title: Dual-energy CT for detection of endoleaks after endovascular abdominal aneurysm repair: usefulness of colored iodine overlay.
abstract: OBJECTIVE
  The purpose of our study was to evaluate the value of dual-source dual-energy CT with colored iodine overlay for detection of endoleaks after endovascular abdominal aortic aneurysm repair. We also calculated the potential dose reduction by using a dual-energy CT single-phase protocol.
  
  
  METHODS
  From November 2007 to November 2009, 74 patients underwent CT angiography 2-7 days after endovascular repair during single-energy unenhanced and dual-energy venous phases. By using dual-energy software, the iodine overlay was superimposed on venous phase images with different percentages ranging between 0 (virtual unenhanced images) and 50-75% to show the iodine in an orange color. Two blinded readers evaluated the data for diagnosis of endoleaks during standard unenhanced and venous phase images (session 1, standard of reference) and virtual unenhanced and venous phase images with colored iodine overlay images (session 2). We compared the effective dose radiation of a single-energy biphasic protocol with that of a single-phase dual-energy protocol. The diagnostic accuracy of session 2 was calculated.
  
  
  RESULTS
  The mean dual-energy effective dose was 7.27 mSv. By using a dual-energy single-phase protocol, we obtained a mean dose reduction of 28% with respect to a single-energy biphasic protocol. The diagnostic accuracy of session 2 was: 100% sensitivity, 100% specificity, 100% negative predictive value, and 100% positive predictive value. Statistically significant differences in the level of confidence for endoleak detection between the two sessions were found by reviewers for scores 3-5.
  
  
  CONCLUSIONS
  Dual-energy CT with colored iodine overlay is a useful diagnostic tool in endoleak detection. The use of a dual-energy single-phase study protocol will lower radiation exposure to patients.
authors: Department of Radiological Sciences, University of Messina, Policlinico G. Martino, Via Consolare Valeria 1, 98100, Messina, Italy.
authors: Giorgio
authors: G
authors: Ascenti
authors: Silvio
authors: S
authors: Mazziotti
authors: Salvatore
authors: S
authors: Lamberto
authors: Antonio
authors: A
authors: Bottari
authors: Simona
authors: S
authors: Caloggero
authors: Sergio
authors: S
authors: Racchiusa
authors: Achille
authors: A
authors: Mileto
authors: Emanuele
authors: E
authors: Scribano