Toshiharu Miyoshi, Presenter: Nothing to Disclose

Masayuki Kanematsu MD, Abstract Co-Author: Nothing to Disclose

Satoshi Goshima MD,PhD, Abstract Co-Author: Nothing to Disclose

Hiroshi Kondo MD, Abstract Co-Author: Nothing to Disclose

Yusuke Tsuge MD, Abstract Co-Author: Nothing to Disclose

Kyongtae Tyler Bae MD, Abstract Co-Author: Patent agreement, Tyco Healthcare (Mallinckrodt Inc) Patent agreement, Schering AG (MEDRAD, Inc)

To assess depiction of vessels, image noise, and CT dose index (CTDI) with 16-detector row CT angiography (CTA) and multiplanar reformatted images (MPR) of the abdomen with auto-milliampere system, comparing 0.625- and 1.25-mm scan collimations.

In 60 patients, dual-phase source images were obtained by bolus tracking after IV 30-sec injection of 2 mL/kg contrast material (300 mgI/mL). Patients were prospectively randomized into two groups with different scan collimation (= slice thickness) and overlap (0.625 mm/0% overlap and 1.25 mm/50%). Scan time was 7.4 seconds in both groups. CTDI was monitored on the CT consol. Arterial-phase (AP) volume-rendering CTA (AP-CTA), AP-MPR, and portal venous-phase MPR (VP-MPR) were generated. Two blinded readers evaluated AP-CTA, AP-MPR, and VP-MPR for depiction of celiac trunk, hepatic, splenic, gastric, gastroduodenal, superior and inferior mesenteric, renal, adrenal arteries and veins, and their peripheral branches using a 4-point scale. Likewise, image noise was qualitatively evaluated.

For overall vascular depiction with AP-CTA, AP-MPR, and VP-MPR, no difference was found between the two groups. However, some fine arteries (lumbar, intercostal, and some 3rd-order branches) were less visualized with AP-CTA by 1.25-mm collimation (P P P = .012), but there was no difference in patients 60 kg or heavier owing to upper limit of radiation exposure by auto-milliampere system.

By using 1.25-mm collimation with 16-detector row CT, high-quality CTA and MPR with less image noise sufficient for routine examination were obtained, although some peripheral fine arteries were somewhat obscured with volume-rendering CTA. CTDI reduced with 1.25-mm collimation in patients weighing = 60 kg.

1.25-mm collimation is sufficient for routine CTA and MPR with 16-detector row CT. For better visualizing fine vessels with volume-rendering CTA, 0.625 mm may be considered despite increased noise.

Miyoshi, T, Kanematsu, M, Goshima, S, Kondo, H, Tsuge, Y, Bae, K, Vascular Depiction, Image Noise, and CT Dose Index with 16-Detector Row CT Angiography of the Abdomen: Comparison of 0.625- versus 1.25-mm Collimation Using Auto-milliampere System.  Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL. http://archive.rsna.org/2006/4432436.html