Evaluation of signal detection performance with pseudocolor display and lumpy backgrounds

Historically, gray scale has been the standard method of displaying univariate medical images. With the advent of digital imaging, color scales have been used for display of quantitative nuclear medicine images and for quantitative overlays in ultrasound images. There has been no interest shown in using color for anatomically based imaging such as radiography or CT. The one exception has been attempts to do multi-spectral (T1, T2, (rho) ) image display in MRI. A few color scales have been proposed and evaluated, but have had little acceptance by radiologists. It is possible that carefully designed scales might give lesion detection performance that equals gray scale and improves performance of other tasks. We investigated 13 display scales including the physically linear gray scale, the popular rainbow scale, and 11 perceptually linearized scales. One was the heated object scale and the other 10 were spiral trajectories in the CIELAB uniform color space. The experiments were performed using signals added to white noise and a statistically defined (lumpy) background. In general, the best performance was obtained using the gray scale and the heated object scale. Performance for the spiral trajectory scales was typically 25% lower. Performance for the rainbow scale was very poor (about 30% of gray scale performance).