Gonzalo Tardaguila De La Fuente MD, Presenter: Nothing to Disclose

Carlos Delgado MD, Abstract Co-Author: Nothing to Disclose

Daniel Castellon PhD, Abstract Co-Author: Nothing to Disclose

María Vázquez, Abstract Co-Author: Nothing to Disclose

Marcelo Sanmartin, Abstract Co-Author: Nothing to Disclose

Francisco Tardaguila Montero MD, Abstract Co-Author: Nothing to Disclose

Prospective high pitch acquisitions in cardiac imaging allow us to obtain the whole heart in one beat. Low dose studies are performed but when artifact appears we cannot edit the ECG or change the phase so the solution is to repeat the study. The aim of this study is to determinate how often studies have to be repeated, why they have to be done again and radiation dose of the original study and the total dose of both acquisitions

118 patients underwent high pitch cardiac DSCT(September 09 and March 10) High pitch technique was used when heart rate<65bpm spontaneously or after the administration of betablockers. Patients received vasodilatator if no contraindicated. Imaging protocol: rotation speed: 0,28 s, table speed: 460 mm/s, pitch: 3,4, collimation: 2x128x0.6mm and tube current 320mAs/rotation. Tube potential was 100Kv (patients<80Kg), 120Kv (patients>80Kg) and 140Kv (stent studies). We analyzed dose of the study, number non repeated studies, number of cases that need to be repeated, cause of the repetition, type of acquisition of the repetition (high pitch, prospectively or retrospectively triggered) and total dose of repeated studies  

118 patients were studied. 25 needed to be repeated (21,2%). Causes: 16 studies had to be repeated because of rhythm alterations during the acquisition, 6 due to isolated extrasystoles and 3 due to unclear reasons. The second acquisition was another high pitch CT in 12 patients (48%), in 4 (16%) cases a prospectively triggered scan was obtained and a retrospectively triggered CT was performed in 9 cases (36%). Radiation dose of non repeated studies was 1,23±0,54mSv. Total dose of repeated studies (including the initial high pitch) was 4,8mSv. 3,04±1,04mSv when a second high pitch is done, 5,51±2,3mSv when a prospectively triggered and 7,53±3,72mSv when retrospectively triggered is performed.  

Although a relevant number of high pitch cardiac studies (21%) had to be repeated, the low dose of these studies makes it worth to choose this type of acquisition when possible. Even if it has to be repeated the total dose is acceptable and when a second high pitch is done even lower than the dose of standard pitch MDCT.

 Up to 20% of the prospective high pitch cardiac studies have to be repeated, but radiation dose is so low that it should be considered as the first option when heart rate is lower than 65 bpm.

Tardaguila De La Fuente, G, Delgado, C, Castellon, D, Vázquez, M, Sanmartin, M, Tardaguila Montero, F, Study Repetition of Nonsatisfactory Prospective High Pitch Acquisitions in Cardiac Imaging with 128 DSCT: Frequency, Radiation Dose, and Meaning.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9013874.html