Multidetector-row CT cardiac imaging with 4 and 16 slices for coronary CTA and imaging of atherosclerotic plaques

Abstract

IntroductionDespite a multitude of different medical and interventional strategies to treat coronary artery disease (CAD), the natural course of CAD is a relentless progression. The current gold standard to assess the degree of stenosis is coronary angiography. In Germany alone, the total number of angiographic procedures rose by 45% from 1995 to 2000, while the fraction of interventional procedures remained almost constantly low at about 30% [1]. Although coronary angiography has become a safe procedure with only a small risk associated [2], the inconvenience for the patient as well as the economic burden have fueled the quest to find an alternative, noninvasive method to visualize and assess coronary arteries. In the last two years mechanical multidetector-row CT (MDCT) systems with simultaneous acquisition of four slices and half-second scanner rotation have become available [3][4][5]. Multi-row acquisition with these scanners allows for considerably improved visualization of the coronary arteries [6]. Initial experiences have shown that coronary lesions can be detected with good sensitivity and specificity [5,[7][8][9][10]. Data acquisition with MDCTCardiac MDCT imaging can be done using two basic modes of operation for image acquisition: prospective triggering and retrospective gating [11]. Retrospective gating is needed for spiral scanning. Retrospective electrocardiography (ECG)-gating was observed to improve cardiac image quality compared to prospective ECG-triggering techniques due to overlapping image reconstruction and reduced sensitivity to cardiac arrhythmia [12,13]. Calcium scoringCurrent electron beam CT protocols are used for measuring coronary arterial calcification by acquiring a stack of contiguous 3-mm sections [14]. The calcium score, as originally proposed by Agatston [15], is determined on the basis of the product of the total area of a calcified plaque and an arbitrary scoring system for those pixels with an attenuation greater than 130 HU. Theoretically, this multisection data set should give a clear representation of the amount of calcification in the major coronary arterial tree, yet high interscan variability up to 60% has impaired the ability to measure coronary arterial calcification precisely and repeatedly [16]. Spiral multislice CT holds promise to overcome this limitation: coupling the technique of retrospective gating with nearly isotropic volumetric imaging significantly improved the reliability of coronary calcium quantification, especially for small plaques [17]. Using ECG-gated volume coverage with multislice spiral CT and overlapping image reconstruction (2.5 mm collimation, 1 mm increment), an interscan variability of approximately 5%-8% can be achieved [18]. With the advent of multislice CT with significantly reduced interstudy variability, we can now begin to define the effects of treatment regimens on coronary arterial calcification and to determine whether changes in coronary arterial calcification in individual patients have predictive value for future coronary events...

Performance Evaluation of a Multi-Slice CT System with 16-Slice Detector and Increased Gantry Rotation Speed for Isotropic Submillimeter Imaging of the Heart

“…On first patient scans we demonstrated significantly improved visualization of calcified and noncalcified plaques and of stents owing to submillimeter slice width and optimized in-plane resolution. Meanwhile, clinical experience has shown the potential of 16-slice technology for cardiac imaging [27,28].…”

Coronary arteries: assessment of image quality and optimal reconstruction window in retrospective ECG-gated multislice CT at 375-ms gantry rotation time

“…The arrow shows the non-assessable segment This generation of scanner offers the simultaneous acquisition of 16 slices with sub-millimeter collimation, e.g., 0.75 mm. The breath-hold time decreases to less than 20 s, and the voxel becomes truly isotropic with a spatial resolution of 0.5×0.5×0.6 mm [5,13]. With this technique, Ropers could assess 88% of coronary arteries with a diameter of at least 1.5 mm in a group of 77 patients [14].…”

Sixty-four–slice multidetector computed tomography: the future of ED cardiac care

“…Initial studies reported sensitivity and specificity rates of 59% to 95% and 79% to 98%, respectively, primarily in patients with stable angina pectoris referred for cardiac catheterization ( Table 1). The rate of adequate visualization of coronary vessels in these studies ranged from 68% to 96% [18][19][20][21][22][23][24][25][26][27][28]. These results have compared favorably with other modalities such as intravascular ultrasound and cardiac magnetic resonance imaging [29,30] but are still inadequate.…”