Quantification of Coronary Artery Stenosis in Very-High-Risk Patients Using Ultra-High Resolution Spectral Photon-Counting CT.

Development of spectral photon-counting computed tomography (SPCCT) for ultra-high-resolution coronary CT angiography (CCTA) has the potential to accurately evaluate the coronary arteries of very-high-risk patients. The aim of this study was to compare the diagnostic performances of SPCCT against conventional CT for quantifying coronary stenosis in very-high-risk patients, with invasive coronary angiography (ICA) as the reference method. In this prospective institutional review board-approved study, very-high-risk patients addressed for ICA following an acute coronary syndrome were consecutively included. CCTA was performed for each patient with both SPCCT and conventional CT before ICA within 3 days. Stenoses were assessed using the minimal diameter over proximal and distal diameters method for CCTA and the quantitative coronary angiography method for ICA. Intraclass correlation coefficients and mean errors were assessed. Sensitivity and specificity were calculated for a >50% diameter stenosis threshold. Reclassification rates for conventional CT and SPCCT were assessed according to CAD-RADS 2.0, using ICA as the gold standard. Twenty-six coronary stenoses were identified in 26 patients (4 women [15%]; age 64 ± 8 years) with 19 (73%) above 50% and 9 (35%) equal or above 70%. The median stenosis value was 64% (interquartile range, 48%-73%). SPCCT showed a lower mean error (6% [5%, 8%]) than conventional CT (12% [9%, 16%]). SPCCT demonstrated greater sensitivity (100%) and specificity (90%) than conventional CT (75% and 50%, respectively). Ten (38%) stenoses were reclassified with SPCCT and one (4%) with conventional CT. In very-high-risk patients, ultra-high-resolution SPCCT coronary angiography showed greater accuracy, sensitivity, and specificity, and led to more stenosis reclassifications than conventional CT.

Fahrni G ，Boccalini S ，Mahmoudi A ，Lacombe H ，Houmeau A ，Elbaz M ，Rotzinger D ，Villien M ，Bochaton T ，Douek P ，Si-Mohamed SA ... -  《-》

Ultra-high-resolution 40 keV virtual monoenergetic imaging using spectral photon-counting CT in high-risk patients for coronary stenoses.

To assess the image quality of ultra-high-resolution (UHR) virtual monoenergetic images (VMIs) at 40 keV compared to 70 keV, using spectral photon-counting CT (SPCCT) and dual-layer dual-energy CT (DECT) for coronary computed tomography angiography (CCTA). In this prospective IRB-approved study, 26 high-risk patients were included. CCTA was performed both with an SPCCT in UHR mode and with one of two DECT scanners (iQOn or CT7500) within 3 days. 40 keV and 70 keV VMIs were reconstructed for both modalities. Stenoses, blooming artefacts, and image quality were compared between all four reconstructions. Twenty-six patients (4 women [15%]) and 28 coronary stenoses (mean stenosis of 56% ± 16%) were included. 40 keV SPCCT gave an overall higher quality score (5 [5, 5]) than 70 keV SPCCT (5 [4, 5], 40 keV DECT (4 [3, 4]) and 70 keV SPCCT (4 [4, 5]), p < 0.001). Less variability in stenosis measurement was found with SPCCT between 40 keV and 70 keV (bias: -1% ± 3%, LoA: 6%) compared with DECT (-6% ± 8%, LoA 16%). 40 keV SPCCT vs 40 keV DECT showed a -3% ± 6% bias, whereas 40 keV SPCCT vs 70 keV DECT showed a -8% ± 6% bias. From 70 keV to 40 keV, blooming artefacts did not increase with SPCCT (mean +2% ± 5%, p = 0.136) whereas they increased with DECT (mean +7% ± 6%, p = 0.005). UHR 40 keV SPCCT VMIs outperformed 40 keV and 70 keV DECT VMIs for assessing coronary artery stenoses, with no impairment compared to 70 keV SPCCT VMIs. Question Use of low virtual mono-energetic images at 40 keV using spectral dual-energy and photon-counting CT systems is not yet established for diagnosing coronary artery stenosis. Findings UHR 40 keV SPCCT enhances diagnostic accuracy in coronary artery assessment. Clinical relevance By combining spectral sensitivity with lower virtual mono-energetic imaging and ultra-high spatial resolution, SPCCT enhances coronary artery assessment, potentially leading to more accurate diagnoses and better patient outcomes in cardiovascular imaging.

Fahrni G ，Boccalini S ，Lacombe H ，de Oliveira F ，Houmeau A ，Francart F ，Villien M ，Rotzinger DC ，Robert A ，Douek P ，Si-Mohamed SA ... -  《-》

The value of fractional flow reserve based on coronary computed tomography angiography with low-dose contrast agent in noninvasive diagnosis of coronary artery disease.

