New prospective research reveals that photon-counting computed tomography (PCCT) may provide a comparable option to magnetic resonance elastography (MRE) for staging liver fibrosis.
For the comparative study, recently published in Radiology, researchers compared PCCT-derived extracellular volume fraction (ECV) to MRE-derived liver stiffness measurement (LSM) for liver fibrosis staging in 139 patients (mean age of 62) with suspected hepatic malignancies. Eighty-two percent of the cohort were men, approximately 25 percent had a body mass index (BMI) > 25 and over 78 percent had hepatitis B, according to the study. The study authors utilized the METAVIR (Meta-Analysis of Histological Data in Viral Hepatitis) system for liver fibrosis staging (F0-F4).
The researchers found that PCCT-derived ECV had a 99 percent AUC for patients with > F2 staging and a 98 percent AUC for those with > F3 staging and patients with an F4 stage.
Is PCCT-Derived Extracellular Volume Fraction Comparable to MRE-Derived Liver Stiffness Measurement for Staging of Liver Fibrosis?
The study authors also found that PCCT-derived ECV offered higher sensitivity than MRE-derived LSM for patients with > F2 staging (94 percent vs. 86 percent) and equivalent specificity and positive predictive value (PPV) (both at 100 percent). The ECV assessments with PCCT offered higher sensitivity and lower specificity than LSM for patients with F3 and F4 staging, according to the study. However, the researchers also noted comparable AUCs in both cohorts (between 97 to 98 percent).
“Photon-counting CT–derived extracellular volume fraction (ECV) was strongly correlated with MR elastography–derived liver stiffness measurement (LSM) and showed equivalent, clinically feasible performance for liver fibrosis staging in participants with stage F1–F4 fibrosis,” noted lead study author Xinyu Wu, MMed, who is affiliated with the Department of Radiology at Ruijin Hospital and the Shanghai Jiao Tong University School of Medicine in Shanghai, China, and colleagues.
Three Key Takeaways
• PCCT-derived ECV performs on par with (and may exceed) MRE for fibrosis staging. For ≥ F2 fibrosis, ECV showed higher sensitivity than MRE-based LSM (94 percent vs. 86 percent) with equivalent specificity and PPV (both 100 percent). AUCs were comparable across all thresholds (97 to 99 percent), suggesting PCCT could serve as a viable alternative when MRE isn't available or feasible.
• ECV accuracy holds up in confounding conditions. Performance remained high (91 to 97 percent) in patients with steatosis, inflammation, or elevated BMI (>25), populations in which conventional dual-energy CT iodine-concentration measures have historically struggled. This robustness stems from PCCT's improved spectral information/energy resolution, reduced noise and enhanced material decomposition, according to the study authors.
• What About PCCT-derived ECV in patients already undergoing CT for hepatic malignancy workup? Since the cohort consisted of patients with suspected hepatic malignancies, ECV quantification may offer opportunistic fibrosis staging without requiring a separate MRE exam. However, the researchers emphasized that further validation is warranted before broad practice change.
Is PCCT-Derived ECV Still Accurate in Staging in Patients with Accompanying Steatosis, Inflammation or High BMI?
In subgroup analysis, the study authors pointed out that PCCT-derived ECV maintained high accuracy rates across different liver fibrosis stages in patients with steatosis (91 to 97 percent), those with inflammation (95 to 97 percent) and patients with BMI > 25 (91 to 97 percent).
“By providing inherent spectral information with greater energy resolution and reduced noise, PCCT enables more robust material decomposition and quantitative evaluations, addressing key limitations of prior dual-energy CT–derived liver iodine concentration and reducing confounding from steatosis and inflammation,” added Wu and colleagues.
(Editor’s note: For related content, see “Could Photon-Counting CT Supplant MRI for Imaging Assessment of Hepatic Steatosis?,” “Study: PCCT Facilitates Superior SNR and CNR in Lung Cancer Imaging with 55 Percent Reduction in Radiation Dosing” and “Study Looks at Combining PCCT and Lung Texture Analysis for Evaluating ILD in Patients with Systemic Sclerosis.”)
In regard to study limitations, the authors acknowledged there may have been a lack of exact correspondence between the surgical samples employed for fibrosis staging and the ROIs derived from PCCT. They also conceded an absence of cohort participants with stage F0 and the use of a three-minute delayed phase for ECV assessment in contrast to other studies that employed a three- to five-minute delayed phase.
