Black spots on a thyroid ultrasound, What are they?

On ultrasound black means fluid.

So probably cysts right? @Rarebear

It could be anything fluid filled.

I am not about to make a diagnosis based upon this post. I’m just saying that anything with fluid will appear black on an ultrasound since water is transparent to ultrasound.

@Rarebear, do you mean transparent or opaque?

@Jeruba Transparent. Water transmits ultrasound, so it will appear transparent. On ultrasound, transparent is black. Opaque is white. An example of something that would appear white is bone. Thyroid tissue, being somewhere in between water and bone will appear grey.

I see. I guess I was assuming a light background as a default, but ultrasound has a dark background, correct?—so black means it doesn’t show up?

@Jeruba Ultrasound transmits a signal from an emitter and then measures any reflected sound. If sound is reflected, it comes up as white. If it is not, it stays black. Water transmits the signal, so there is no reflection. Ergo, black.

This is a little technical, but has some decent diagrams. You’ll get the gist
http://www.signosticsmedical.com/documents/D04433_Signos_RT_Training_Basic_Ultrasound_Physics.pdf

@Jeruba
Here’s an example. Random internet search on fetal ultrasound came up with this:
http://puremodlife.com/wp-content/uploads/2011/05/sonogram-human-foetal-fetal-ultrasound-scan-at-10-weeks-mono-1-ANON.jpg

The black is the amniotic fluid. The white and grey are the denser tissue.

@Emmy1234, it really is better that they don’t say anything. When my husband had a chest x-ray once, the technician said good-bye when they were through—and then added “Good luck!” It freaked him out, and he was in a bad state for days, until his doctor gave him a negative report.

Thanks, @Rarebear, I have a much better idea now. I just forgot they were essentially negatives in terms of what’s present versus what isn’t.

@Jeruba No worries. Happy to help when I can.

@Rarebear found out my ultrasound results- I have an abnormal lesion on the Lt. lobe and 2 solid cystic masses on the right going for a biopsy next.

@Jeruba- I know why she didn’t say anything now. I guess its best that she didn’t. : /