Thresholding

Hello

I have images acquired using metamorph which saves them as 16bit images. When I view the files I have to use True Range which gives very good results, however, when I threshold it defaults back to 16bit rendering the features I'm trying to pick out invisible. The intensity is quite low around 500-800 max intensity. I can change the bit depth to 12 bit which helps a little but the features are still almost impossible to pick out accurately. Is there a way to force the Thresholding tool to keep the True Range settings and stop it from defaulting back to the original bit depth. I can't really go down to 8bit as that would clip the intensity data I'm trying to measure. Any suggestions would be great. I'm using Premier version 9.1.23 Build 5231. 

Regards

David