Effects of instrument adjustments on quantitative echocardiographic gray level texture measures

Quantitative echocardiographic gray level texture measures have proved useful in characterizing a variety of cardiac abnormalities, including contusion, ischemia, and cardiomyopathies. However, alterations of echocardiographic signal processing controls could potentially affect the resulting data. The purpose of this study was to assess the effect of common echocardiographic instrument adjustments on texture data. We imaged a graphite-in-gel phantom on five separate occasions, each time using 12 combinations of adjustments of transmit power, compression, and postprocessing curves over a clinically applicable range. Image texture was assessed using gray level run length and gray level difference texture measures; 42 individual measures were calculated. Significance of texture measure variations was assessed by analysis of variance. Changes in all three controls were associated with significant alterations in texture measures. Adjustments of transmit power and compression produced larger changes in texture measures than did adjustments of postprocessing curves. There were significant transmission-compression-postprocessing interaction effects (p less than 0.05) for all but eight of the texture measures. For each texture measure, there were significant transmission-compression interaction effects (p less than 0.05). In summary, instrument adjustments had significant effects on quantitative texture measures, and these effects should be considered when evaluating quantitative echocardiographic gray level texture measures.