Noninvasive Discrimination of Coronary Chronic Total Occlusion and Subtotal Occlusion by Coronary Computed Tomography Angiography

Deep Learning and Radiomics Discrimination of Coronary Chronic Total Occlusion and Subtotal Occlusion using CTA

RATIONALE AND OBJECTIVES

Coronary chronic total occlusion (CTO) and subtotal occlusion (STO) pose diagnostic challenges, differing in treatment strategies. Artificial intelligence and radiomics are promising tools for accurate discrimination. This study aimed to develop deep learning (DL) and radiomics models using coronary computed tomography angiography (CCTA) to differentiate CTO from STO lesions and compare their performance with that of the conventional method.

MATERIALS AND METHODS

CTO and STO were identified retrospectively from a tertiary hospital and served as training and validation sets for developing and validating the DL and radiomics models to distinguish CTO from STO. An external test cohort was recruited from two additional tertiary hospitals with identical eligibility criteria. All participants underwent CCTA within 1 month before invasive coronary angiography.

RESULTS

A total of 581 participants (mean age, 50 years ± 11 [SD]; 474 [81.6%] men) with 600 lesions were enrolled, including 403 CTO and 197 STO lesions. The DL and radiomics models exhibited better discrimination performance than the conventional method, with areas under the curve of 0.908 and 0.860, respectively, vs. 0.794 in the validation set (all p＜0.05), and 0.893 and 0.827, respectively, vs. 0.746 in the external test set (all p＜0.05).

CONCLUSIONS

The proposed CCTA-based DL and radiomics models achieved efficient and accurate discrimination of coronary CTO and STO.

Preprocedural Planning for Chronic Total Occlusion Percutaneous Coronary Intervention

Chronic total occlusions (CTO) are frequently encountered in clinical practice. Although the success rates and safety of CTO percutaneous coronary intervention (PCI) have significantly improved with the development of newer equipment, use of an algorithmic approach, and advancement in procedural techniques, CTO PCI has a higher rate of complication than does non-CTO PCI. Therefore, meticulous preprocedural planning before CTO PCI is paramount to improve success and reduce the risk of complications. In this report, we review multiple aspects of preprocedural CTO PCI planning, including procedural indications, efficacy, safety, diagnostic angiography, scoring tools for procedural success and risk prediction, and preprocedural use of computed tomography coronary angiography.

Quantitative coronary computed tomography assessment for differentiating between total occlusions and severe stenoses

BACKGROUNDS

The impact of quantitative assessment to differentiate total occlusions (TOs) from severe stenoses on coronary computed tomography angiography (CCTA) remains unknown.

OBJECTIVE

This study investigated whether quantitative characteristics assessed on CCTA could help differentiate a TO from a severe stenosis on invasive coronary angiography (ICA).

METHODS

This study is a sub-analysis of the FASTTRACK CABG (NCT04142021) in which both CCTA and ICA were routinely performed. Quantitative analysis was performed with semi-automated CCTA plaque-analysis software. Blinded analysts compared TOs on CCTA, defined as a complete lack of contrast opacification within the coronary occlusion, with corresponding ICA.

RESULTS

Eighty-four TOs were seen on CCTA in 59 of the 114 patients enrolled in the trial. The concordance in diagnosing a TO between ICA and CCTA was 56.0% (n ​= ​47). Compared to severe stenoses, TOs had a significantly longer lesion length (25.1 ​± ​23.0 ​mm vs 9.4 ​± ​11.2 ​mm, P ​< ​0.001). The best cut-off value to differentiate a TO from severe stenosis was a lesion length of 5.5 ​mm (area under the curve 0.77, 95% CI: 0.66-0.87), with a 91.1% sensitivity and 61.1% specificity. Dense calcium percentage atheroma volume (PAV) was significantly higher in TOs compared to severe stenoses (18.7 ​± ​19.6% vs. 6.6 ​± ​13.0%, P ​< ​0.001), whilst the opposite was seen for fibro-fatty PAV (31.3 ​± ​14.2% vs. 19.5 ​± ​10.5%, P ​< ​0.001). On a multivariable logistic regression analysis, lesion length (>5.5 ​mm) was the only parameter associated with differentiating a TO from a severe stenosis.

CONCLUSION

In quantitative CCTA analysis, a lesion length >5.5 ​mm was the only independent predictor differentiating a TO from a severe stenosis.

