Comparison of submillisievert CT with standard-dose CT for urolithiasis

Patients with renal stones receive multiple computed tomography (CT) examinations. We investigated whether submillisievert (sub-mSv) CT for stone detection could reduce radiation dose at exposure levels comparable to kidney, ureter, and bladder (KUB) radiography.

To evaluate the radiation dose exposure, diagnostic performance, and image quality of sub-mSv non-contrast CT using advanced modelled iterative reconstruction algorithm with spectral filtration for the detection of urolithiasis.

A total of 145 consecutive patients underwent non-contrast CT using a third-generation dual-source scanner to obtain two datasets, i.e. 16.7% (sub-mSv CT, tube detector A) and 100% (standard-dose CT, combination of tube detector A and B) tube loads with spectral filtration. The performance of sub-mSv CT for the detection of stones was analyzed by two readers and compared with that of standard-dose CT. Image quality was measured subjectively and objectively.

In total, 171 stones were detected in 79 patients. The mean effective radiation doses of sub-mSv CT was 0.3 mSv. The sensitivity and specificity values for diagnosis of stones measuring ≥3 mm was 95.1% and 100% for sub-mSv CT. The sensitivity and specificity for all stone detection was 74.9% and 97.8%, respectivey, for sub-mSv CT. The image quality was lower for sub-mSv CT than for standard-dose CT (P < 0.01).

Sub-mSv CT can be achieved with radiation doses close to KUB radiography. Sub-mSv CT with spectral filtration can be used to detect stones measuring ≥3 mm and be used as a follow-up imaging modality as an alternative to KUB radiography.