Lisan Anna Neefjes MD, Abstract Co-Author: Nothing to Disclose

Alexia Rossi MD, Presenter: Nothing to Disclose

Anoeshka Shashikala Dharampal MD, Abstract Co-Author: Nothing to Disclose

Annick C. Weustink MD, PhD, Abstract Co-Author: Nothing to Disclose

Gabriel P. Krestin MD, PhD, Abstract Co-Author: Consultant, General Electric Company Research grant, General Electric Company Research grant, Bayer AG Research grant, Siemens AG

Nico R. Mollet MD, Abstract Co-Author: Nothing to Disclose

Koen Nieman MD, PhD, Abstract Co-Author: Nothing to Disclose

Pim J. De Feyter MD, PhD, Abstract Co-Author: Nothing to Disclose

To compare radiation dose and diagnostic performance to detect significant coronary stenosis of 3 CT coronary angiography protocols using a 128-slice Dual Source CT scanner (Siemens): a prospective high pitch spiral (HPS), a prospective step-and-shoot (SAS), and a retrospective (RS) scan protocol.

We prospectively included 459 symptomatic patients with a regular heart rate (HR). Patients were categorized into 2 groups: pre-scan HR <65 bpm (group A) or ≥ 65 bpm (group B). Patients in group A (231 patients, 146 men, mean HR 58±7 bpm) were randomized to have a HPS or SAS (scan window 62-74% of the RR-interval) scan. Patients in group B (228 patients, 132 men, mean HR 75±11 bpm) were randomized to have a SAS (scan window 31-75%) or RS scan (pulsing window 31-75%). The presence of a significant stenosis (>50% lumen reduction) was assessed on a per segment level and compared with quantitative coronary angiography. The estimated radiation exposure was calculated.

Group A: Sensitivity and negative predictive value (NPV) of CT coronary angiography using HPS were significantly lower than by using the SAS protocol (89% vs. 97%, p<0.05, and 99% vs. 100%, p<0.05). Specificity and positive predictive value (PPV) were similar (95% vs. 97%, NS, and 62% vs. 73%, NS). The estimated radiation dose was significantly lower with the HPS protocol than with the SAS protocol (tube voltage 100 kV: 0.74±0.15 vs. 2.65±1.0 mSv, p<0.001 and 120 kV: 1.60±0.57 vs. 4.65±1.51 mSv, p<0.001). Group B: Sensitivity, specificity, PPV and NPV of CT coronary angiography were not significantly different using a SAS (93%, 95%, 67% and 99%, respectively) or RS scan protocol (92%, 95%, 65% and 99%, respectively, NS) . The estimated radiation dose was significantly lower with the SAS protocol than with the RS protocol (tube voltage 100 kV: 4.05±1.46 vs. 5.66±2.30 mSv, p<0.001 and 120 kV: 7.53±2.18 vs. 10.21±4.98 mSv, p<0.001).

A prospectively triggered step and shoot scan protocol using a narrow (≤65 bpm) or wide (>65 bpm) scan window is the preferred CT coronary angiography scan protocol in patients with regular heart rates using 128-slice Dual Source CT, providing optimal diagnostic quality with an “as low as reasonably achievable” radiation dose.

Careful selection of the CT coronary angiography scan protocol is mandatory to obtain diagnostic quality with an “as low as reasonably achievable” radiation dose.

Neefjes, L, Rossi, A, Dharampal, A, Weustink, A, Krestin, G, Mollet, N, Nieman, K, De Feyter, P, Diagnostic Performance of 128-slice Dual-Source CT Coronary Angiography Using Three Different Scan Protocols: A Randomized Study.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11011394.html