Abstract 1602: Image Quality and Diagnostic Accuracy of CTA for Acute Pulmonary Embolism: Comparison of Various Protocols for Contrast Administration
AUTHORS:
M. Prokop, MD, C.M. Schaefer-Prokop, MD, J. Hahne, C.J. Herold, MD.
ABSTRACT:
PURPOSE: To assess the influence of contrast administration protocols on image quality and diagnostic accuracy of CT angiography for the diagnosis of acute pulmonary embolism.
METHOD AND MATERIALS: From all patients that entered the ESTIPEP multi-center trial on CT angiography for suspected pulmonary embolism we selected the examinations that used one of the following four contrast administration protocols: A. 80ml, flow 2.7ml (low volume / low flow): n = 130 B. 120ml, flow 3ml/s (moderate volume / moderate flow): n = 289 C. 140-150ml, flow 4-5ml/s (high volume / high flow): n = 36 D. 200ml (150mg iodine/ml), flow 3.3ml/s (high volume / low concentration): n = 41. Images were subjectively scored according to contrast enhancement at various levels, artifacts, and overall image quality. Diagnostic accuracy was assessed in the subset of patients that completed the ESTIPEP study protocol and thus had a gold standard available (n = 226).
RESULTS: Diagnostic accuracy was best for protocols C (94%) and B (88%) versus D (77%) and A (70%). Image quality was rated excellent in 78% with protocol C versus 68%, 56%, and 12% for protocols D, B, and A, respectively. The number of examinations with excellent contrast enhancement was highest with protocol C (61%) versus 47-48% with protocols B and D, and only 22% for protocol A. With respect to artifacts (streaks, motion, noise), differences between protocols were less pronounced. The percentage of exams that were rated indeterminate or non-diagnostic was least for protocol C (3%), followed by protocols B (6%), D (20%) and A (27%).
CONCLUSIONS: For CTA of pulmonary embolism a high volume / high flow protocol yields significantly superior results with respect to image quality and diagnostic accuracy.
