الفهرس 
GROSS ANATOMY OF THE CORONARY ARTERYOnly 14 pages are availabe for public view
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Abstract
Multislice CT is recent development in the spiral CT. The MSCT scanners are equipped with multiple and thinner detector rows, and has a faster tube rotation speed creating two major advantages; high spatial resolution and short acquisition time that enable high-quality examinations. It is only with this immense increase in the data acquisition volume per unit time, that CT assessment of the coronary arteries has become possible .
Challenges in evaluation the coronary arteries at CT are the small size and tortuous courses of the vessels and their continuous movements being intimately related to the cardiac chambers. Controlled heart rate and good breath-holding help to reduce cardiac and respiratory motion artifacts respectively. Retrospective ECG gating and proper choice of the reconstruction window would significantly improve the examination quality.
Contraindications to CTCA include irregular heart beats (arrhythmias), contra-indications to iodinated contrast material including allergy, renal insufficiency and hyperthyroidism, contra-indications to radiation exposure, pregnancy, respiratory impairment and marked heart failure .
The study included 51 patients who were referred for invasive coronary angiography after having a MSCT coronary angiography revealing a significant coronary artery disease.
All patients had the MSCT conducted using a 64-slice Toshiba CT scanner with 64X0.5 mm collimation. The study included a pre scan calcium scoring, followed by a contrast enhanced scan. We excluded patients with dense localized calcification involving certain coronary segments (especially the proximal segments) regardless of the total coronary calcium score. The contrast was injected intravenously using a dual head power injector. All patients received non ionic, low osmolar contrast. The bolus tracking technique was used, the scan was automatically started when the contrast reached a peak concentration in the left side of the heart. All the scan were ECG gated. The ECG gating was used to retrospectively reconstruct the datasets at the mid to late diastolic phase of each cardiac cycle (75%). Few scans needed an additional systolic reconstruction to better visualize some non evaluated segments on diastolic reconstruction. Heart rate control was attempted in every patient using a beta blocker (atenolol) orally. Patients with uncontrolled heart rates and contraindication for beta blockade were excluded from the study.
All patients had their invasive coronary angiographies done within a week from the MSCT.
Both the MSCT and invasive coronary angiography data were evaluated by operators blinded to the results of the other test.
MSCT data were evaluated using the transaxial images, as well as other reconstruction modalities; multiplanar reconstructions, MIP and curved MPR. A 15-segment coronary tree model was used. Each segment was evaluated both with MSCT and coronary angiography. By MSCT segments were labeled either with significant stenosis (≥50% luminal narrowing) or with no significant stenosis (< 50% luminal narrowing). Non evaluable coronary segment were also recorded. Using invasive coronary angiography each coronary segment was labeled either normal or atherosclerotic with the degree of luminal stenosis recorded. Visual analysis was used with both tests.