NCT REGISTRATION NUMBER

NCT04142021.

Coronary chronic total occlusion on coronary CT angiography: what radiologists should know?

Coronary chronic total occlusion (CTO) often occurs in patients with obstructive coronary artery disease, which remains one of the greatest challenges for interventional cardiologists. Coronary computed tomography angiography (CCTA) with its emerging post-processing techniques can provide a detailed assessment of CTO lesions before percutaneous coronary intervention (PCI), playing an important role in the clinical management of CTO PCI, from early diagnosis, pre-procedural outcome prediction, the crossing algorithm planning, intraprocedural guidance, and finally post-procedural assessment and follow-up. In addition, the feasibility of CT perfusion (CTP) in patients with CTO has been validated. Combined CCTA and CTP have the great potential to be the one-stop-shop imaging modality for assessing both anatomy and function of CTO lesions. This review aims to make radiologists understand the role of CCTA in the diagnosis and assessment of CTO lesions, thus assisting interventionalists in optimizing CTO PCI crossing strategies with the expertise of radiologists.Critical relevance statement The anatomical features of CTO on CCTA can reveal the complexity of CTO lesions and are associated with CTO PCI outcome, thus helping interventionalists optimize CTO PCI crossing strategies.Key points • CTO is the common lesion in invasive coronary angiography, and CTO PCI is technically difficult and its success rate is relatively low.• Length, collaterals, and attenuation-related signs can help distinguish CTO from subtotal occlusion.• The anatomical features of CTO lesions can help grade the difficulty of CTO PCI and predict procedural outcomes and long-term outcomes of CTO PCI.• The real-time fusion of CCTA with fluoroscopic angiography can be applied in highly complicated CTO lesions.• After CTO PCI, CCTA can help guide a second CTO PCI re-entry or follow up stent patency.

Deep Learning-based Prediction of Percutaneous Recanalization in Chronic Total Occlusion Using Coronary CT Angiography

Background CT is helpful in guiding the revascularization of chronic total occlusion (CTO), but manual prediction scores of percutaneous coronary intervention (PCI) success have challenges. Deep learning (DL) is expected to predict success of PCI for CTO lesions more efficiently. Purpose To develop a DL model to predict guidewire crossing and PCI outcomes for CTO using coronary CT angiography (CCTA) and evaluate its performance compared with manual prediction scores.

MATERIALS AND METHODS

Participants with CTO lesions were prospectively identified from one tertiary hospital between January 2018 and December 2021 as the training set to develop the DL prediction model for PCI of CTO, with fivefold cross validation. The algorithm was tested using an external test set prospectively enrolled from three tertiary hospitals between January 2021 and June 2022 with the same eligibility criteria. All participants underwent preprocedural CCTA within 1 month before PCI. The end points were guidewire crossing within 30 minutes and PCI success of CTO.

Results A total of 534 participants (mean age, 57.7 years ± 10.8 [SD]; 417 [78.1%] men) with 565 CTO lesions were included. In the external test set (186 participants with 189 CTOs), the DL model saved 85.0% of the reconstruction and analysis time of manual scores (mean, 73.7 seconds vs 418.2-466.9 seconds) and had higher accuracy than manual scores in predicting guidewire crossing within 30 minutes (DL, 91.0%; CT Registry of Chronic Total Occlusion Revascularization, 61.9%; Korean Multicenter CTO CT Registry [KCCT], 68.3%; CCTA-derived Multicenter CTO Registry of Japan (J-CTO), 68.8%; P < .05) and PCI success (DL, 93.7%; KCCT, 74.6%; J-CTO, 75.1%; P < .05). For DL, the area under the receiver operating characteristic curve was 0.97 (95% CI: 0.89, 0.99) for the training test set and 0.96 (95% CI: 0.90, 0.98) for the external test set. Conclusion The DL prediction model accurately predicted the percutaneous recanalization outcomes of CTO lesions and increased the efficiency of noninvasively grading the difficulty of PCI. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Pundziute-do Prado in this issue.

