Sonography under Daylight Conditions.

PURPOSE

Gray scale image assessment in clinical ultrasound requires working in dim light or a dark room. Daylight conditions offer the advantage of shorter visual reaction time and enhanced visual perception. Look-up table manipulations could improve image brightness.

MATERIALS AND METHODS

We investigated the possibility of brightness and contrast enhancement of coloured adaptive linear look-up tables (CALUT's) and their artifact resistance. Therefore under real-time conditions red/brown, green and blue CALUT's were calculated using the gray scale distribution (mean and standard deviation) of the actual image. The changes in contrast of several structural features (echo-poor and echogenic lesions, artifacts) were assessed by clinical investigators (n = 7).

RESULTS

The CALUT's produced, independent of the original, images with constant brightness and contrast. Even under daylight conditions no artifacts appeared. Under scotopic conditions the red/brown CALUT's showed the best results compared to the unchanged image and the gray, green, and blue CALUT's. Hyper and hypoechoic differences with small contrast to the surrounding tissue are enhanced and can be detected more easily.

CONCLUSION

Daylight sonography allows examination even in non-darkened rooms without loss of information. Eye adaptation to changing light conditions is no longer necessary; the offered image information is more suitable for the eye.