Imaging
Imaging is a key component in the evaluation of patients with urolithiasis, as it is essential for the diagnosis and for determining the appropriate treatment of renal and ureteral stone disease. The ideal imaging study would be rapidly performed, have high sensitivity and specificity, and expose the patient to minimal or no radiation. Non-contrast computed tomography (NCCT) remains the first-line imaging modality for the evaluation of patients with suspected urolithiasis. It allows for rapid and accurate diagnosis. The major limitation of NCCT is radiation exposure, though low-dose NCCT protocols help to minimize this risk. Ultrasound is also useful for the evaluation of patients with suspected urolithiasis and should be considered the imaging study of choice in pediatric patients and pregnant women with suspected stones. Ultrasound has the advantage of no radiation exposure, but at the cost of decreased sensitivity and specificity compared to NCCT. Plain film radiography of the abdomen/pelvis (KUB) is useful as an adjunct to ultrasound. The role of intravenous pyelography (IVP) has been largely supplanted by NCCT; however, IVP is still useful in evaluation for obstruction and anatomic abnormalities that may impact in treatment decisions. The main utility of magnetic resonance imaging (MRI) for patients with urolithiasis is in detecting secondary signs of obstruction, especially in those patients who must avoid radiation exposure.
