Energy-resolved attenuation behaviour on dual-source photon-counting CT: Implications for quantitative assessment of femoral bone marrow in multiple myeloma
Anke Heidemeier1, Franzisca Scheiner1, Henner Huflage1
1Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany.
Rationale And Objectives:
Quantitative CT assessment of multiple myeloma relies on threshold-based differentiation between physiological tissue and myeloma infiltration, yet bone marrow attenuation may be influenced by photon energy. The aim of this study was to evaluate the energy-dependent attenuation behaviour of femoral bone marrow on virtual monoenergetic images derived from dual-source photon-counting CT (PCD-CT) and its implications for quantitative analysis.
Methods:
This retrospective single-centre study included 103 patients who underwent unenhanced ultra-high-resolution whole-body PCD-CT for multiple myeloma assessment. VMI were reconstructed at 40-190 keV. Attenuation was measured in femoral bone marrow, adjacent muscle, and subcutaneous fat. Contrast-to-noise ratios were calculated and differences across energy levels were analysed using Friedman tests with Bonferroni correction.
Results:
Femoral bone marrow attenuation increased with higher keV from -83.4 HU at 40 keV to -58.7 HU at 190 keV, while fat attenuation increased more markedly and muscle attenuation decreased (all p < 0.001). As a result, the attenuation difference between marrow and fat declined substantially from 99.9 HU at 40 keV to 26.9 HU at 190 keV (p < 0.001). Although image noise decreased toward higher keV, CNR declined from 8.4 at 40 keV to 4.1 at 190 keV (p < 0.001).
Conclusions:
Bone marrow attenuation on dual-source PCD-CT is energy-dependent and should not be interpreted independently of the selected monoenergetic level. Quantitative assessment requires contextualization relative to surrounding tissues rather than reliance on fixed attenuation thresholds.
