While ultrasound and magnetic resonance imaging (MRI) are commonly utilized in screening and longitudinal surveillance for steatosis, non-contrast computed tomography (NCCT) may offer a viable alternative for diagnosing moderate steatosis, according to a new meta-analysis.
For the meta-analysis, recently published in Radiology, researchers examined the capability of NCCT, contrast-enhanced CT (CECT) and dual-energy CT (DECT) to diagnose hepatic steatosis in 42 studies involving a total of 14,186 participants.
The researchers found that NCCT offers 72 percent sensitivity and 88 percent specificity for steatosis (defined as > 5 percent at biopsy) detection in comparison to 66 percent and 90 percent, respectively, for CECT. The use of DECT had 85 percent sensitivity and 88 percent specificity, according to the study authors.
For patients with moderate hepatic steatosis (defined as ranging between 20 to 33 percent fat at biopsy), the researchers pointed out that NCCT demonstrated 82 percent sensitivity and 94 percent specificity in contrast to 68 percent and 93 percent, respectively, for CECT.
“Although not currently considered a screening tool for this task, CT can play an important role in opportunistic identification of steatosis when patients undergo scanning for other indications. These patients can be referred for clinical and laboratory assessment to screen for risk factors for advanced fibrosis that would require more advanced care,” wrote lead meta-analysis author Maryam Haghshomar, M.D., who is affiliated with the Department of Radiology at the Northwestern University Feinberg School of Medicine in Chicago, and colleagues.
The study authors also found that high specificity for moderate hepatic steatosis was associated with absolute liver attenuation under 40-45 HU, a liver-spleen attenuation ratio under 0.9-1 or liver-spleen attenuation differences less than -5 to 0 HU.
Three Key Takeaways
1. Non-contrast CT as a diagnostic tool for steatosis. Non-contrast CT (NCCT) demonstrated promising sensitivity (72 percent) and specificity (88 percent) for detecting hepatic steatosis, potentially offering an alternative when MRI or ultrasound is unavailable.
2. Higher sensitivity and specificity for moderate steatosis. For diagnosing moderate hepatic steatosis (defined as 20-33% fat at biopsy), NCCT showed 82 percent sensitivity and 94 percent specificity, outperforming contrast-enhanced CT (CECT), which had lower sensitivity (68 percent) but comparable specificity (93 percent).
3. Opportunistic screening potential. Although not a primary screening tool, CT imaging may help opportunistically detect steatosis when patients undergo scans for other medical reasons. This could lead to referrals for further assessment and potential management of risk factors related to advanced fibrosis.
“The difference in liver and spleen attenuation appeared to be the most consistent (for NCCT),” noted Haghshomar and colleagues. “This parameter is also theoretically less prone to variations with CT tube voltage and scanner type.”
While a subgroup analysis revealed 99 percent and 93 percent specificity rates, respectively, for CECT and DECT, the researchers cautioned that high heterogeneity and inconsistent reference standards in the lower number of studies for these modalities prevented any definitive conclusions.
(Editor’s note: For related content, see “Could Photon Counting CT Supplant MRI for Imaging Assessment of Hepatic Steatosis?,” “Can Photon Counting CT Facilitate a Viable Alternative to MRI for Liver Fat Quantification in Patients with MASLD?” and “Can Multiparametric Ultrasound Enhance Detection of Metabolic Dysfunction-Associated Steatohepatitis (MASH)?”)
In regard to study limitations, the authors noted the lack of a consistent threshold for defining what constituted moderate stenosis. They also pointed out that changes in CT acquisition and reconstruction techniques during the 26-year period range for the reviewed studies may have factored into variability with study results.
