Photon counting detector CT-derived virtual non-contrast images of the liver: comparison of conventional and liver-specific algorithms across arterial and portal venous phase scans

Abstract Background The aim of this retrospective study is to compare photon-counting detector computed tomography (PCD-CT) derived virtual non-contrast (VNC) images of the liver reconstructed from both arterial and portal venous phase using conventional and liver-specific VNC algorithm to true non-...

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Main Authors: Anna-Katharina Gerstner, Franka Risch, Luca Canalini, Gerlig Widmann, Elke R. Gizewski, Stefanie Bette, Simon Hellbrueck, Thomas Kroencke, Josua A. Decker
Format: Article
Language:English
Published: BMC 2025-08-01
Series:BMC Medical Imaging
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Online Access:https://doi.org/10.1186/s12880-025-01849-0
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author Anna-Katharina Gerstner
Franka Risch
Luca Canalini
Gerlig Widmann
Elke R. Gizewski
Stefanie Bette
Simon Hellbrueck
Thomas Kroencke
Josua A. Decker
author_facet Anna-Katharina Gerstner
Franka Risch
Luca Canalini
Gerlig Widmann
Elke R. Gizewski
Stefanie Bette
Simon Hellbrueck
Thomas Kroencke
Josua A. Decker
author_sort Anna-Katharina Gerstner
collection DOAJ
description Abstract Background The aim of this retrospective study is to compare photon-counting detector computed tomography (PCD-CT) derived virtual non-contrast (VNC) images of the liver reconstructed from both arterial and portal venous phase using conventional and liver-specific VNC algorithm to true non-contrast images, in context of the body mass index (BMI). Methods VNC images reconstructed from multiphase (non-contrast, arterial and portal venous phase) PCD-CT scans performed between April 2021 and February 2023 were analysed retrospectively. For each patient, four VNC series were generated: two series (arterial and portal venous) using a conventional VNC algorithm (VNCconv art; VNCconv pv) and two using a liver-specific “Liver VNC” algorithm (VNCLiver art; VNCLiver pv). Regions of interest were placed in the left and right liver lobes and in the spleen, avoiding large vessels and focal lesions. The VNC CT-values were then compared to those of the corresponding true non-contrast images (TNC). The subsequent analysis involved the calculation of both correlation and mean offsets. The median split was utilised to ascertain distinct cohorts of patients with elevated and reduced body mass indices. These cohorts were then subjected to a comparative analysis of attenuation values to discern potential disparities between them. The results were compared by using parametric and non-parametric tests; Pearson’s correlation coefficient was employed. Bland-Altman plots were utilised to visually assess the agreement between results and Passing-Bablok regression, thereby quantifying the observed agreement. Results The study population comprised 42 patients (mean age 70.0 ± 10.2 years, 33 males). Mean offsets between TNC and VNCconv art was 0.62 ± 5.23 HU, TNC-VNCconv pv 1.24 ± 6.67 HU, TNC-VNCLiver art -0.94 ± 5.59 and TNC-VNCLiver pv -0.35 ± 6.99 with no significant difference. Significant differences were found for VNCconv art, VNCconv pv and VNCLiver art images regarding spleen attenuation. Bland-Altman plots demonstrated good agreement and the absence of any systematic difference in liver attenuation. As for the TNC-VNCconv art, TNC-VNCconv pv, TNC-VNCLiver art and TNC-VNCLiver pv variables, strong correlations were obtained (Pearson’s coefficient: 0.79, 0.69, 0.79 and 0.7, all p < 0.001). The investigation revealed no statistically significant disparities between the BMI groups with respect to the mean offset of liver density (p-value:TNC-VNCconv art 0.51; VNCconv pv 0.61; VNCLiver art 0.68; VNCLiver pv 0.45). Furthermore, no significant offset between TNC and VNC images was detected within each BMI group. A Passing-Bablok regression analysis revealed no systematic or proportional difference between the two methods. Conclusion It is evident that PCD-CT-derived VNC images generally constitute a corresponding alternative to TNC images. However, caution is advised in the interpretation of images, as there are outliers with differences exceeding 15 HU are present. In general, the mean values obtained from the analysis of, VNC images reconstructed from arterial and portal venous phases employing both the liver-specific and general VNC reconstruction algorithm did not demonstrate any clincially significant difference when compared with TNC images. Furthermore, no significant discrepancy was observed in the utilisation of the conventional and the liver-specific algorithm. The findings of this study demonstrated that, within the limitations of the study, the patients’ BMI did not have a significant impact on the VNC images.
