Value of ultra-low-dose chest CT with iterative reconstruction for selected emergency room patients with acute dyspnea.

OBJECTIVE: To compare the diagnostic confidence between low-dose computed-tomography (LDCT) and ultra-low-dose CT (ULDCT) of the chest on a single source CT system (SSCT) for patients with acute dyspnoea.

MATERIALS AND METHODS: One hundred thirty-three consecutive dyspnoeic patients referred from the emergency room (ER) were selected to undergo two sequential non-enhanced chest CT acquisitions: LDCT first acquisition (100kVp and 60mAs), followed by ULDCT (100kVp±20 and 10mAs). Images were reconstructed with sinogram affirmed reconstruction (SAFIRE). Objective and subjective image quality assessments were made. Two radiologists evaluated subjective image quality and the level of diagnostic confidence as certain or uncertain.

RESULTS: The mean effective doses (ED) were 1.164±0.403 and 0.182±0.028mSv for LDCT and ULDCT, respectively. Objective image quality improved significantly on lung images of ULDCT compared with LDCT (p<0.05). Subjective image quality was rated excellent/good in 90% of patients with BMI=25kg/m(2) for ULDCT. The level of diagnostic confidence was "certain" in all cases for both radiologists with excellent inter-observer agreement (k=1).

CONCLUSION: Chest ULDCT with SAFIRE on a SSCT allows a high level diagnostic confidence for the evaluation of selected acute dyspnoeic patients.