Calcium evaluation using coronary computed tomography in combination with optical coherence tomography

Optical coherence tomography (OCT) can assess calcium thickness, a key factor for predicting good stent expansion; however, it underestimates coronary calcium severity due to its penetration limitation. This study aimed to evaluate computed tomography (CT) and OCT images to assess calcification. We investigated 25 left anterior descending arteries of 25 patients, using coronary CT and OCT, and assessed their calcification. Of the 25 vessels, 1811 pairs of CT and OCT cross-sectional images were co-registered. Of the 1811 cross-sectional CT images, calcification was not detectable in 256 (14.1%) of the corresponding OCT images due to limited penetration. In the 1555 OCT calcium-detectable images, the maximum calcium thickness was not detectable in 763 (49.1%) images compared to the CT images. In CT images of slices corresponding to undetected calcium in OCT images, the angle, thickness, and maximum density of calcium were significantly smaller compared to slices corresponding to detected calcium in OCT. Calcium with an undetectable maximum thickness in the corresponding OCT image had a significantly greater calcium angle, thickness, and density than calcium with a detectable maximum thickness. There was an excellent correlation between CT and OCT with respect to calcium angle ( R= 0.82, P < 0.001). The calcium thickness on the OCT image had a stronger correlation with the maximum density on the corresponding CT image (R = 0.73, P < 0.001) than with the calcium thickness on the CT image (R = 0.61, P < 0.001). Cross-sectional CT imaging allows for pre-procedural assessment of calcium morphology and severity and could complement the lack of information on calcium severity in OCT-guided percutaneous coronary intervention.

The Clinical Effects of Intravascular Ultrasound-Guided Percutaneous Coronary Intervention in Patients with Chronic Total Occlusion: A Meta-Analysis

Background

The clinical effects of intravascular ultrasound (IVUS)-guided percutaneous coronary intervention (PCI) in patients with chronic total occlusion (CTO) lesions remain unclear.

Methods

We identified all full-text published studies that compared the effects of IVUS-guided CTO-PCI with angiography-guided CTO-PCI by searching electric databases including PubMed, Embase, Cochrane Library, and ISI Web of Science from the establishment to Nov 2021. There was no language limitation. The endpoints included the incidence of major adverse cardiac events (MACE), cardiac death, all-cause death, myocardial infarction (MI), and target vessel revascularization (TVR).

Results

Five studies involving a total of 2320 patients were included in this meta-analysis. Compared to the angiography-guided group, IVUS-guided PCI showed no significant reduction in the incidence of MACE (I² = 27.4%, P = 0.239; RR 0.929, 95% CI 0.765 to 1.128, P = 0.457), cardiac death (I² = 0.0%, P = 0.459; RR 0.574, 95% CI 0.299 to 1.103, P = 0.096), all-cause death (I² = 0.0%, P = 0.964; RR 0.677, 95% CI 0.395 to 1.163, P = 0.158), MI (I² = 46.7%, P = 0.131; RR0.836, 95% CI 0.508 to 1.377, P = 0.482), and TVR (I² = 21.2%, P = 0.279; RR 0.929, 95% CI 0.679 to 1.272, P = 0.648).

Conclusions

IVUS-guided PCI demonstrated no significant benefit on MACE, cardiac death, all-cause death, MI, and TVR in patients with CTO lesions. However, given the study's limitations, additional high-quality RCTs are needed.

Non-invasive Imaging in Patients With Chronic Total Occlusions of the Coronary Arteries-What Does the Interventionalist Need for Success?

Chronic total occlusion (CTO) of coronary arteries is a common finding in patients with known or suspected coronary artery disease (CAD). Although tremendous advances have been made in the interventional treatment of CTOs over the past decade, correct patient selection remains an important parameter for achieving optimal results. Non-invasive imaging can make a valuable contribution. Ischemia and viability, two major factors in this regard, can be displayed using echocardiography, single-photon emission tomography, positron emission tomography, computed tomography, and cardiac magnetic resonance imaging. Each has its own strengths and weaknesses. Although most have been studied in patients with CAD in general, there is an increasing number of studies with positive preselectional factors for patients with CTOs. The aim of this review is to provide a structured overview of the current state of pre-interventional imaging for CTOs.

Preprocedural computed tomography angiography in differentiating chronic total from subtotal coronary occlusions

INTRODUCTION

Differentiation of chronic total occlusion (CTO) from subtotal coronary occlusions (STOs) is often difficult to make from coronary angiography. These differences are very important, as the technical expertise and tools required are significantly different for revascularization of these lesions. We sought to determine if preprocedural computed tomography angiography (CTA) can help better diagnose and differentiate CTO from STO.

