Liver Fat and Iron Quantification With Spectral Localizer Radiographs From Photon-counting Detector CT

Area of Science:

• Medical Imaging
• Radiology
• Biomedical Engineering

Background:

• Quantifying liver fat content (LFC) using computed tomography (CT) is challenged by hepatic iron deposition and iodinated contrast agents.
• Photon-counting detector CT (PCD-CT) offers spectral imaging capabilities that may overcome these limitations.

Purpose of the Study:

• To assess the feasibility and accuracy of quantifying LFC in the presence of iron using spectral localizer radiographs from PCD-CT.
• To evaluate the impact of varying liver iron concentration (LIC) on LFC measurements.

Main Methods:

• Sixteen liver phantoms with controlled LFC (0-50%) and LIC (0-6 mg/mL) were scanned using PCD-CT spectral localizer radiography.
• Material decomposition was performed to generate water and hydroxyapatite (HA) maps.
• HA values were analyzed as a function of LFC and LIC across different tube current settings.

Main Results:

• Increasing LFC linearly decreased HA values, independent of LIC (r=0.997 to 1.0).
• Increasing LIC linearly increased HA values, independent of LFC (r=0.978 to 1.0).
• A 2D material space using water and HA values enabled LFC estimation irrespective of LIC, with reproducible findings across tube currents.

Conclusions:

• Spectral localizer radiographs from PCD-CT can accurately quantify liver fat content in the presence of hepatic iron deposition.
• This technique holds potential for opportunistic, low-threshold screening for hepatic steatosis and iron overload using precontrast localizer scans.