Michael Kemal Atalay MD, PhD, Abstract Co-Author: Speaker, General Electric Company

Shawn Hajimomenian MD, Presenter: Nothing to Disclose

David J. Grand MD, Abstract Co-Author: Nothing to Disclose

To compare three different contrast injection protocols for ECG-gated 64-slice CTA in terms of vessel density and perceived exam quality.

We reviewed 30 consecutive CTA studies for each of 3 different contrast protocols (P1, P2, P3)—90 studies in total. Studies were conducted on a 64-slice CT scanner (GE VCT) using IV iodixanol 320 (V). Scan parameters were constant (FOV: 25cm, pitch: 0.18-0.22, slice: 0.62 mm), and acquisition was cranio-caudal from aortic arch through diaphragm. All studies had a 20 cc timing bolus (TB), monitored at the aortic root. P1: 50cc V @5 cc/s, 40cc V/10cc saline @4cc/s, 40cc saline @4cc/s. P2: 50cc V @5 cc/s, 30-50cc V @3.5cc/s (dependent on TB), 50cc saline @3.5 cc/s. P3: 60cc V @5.5 cc/s, 50cc V @4.5 cc/s, 50cc saline @3.5 cc/s. Density measurements were made at 30 points in the heart and thoracic vessels. Each study was graded for its diagnostic quality for PE and coronary artery (CA) evaluability by two radiologists independently (0=non-diagnostic, 1=fair, 2=good, 3=very good).

The numbers of non-diagnostic PE studies (ave. grade0.01). Aortic densities at the root and diaphragm for P1 were 400±82 & 354±90, for P2: 379±84 & 357±100, and for P3: 372±82 & 351±96. No significant differences were noted between groups for aortic and CA densities.

All 3 protocols yield high density values in the CAs & aorta and high quality CA evaluation. P2 and P3 are also robust for PE assessment, though P3 is slightly preferred. However, P2 offers a contrast savings of 10-30cc.

A robust “triple rule out” thoracic CTA yielding high density in all vessels of interest is possible with 130cc of contrast.

Atalay, M, Hajimomenian, S, Grand, D, Three Contrast Injection Protocols for ECG-gated 64-slice CT Angiography (CTA): A Search for the Best and Brightest.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5012226.html