Lee M. Mitsumori MD, MS, Presenter: Nothing to Disclose

Bill H. Warren MD, Abstract Co-Author: Nothing to Disclose

Janet M. May MS, Abstract Co-Author: Research grant, General Electric Company

Kelley Branch MD, Abstract Co-Author: Research grant, General Electric Company, Milwaukee, WI

Florence H. Sheehan MD, Abstract Co-Author: Nothing to Disclose

William Phelps Shuman MD, Abstract Co-Author: Research grant, General Electric Company, Milwaukee, WI

Steven Kohlmyer MS, Abstract Co-Author: Employee, General Electric Company

Theodore J. Dubinsky MD, Abstract Co-Author: Nothing to Disclose

Kalpana M. Kanal PhD, Abstract Co-Author: Nothing to Disclose

Josh Busch MD, Abstract Co-Author: Nothing to Disclose

James Caldwell MD, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

To demonstrate that prospective ECG gating (PG)—which allows cardiac gating at lower radiation doses than retrospective scans—can be used to image the entire aorta and to compare scan performance with nongated (NG) helical CT aortograms.

Since 11/06, 58 clinical 64d CT aortograms have been done with prospective ECG gating. These step-and-shoot scans were prescribed from lung apices to femoral trochanters (0.625 mm, 120 kVp, 75% R-R,). The mA for each scan was set to approximate the average value of a mA look-up table calculated from the scouts. No beta blockers were provided, and a dual syringe injector protocol was used: 50 ml iodixanol (320 mg/ml) at 5 cc/s + 80 ml contrast at 3 cc/s + 20 ml saline at 3 cc/s. Timing was peak + 5s based on a test bolus—ROI in the descending thoracic aorta. To assess differences in image quality of PG scans to our clinical NG helical CT aortograms, 16 of these patients were found that had both a PG and a prior NG 64d CTA. Exam information was removed, then these 16 pairs of studies were separately and randomly evaluated by two blinded reviewers to assess (a) overall exam quality (0-4, 4 highest), and the (b) presence of motion artifacts (0-3, 3 worst) in 7 aortic locations (root, mid ascending thoracic, mid arch, proximal descending, distal descending, infrarenal, bifurcation).

Overall exam quality of the 16 PG CTA studies was better (3.39 ± 0.71) than the NG exams done in the same patients (2.94 ± 1.0). PG did produce lower motion artifact scores in the root (mean 0.4 ± 0.75), ascending thoracic aorta (0.25 ± 0.55), and arch (0.1 ± 0.31) when compared to the NG exams (root 1.38 ± 1.2, ascending 0.69 ± 0.79, arch 0.25 ± 0.45), with the total mean motion score being significantly less with PG than NG scans (p = 0.02).

PG 64d CTA of the entire aorta can be performed with equivalent exam quality as a NG helical scan, but with the benefit of reducing the degree of vascular motion artifacts in the aorta.

Prospective ECG gated 64d CTA of the entire aorta can be performed to reduce aortic motion artifacts, improving visualization of the root and ascending thoracic aorta.

Mitsumori, L, Warren, B, May, J, Branch, K, Sheehan, F, Shuman, W, Kohlmyer, S, Dubinsky, T, Kanal, K, Busch, J, Caldwell, J, et al, , et al, , Prospective ECG-gated 64d CTA of the Thoracoabdominal Aorta with Comparison to Nongated Helical 64d Scans in the Same Patients.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5005780.html