Pushing the Envelope

Siemens Healthcare, Computed Tomography Division, Forchheim, Germany.
Journal of thoracic imaging (Impact Factor: 1.74). 05/2010; 25(2):100-11. DOI: 10.1097/RTI.0b013e3181d7e898
Source: PubMed


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.

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    • "A diagnostic image quality can be achieved in 97% of coronary segments with high-pitch CTCA [16–18]. These studies recommend this prospective, R-wave triggered, high-pitch scanning mode for patients with low and regular heart rates (<55–60 beats per minute) to acquire the complete dataset before the onset of atrial contraction [7, 9, 10]. "
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    ABSTRACT: Purpose. To estimate effective dose and organ equivalent doses of prospective ECG-triggered high-pitch CTCA. Materials and Methods. For dose measurements, an Alderson-Rando phantom equipped with thermoluminescent dosimeters was used. The effective dose was calculated according to ICRP 103. Exposure was performed on a second-generation dual-source scanner (SOMATOM Definition Flash, Siemens Medical Solutions, Germany). The following scan parameters were used: 320 mAs per rotation, 100 and 120 kV, pitch 3.4 for prospectively ECG-triggered high-pitch CTCA, scan range of 13.5 cm, collimation 64 × 2 × 0.6 mm with z-flying focal spot, gantry rotation time 280 ms, and simulated heart rate of 60 beats per minute. Results. Depending on the applied tube potential, the effective whole-body dose of the cardiac scan ranged from 1.1 mSv to 1.6 mSv and from 1.2 to 1.8 mSv for males and females, respectively. The radiosensitive breast tissue in the range of the primary beam caused an increased female-specific effective dose of 8.6%±0.3% compared to males. Decreasing the tube potential, a significant reduction of the effective dose of 35.8% and 36.0% can be achieved for males and females, respectively (P < 0.001). Conclusion. The radiologist and the CT technician should be aware of this new dose-saving strategy to keep the radiation exposure as low as reasonablly achievable.
    05/2012; 2012:724129. DOI:10.1155/2012/724129
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    • "Iterative reconstruction methods became of clinical interest in nuclear medicine imaging with the accelerated convergence achieved by the ordered subset expectation maximisation (OSEM) algorithm [48]. Lately iterative image reconstruction has been proposed for clinical CT imaging as well, particularly as a method of keeping radiation exposure at low levels for an overall reduced patient exposure [49]. "
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    ABSTRACT: Since the 1990s, hybrid imaging by means of software and hardware image fusion alike allows the intrinsic combination of functional and anatomical image information. This review summarises the state-of-the-art of dual-modality imaging with a focus on clinical applications. We highlight selected areas for potential improvement of combined imaging technologies and new applications. In the second part, we briefly review the background of dual-modality PET/CT imaging, discuss its main applications and attempt to predict technological and methodological improvements of combined PET/CT imaging. After a decade of clinical evaluation, PET/CT will continue to have a significant impact on patient management, mainly in the area of oncological diseases. By adopting more innovative acquisition schemes and data processing PET/CT will become a fast and dose-efficient imaging method and an integral part of state-of-the-art clinical patient management.
    Insights into Imaging 06/2011; 2(3):225-34. DOI:10.1007/s13244-011-0069-4
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    ABSTRACT: Computed tomographic (CT) pulmonary angiography (CTPA) has become the de facto clinical gold-standard for the diagnosis of pulmonary embolism (PE) due to its high sensitivity and specificity. Direct detection or exclusion of PE and diagnosis of various other diseases that mimic symptoms of PE can be accomplished in a single exam. In addition, CTPA allows rapid risk assessment by providing a number of predictive markers for accurate risk stratification and patient management. This article reviews the current role of routine CT techniques and recently introduced dual-energy CTPA for the diagnosis of PE as well as the role of CT for the assessment of right ventricular dysfunction in the setting of acute PE.
    Current Cardiovascular Imaging Reports 12/2011; 4(6). DOI:10.1007/s12410-011-9112-6
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