CT-Koronarangiografie: Untersuchungstechnik, klinische Ergebnisse und Ausblick in zukünftige Entwicklungen

Abstract

Multislice computed tomography (MSCT) after intravenous contrast agent administration enables visualization of the coronary arteries with high spatial resolution (voxel sizes down to 0.5 x 0.35 x 0.35 mm (3)) and a short scan time. Magnetic resonance imaging (MRI) is also intensively studied with respect to the noninvasive detection of coronary artery stenosis and thus the detection of coronary artery disease (CAD) without radiation exposure but is not equal to MSCT at present. This article provides an overview of the historical development of CT coronary angiography from 4-slice CT to 16-slice CT and 64-slice CT. A crucial aspect of this development is the improvement in image quality resulting from shorter breath-hold periods and the reduced gantry rotation time. Other techniques that appear to considerably improve image quality and accuracy and make CT independent of patient heart rates are multi-segment reconstruction and dual-source CT. Sublingual nitroglycerin as well as oral or intravenous betablocker administration should be considered in relation to the diagnostic question to be answered and the patient's heart rate. In the studies available CT coronary angiography with at least 12 simultaneous detector rows has a sensitivity of 96.9 % and a specificity of 75.3 % at the patient level. Especially the negative predictive value of CT (94.6 %) emphasizes the idea that this technique may reliably exclude CAD in patients with intermediate pretest likelihood. In the near future, 256-slice CT will allow examination of the entire heart during one heartbeat or even 4D CT scanning with simultaneous assessment of myocardial perfusion. Automatic or semiautomatic software tools will assume a central place in detecting and quantifying coronary artery stenoses and plaques as well as in the analysis of cardiac function in the clinical setting over the next years. Prior to its routine clinical use, the cost-effectiveness of CT coronary angiography must be determined and the clinical role of MSCT must be investigated in multi-center studies including different patient populations.

CT Coronary Angiography Using 16 and 64 Simultaneous Detector Rows: Intraindividual Comparison

“…On the 16-slice CT scanner, contrast agent administration was stopped when the helical scan reached the level of the left main coronary artery to avoid streak artifacts arising from the right ventricle and interfering with the right coronary artery [7]. For the 64-slice system the amount of contrast agent required was calculated using the following formula: (scan time in sec + 10) flow (ml/sec) as recently recommended [13] and was followed by a saline chaser [14]. Nitroglycerin was sublingually administered prior to scanning in all patients to increase the coronary artery diameters and facilitate image assessment [15].…”

“…The scan length that could be used to reconstruct axial images (range of reconstructable images) was significantly longer with 64-slice CT (l " Discussion ! MSCT is a promising approach to noninvasive coronary angiography [1,13,19]. As shown in this study, MSCT coronary angiography using 64 simultaneous detector rows improves the depiction of the coronary arteries by reducing motion artifacts and thereby improving image quality in comparison to 16-slice CT.…”

In-Vivo Measurements of Coronary Blood Flow using 16-Slice Multidetector Spiral Computed Tomography (MDCT) in a Porcine Model

“…Automated tube current modulation (CT automatic exposure control) and other low-dose CT coronary angiography modes like the Step-and-Shoot procedure can reduce exposure by approximately half [24 -26]. Overall, radiation exposure from combined CTCA and CT flow measurements performed on modern CT scanners will be slightly higher than that associated with cardiac catheterization (6)(7)(8)(9)(10)(11) [16,19,27,28].…”

Erste Erfahrungen mit der sequenziellen, prospektiv getriggerten CT-Koronarangiografie an einem 128-Schicht-Computertomografen

“…herzfrequenzbasierte Pitchanpassung, EKG-adaptierter Röh-renstrommodulation) werden effektive Dosiswerte zwischen 6 und 20 mSv erreicht [5 -9]. Mit zunehmend größeren Detektoren ergibt sich die Möglichkeit einer koronaren CTA (korCTA) in sequenzieller Technik in wenigen Tischpositionen während einer einzigen Atemanhaltephase [10,11]. Hier bleibt die Datenakquisition auf einen Ausschnitt des Herzzyklus beschränkt.…”