METHODS

We searched three databases (Ovid MEDLINE, EMBASE, EBM reviews) from 1 January 1946 to 1 March 2019. Studies reporting on the use of computed tomography (CT) to aid in CTO revascularization were included. Case reports and case series were excluded.

RESULTS

We identified 577 articles, and using the Preferred Reporting Items for Systematic Reviews and Meta-analyses method, 4 articles met prespecified inclusion criteria. A total of 669 patients were included. The statistically significant CT-derived parameters determined to help differentiate CTO from STO were found to include longer lesion length (four out of four studies), larger contrast density difference (one out of four studies), presence of collaterals (two out of four studies) and the presence of the reverse attenuation gradient sign (two out of four studies).

CONCLUSION

This systematic review shows the utility of preprocedural CTA to help differentiate CTO from STO using a number of CT-derived parameters as above. Further, this study highlights the need for further research to develop specific validated parameters for differentiation of CTO and STO.

Feasibility of morphological assessment of coronary artery calcification with electrocardiography-gated non-contrast computed tomography: a comparative study with optical coherence tomography

To investigate the feasibility of pre-procedural morphological assessment of coronary artery calcification in severely calcified lesions with electrocardiography (ECG)-gated non-contrast computed tomography (CT). Severely calcified coronary arteries in patients who underwent ECG-gated non-contrast CT prior to optical coherence tomography (OCT)-guided percutaneous coronary intervention (PCI) were studied retrospectively. CT and OCT data were co-registered by marking landmark structures such as side branches and reviewed side by side with cross-sectional images. The maximum calcium angle (MCA) and presence of nodular calcification (NC) were evaluated. A total of 496 cross-sections in 16 lesions were included in this analysis. The Pearson correlation coefficient between CT- and OCT-derived MCA was 0.92 (p < 0.001). Bland-Altman plots of OCT-derived MCA in relation to CT-derived MCA showed a mean bias of 4.8 degrees with 95% limits of agreement of - 69.7 to 79.4 degrees. Sensitivity, specificity, and positive and negative predictive values of CT in identifying MCA > 270 degrees were 90.3%, 79.7%, 92.1%, and 97.4%, respectively. Sensitivity, specificity, and positive and negative predictive values of CT in identifying NC were 73.3%, 97.5%, 47.8%, and 99.2%, respectively. ECG-gated non-contrast coronary CT might be helpful to obtain detailed information of severe coronary artery calcification before PCI.

Cardiac Computed Tomography for Comprehensive Coronary Assessment: Beyond Diagnosis of Anatomic Stenosis

Cardiac computed tomography angiography (CCTA) has evolved into a versatile imaging modality that can depict atherosclerosis burden, determine functional significance of a stenotic lesion, and guide the management and treatment of stable coronary artery disease.1 With newer-generation scanners, diagnostic CCTA can be obtained in the majority of patients with a very acceptable radiation dose. We discuss the ability of CCTA to provide comprehensive assessment of a patient with suspected CAD, including functional techniques of stress-rest myocardial perfusion assessment using a vasodilator and a purely post-processing approach that assesses fractional flow reserve derived by CCTA. In addition, recent data validated the role of CCTA in managing stable patients with chest pain and suspected CAD, serving as a gatekeeper for invasive coronary angiogram as well as optimizing the preprocedural planning of percutaneous coronary revascularization and coronary artery bypass surgery.

Combination of Lesion Stenosis and Myocardial Supply Area Assessed by Coronary Computed Tomography Angiography for Prediction of Myocardial Ischemia

Recent clinical studies revealed that anatomical information assessed by coronary computed tomography angiography (CTA) may be used effectively to diagnose coronary artery disease (CAD). However, a physiological assessment, demonstrating myocardial ischemia, is required to justify a therapeutic strategy for CAD. This study aimed to investigate whether using CTA to assess myocardial supply area can improve the prediction of myocardial ischemia.We analyzed 201 vessels with moderate (luminal narrowing ≥ 50%, < 70%) and severe (luminal narrowing ≥ 70%, < 99%) stenosis on CTA from 174 patients, who were suspected of having stable angina and underwent measurement of fractional flow reserve (FFR). The myocardial area supplied by the coronary artery, distal to the stenosis, was evaluated with CTA, as reported previously (modified Alberta Provincial Project for Outcome Assessment in Coronary Heart score) and was classified into 3 groups (large, medium, and small).Both percentage area stenosis and myocardial supply area were significantly correlated with FFR (r = -0.46, P < 0.01, and r = -0.45, P < 0.01). Among patients who had coronary plaques, with moderate stenosis and a small myocardial supply area, only 3 of 42 lesions (7%) were identified as ischemic; deviation from the ischemic threshold (FFR = 0.80) was P < 0.01. The combined assessment of lesion stenosis and myocardial supply area, using CTA, improved the prediction of myocardial ischemia significantly compared to lesion stenosis alone (77% versus 59%, P < 0.01).Adding the assessment of myocardial supply area to standard CTA might help predict myocardial ischemia in patients with stable angina pectoris.

