Feasibility of coronary calcium and stent image subtraction using 320-detector row CT angiography

Abstract

Background The reader confidence and diagnostic accuracy of coronary CT angiography (CCTA) can be compromised by the presence of calcified plaques and stents causing blooming artifacts. Compared to conventional invasive coronary angiography(ICA), this may cause an overestimation of stenosis severity leading to false positive results. In a pilot study we tested the feasibility of a new coronary calcium image subtraction algorithm in relation to reader confidence and diagnostic accuracy. Materials and Methods Forty-three patients underwent clinically indicated ICA and CCTA using a 320–detector row CT. Median Agatston score was 510. Two datasets were reconstructed: a conventional CCTA (CCTAconv) and a subtracted CCTA (CCTAsub), where calcifications detected on non-contrast images were subtracted from the CCTA. Reader confidence and concordance with ICA for identification of >50% stenosis were recorded. We defined target segments on CCTAconv as motion free coronary segments with calcification/stent and low reader confidence. The impact of CCTAsub was assessed. No approval from the ethics committee was required according to Danish law. Results A total of 76 target segments were identified. The use of coronary calcium image subtraction improved the reader confidence in 66% of these segments. In target segments specificity (86% vs. 65%, p<0.01) and positive predictive value (71% vs. 51%, p=0.03) were improved using CCTAsub compared to CCTAconv, without loss in negative predictive value. Conclusions Our initial experience with coronary calcium image subtraction suggests that it is feasible and could lead to an improvement in reader confidence and diagnostic accuracy for identification of significant coronary artery disease.

Magnetic Particle Imaging (MPI): Experimental Quantification of Vascular Stenosis Using Stationary Stenosis Phantoms

“…However, both CT and MRI have drawbacks, like (high) doses of ionizing radiation, nephrotoxic contrast agents, impaired visualization of stenosis in stents and highly calcified vessels for CT and limited spatial and temporal resolution, limited patient access and restrictions for certain implants and medical devices for MRI. Current research addresses these issues: in CT, progress in reduction of ionizing radiation using iterative reconstruction [39, 40], visualization of vessel lumina along stents and calcifications [41, 42] and characterization of atherosclerotic plaques [43, 44] has been made. The development of free-breathing, ECG-triggered, navigator-gated, T2-prepared, 3-dimensional coronary MR angiography using steady state free precession (SSFP) sequence allows coronary imaging in MRI now, in principle without the need for contrast agents [45].…”

Diagnostic accuracy of a modified subtraction coronary CT angiography method with short breath-holding time: a feasibility study

“…The main disadvantage of this method is that there is a high likelihood of misregistration artefacts because the two breath-holding positions do not exactly match. Fuchs et al 15 reported that misregistration artefacts were seen in approximately half of the target segments in two breathhold subtraction CCTA. Third, the mean coronary calcium score in this study was only 898.…”

The Possibility of Using Subtraction MSCT-Coronary Angiography in the Diagnosis of Changes in the Coronary Arteries With Massive Calcification and the Presence of Stents

“…After performing subtraction using the contrast (a) and noncontrast image (b), a diagnostic image is obtained (c), which closely resembles the invasive coronary angiogram (d). [28,16]. Оценивали только сегменты с наличием выраженной кальцификации или наличием стентов.…”

“…Максимальное время задержки дыхания при этом составляло около 5-6 секунд. Но из-за разной глубины вдоха в ряде случаев происходило небольшое смещение анатомических структур друг относительно друга в разных наборах данных, что снижало точность выполнения дальнейшей субтракции [28,31,33].…”