Reduced beam hardening in urogenital imaging with photon-counting CT: a retrospective direct comparison with conventional CT

Background: Beam-hardening artefacts and image noise are very common causes of reduced image quality with computed tomography (CT) imaging of the lower pelvis and perirenal area affecting precision of diagnoses in urogenital imaging. Purpose: To investigate whether photon-counting CT (PCCT) improves image quality and/or reduces beam-hardening artefacts in the lower pelvis and in the perirenal area compared to energy-integrating CT (EIDCT). Material and Methods: We retrospectively identified 35 patients scanned using both EIDCT and PCCT. Four radiologists read both PCCT and EIDCT images. Readers evaluated image quality both subjectively and quantitatively over the left medial perirenal fat and the urinary bladder. Continuous data were compared with a paired t-test and ordinal data with a Wilcoxon signed rank test. Results: Image quality ratings were higher with PCCT compared to EIDCT. Median scores for the left medial perirenal fat were 5 (interquartile range [IQR] = 4–5) for PCCT and 3 (IQR = 3–4) for EIDCT (P <0.001) and for the lower pelvis 5 (IQR = 4–5) for PCCT and 3 (IQR = 2–4) for EIDCT (P <0.001). Image noise was significantly lower in PCCT scans compared to EIDCT scans (urinary bladder 11.9 HU vs. 17.8 HU, P <0.001; left medial perirenal fat 15.6 HU vs. 22.5 HU, P <0.001). Mean dose-length-product was significantly lower in the PCCT scans with a dose reduction of reduction 21.2% (P <0.001). Conclusion: Beam-hardening artefacts were considerable reduced and image noise was significantly lower with PCCT compared to EIDCT at significantly reduced radiation doses. This could have potential implications in the radiological assessment of urogenital diseases.