Use of Coronary Computed Tomographic Angiography to Facilitate Percutaneous Coronary Intervention of Chronic Total Occlusions

Chronic total coronary occlusions (CTO) are found frequently in coronary artery disease; however, the technical challenge to open the occlusion by percutaneous coronary intervention is considerably higher than for nonocclusive lesions. The angiographic analysis is limited by the inability to visualize the occluded segment and requires a dual injection approach from donor and recipient vessel to assess the CTO. Therefore, imaging of the CTO by computed tomographic angiography can provide additional information on the vessel course within the CTO segment, specifically the degree and extent of calcification, and maybe even be superior to angiography to analyze the proximal cap morphology. This had been integrated in a score to predict the interventional success. This information provides a valuable means to better plan the procedure and the required strategy. In addition, an integration of the computed tomographic angiography is possible by synchronization with the gantry position and movement of the angiography system during percutaneous coronary intervention, illustrating the course of the occluded segment and possible obstacles in the way. It remains to be established which patient will most likely profit from this additional preprocedural examination involving increased radiation and contrast media exposure and institutional expenses.

Differences in patients and lesion and procedure characteristics depending on the age of the coronary chronic total occlusion

Introduction

Whether duration of chronic total occlusion (CTO) affects lesion and procedural characteristics remains largely unknown.

Aim

To investigate whether CTO duration influences lesion characteristics and revascularization success.

Material and methods

EuroCTO Registry data on patients who had CTO percutaneous coronary intervention between January 2015 and April 2017 were analyzed. Three groups were created based on occlusion age: 3 to 6 months (n = 1415), 7 to 12 months (n = 973), > 12 months (n = 1656).

Results

Patients with greater CTO duration were older (63.0 (56.0–70.0); 63.0 (56.0–71.0); 66.0 (59.0–73.0) years respectively; p < 0.001), had more 3-vessel disease (32.2%; 30.9%; 46.1% respectively; p < 0.001) and more frequent prior coronary artery bypass grafting (8.2%; 9.9%; 29.4% respectively; p < 0.001). In multivariate analysis, occlusion duration was associated with moderate/severe calcification (OR = 1.52; 95% CI: 1.28–1.80; p < 0.001), lesion length > 20 mm (OR 1.77; 95% CI 1.49–2.10; p < 0.001), and collateral circulation Werner type 2 (OR = 1.20; 95% CI: 1.01–1.43; p = 0.041). The CTO duration was associated with lower procedural success (OR for success 0.60; 95% CI: 0.46–0.79; p < 0.001). In multivariate analysis in-hospital adverse events did not differ according to duration of CTO.

Conclusions

Coronary artery CTO duration is associated with greater extent of calcification, lesion length, development of collateral circulation and, most importantly, with lower procedural success.

Non-invasive coronary physiology based on computational analysis of intracoronary transluminal attenuation gradient

Invasive procedure is a prerequisite for studying coronary physiology. We established the measurement of non-invasive physiological parameters including coronary blood flow (CBF), flow velocity, and microvascular resistance using coronary computed tomography angiography (CCTA). Vessel-specific CBF was derived from transluminal attenuation flow encoding (TAFE) and then tested using three separate datasets consisted of computational simulation, human perfusion CT, and human CCTA. TAFE-derived CBF correlated well with measured vessel-specific myocardial blood flow and CBF. TAFE-derived CBF per myocardial mass consistently decreased with the progressive severity of stenosis, and it was found to better to detect significant stenosis than transluminal attenuation gradient (TAG). With the addition of vessel anatomy, TAFE-derived CBF could calculate flow velocity and microvascular resistance. The results of non-invasively acquired parameters according to the severity of stenosis were similar to those obtained through invasive physiology studies. Our study demonstrated that non-invasive comprehensive coronary physiology parameters can be derived from CCTA without any pre-specified condition or performing complex heavy computational processes. Our findings are expected to expand the clinical coverage of CCTA and coronary physiology.

