Guillermo Viteri-Ramírez, Abstract Co-Author: Nothing to Disclose

Amaja Garcia-Lallana, Abstract Co-Author: Nothing to Disclose

Jordi Broncano MD, Presenter: Nothing to Disclose

Isabel Simón-Yarza MD, Abstract Co-Author: Nothing to Disclose

Jesus Pueyo MD, PhD, Abstract Co-Author: Nothing to Disclose

Gorka Bastarrika MD, Abstract Co-Author: Nothing to Disclose

Pulmonary CT Angiography (CTA) is being increasingly used for the diagnosis and follow-up of pulmonary embolism (PE). However, it implies a non-negligible amount of intravenous contrast and radiation dose. The aim of this prospective study was to determine image quality and diagnostic performance of an optimized CTA protocol in terms of radiation exposure and volume of contrast, with respect to a standard CTA protocol.

After written informed consent, 86 consecutive patients (49 male, 37 female, mean age 62.8±17.1 years, mean body weight 71.9±12.9 kg) with clinical suspicion of PE were prospectively enrolled. Individuals weighting ≤ 80 kg (group A) were evaluated with a low-contrast, low-radiation pulmonary CTA protocol (80kV/60 ml at 4ml/s) whereas a conventional CTA protocol (100 kV/80 ml at 4ml/s) was used for patients >80 kg (group B). In all exams, the presence of PE and image quality parameters (contrast attenuation in central and peripheral pulmonary arteries, the contrast to noise ratio-CNR and the signal to noise ratio-SNR) were assessed. Effective radiation dose (mSv) was estimated. An independent sample student t-test was employed to compare quantitative image quality parameters and estimated effective radiation doses in both groups. A p value <0.05 was considered statistically significant.

PE was found in 14 patients (5 of group A, 9 of group B). The mean attenuation of the pulmonary arteries was significantly higher in group A (365.5±98.6 HU) than in group B (255. 9±120.4) whereas CNR and SNR did not statistically differ (14.8±7.4 and 16.2±7.4 for group A and 12.1±7.9 and 13.3±8.2 for group B, respectively). The estimated effective radiation dose was significantly lower with 80 kV protocol (1.1±0.7 mSv) as compared with 100 kV acquisition mode (2.8±1.1 mSv).

In individuals weighting ≤ 80 kg the evaluated low-radiation-dose, low-contrast pulmonary CTA protocol allows accurate depiction of PE with a similar image quality as conventional pulmonary CTA while reducing patient exposure to radiation by more than 50% and the contrast media volume by 20%.

A low radiation and low-contrast dose CTA protocol enables accurate depiction of PE with unimpaired image quality and significant reduction of the contrast and radiation dose in non-obese patients.

Viteri-Ramírez, G, Garcia-Lallana, A, Broncano, J, Simón-Yarza, I, Pueyo, J, Bastarrika, G, Low Radiation and Low Contrast Dose Pulmonary CT Angiography: Comparison of 80kV/60mL and 100 kV/80mL Protocols.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9011282.html