الفهرس 
Anatomy of the Coronary by Multi-Slice CT
Frequent Coronary Artery VariantsOnly 14 pages are availabe for public view
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Abstract
CT atherosclerosis imaging is a major area of imaging research with CTA. By simultaneously assessing luminal stenosis and plaque burden, CTA allows the description of atherosclerotic disease patterns.
The technology advancement from 16- to 64-slice systems progressed in a relatively uniform fashion with improved craniocaudal volume coverage, decreased gantry rotation time, and smaller detector elements.
Scanners with significant further increase in the number of detectors will allow imaging of the entire heart in one rotation, therefore obviating the need to move the patient table represented currently by the 320-slice dynamic volume CT scanner.
The recent introduction of 320-slice MSCT has further reduced acquisition time and contrast administration and also eliminates stair-step artifacts seen in helical scanning techniques. Preliminary observations with this novel technique show promising results with respect to image quality and diagnostic performance.
The 320MDCT scanner allows 16-cm coverage of any part of the body in one scan rotation and clinical advantages of 320MDCT cardiac scanning compared with 64MDCT include:
1. Improved cardiac coverage which allows whole heart to be imaged in one scan rotation, which reduces imaging and breath hold times.
2. Step artifacts, which are commonly seen using prospective gating with 64MDCT, are no longer present with 320MDCT.
3. Reduced amount of contrast medium injected to 50 ml instead of 80–90 ml, due to fast scan time.
4. Prospective gating is default scanning method with 320MSCT scanner and phase window of scanning can be a single phase or performed with wider scanning window which allows higher percentage of diagnostic scans.
5. Spatial resolution has improved even though we did not expect it, as detector width is unchanged at 0.5 mm, but due to single volume acquisition and absence of helical reconstruction algorithms, there is now much less blooming seen with calcium and stent imaging has improved.
6. New arrhythmia software allows us to image when ectopics or PVCs occur and atrial fibrillation is now also easily imaged.
7. Myocardial perfusion imaging is the next frontier in cardiac CT & now there is multicentre trial to assess myocardial perfusion.
Several limitations of MSCT coronary angiography remain despite current developments. Importantly, the presence of extensively calcified plaque may cause overestimation of stenosis severity. Finally, the evaluation of degree of lumen stenosis is limited to visual assessment, while no validated quantitative algorithms are yet available for this purpose. To improve accuracy and reproducibility, a validated approach to stenosis quantification would be desirable.
Conclusions
The recent introduction of 320-row MDCT has further reduced acquisition time, radiation and contrast administration and also eliminates stair-step artifacts seen in helical scanning techniques. Preliminary observations with this novel technique show promising results with respect to image quality and diagnostic performance. For the first time, patients with cardiac arrhythmias are now candidates for CT non-invasive angiography. Furthermore, initial studies have demonstrated that 320-row detector CT enables comprehensive coronary arterial and perfusion imaging.