What is a stone protocol CT?
When a patient presents with suspected renal colic, the most common method used for evaluation is an abdominopelvic CT performed without oral or intravenous contrast material. This is referred to as a stone-protocol CT. The presence of a stone within the ureter, dilation of the upstream collecting system and ureter, and perinephric fluid and perinephric stranding are imaging findings that are highly suggestive of the presence of an obstructing stone. If a stone is impacted within the ureter, there may be surrounding soft tissue edema at the site, which is referred to as a “soft tissue rim” sign.