time since its inaugural issue in 2019, with an impact factor of 7.0. The current review article, led by the Radiology: Cardiothoracic Imaging trainee editorial board, highlights the most impactful articles published in the journal between November 2022 and October 2023. The review encompasses various aspects of coronary CT, photon-counting detector CT, PET/MRI, cardiac MRI, congenital heart disease, vascular imaging, thoracic imaging, artificial intelligence, and health services research. Key highlights include the potential for photon-counting detector CT to reduce contrast media volumes, utility of combined PET/MRI in the evaluation of cardiac sarcoidosis, the prognostic value of left atrial late gadolinium enhancement at MRI in predicting incident atrial fibrillation, the utility of an artificial intelligence tool to optimize detection of incidental pulmonary embolism, and standardization of medical terminology for cardiac CT. Ongoing research and future directions include evaluation of novel PET tracers for assessment of myocardial fibrosis, deployment of AI tools in clinical cardiovascular imaging workflows, and growing awareness of the need to improve environmental sustainability in imaging. Keywords: Coronary CT, Photon-counting Detector CT, PET/MRI, Cardiac MRI, Congenital Heart Disease, Vascular Imaging, Thoracic Imaging, Artificial Intelligence, Health Services Research © RSNA, 2024.