Pilot multi-reader study demonstrating potential for dose reduction in dual energy hepatic CT using non-linear blending of mixed kV image datasets

To determine the potential for radiation dose reduction using sigmoidally-blended mixed-kV images from dual energy (DE) hepatic CT. Multiple contrast-enhanced, DE (80 kV/140 kV) datasets were reconstructed from 34 patients undergoing clinically-indicated examinations using routine CTDIvol. Noise was inserted in projection-space to simulate six dose levels reflecting 25-100% of the original dose. Three radiologists, blinded to dose, evaluated image preference, image quality, and diagnostic confidence (scale 1 to 5) using sigmoidally-blended, mixed-kV images, identifying the lowest acceptable dose (both image quality and confidence scores a parts per thousand yen4). At this lowest acceptable dose, the sigmoidal, 0.5 and 0.3 linear blended images were ranked in order of preference. Radiation dose level correlated with image preference (correlation coefficients = 0.94, 0.81, 0.94). However, 82% (28/34) and 97% (33/34) of examinations corresponding to dose reductions of 45% and 30%, respectively, yielded acceptable image quality and confidence for all three radiologists. These frequencies were similar whether or not a lesion was present. Each radiologist had specific preferences between mixed-kV image display techniques (p a parts per thousand currency signaEuro parts per thousand 0.006), with two most often preferring sigmoidally-blended images. There is potential for further dose reduction utilizing DE hepatic CT. Radiologist visual preference for mixed-kV images is idiosyncratic.