Review ArticleCardiac CT: How much can temporal resolution, spatial resolution, and volume coverage be improved?
Section snippets
Challenges for cardiac CT
Scan data acquisition in computed tomography (CT) imaging of the heart is controlled by the patient's electrocardiogram (ECG) to provide images in the same relative phase of the cardiac cycle. Cardiac CT requires high temporal resolution, ie, short exposure time of the individual images, to avoid image distortion by cardiac motion. Excellent spatial resolution (at best submillimeter) is a prerequisite for adequate visualization of the heart's small anatomical structures, such as the coronary
Spatial resolution
The in-plane spatial resolution of a CT system is limited by the number of active detector channels in a detector row and by their aperture, ie, the width of each individual detector channel. With 700–900 detector channels covering a scan field of view (SFOV) of usually 500 mm, the in-plane sampling distance, ie, the distance between 2 detector channels, is 0.56–0.71 mm in the isocenter of the scanner. Modern CT scanners use techniques such as quarter detector offset or in-plane flying focal spot
Temporal Resolution
In ECG-synchronized cardiac MDCT, scan data acquisition and image reconstruction are controlled by the patient's ECG. In prospectively ECG-triggered sequential CT, the patient's ECG signal is used to trigger axial scans at different z-positions (different anatomical levels) with a user-defined temporal offset relative to the R waves.25, 26 A volume image of the heart consists of several image slabs reconstructed from axial scan data acquired in multiple consecutive heart beats. The number of
Volume Coverage
With typical MDCT detector z-coverages of 40 mm and recently up to 80 mm (the z-direction is the patient's longitudinal direction), an ECG-synchronized volume image of the heart still consists of several image slabs reconstructed from data acquired in multiple consecutive heart beats (Fig. 6 and Fig. 7). As a consequence of insufficient temporal resolution and variations of the heart motion from one cardiac cycle to the next, in particular in the case of arrhythmia, these image slabs can be
Conclusion
We presented various approaches to improve temporal resolution, spatial resolution, and volume coverage in ECG-synchronized cardiac CT, and we discussed the technical and practical limitations. Technical progress alone, however, does not necessarily translate into better diagnostic or prognostic value of cardiac imaging or into improved patient outcomes. Complementary to the ongoing refinement of imaging techniques clinical studies are required as a basis for establishing cardiac CT in routine
References (36)
- et al.
Usefulness of multislice spiral computed tomography angiography for determination of coronary artery stenoses
Am J Cardiol
(2001) - et al.
Coronary angiography with multi-slice computed tomography
Lancet
(2001) - et al.
Multislice spiral computed tomography coronary angiography in patients with stable angina pectoris
J Am Coll Cardiol
(2004) - et al.
Noninvasive detection of coronary lesions using 16-detector multislice spiral computed tomography technology
J Am Coll Cardiol
(2004) - et al.
Quantification of obstructive and nonobstructive coronary lesions by 64-slice computed tomography
J Am Coll Cardiol
(2005) - et al.
Diagnostic accuracy of noninvasive coronary angiography using 64-slice spiral computed tomography
J Am Coll Cardiol
(2005) - et al.
Technical principles of dual source CT
Eur J Radiol
(2008) - et al.
Contrast-enhanced coronary artery visualization by dual-source computed tomography–initial experience
Eur J Radiol
(2006) - et al.
Influence of heart rate on the diagnostic accuracy of dual-source computed tomography coronary angiography
J Am Coll Cardiol
(2007) - et al.
ECG-correlated image reconstruction from subsecond multi-slice spiral CT scans of the heart
Med Phys.
(2000)
High temporal resolution for multi-slice helical computed tomography
Med Phys.
Cardiac imaging by means of electro-cardiographically gated multisection spiral CT–initial experience
Radiology
Noninvasive coronary angiography by retrospectively ECG-gated multislice spiral CT
Circulation
Imaging of noncalcified coronary plaques using helical CT with retrospective EKG gating
AJR Am J Roentgenol
Coronary arteries: retrospectively ECG-gated multi-detector row CT angiography with selective optimization of the reconstruction window
Radiology
Image reconstruction and performance evaluation for ECG-gated spiral scanning with a 16-slice CT system
Med Phys
Reliable noninvasive coronary angiography with fast submillimeter multislice spiral computed tomography
Circulation
Detection of coronary artery stenoses with thin-slice multi-detector row spiral computed tomography and multiplanar reconstruction
Circulation
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2013, Earth-Science ReviewsCitation Excerpt :Following technological advances, different generations of CT scanners have been conceived (Goldman, 2007), with recent developments towards dual-energy (Flohr et al., 2006; Primak et al., 2007; Graser et al., 2009) and energy selective CT (Barber et al., 2011). Temporal resolution has improved to less than 100 ms (Flohr et al., 2009). In contrast, spatial resolution remains limited to several hundreds of micrometres due to the dimension of the investigated object, i.e. a human patient.
Conflict of interest: The authors are employees of Siemens Healthcare, Forchheim, Germany.