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spelling doaj-art-b526251e04eb40e8a82a21f12ff05bbd2025-08-20T03:06:29ZengBMCBMC Medical Imaging1471-23422025-08-0125111210.1186/s12880-025-01849-0Photon counting detector CT-derived virtual non-contrast images of the liver: comparison of conventional and liver-specific algorithms across arterial and portal venous phase scansAnna-Katharina Gerstner0Franka Risch1Luca Canalini2Gerlig Widmann3Elke R. Gizewski4Stefanie Bette5Simon Hellbrueck6Thomas Kroencke7Josua A. Decker8Department of Radiology, Medical University InnsbruckDepartment of Diagnostic and Interventional Radiology, University Hospital AugsburgDepartment of Diagnostic and Interventional Radiology, University Hospital AugsburgDepartment of Radiology, Medical University InnsbruckDepartment of Radiology, Medical University InnsbruckDepartment of Diagnostic and Interventional Radiology, University Hospital AugsburgDepartment of Diagnostic and Interventional Radiology, University Hospital AugsburgDepartment of Diagnostic and Interventional Radiology, University Hospital AugsburgDepartment of Diagnostic and Interventional Radiology, University Hospital AugsburgAbstract Background The aim of this retrospective study is to compare photon-counting detector computed tomography (PCD-CT) derived virtual non-contrast (VNC) images of the liver reconstructed from both arterial and portal venous phase using conventional and liver-specific VNC algorithm to true non-contrast images, in context of the body mass index (BMI). Methods VNC images reconstructed from multiphase (non-contrast, arterial and portal venous phase) PCD-CT scans performed between April 2021 and February 2023 were analysed retrospectively. For each patient, four VNC series were generated: two series (arterial and portal venous) using a conventional VNC algorithm (VNCconv art; VNCconv pv) and two using a liver-specific “Liver VNC” algorithm (VNCLiver art; VNCLiver pv). Regions of interest were placed in the left and right liver lobes and in the spleen, avoiding large vessels and focal lesions. The VNC CT-values were then compared to those of the corresponding true non-contrast images (TNC). The subsequent analysis involved the calculation of both correlation and mean offsets. The median split was utilised to ascertain distinct cohorts of patients with elevated and reduced body mass indices. These cohorts were then subjected to a comparative analysis of attenuation values to discern potential disparities between them. The results were compared by using parametric and non-parametric tests; Pearson’s correlation coefficient was employed. Bland-Altman plots were utilised to visually assess the agreement between results and Passing-Bablok regression, thereby quantifying the observed agreement. Results The study population comprised 42 patients (mean age 70.0 ± 10.2 years, 33 males). Mean offsets between TNC and VNCconv art was 0.62 ± 5.23 HU, TNC-VNCconv pv 1.24 ± 6.67 HU, TNC-VNCLiver art -0.94 ± 5.59 and TNC-VNCLiver pv -0.35 ± 6.99 with no significant difference. Significant differences were found for VNCconv art, VNCconv pv and VNCLiver art images regarding spleen attenuation. Bland-Altman plots demonstrated good agreement and the absence of any systematic difference in liver attenuation. As for the TNC-VNCconv art, TNC-VNCconv pv, TNC-VNCLiver art and TNC-VNCLiver pv variables, strong correlations were obtained (Pearson’s coefficient: 0.79, 0.69, 0.79 and 0.7, all p < 0.001). The investigation revealed no statistically significant disparities between the BMI groups with respect to the mean offset of liver density (p-value:TNC-VNCconv art 0.51; VNCconv pv 0.61; VNCLiver art 0.68; VNCLiver pv 0.45). Furthermore, no significant offset between TNC and VNC images was detected within each BMI group. A Passing-Bablok regression analysis revealed no systematic or proportional difference between the two methods. Conclusion It is evident that PCD-CT-derived VNC images generally constitute a corresponding alternative to TNC images. However, caution is advised in the interpretation of images, as there are outliers with differences exceeding 15 HU are present. In general, the mean values obtained from the analysis of, VNC images reconstructed from arterial and portal venous phases employing both the liver-specific and general VNC reconstruction algorithm did not demonstrate any clincially significant difference when compared with TNC images. Furthermore, no significant discrepancy was observed in the utilisation of the conventional and the liver-specific algorithm. The findings of this study demonstrated that, within the limitations of the study, the patients’ BMI did not have a significant impact on the VNC images.https://doi.org/10.1186/s12880-025-01849-0Virtual non-contrast imagesVNCTNC, Photon counting CT“Liver VNC”“Virtual unenhanced”BMI
spellingShingle Anna-Katharina Gerstner
Franka Risch
Luca Canalini
Gerlig Widmann
Elke R. Gizewski
Stefanie Bette
Simon Hellbrueck
Thomas Kroencke
Josua A. Decker
Photon counting detector CT-derived virtual non-contrast images of the liver: comparison of conventional and liver-specific algorithms across arterial and portal venous phase scans
BMC Medical Imaging
Virtual non-contrast images
VNC
TNC, Photon counting CT
“Liver VNC”
“Virtual unenhanced”
BMI
title Photon counting detector CT-derived virtual non-contrast images of the liver: comparison of conventional and liver-specific algorithms across arterial and portal venous phase scans
title_full Photon counting detector CT-derived virtual non-contrast images of the liver: comparison of conventional and liver-specific algorithms across arterial and portal venous phase scans
title_fullStr Photon counting detector CT-derived virtual non-contrast images of the liver: comparison of conventional and liver-specific algorithms across arterial and portal venous phase scans
title_full_unstemmed Photon counting detector CT-derived virtual non-contrast images of the liver: comparison of conventional and liver-specific algorithms across arterial and portal venous phase scans
title_short Photon counting detector CT-derived virtual non-contrast images of the liver: comparison of conventional and liver-specific algorithms across arterial and portal venous phase scans
title_sort photon counting detector ct derived virtual non contrast images of the liver comparison of conventional and liver specific algorithms across arterial and portal venous phase scans
topic Virtual non-contrast images
VNC
TNC, Photon counting CT
“Liver VNC”
“Virtual unenhanced”
BMI
url https://doi.org/10.1186/s12880-025-01849-0
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