Evaluation of a High Iodine Delivery Rate in Combination With Low Tube Current for Dose Reduction in Pulmonary Computed Tomography Angiography

Purpose: The present study evaluates the combination of a high iodine delivery rate with a low tube current-time product for pulmonary computed tomography angiography (CTA). Materials and Methods: One-hundred nineteen consecutive patients undergoing pulmonary CTA for suspected pulmonary embolism were included and imaged on a 128-row computed tomography scanner at 100 kVp using highly concentrated contrast material (85mL Iomeprol; 400mg iodine/mL). The protocol entailed a flow rate of 5 mL/s and 90 mAs for group A, 3.5 mL/s and 135 mAs for group B, 5 mL/s and 135 mAs for group C, and 3.5 mL/s and 90 mAs for group D. Signal-to-noise ratio and contrast-to-noise ratio (CNR) were determined for the pulmonary artery. Subjective image quality (IQ) was rated on a 5-point scale (1 = nondiagnostic IQ to 5 = excellent IQ). Results: CNR did not differ significantly between groups A (43.7 +/- 27.7), B (34.5 +/- 17.9), and C (38.9 +/- 13.8), as well as between groups B and D (29.9 +/- 11.2). CNR was higher in groups A and C than in group D (P < 0.02). Subjective IQ was higher in group A than in groups B and D (P < 0.05). Subjective IQ was significantly higher in group A compared with group D (P = 0.026) and in group C compared with group D (P = 0.007). Conclusions: A high iodine delivery rate permits dose reduction in pulmonary CTA and can be recommended in patients with suspected pulmonary embolism.