Simultaneous presentation of soft tissue and bone tissue in computed tomography with combined window.

OBJECTIVES

To examine whether in computed tomography (CT) soft tissue and bone tissue can be simultaneously presented with a combined window without loss of diagnostic information compared to the separate presentations with soft tissue and bone tissue windows.

MATERIALS AND METHODS

Forty-seven CT examinations from different patients with pathological changes at the soft tissue or bone tissue after an accident or due to malignant tumour were evaluated. The CT data were transformed into grey level data with three different windows: (1) soft tissue window; (2) bone tissue window to show spongiosa and bone cortex; and (3) special window to show ethmoidal sinus and mastoidal cells. The images were then weighted with a weighting factor of 2, 3 and 1, respectively, resulting in one image with combined window. This image was compared with the conventional soft tissue and bone tissue images.

RESULTS

All diagnostic information could be obtained and anatomical details be recognized on the image with combined window. In some cases soft tissue structures could be delineated from each other or from adjacent bone better on this image than on the soft tissue image.

CONCLUSIONS

Combined window could enable a reduction of film consumption or digital storage because soft tissue and bone tissue are presented on the same image and not separately. The risk for overlooking important pathological changes might be reduced as both tissues are always presented.