Wenshuai Wan BA, Presenter: Nothing to Disclose

Beverley Newman MD, Abstract Co-Author: Nothing to Disclose

Shreyas Shreenivas Vasanawala MD, PhD, Abstract Co-Author: Research support, General Electric Company Consultant, Zimmer Holdings, Inc Consultant, ArthroCare Corporation

Jeffrey A. Feinstein MD, Abstract Co-Author: Nothing to Disclose

Frandics Pak Chan MD, PhD, Abstract Co-Author: Nothing to Disclose

Conventional first-pass CTA that employs a single contrast injection rate and a single injection site may not uniformly opacify the entire cavopulmonary and Fontan circuit, confounding assessment of vascular pathology. We present a biphasic contrast injection technique in which the superior vena cava (SVC) is opacified by front loaded contrast in the upper body and the inferior vena cava (IVC) is opacified by diluted maintenance contrast injected in the lower extremity.

From 9/2006 to 11/2010, consecutive cases of CTA of the chest performed for the evaluations of cavopulmonary shunt or Fontan circuit were reviewed with retrospective IRB approval. The biphasic injection protocol required an intravenous access in a lower extremity and a dual-injector programmable for contrast dilution. A contrast volume at a dose of 3cc/kg Omnipaque-350 or Visipaque-320 was divided into two halves. The first half was injected at 100% strength for a duration equal to the scan time. The second half was injected at 30% strength for 45-60 seconds. The injection rate was adjusted to the injection volume divided by the injection duration. Bolus tracking technique was used to trigger the scan when contrast arrived at the SVC. Quality of the angiogram was assessed by the average and standard deviation of measured densities at the IVC, SVC, aorta.

13 cases of cavopulmonary shunt and 10 cases of Fontan circuit were identified. The patient’s age ranged from 3 months to 38 years. The most common cause of their single ventricle physiology was hypoplastic left heart syndrome (10), followed by large ventricular septal defect (4), double inlet left ventricle (2), atrioventricular canal defect (2), and pulmonary atresia with intact ventricular septum (2), and others (3). CTA were retrospectively gated in 15/24 cases. For cavopulmonary shunt, the contrast densities at the IVC, SVC, aorta, left were 525±226, 368±107, 401±107 HU. For Fontan circuit, they were 541±171, 285±49, 363±59 HU.

CTA with the biphasic contrast injection technique is an effective and practical method of evaluating cavopulmonary shunt and Fontan circuit.

An optimal CTA technique is needed to assess thrombosis, stenosis, and pulmonary embolism in patients with cavopulmonary shunt and Fontan circuit.

Wan, W, Newman, B, Vasanawala, S, Feinstein, J, Chan, F, Biphasic Contrast Injection Technique for CT Angiography of Cavopulmonary Shunt and Fontan Circuit.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11016952.html