90-kVp low-tube-voltage CT pulmonary angiography in combination with advanced modelled iterative reconstruction algorithm: effects on radiation dose, image quality, and diagnostic accuracy for the detection of pulmonary embolism.
To evaluate low-tube-voltage 90-kVp computed tomography pulmonary angiography (CTPA) with advanced modelled iterative reconstruction algorithm (Admire) compared to 120-kVp equivalent dual-energy acquisition with regards to radiation exposure, image quality, and diagnostic accuracy for pulmonary embolism (PE) assessment.
CTPA studies of 40 patients with suspected PE (56.7 ± 16.3 years) performed on a third-generation 192-slice dual-source CT scanner were retrospectively included. 120-kVp equivalent linearly-blended (60% 90-kVp, 40% 150-kVp) and 90-kVp images were reconstructed. Attenuation and noise of the pulmonary trunk were measured to calculate contrast-to-noise ratios (CNR). Three radiologists assessed the presence of central and segmental PE and diagnostic confidence. Inter-observer agreement was calculated using intraclass correlation coefficient (ICC). Radiation exposure was assessed as effective dose (ED).
Pulmonary trunk CNR values were significantly increased in 90-kVp compared to linearly-blended series (15.4 ± 6.3 vs . 11.3 ± 4.6, p < 0.001). Diagnostic accuracy for PE assessment was similar in both series with excellent inter-observer agreement (p = 0.48; ICC, 0.83; p = 0.48). Overall confidence for PE assessment was rated excellent for both series with a significant advantage for linearly-blended series (p < 0.001; 4.1 vs 3.8). ED was reduced by 37.2% with 90-kVp compared to 120-kVp equivalent image series (1.1 ± 0.6 vs . 1.7 ± 0.7 mSv, p < 0.001).
90-kVp CTPA with Admire provided increased quantitative image quality with similar diagnostic accuracy and confidence for PE assessment compared to 120-kVp equivalent acquisition, while radiation dose was reduced by 37.2%. Advances in knowledge: 90-kVp CTPA with an advanced iterative reconstruction algorithm results in excellent image quality and reduction of radiation exposure without limiting diagnostic performance.