Pilot multi-reader study demonstrating potential for dose reduction in dual energy hepatic CT using non-linear blending of mixed kV image datasets.
OBJECTIVE
To determine the potential for radiation dose reduction using sigmoidally-blended mixed-kV images from dual energy (DE) hepatic CT.


METHODS
Multiple contrast-enhanced, DE (80 kV/140 kV) datasets were reconstructed from 34 patients undergoing clinically-indicated examinations using routine CTDI(vol). 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 ≥4). At this lowest acceptable dose, the sigmoidal, 0.5 and 0.3 linear blended images were ranked in order of preference.


RESULTS
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 ≤ 0.006), with two most often preferring sigmoidally-blended images.


CONCLUSIONS
There is potential for further dose reduction utilizing DE hepatic CT. Radiologist visual preference for mixed-kV images is idiosyncratic.
Apel
Anja
A
Siemens Healthcare USA, Malvern, PA, USA.
Fletcher
Joel G
JG
Fidler
Jeff L
JL
Hough
David M
DM
Yu
Lifeng
L
Guimaraes
Luis S
LS
Bellemann
Matthias E
ME
McCollough
Cynthia H
CH
Holmes
David R
DR
Eusemann
Christian D
CD
D001822:Body Burden; D003287:Contrast Media; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D016014:Linear Models; D008107:Liver Diseases / Q000000981:diagnostic imaging*; D008297:Male; D015588:Observer Variation; D010865:Pilot Projects; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods*; D015900:Radiography, Dual-Energy Scanned Projection / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
D003287:Contrast Media