Orthopaedic metallic artifact reduction algorithm facilitates CT evaluation of the urinary tract after hip prosthesis

Kaposi Novák, Pál and Youn, Taewoong and Tóth, Ambrus and Frank, Veronica Grace and Shariati, Shiraz and Szendői, Attila and Magyar, Péter and Bérczi, Viktor (2019) Orthopaedic metallic artifact reduction algorithm facilitates CT evaluation of the urinary tract after hip prosthesis. CLINICAL RADIOLOGY. ISSN 0009-9260 (In Press)

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Abstract

AIM: To examine the improvement in the visualisation of bladder and ureteric pathologies next to a hip prosthesis with metallic artefact reduction for orthopaedic implants (O-MAR). MATERIALS AND METHODS: Thirty-four patients who underwent pelvic computed tomography (CT) for non-prosthesis-related causes were enrolled retrospectively. Portal venous phase scans were reconstructed both with standard iterative reconstruction (ITR) and with OMAR. The density of the ureters and the bladder was measured at both sides in the plane of the prosthesis. A semi-quantitative score was also used to assess visibility. The R (version 3.4.1) package was used for statistical analysis. RESULTS: The average (m) density of the 41 prosthesis side ureters was significantly lower on ITR images (m¼e94.76�150.48 [�SD] HU) than on O-MAR images (m¼e13.40�36.37 HU; p<0.0004). The difference between the ITR and O-MAR (m¼e138.62�182.64 versus e35.55�40.21 HU; p<0.0003) was also significant at the prosthesis side of the bladder. The visibility of the prosthesis side ureters was improved: 53.7% was obscured on ITR series compared to 4.9% on O-MAR. The visibility score was also better across all levels (p<0.001) with O-MAR. In four cases (13%), the O-MAR images significantly changed the diagnosis: in two cases ureteric stones, in one case each a bladder stone and a bladder tumour were discovered. CONCLUSIONS: O-MAR reconstruction of CT images significantly improves the visibility of the urinary tract adjacent to metallic hip implants. Thus, O-MAR is essential for detecting ureteric and bladder pathologies in patients with a hip prosthesis.

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