الفهرس 
STABLE CORONARY ARTERY DISEASE (SCAD)Only 14 pages are availabe for public view
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Abstract
In the evaluation of patients with suspected coronary artery disease (CAD), the role of non-invasive imaging has increased exponentially over the past decades, particularly in patients with an intermediate likelihood of CAD.
Multi-detector computed tomography (MDCT) has emerged as a powerful tool for accurate non-invasive assessment of CAD whenever “appropriate”. It has a high sensitivity and specificity for diagnosis and risk assessment of CAD if used appropriately and with proper patient selection.
Arterial enhancement is generally determined by the number of iodine molecules administered. The rate of iodine administration can be increased either by increasing the injection flow rate or by increasing the iodine concentration of the contrast agent. However, the degree of arterial enhancement following the intravenous injection of the same amount and type of contrast material is highly variable among individuals for many factors.
Each of the contrast medium concentrations has its advantages and disadvantages. Moderate concentration contrast media are currently used for most types of CT examinations, which results in a logistic advantage if the contrast medium (concentration) does not need to be changed for cardiac CTA. However, the use of lower concentration contrast media for cardiac CTA requires high injection rates and thus large needles that can facilitate these high injection rates. The use of high concentration contrast medium, on the other hand, allows lower flow rates and thus smaller needles. Also smaller contrast medium volumes are needed for administration of an identical iodine dose. High concentration contrast medium doses, however, need to be preheated because of its high viscosity at room temperature. Costs of the two concentrations are probably comparable: high concentration contrast medium is generally more expensive per volume unit.
On one hand many authors believe that contrast material with higher iodine concentration are more potent giving higher attenuation values and better image quality than lower iodine contrast materials.
In our study, we compared between image quality and attenuation values between iopromide 300 and iopromide 370 in terms of Hounsfield units (HU) in 60 patients with intermediate pretest probability of coronary artery disease coming to Ain Shams University specialized hospitals to undergo MDCT.
The study population was divided into 2 groups, group A: iopromide 300 and group B: iopromide 370.
The study population was subjected to full history taking, physical examination, 12-lead ECG, Echo, laboratory investigations and then they underwent MDCT to assess image quality and attenuation values in proximal coronaries and great arteries.
Our results showed that there is no statistically significant difference between image quality and attenuation values between iopromide 300 and iopromide 370 thus concluding that iopromide 300 is not inferior to iopromide 370 using identical amount of total iodine with fewer cost and less estimated adverse effects owing to low iodine concentration of iopromide 300.
To the best of our knowledge, there is currently no evidence that any given iodine concentration is in itself superior to the others as to the overall optimization of CTA protocols. Rather, it is the operators’ duty to make any effort to choose the most appropriate CTA protocol (ie, scanning and CM injection parameters, including iodine concentration), tailored to any single patient for any single diagnostic query by leveraging the wide variety of available iodine concentrations and scanning techniques and the flexibility of modern power injectors, in line with the ALARA (as low as reasonably achievable) principle.