We used the EKG modulation of the anodic electricity (maximal current between 40% and 80% of the R-R interval of the cardiac cycle; outside of this interval,
30% of maximum electricity value was used).
The highest mA value to be employed in the percentage of the evaluated R-R interval was chosen based on the patients' BMI index,
so as to obtain values between 116,7 ± 10 mA and 388,9 ± 33,3 mA.
Between June 2017 and September 2017,
9 patients (post- optimised protocol) were studied by coronary CTA.
Acquisition parameters were the following: dual-source CT system with 64 x 0.625 collimation,
slice thickness 0,625 mm,
0.35-s rotation time with 100-kV tube.
In another group of 9 patients (pre-optimised protocol) acquisition parameters of cCTA were the following: 120-kV tube voltage and current from 600 mA to 250 mA at 40-80% of R-R interval of cardiac cycle.
The scan for the evaluation of the coronary circulation spanned from the main pulmonary artery to a few inches below the cardiac apex.
All patients were administered a bolus of 60 ml of Iomeron 400,
and the scan was synchronized using Smart Prep bolus tracking.
The images of each group of patients were sent to a dedicated workstation,
where a skilled radiologist evaluated them and filled in the diagnostic report.
To be able to compare the images,
and to assess the eligibility of each image in order to work out a diagnosis,
we developed a grading system consisting of a score fom 1 to 4,
where 1 corresponds to “poor image quality,
insufficient for a diagnostic report”,
2 is “image quality sufficient for a diagnostic report”,
3 is “good image quality” and 4 corresponds to “optimal image quality”.
Data was expressed as mean ± standard deviation.
The dosimetric indexes DLP (dose lenght product) and E (effective dose) were employed to compare the dosimetric parameters.
Mean,
maximum and minimum levels for each parameter were compared by means of two-tail Student t-test.
A p value <0.05 was considered statistically significant,
while p<0.01 was considered highly significant.