In vitro validation of coronary CT angiography for the evaluation of complex lesions

AIMS

The aim of this study was to assess in vitro the diagnostic accuracy of computed tomography angiography (CTA) for the evaluation of complex coronary lesions.

METHODS AND RESULTS

Five Plexiglas phantoms with three bifurcation lesions each were designed to mimic the anatomic variations and fractal phenomena of the coronary tree. In addition, luminal stenoses were scaled up with increases of 10% from 40% to 80%, corresponding to luminal areas ranging from 3.0 mm2 to 0.22 mm2. Third-generation dual-source computed tomography was used. Automated quantitative CTA analysis was performed according to the bifurcation segment model. The primary objective was to determine the diagnostic accuracy of quantitative CTA in assessing bifurcation lesions with the phantoms as a reference. The accuracy of CTA for the assessment of minimal luminal diameter was -0.07 mm (limits of agreement -0.75 to 0.61), for reference vessel diameter 0.19 mm (limits of agreement -0.25 to 0.63) and diameter stenosis 8.2% (limits of agreement -13.2 to 29.5) with no difference regarding the location within the bifurcation (i.e., proximal and distal main vessel and side branch). In stenosis with minimal luminal diameter ≥1 mm, CTA overestimated the lesion severity (bias 0.19 mm, limits of agreement -0.09 to 0.47), whereas in lesions with severe stenosis and minimal luminal diameter ≤1 mm, CTA underestimated the lesion severity (bias -0.48 mm, limits of agreement -0.55 to -0.41). CTA was able to identify the contrast-filled lumen in all degrees of lesion severity.

CONCLUSIONS

In vitro, CTA is accurate for the evaluation of bifurcation lesions. CTA was able to distinguish contrast-filled lumen even in severe obstructive lesions. These findings require further validation in the clinical setting.

Automated Quantitative Plaque Analysis for Discrimination of Coronary Chronic Total Occlusion and Subtotal Occlusion in Computed Tomography Angiography

PURPOSE

The aim of this study was to evaluate the utility of automated plaque analysis in differentiating chronic total occlusion (CTO) from subtotal occlusion (SO) in patients with ambiguous coronary lesions on coronary computed tomography angiography (CTA).

MATERIALS AND METHODS

A total of 63 patients with 63 ambiguous coronary lesions on CTA were included. The lesion length (LL), diameter stenosis, plaque volume and composition, remodeling index, and contrast density difference (CDD) (reflecting intraluminal contrast kinetics over the lesion) were assessed using an automatic software tool. All patients underwent invasive coronary angiography.

RESULTS

Coronary angiography confirmed 28 CTOs and 35 SOs. CTOs showed significantly longer LL (6.4±12.3 vs. 1.0±2.2 mm, P=0.03) and higher CDD (74%±31% vs. 55%±32%, P=0.02) compared with SO. The optimal thresholds for prediction of CTO for CDD and LL were ≥43% and ≥1 mm, respectively (max. sensitivity: 82% for CDD, max. specificity: 77% for LL). The guidewire manipulation time correlated with LL (r=0.529, P=0.004) and CDD (r=0.435, P=0.021) in lesions attempted by percutaneous coronary intervention.

CONCLUSIONS

Automated computed tomography plaque analysis may be applied as a noninvasive tool to differentiate CTO from SO.

Coronary Computed Tomography Angiography Predicts Guidewire Crossing and Success of Percutaneous Intervention for Chronic Total Occlusion

Background—

We developed a model that predicts difficulty of percutaneous coronary intervention for coronary chronic total occlusion (CTO) using coronary computed tomographic angiography.

