Variability of HCC Tumor Diameter and Density Measurements on Dynamic Contrast-Enhanced Computed Tomography

Area of Science:

• Radiology
• Oncology
• Medical Imaging

Background:

• Contrast-enhanced CT protocols are vital for assessing treatment response in hepatocellular carcinoma (HCC).
• Standard guidelines rely on lesion size (mm) and density (Hounsfield units [HU]).
• Understanding measurement variability across contrast phases is crucial for accurate assessment.

Purpose of the Study:

• To investigate the variability of maximal lesion diameter and mean lesion density of HCC on CT scans.
• To analyze this variability across four contrast enhancement phases: non-contrast-enhanced (NCE), early arterial (E-AP), late arterial (L-AP), and portal venous (PVP).
• To determine the impact of contrast timing on measurement accuracy for treatment response evaluation.

Main Methods:

• Maximal lesion diameter and mean lesion density of HCC lesions were measured on CT scans.
• Measurements were taken across NCE, E-AP, L-AP, and PVP contrast phases.
• Variability was assessed using coefficients of variance (CVs), absolute and relative differences, stratified by phase and lesion size.

Main Results:

• Lesion diameter showed a CV of 5.11%, with ~20% of relative changes exceeding 10%.
• Diameter measurements did not differ significantly across phases, but smaller lesions showed greater percent differences.
• Lesion density exhibited significant variability across phases (overall CV 26.19%), with a 47% relative difference in the L-AP phase.

Conclusions:

• Tumor diameter changes within 10% may be attributable to measurement variability.
• Lesion density is highly sensitive to contrast enhancement timing.
• Accurate evaluation of tumor response in HCC requires careful consideration of both lesion size and density variability related to contrast timing.