James P. Earls MD, Presenter: Research support, General Electric Company

Bruce Andrew Urban MD, Abstract Co-Author: Nothing to Disclose

Charlene Andrea Curry MD, Abstract Co-Author: Nothing to Disclose

Elise L. Berman MD, Abstract Co-Author: Nothing to Disclose

Judy L. Lane, Abstract Co-Author: Nothing to Disclose

Robert Jennings RT, Abstract Co-Author: Nothing to Disclose

Prospectively Gated Axial (PGA) CT is a new method for performing coronary CT angiography. Preliminary studies have found Coronary CT angiography performed with PGA technique to be reliable, have improved image quality, and substantially reduced effective radiation dose to the patient as compared with retrospectively gated helical (RGH) CTA. Contraindication to PGA use is primarily a heart rate of greater than 70. We evaluated effective dose and reliability in a large patient cohort.

We retrospectively evaluated CT coronary angiography performed with a 64-detector row MDCT on 906 clinical patients referred for CCTA. All studies were evaluated for technique used, physiologic parameters, anatomic coverage, radiation dose, and reliability.

Of 906 patients presenting for CCTA, PGA technique was used in 854(94.3%), RGH was used in 52(5.5%). A HR of > 70 bpm was the most common reason for not using PGA technique (n=45). The PGA group included 570 males and 336 females, mean age 53.9 yrs, mean BMI 27.7 (range 14.6 to 58.0). 839 (97%) of 854 PGA exams were considered successful and of diagnostic quality, 25 exams had to either be repeated or were cancelled. The mean effective dose of PGA studies was 2.60 mSv (range 0.55 to 6.7 mSv). The mean volume CT dose index (CTDIvol) was 13.0 mGy (range 3.4 to 37.4 mGy). The z-axis coverage was obtained by acquiring 3 groups of 64 images (with 2 incremental translations) in 40.0%, 4 groups in 58.5%, and 5 groups in 1.5%. The tube current averaged 511 mA (range 300 to 800 mA), and the tube on time averaged 0.9 sec (range 0.7 to 1.9 sec).

In a large patient cohort, prospectively gated axial CT coronary angiography demonstrated substantial radiation dose savings. The reliability of the technique remains high with a small percentage of non-diagnostic studies. With beta-blockade, the large majority of clinical patients can be scanned using this technique.

Prospectively gated axial CT can be used clinically with similar reliability rates and substantially reduced radiation dose as compared with helical CT for performing coronary CTA.

Earls, J, Urban, B, Curry, C, Berman, E, Lane, J, Jennings, R, Prospectively-gated Coronary CT Angiography: An Evaluation of Effective Dose and Reliability in a Large Patient Group.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5009018.html