Diagnostic image quality of a comprehensive high-pitch dual-spiral cardiothoracic CT protocol in patients with undifferentiated acute chest pain.
ABSTRACT OBJECTIVE: To evaluate diagnostic image quality of high-pitch dual source comprehensive cardiothoracic CT protocol in patients presenting with acute undifferentiated chest pain. MATERIALS AND METHODS: Consecutive symptomatic subjects (n=51) with undifferentiated acute chest pain underwent ECG-synchronized high-pitch dual-spiral chest CT angiography (Definition Flash, Siemens Medical Solutions, 2×100kVp or 2×120kV if BMI>30, collimation: 128×0.6mm, pitch: 3.2). Independent investigators determined the image quality of each cardiac and pulmonary vessel segment, measured contrast-to-noise-ratio (CNR), and determined radiation exposure. In addition, the prevalence of CT findings (pulmonary embolism (PE), aortic dissection (AD) and significant coronary stenosis (≥50%)) was determined. Univariate and multivariate analysis were performed to determine the subpopulation with highest diagnostic quality. RESULTS: Among 51 subjects (66% male, average age: 63±15.8), the prevalence of positive CT findings was moderate (overall: 11.7%). Overall, image quality of the pulmonary, aortic and coronary vasculature was good (1.26±0.43 and CNR: 2.52) with an average radiation dose of 3.82mSv and 3.2% of segments rated non-evaluable. The image quality was lowest in the coronary arteries (p=0.02), depending on the heart rate (r=0.52, p<0.001). In subjects with a heart rate of ≤65bpm (n=30) subjective image quality and CNR of the coronary arteries were higher (1.6±0.5 vs. 2.1±0.5, p=0.03 and 1.21±0.3 vs. 1.02±0.3, p=0.05) with only 1.5% segments classified as non-evaluable. CONCLUSION: High-pitch dual-spiral comprehensive cardiothoracic CT provides low radiation exposure with excellent image quality at heart rates ≤65bpm. In subjects with higher heart rates, image quality of the aortic and pulmonary vasculature remains excellent, while the assessment of the coronary arteries degrades substantially.