The study aimed, using invasive coronary angiography (ICA) as the gold standard, to investigate the noninvasive diagnostic value of flow reserve fraction derived from coronary computed tomography angiography (CCTA) with low-dose contrast agent in coronary artery disease (CAD). A total of 163 patients with clinical symptoms related to CAD were enrolled between 1 January 2022 and 30 January 2023. The patients received CCTA with a low dose of contrast agent to rule out CAD. If significant (CCTA ≥ 50%) stenosis is suspected, ICA is performed to further evaluate the CCTA for coronary lesions. CT-FFR is calculated from the CCTA dataset using a machine learning-based algorithm. Compared with ICA as a reference standard, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of low-dose contrast agent CT-FFR in the diagnosis of myocardial ischemia were calculated. Coronary lesions with CT-FFR ≤0.80 were defined as hemodynamically significant. Obstructive CAD was excluded by low-contrast CCTA in 87 of 163 patients (53.7%). In the remaining 75 patients (42.35%), at least one coronary artery stenosis was greater than 50%. The accuracy, sensitivity, specificity, PPV, and NPV of low-dose contrast agent CT-FFR on a patient-based evaluation in diagnosing CAD were 93.06, 93.44, 90.01, 98.28, and 71.43%, respectively (Kappa = 0.759). The accuracy, sensitivity, specificity, PPV, and NPV of low-dose contrast agent CT-FFR on a vessel-based evaluation in diagnosing CAD were 86.72, 82.76, 91.58, 92.31, and 81.31%, respectively (Kappa = 0.735). Pearson correlation analysis showed that the ICA examination had a good correlation with CT-FFR value of low-dose contrast media ( r  = 0.731, P  < 0.01). Moreover, in 81.31% of cases, additional analysis of CT-FFR correctly excluded the hemodynamic significance of stenosis. CT-FFR based on low-dose contrast agent CCTA is a very promising noninvasive approach to exclude hemodynamically significant coronary artery stenosis in patients with suspected coronary heart disease while reducing renal burden and helping to reduce the rate of ICA in this high-risk population.

Wang Z ，Luan X ，Zhang Q ，Chu C ，Xu X ，Chai H ，Song P ... -  《-》

Improvement of coronary stent visualization using ultra-high-resolution photon-counting detector CT.

This study aimed to compare the image quality and diagnostic performance of standard-resolution (SR) and ultra-high-resolution (UHR) coronary CT angiography (CCTA) based on photon-counting detector CT (PCD-CT) of coronary stents and explore the best reconstruction kernel for stent imaging. From July 2023 to September 2023, patients were enrolled to undergo CCTA using a dual-source PCD-CT system after coronary angioplasty with stent placement. SR images with a slice thickness/increment of 0.6/0.4 mm were reconstructed using a vascular kernel (Bv48), while UHR images with a slice thickness/increment of 0.2/0.2 mm were reconstructed using vascular kernels of six sharpness levels (Bv48, Bv56, Bv60, Bv64, Bv72, and Bv76). The in-stent lumen diameters were evaluated. Subjective image quality was also evaluated by a 5-point Likert scale. Invasive coronary angiography was conducted in 12 patients (25 stents). Sixty-nine patients (68.0 [61.0, 73.0] years, 46 males) with 131 stents were included. All UHR images had significantly larger in-stent lumen diameter than SR images (p < 0.001). Specifically, UHR-Bv72 and UHR-Bv76 for in-stent lumen diameter (2.17 [1.93, 2.63] mm versus 2.20 [1.93, 2.59] mm) ranked the two best kernels. The subjective analysis demonstrated that UHR-Bv72 images had the most pronounced effect on reducing blooming artifacts, showcasing in-stent lumen and stent demonstration, and diagnostic confidence (p < 0.001). Furthermore, SR and UHR-Bv72 images showed a diagnostic accuracy of 78.3% (95% confidence interval [CI]: 56.3%-92.5%) and 88.0% (95%CI: 68.8%-97.5%), respectively. UHR CCTA by PCD-CT leads to significantly improved visualization and diagnostic performance of coronary stents, and Bv72 is the optimal reconstruction kernel showing the stent struts and in-stent lumen. The significantly improved visualization of coronary stents using ultra-high resolution CCTA could increase the diagnostic accuracy for in-stent restenosis and avoid unnecessary invasive quantitative coronary angiography, thus changing the clinical management for patients after percutaneous coronary intervention. Coronary stent imaging is challenging with energy-integrating detector CT due to "blooming artifacts." UHR images using a PCD-CT enhanced coronary stent visualization. UHR coronary stent imaging demonstrated improved diagnostic accuracy in clinical settings.

Qin L ，Zhou S ，Dong H ，Li J ，Zhang R ，Yang C ，Liu P ，Xu Z ，Yan F ，Yang W ... -  《-》

Urgent carotid endarterectomy with distal mechanical thrombectomy.

We review the technique for carotid endarterectomy (CEA) and direct carotid access for distal thrombectomy after attempted proximal thrombectomy in the setting of tandem occlusions. A patient in their 70s presented with right facial droop and drooling and was found to have critical left carotid stenosis with filling defect in the cavernous segment of the left internal carotid artery consistent with vessel occlusion, Thrombolysis in Cerebral Infarction (TICI) 0, and left M2 middle cerebral artery (MCA) occlusion. After multiple attempts with different wire shapes guided by microcatheter injections within the carotid bulb, we were unable to cross the occlusion. Conversion to open CEA with distal thrombectomy was elected. Following closure of the arteriotomy, direct carotid access using a 5Fr radial artery sheath was achieved within the open surgical field for distal thrombectomy. A 5Fr aspiration catheter was navigated to the left M2 MCA where a stent retriever was then recaptured and TICI 2B reperfusion was achieved.

Muhammad N ，Ramayya A ，Burkhardt JK ，Srinivasan VM ... -  《-》