Black spots on a thyroid ultrasound, What are they?

Okay so just had my thyroid ultrasound because my thyroid is slightly enlarged and the tech wouldn’t say anything and rushed out of the room when she was done. I know they aren’t allowed to say anyway but I wish she could have just said oh looks pretty good. I was looking at the images she had left up on the screen and a couple of them showed 3 well defined black circles on the left and 1 well defined black circle on the right. Are these vascular areas like the carotid artery? Does anyone know what black circles are? Are they cysts, tumors, nodules? They weren’t cloudy or gray at all just black circles with a fine white outline.