Table 2.

Imaging Studies in Evaluation of Nephrolithiasis

Imaging Modality	Advantages	Limitations	Clinical Uses
Plain radiography of the kidneys, ureters, and bladder (KUB)	Small radiation dose Wide availability Low cost	Misses small and/or radiolucent stones Can be limited by overlying bowel gas, body habitus, extra-renal calcification Limited anatomical information	Follow-up of known radiopaque calculi Planning of fluoroscopically guided SWL
Intravenous Urography	Wide availability Estimation of renal function and of degree of obstruction Detection of anatomical abnormalities	Contrast use Moderate radiation dose	Occasional used in pre-operative planning Largely replaced by CT scan
Computed Tomography (CT) scan	Sensitive/specific Fast Widely available No contrast needed Detects extra-urinary pathology	Expensive High radiation dose	Modality of choice in suspected renal colic patient May be useful in identifying stone composition
Ultrasound	No contrast No radiation Low cost Wide availability	Poor visualization of ureteral stones Poor estimation of stone size	Modality of choice in pediatric and pregnant patients
Magnetic Resonance Urography	No radiation	Limited availability High cost Contrast risk in CKD patients Cannot distinguish stone from blood clot	Rarely used, primarily in pregnant or pediatric patients