From the Guidelines
To confirm kidney stones, a non-contrast CT scan of the abdomen and pelvis is the preferred imaging test. This recommendation is based on the highest quality and most recent evidence, which suggests that non-contrast CT has a high sensitivity of up to 97% for detecting renal calculi, as reported in the study published in the Journal of the American College of Radiology in 2023 1. The use of non-contrast CT allows for accurate detection of even small stones, as well as visualization of secondary signs of urolithiasis and complications such as periureteral and perinephric inflammation and ureteral dilatation.
Some of the key benefits of non-contrast CT include:
- High spatial resolution and ability for multiplanar reformations
- Ability to accurately detect stones as small as 1mm
- Ability to determine the exact location and measure the size of stones, which helps guide treatment decisions
- Low-dose non-contrast CT options are available, which can reduce radiation exposure, especially in young patients
Alternative imaging options, such as ultrasound, X-ray (KUB), and intravenous pyelogram (IVP), may be considered in certain situations, but non-contrast CT remains the reference standard for the evaluation of urolithiasis due to its high accuracy and ability to provide detailed images of the kidneys, ureters, and bladder 1.
From the Research
Imaging Options for Kidney Stones
To confirm kidney stones, the following imaging options are available:
- Non-contrast computed tomography (CT) scan: This is a commonly recommended imaging test for suspected renal calculus, as it can help identify kidney stones without the need for contrast agents 2, 3.
- Ultrasonography: This imaging modality can also be used to diagnose kidney stones, and it has the advantage of being radiation-free 4.
- Dual-energy CT: This advanced imaging technique can provide more accurate characterization of stone disease and help direct therapy 5.
Recommendations
The choice of imaging test may depend on various factors, including the patient's symptoms, medical history, and renal function. According to the guidelines, a non-contrast CT scan is often the preferred initial imaging test for suspected kidney stones 3.
- Non-contrast CT scan is recommended for its high diagnostic accuracy and ability to detect kidney stones without contrast agents.
- Ultrasonography may be considered as an alternative imaging option, especially for patients with limited renal function or those who are allergic to iodinated contrast agents.
Key Considerations
When ordering an imaging test to confirm kidney stones, it is essential to consider the following factors:
- Radiation exposure: Ultrasonography is a radiation-free imaging modality, while CT scans involve radiation exposure 4.
- Contrast agents: Non-contrast CT scans do not require contrast agents, while contrast-enhanced CT scans may be necessary in certain cases 2.
- Diagnostic accuracy: The choice of imaging test should be based on its diagnostic accuracy and ability to detect kidney stones 3, 5.