Background and significance: Renal colic is a common presentation to emergency departments in worldwide, which is suggested by its clinical presentation, however it requires confirmation with a diagnostic image, being the most common and today considered the gold standard: non-contrast computed tomography (CT). Thanks to this image, we were able to determine the location, volume and density of the stone, among others; However, we cannot ignore the fact that it is not an innocuous procedure for our patients and that by performing each CT they are accumulating radiation exposure, with a standard dose (SDCT) estimated at 4.5–5 mSV. For this reason, based on this concern, several publications already exist in the literature, including meta-analyzes and systematic reviews on the use of low-dose CT (LDCT <3–3.5 mSv) or ultra-low-dose CT (ULDCT <1 –1.9 mSv). Even in the guidelines of the European Society of Urology (EAU Guidelines on Urolithiasis 2019), it is suggested that in patients with a body mass index (BMI) <30, low-dose CT can have adequate specificity and sensitivity to be the first line of choice.
Summary: This article is prospective and comparative, conducted in Australia over a period of 3 months and aims to determine the diagnostic accuracy of ULDCT vs. SDCT in the evaluation of patients with clinical suspicion of renal colic, in addition to secondary characteristics and additional pathological processes. Patients from the emergency department with signs and symptoms suggestive of renal colic were included, patients younger than 18 years and with a positive pregnancy test were excluded. All patients underwent both SDCT and ULDCT and all images were reviewed with a single-blind system by 3 radiologists independently.
A total of 21 patients were included, of whom 12 (57.1%) had urolithiasis, 3 hydronephrosis without lithiasis, one with bladder wall thickening and 5 without any alteration. There were no overall significant differences between ULDCT and SDCT for stone detection rate or size estimate. For kidney stone, ULDCT failed to detect stones <3 mm and incorrectly detected three (vascular calcification). A high concordance rate was observed for hydroureteronephrosis, while SDCT identified more parenchymal lesions due to better lesion detection <2 cm. In general, we found that ULDCT resulted in a diagnostic precision equivalent to SDCT for clinically significant calculations, being> 3 mm, with 100% sensitivity and 100% specificity and with a considerable difference in radiation exposure between ULDCT (1.02 mSv) and SDCT (4.97 mSv).
Personal assessment:
Strengths:
• The most important is to be a prospective study.
• It is a relatively easy to read article, it explains in a concise way the methodology and results.
• Collect the different study groups in tables that facilitate a quick visualization of the content of the study and the result.
• It shows comparative images with the different radiation doses on CT.• Radiation risk can be reduced by low-dose CT while maintaining adequate sensitivity and specificity of the study in the diagnosis of urolithiasis. Mainly in the follow-up of patients with recurrent renal colic, where this procedure is essential to decrease radiation exposure.
Weaknesses:
• Sample size is too small
• They did not perform the BMI calculation in a prospective way according to the type of study carried out, since it is already known that this may be a determining factor.
• There is an alteration in the evaluation of the stone density (UH) that, as we know, can be decisive for the urologist.
• Be difficult to introduce in standard clinical practice.
Ana Maria Diaz B. MD
Urologist
Endourology Fellow – UNESP-Endourological Society
