Pushing the Envelope

Abstract

Multidetector row computed tomography (MDCT) has been used for cardiothoracic imaging since the advent of 4-slice computed tomography (CT) in 1999. Available since 2004, 64-slice CT systems are currently considered a prerequisite for successfully integrating cardiothoracic CT into routine clinical algorithms. Developments are ongoing that aim to solve the remaining challenges of cardiothoracic CT. In this review article, we focus on 3 aspects that have significantly influenced the design of newer CT scanners. (1) A faster scan speed enables coverage of the cardiothoracic anatomy in shorter scan times, which is beneficial for patients with limited ability to cooperate and opens new clinical possibilities. A coveted goal for cardiac CT is a "snapshot image" of the entire heart in 1 cardiac cycle, which can be obtained by using MDCT systems with area detectors or dual-source CT systems with electrocardiogram (ECG)-triggered high-pitch spiral. (2) Techniques to reduce the radiation dose to the patient, such as ECG-controlled dose modulation, ECG-triggered sequential CT, low kV scanning, and iterative reconstruction, have gained considerable attention as a consequence of the ongoing discussion of radiation exposure by CT. (3) New developments aim to establish a role for CT in the functional imaging of the lung and of the heart beyond the mere visualization of anatomy. Evaluation of the first-pass enhancement of the myocardium, with single-energy or with dual-energy data acquisition, and cardiac perfusion examinations may have the potential to enhance the application spectrum of cardiac CT by providing the means to determine the hemodynamic relevance of coronary artery stenosis.