Strand and deliver

This was a standard KUB done for renal colic but there is something odd about it.
Normal patient haemodynamically and in all other ways.
Any guesses?

Xray

- there is no obvious stone, nor is there any vascular pathology visible (sometimes AAA with its calcified wall does show up!)

- what we can see is a "halo" around the right kidney (lower pole)

All we could think of was maybe this is sort of an inflammatory reaction and hence got a CT KUB. It did turn out to be renal colic with some element of hydro-ureter and fat stranding around the kidney. A slice is shown below. He did in fact have a stone distally which required only soncervative measures. A radiologist we know said stranding is not visible on plain films so let us know if you have any bright ideas on what that halo is.

Does not detract from the normal therapy though
- Analgesia (including anti inflammatories/spasmodic)
- Tamsulosin
- Urological follow up