Jeffrey David Jaskolka MD, Presenter: Nothing to Disclose

Claire Bent MBBS, Abstract Co-Author: Nothing to Disclose

Dheeraj Kumar Rajan MD, Abstract Co-Author: Nothing to Disclose

To develop and evaluate a protocol for CT angiography (CTA) of the abdomen and lower extremities using 320 channel multidetector CT.

The study was approved by the local IRB and all patients provided written informed consent. This was a prospective pilot study in 15 healthy male volunteers aged 21-50 (mean 33). Subjects were scanned from diaphragm to the toes in a wide-volume step-and-shoot mode after bolus intravenous injection of 80mL of nonionic isosmolar iodinated contrast, 320mgI/mL. The scan was triggered using bolus tracking software when the attenuation of the juxtarenal abdominal aorta reached 180HU. The scan was performed in 2 parts: from diaphragm-knees and knees-toes, with a small overlap at the knees. The vascular tree was divided into 22 segments for subjective and objective image quality assessment. Subjective quality was assessed by 2 blinded readers who rated each segment on a 5 point Likert scale. Objective quality was assessed at each segment by calculation of signal-to-noise ratio in the artery and contrast-to-noise ratio of the artery relative to muscle. Interobserver agreement was analyzed with a weighted kappa statistic and the relationship between subjective and objective measures of quality was assessed with Spearman’s correlation coefficient.

Average vessel SNR was 6.04 +/- 3.05 and average CNR was 3.34 +/- 1.88. Mean overall subjective quality was rated as 3.6 +/- 0.8 by reader 1 and 4.0 +/- 0.8 by reader 2. Weighted kappa value was 0.783 (CI 0.557-1.000, p=0.0003) for these ratings. 93% of scans were rated as diagnostic quality (Likert score 3 or higher) by both readers. Spearman's correlation coefficient between subjective image quality and SNR was 0.752 and 0.766 for reader 1 and 2 respectively. Spearman's correlation coefficient between subjective image quality and CNR was 0.673 and 0.658 for reader 1 and 2 respectively.

320 detector CTA of the abdomen and lower extremities can be performed using a low volume of intravenous contrast, and results in diagnostic image quality as assessed both subjectively and objectively. Further study is required in patients with peripheral vascular disease to determine the accuracy of this technique.

CT angiography on a 320 detector scanner provides opportunities for using decreased iodinated contrast in patients with renal insufficiency and decreased artifacts from heavily calcified vessels.

Jaskolka, J, Bent, C, Rajan, D, Preliminary Experience with 320 Detector CT Angiography of the Abdomen and Lower Extremities.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8004874.html