Size and volume of kidney stones in computed tomography: Influence of acquisition techniques and image reconstruction parameters. Issue 132 (November 2020)

• Record Type: Journal Article
• Authors: Reimer, Robert Peter; Salem, Johannes; Merkt, Martin; Sonnabend, Kristina; Lennartz, Simon; Zopfs, David; Heidenreich, Axel; Maintz, David; Haneder, Stefan; Große Hokamp, Nils
• Is Part Of: European journal of radiology. Issue 132(2020)
• Publication Date: 2020-11
• Subjects: CT Computed tomography -- FBP Filtered back-projection -- HIR Hybrid-iterative reconstruction algorithm -- Man-M Manual measurements -- MBIR Model-based iterative reconstruction algorithm -- CTDIvol Volumetric computed tomography dose index; Computed tomography -- Urolithiasis -- Kidney stones; Medical radiology -- Periodicals; Radiology -- Periodicals; Radiologie médicale -- Périodiques; Medical radiology; Periodicals; 616.075705
• DOI: 10.1016/j.ejrad.2020.109267
• Languages: English
• ISSNs: 0720-048X

Abstract

Highlights: Semi-automated volumetric CT-based measurements of kidney stone size overestimate true stone size. CT-based measurements of kidney stone size are unaffected by radiation dose and denoising technique, while reconstruction algorithms and kernels demonstrate a relevant impact on size measurements. Smallest differences between CT-based measurements and true stone size were found using a model-based iterative reconstruction algorithm and a sharp image kernel. Abstract: Purpose: Computed tomography (CT) is routinely used to assess suspected urolithiasis. Information obtained from CT include presence, location and size of stones, with the latter frequently determining treatment strategy. While there is consensus regarding measurements procedures of kidney stones, influence of radiation dose and reconstruction techniques on stone measurements are unknown. The purpose of this study was to systematically evaluate the influence of these technical determinants on kidney stone size measurements. Method: 47 kidney stones of different composition were scanned using a 64-row-multi-detector CT in a 3D-printed, semi-anthropomorphic phantom. Reference stone sizes were measured manually with a digital caliper (Man-M). Stones were imaged with 2 and 10 mGy CTDI. Images were reconstructed using filtered-back-projection, hybrid-iterative and model-based-iterative reconstruction algorithms (FBP, HIR, MBIR) in combination with different kernels and denoising levels. All stones underwent semi-automatic, threshold-based segmentation for computation of maximum diameter and volume. Statistics were conducted using ANOVA ± correction for multiple comparisons. Results: Overall stone size as compared to manual measurements was overestimated in CT (10.0 ± 3.1 vs. 8.8 ± 2.9 mm, p < 0.05) yet showing a good correlation (R 2 = 0.66). Radiation dose and denoising levels did not significantly influence measurements (p > 0.05). MBIR and sharp kernels showed closest agreement with Man-M (9.3 ± 3.1 vs. 8.8 ± 2.9 mm, p < 0.05). Differences within single stones were as high as 40 % (e.g. Man-M: 5.9 mm, CT: 7.3–12.0 mm). Conclusions: CT-based measurements of kidney stone size appear unaffected by radiation dose and denoising technique, whereas reconstruction algorithms and kernels demonstrate a relevant impact on size measurements. Smallest differences were found using MBIR with a sharp kernel.