Methods and Results—

A total of 684 CTO lesions with preprocedural computed tomographic angiography were enrolled from 4 centers. Data were randomly divided into derivation and validation datasets at 2:1 ratio. The end point was successful guidewire crossing ≤30 minutes, which was met in 50%. The KCCT (Korean Multicenter CTO CT Registry) score was developed based on independent predictors identified by multivariable analysis, which were proximal blunt entry, proximal side branch, bending, occlusion length ≥15 mm, severe calcification, whole luminal calcification, reattempt, and ≥12 months or unknown duration of occlusion. The KCCT score was compared with the other prediction scores, including angiography-based J-CTO, PROGRESS-CTO, CL-score, and CT-based CT-RECTOR. The probability of guidewire crossing ≤30 minutes declined consistently from 100% to 0% according to the KCCT score ( P <0.01, all). The KCCT score showed higher discriminative performance compared with the other scoring systems (c-statistics=0.78 versus 0.65–0.72, P <0.001, all). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of a KCCT score of <4 for guidewire crossing ≤30 minutes was 70%, 68%, 72%, 73%, and 70%, respectively. The KCCT score also showed consistent results with procedural success ( P <0.05, all). These results could be reproduced in validation data set ( P <0.05, all).

Conclusions—

KCCT scoring could predict successful guidewire crossing ≤30 minutes and also procedural success. KCCT scoring may enable noninvasive grading difficulty of CTO percutaneous coronary intervention.

Transluminal attenuation gradient and corrected models in coronary CT angiography for determining stenosis severity: a primary study using dual-source CT

AIM

To compare the incremental value of transluminal attenuation gradient (TAG), TAG with corrected contrast opacification (TAG-CCO), and TAG with exclusion of calcified coronary segments (TAG-ExC) in determining the stenosis severity of coronary arteries using coronary angiography (CAG) as the reference standard.

MATERIALS AND METHODS

One hundred and fifteen patients who underwent computed tomography coronary angiography (CTCA) and confirmed by coronary angiography (CAG) were included in the retrospective analysis. TAG, TAG-CCO, and TAG-ExC were calculated in 311 major epicardial coronary arteries. Changes in different TAG models were compared with corresponding stenosis severities ascertained by CAG. The diagnostic performances of TAG, TAG-CCO, TAG-ExC, and the TAG/CTCA, TAG-CCO/CTCA, and TAG-ExC/CTCA combinations over CTCA alone in evaluating stenosis severity were then analysed and compared. Furthermore, the incremental value of the TAG and the corrected models in the reclassification of CTCA-evaluated stenosis severity were calculated.

RESULTS

TAG, TAG-CCO, and TAG-ExC decreased gradually with increased stenosis severity (p<0.001 for all TAG models). TAG and TAG-ExC improved the diagnostic performance over CTCA in total vessel evaluation (c statistic= 0.926 versus 0.907, p=0.018; c statistic= 0.922 versus 0.907, p=0.030, respectively), but TAG-CCO did not. Meanwhile, adding TAG to CTCA enabled a significant reclassification in calcified vessels (n=95; net reclassification improvement = 0.143, p=0.038).

CONCLUSIONS

TAG and TAG-ExC improved the diagnostic performance of CTCA in all vessels. Adding TAG to CTCA significantly reclassified the calcified vessels. The additional value of TAG-CCO over CTCA alone in determining the stenosis severity is limited.

Influence of scan technique on intracoronary transluminal attenuation gradient in coronary CT angiography using 128-slice dual source CT: multi-beat versus one-beat scan

The purpose of our study was to investigate the impact of temporal uniformity and adjustment by the contrast opacification enhancement in the aorta on the performance of transluminal attenuation gradient (TAG) for obstructive coronary artery disease. A total of 274 coronary arteries from 94 patients who underwent both multi- and single-beat scan using 128-slice scanner at the same time were enrolled. TAG and corrected coronary opacification (CCO) of both scan technique were compared against obstructive coronary arteries defined by diameter stenosis ≥50%. In per-vessel analysis, both TAG and CCO were slight but significantly different between multi- and single-beat scan in overall (-13.3 vs. -14.3 HU/10 mm; 0.31 vs. 0.38; p < 0.05, all). However, the difference was evident only in right coronary artery (p < 0.05) but not in left coronary arteries (p = NS). Correlation coefficient value are more than 0.8 for all coronary arteries (0.84) and each of the three vessels (RCA: 0.87, LAD: 0.84, LCX: 0.81) in TAG in single-beat versus multi-beat scans (p < 0.0001). Radiation exposure was significantly lower in single-beat scan compared to multi-beat scan (0.9 vs. 3.7 mSv, p < 0.001). TAGs of multi- and single beat scans well correlated each other in all coronary arteries and were not affected by temporal non-uniformity.