Toshihiro Ishihara RT, Presenter: Nothing to Disclose

Yoshiaki Honda RT, Abstract Co-Author: Nothing to Disclose

Norikazu Ymada, Abstract Co-Author: Nothing to Disclose

Ayako Kobayashi, Abstract Co-Author: Nothing to Disclose

Eiko Morita RT, Abstract Co-Author: Nothing to Disclose

Shuhei Oohashi RT, Abstract Co-Author: Nothing to Disclose

Tsutomu Sugiyama RT, Abstract Co-Author: Nothing to Disclose

The purpose of the present study was to compare the data acquired with and without the use of variable helical pitch in order to reduce the volume of contrast medium and ensure acceptable HU values in the coronary arteries in CT studies performed following coronary artery bypass grafting (CABG) to assess graft patency and evaluate the coronary arteries.

Twenty patients underwent MSCT for follow-up after CABG: 12 without variable helical pitch (10 men and 2 women, mean age 66.8 years, age range 53-77 years) and 8 with variable helical pitch (2 men and 6 women, mean age 67 years, age range 63-75 years). Graft patency could be accurately assessed in all patients. A 64-DAS CT scanner (Aquilion 64, Toshiba) was used. Contrast medium (370 mgI/mL) was injected (rate = [body weight  0.07] mL, volume = [scan time  injection rate] mL) followed by a saline solution flush ([body weight  0.25] mL), and ECG-gated scanning was performed to generate axial images using the retrospective gating method. The total volume of contrast medium injected and the HU value in the aorta at the origin of the left main trunk (LMT) were then measured to evaluate the effects of using variable helical pitch.  

In the group without variable helical pitch, the average contrast medium injection volume was 71.7 mL (range 50-88 mL) and the average HU value in the aorta at the origin of the LMT was 526.9 HU (range 432.3-583.7 HU). In the group with variable helical pitch, the average contrast medium injection volume was 48 mL (range 42-58 mL) and the average HU value was 510 HU (range 455.2-540.7 HU). The use of variable helical pitch allowed the contrast medium injection volume to be reduced by about 33% while maintaining a comparable HU value.

In examinations for assessing graft patency following CABG, the use of variable helical pitch permits the volume of contrast medium to be substantially reduced without a significant reduction in the HU value.

A wide scan range is needed in follow-up examinations after CABG, and the volume of contrast medium must be minimized. The volume can be reduced by using variable helical pitch.

Ishihara, T, Honda, Y, Ymada, N, Kobayashi, A, Morita, E, Oohashi, S, Sugiyama, T, Usefulness of Variable Helical Pitch in Reducing the Volume of Contrast Medium Required in 64-DAS MSCT Studies for Assessing Graft Patency Following CABG.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9006357.html