Improved assessment of coronary artery luminal stenosis with heavy calcifications using high-resolution photon-counting detector CT

Koons, Emily K; VanMeter, Patrick D.; Rajendran, Kishore; Yu, Lifeng; McCollough, Cynthia H.; Leng, Shuai

doi:10.1117/12.2613019

Cited by 22 publications

(24 citation statements)

References 9 publications

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“…16 More accurate physical dimension measurements compared to EID using a high resolution (0.25 mm detector collimation) prototype PCD system (SOMATOM CounT; Siemens Healthineers) was exhibited by Rajagopal et al 15 Koons et al evaluated use of PCD-CT UHR mode on the clinical scanner (NAEOTOM Alpha, Siemens Healthineers) with phantom vessels mimicking blood and iodinated lumens with varied degree of stenosis. 29 Mergen et al recently demonstrated the benefits of this clinical PCD-CT system and UHR mode in patients with coronary artery calcification visualization. 30 Here, our study quantitatively evaluated visualization of coronary artery stent inner lumen with the first clinical PCD-CT using the 0.2 mm detector pixels, a dedicated UHR sharp kernel, The investigated PCD-CT system has a UHR focal spot (0.4 × 0.5 mm 2 ) to accommodate the small detector size.…”

Section: Discussionmentioning

confidence: 99%

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Quantifying lumen diameter in coronary artery stents with high‐resolution photon counting detector CT and convolutional neural network denoising

et al. 2023

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Background Small coronary arteries containing stents pose a challenge in CT imaging due to metal‐induced blooming artifact. High spatial resolution imaging capability is as the presence of highly attenuating materials limits noninvasive assessment of luminal patency. Purpose The purpose of this study was to quantify the effective lumen diameter within coronary stents using a clinical photon‐counting‐detector (PCD) CT in concert with a convolutional neural network (CNN) denoising algorithm, compared to an energy‐integrating‐detector (EID) CT system. Methods Seven coronary stents of different materials and inner diameters between 3.43 and 4.72 mm were placed in plastic tubes of diameters 3.96–4.87 mm containing 20 mg/mL of iodine solution, mimicking stented contrast‐enhanced coronary arteries. Tubes were placed parallel with or perpendicular to the scanner's z‐axis in an anthropomorphic phantom emulating an average‐sized patient and scanned with a clinical EID‐CT and PCD‐CT. EID scans were performed using our standard coronary computed tomography angiography (cCTA) protocol (120 kV, 180 quality reference mAs). PCD scans were performed using the ultra‐high‐resolution (UHR) mode (120 × 0.2 mm collimation) at 120 kV with tube current adjusted so that CTDIvol was matched to that of EID scans. EID images were reconstructed per our routine clinical protocol (Br40, 0.6 mm thickness), and with the sharpest available kernel (Br69). PCD images were reconstructed at a thickness of 0.6 mm and a dedicated sharp kernel (Br89) which is only possible with the PCD UHR mode. To address increased image noise introduced by the Br89 kernel, an image‐based CNN denoising algorithm was applied to the PCD images of stents scanned parallel to the scanner's z‐axis. Stents were segmented based on full‐width half maximum thresholding and morphological operations, from which effective lumen diameter was calculated and compared to reference sizes measured with a caliper. Results Substantial blooming artifacts were observed on EID Br40 images, resulting in larger stent struts and reduced lumen diameter (effective diameter underestimated by 41% and 47% for parallel and perpendicular orientations, respectively). Blooming artifacts were observed on EID Br69 images with 19% and 31% underestimation of lumen diameter compared to the caliper for parallel and perpendicular scans, respectively. Overall image quality was substantially improved on PCD, with higher spatial resolution and reduced blooming artifacts, resulting in the clearer delineation of stent struts. Effective lumen diameters were underestimated by 9% and 19% relative to the reference for parallel and perpendicular scans, respectively. CNN reduced image noise by about 50% on PCD images without impacting lumen quantification (<0.3% difference). Conclusion The PCD UHR mode improved in‐stent lumen quantification for all seven stents as compared to EID images due to decreased blooming artifacts. Implementation of CNN denoising algorithms to PCD data substantially improved image quality.

