Riccardo Ferrari MD, Presenter: Nothing to Disclose

Marco Rengo MD, Abstract Co-Author: Nothing to Disclose

Luca Bertana MD, Abstract Co-Author: Nothing to Disclose

Davide Bellini MD, Abstract Co-Author: Nothing to Disclose

Tommaso Biondi, Abstract Co-Author: Nothing to Disclose

Andrea Laghi MD, Abstract Co-Author: Speaker, Bracco Group Speaker, Bayer AG Speaker, General Electric Company Speaker, Koninklijke Philips NV

The aim of our study was to compare the use of very low dose protocol in virtual colonoscopy(VC) with the use of iterative reconstruction protocols, with normal dose protocol.

55 patients underwent VC after incomplete colonoscopy.We performed two randomized different protocols in prone and supine scan: a very low radiation dose protocol (100 Kv, 50 mA, 0,5 s rotation time) with ASIR recon 50%;normal protocol without ASIR recon (120 Kv, 100 mA, 0,5 s rotation time). Preparation of patients was performed using a same day fluid tagging by mean of 60 ml of gastrografin administered 3 h before the exam. Two different expert radiologists read one series per time at one month apart. Diagnostic accuracy was compared with weighted-K test. Cad software as a second reader was used,we evaluated false positive numbers in both scans.

Diagnostic accuracy of the same reader was comparable between prone and supine scan(k=0.98); inter-readers agreement was comparable(k=0.91).15 polyps,3 cancer,7 diverticulosis disease were found.17 extracolonic findings were found. Mean mSv of low dose (LD) scans was 0,7; normal dose (ND) scans was 2,2 mSv. Mean false positive with CAD were comparable (5,6 LD; 5: ND scans ).

The correct selection of low dose protocol with iterative reconstruction can decrease the patient radiation exposition with a comparable diagnostic performance. The necessity of limited spatial resolution (polyp>6 mm) and the high difference in attenuation value between fluid marked residual, air and colon mucosa could justify the use of a very low dose protocol. Limited evaluation of abdominal organs' parenchyma, especially the liver, has to be taken into consideration, while other extracolonic findings (i.e. aortic aneurysm, rena stones) can be well evaluated.

To compare the performances of reading normal virtual colonoscopy protocols comparing them with a very low dose protocols with iterative reconstruction.

Ferrari, R, Rengo, M, Bertana, L, Bellini, D, Biondi, T, Laghi, A, Virtual Colonoscopy under 2 mSv with Iterative Reconstruction, Are We Ready?.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14016893.html