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Section: Discussionmentioning

confidence: 99%

“…Koons et al. evaluated use of PCD‐CT UHR mode on the clinical scanner (NAEOTOM Alpha, Siemens Healthineers) with phantom vessels mimicking blood and iodinated lumens with varied degree of stenosis 29 . Mergen et al.…”

Section: Discussionmentioning

confidence: 99%

Quantifying lumen diameter in coronary artery stents with high‐resolution photon counting detector CT and convolutional neural network denoising

et al. 2023

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“…Koons et al 84 demonstrated accurate quantification of luminal stenosis in the presence of heavy calcifications in a phantom model using the ultra-high-resolution mode of the clinical PCD-CT system. In cases of severe stenosis (50%–75% occlusion in a ring-shaped calcification) investigated using a calcific stenosis phantom, PCD-CT images were able to indicate that the lumen was not completely occluded, whereas EID-CT images of the same phantom showed near-complete or complete occlusion of lumen.…”

Section: Pcd-ct Improves Spatial Resolution and Geometric Quantificat...mentioning

confidence: 99%

Standardization and Quantitative Imaging With Photon-Counting Detector CT

2023

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Computed tomography (CT) images display anatomic structures across 3 dimensions and are highly quantitative; they are the reference standard for 3-dimensional geometric measurements and are used for 3-dimensional printing of anatomic models and custom implants, as well as for radiation therapy treatment planning. The pixel intensity in CT images represents the linear x-ray attenuation coefficient of the imaged materials after linearly scaling the coefficients into a quantity known as CT numbers that is conveyed in Hounsfield units. When measured with the same scanner model, acquisition, and reconstruction parameters, the mean CT number of a material is highly reproducible, and quantitative applications of CT scanning that rely on the measured CT number, such as for assessing bone mineral density or coronary artery calcification, are well established. However, the strong dependence of CT numbers on x-ray beam spectra limits quantitative applications and standardization from achieving robust widespread success. This article reviews several quantitative applications of CT and the challenges they face, and describes the benefits brought by photon-counting detector (PCD) CT technology. The discussed benefits of PCD-CT include that it is inherently multienergy, expands material decomposition capabilities, and improves spatial resolution and geometric quantification. Further, the utility of virtual monoenergetic images to standardize CT numbers is discussed, as virtual monoenergetic images can be the default image type in PCD-CT due to the full-time spectral nature of the technology.

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“…PC CT imaging offers high temporal (66 milliseconds) and spatial (130 micrometers) resolution and multi-energy acquisitions that have improved its spectral resolution ( 41 ). The anticipated improvement in feature detection and material quantification will allow the selective isolation of different materials (e.g., calcium, iodinated contrast) and lead to more accurate calcium characterization (thickness), reduction of blooming artifacts, and superior luminal stenosis evaluation ( 42 , 43 ). The first imaging systems have been installed and although early-stage, clinical experience is promising ( Figure 8 ).…”

Section: Coronary Computed Tomography Angiographymentioning

confidence: 99%

The role of invasive and non-invasive imaging technologies and calcium modification therapies in the evaluation and management of coronary artery calcifications

Wopperer

Kotronias

Marin

et al. 2023

Front. Cardiovasc. Med.

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The treatment of coronary artery disease (CAD) has advanced significantly in recent years due to improvements in medical therapy and percutaneous or surgical revascularization. However, a persistent obstacle in the percutaneous management of CAD is coronary artery calcification (CAC), which portends to higher rates of procedural challenges, post-intervention complications, and overall poor prognosis. With the advent of novel multimodality imaging technologies spanning from intravascular ultrasound to optical coherence tomography to coronary computed tomography angiography combined with advances in calcium debulking and modification techniques, CACs are now targets for intervention with growing success. This review will summarize the most recent developments in the diagnosis and characterization of CAC, offer a comparison of the aforementioned imaging technologies including which ones are most suitable for specific clinical presentations, and review the CAC modifying therapies currently available.

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Improved assessment of coronary artery luminal stenosis with heavy calcifications using high-resolution photon-counting detector CT

Cited by 22 publications

References 9 publications

Quantifying lumen diameter in coronary artery stents with high‐resolution photon counting detector CT and convolutional neural network denoising

Quantifying lumen diameter in coronary artery stents with high‐resolution photon counting detector CT and convolutional neural network denoising

Standardization and Quantitative Imaging With Photon-Counting Detector CT

The role of invasive and non-invasive imaging technologies and calcium modification therapies in the evaluation and management of coronary artery calcifications

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