Dual-energy computed tomography quantification of creeping fat in Crohn’s disease: A new radiologic biomarker for transmural disease monitoring

Abstract

Accurate, noninvasive assessment of disease activity remains one of the central challenges in the management of Crohn’s disease (CD). The study by Dong et al in World Journal of Radiology represents a meaningful advance in this effort, demonstrating that dual-energy computed tomography with the material decomposition algorithm can reliably quantify intestinal creeping fat (CrF), a pathological hallmark of CD, and that this measurement correlates robustly with clinical, endoscopic, histological, and molecular indicators of disease activity. Notably, CrF volume tracked not only inflammatory burden and fibrosis, but also the expression of peroxisome proliferator-activated receptor gamma 2 and occludin, implicating CrF in both adipogenesis and intestinal barrier dysfunction. Crucially, CrF remained elevated during clinical remission, underscoring its potential as a more sensitive marker of subclinical disease persistence than conventional activity indices alone. As the field continues to seek non-invasive surrogates for mucosal healing and histological remission, dual-energy computed tomography-based CrF quantification emerges as a promising, clinically accessible tool. With further validation in larger, multicenter cohorts, this approach could meaningfully reshape how we monitor disease activity, evaluate treatment response, and predict disease course in CD.

Key Words: Crohn’s disease; Dual-energy computed tomography; Creeping fat; Spectral imaging; Multi-material decomposition; Transmural inflammation; Intestinal fibrosis

Core Tip: Dual-energy computed tomography with multi-material decomposition allows objective quantification of creeping fat in Crohn’s disease. This radiologic marker correlates with clinical, endoscopic, histologic, and molecular indices of disease activity and may help assess transmural and mesenteric disease beyond mucosal healing.

This editorial refers to “Value of dual energy computed tomography with material decomposition algorithm in assessing intestinal creeping fat in Crohn’s disease” by Dong et al, 2026; https://doi.org/10.4329/wjr.122056.

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INTRODUCTION

Accurate assessment of Crohn’s disease (CD) remains a persistent challenge in abdominal radiology. Although endoscopy is central to evaluating mucosal inflammation, CD is not confined to the mucosa. It involves the full thickness of the bowel wall and frequently extends into the mesentery. This distinction is clinically important because mucosal healing does not always indicate complete transmural or mesenteric resolution. Cross-sectional imaging therefore occupies a critical position in modern disease assessment, particularly when the therapeutic goal extends beyond symptom control toward deeper structural remission.

CREEPING FAT AS AN INDICATOR OF CD

The study by Dong et al[1] in World Journal of Radiology contributes to this evolving field by focusing on creeping fat, a characteristic but historically undermeasured feature of CD. Creeping fat refers to the circumferential extension of mesenteric adipose tissue around inflamed bowel segments. Once regarded mainly as an anatomic consequence of chronic inflammation, it is now recognized as an active immunometabolic compartment. Mesenteric adipose tissue in CD participates in cytokine signaling, adipogenesis, angiogenesis, and fibrotic remodeling. For radiologists, this shifts creeping fat from a descriptive imaging sign to a potential quantitative biomarker of disease biology[2].

The main technical strength of the work lies in the use of dual-energy computed tomography (CT) combined with a multi-material decomposition algorithm. Conventional CT can demonstrate mesenteric fat proliferation, fat stranding, mural thickening, and hyperenhancement, but it is limited in its ability to isolate and quantify specific tissue components. Dual-energy CT (DECT) addresses part of this limitation by acquiring two datasets at different X-ray tube voltages; because tissues attenuate low- and high-energy photons differently depending on atomic composition, each material produces a distinct attenuation profile across the two spectra. A three-material decomposition algorithm uses this profile to resolve each voxel into fat, non-fat soft tissue, and iodinated contrast, separating the fat signal of creeping fat from the iodine signal of adjacent enhancing bowel wall and mesenteric vessels, which conventional single-energy CT can struggle to distinguish visually. The result is a fat-specific map that can be volumetrically quantified rather than only visually estimated, allowing Dong et al[1] to report a continuous, reproducible measurement of creeping fat volume.

This approach is radiologically meaningful for several reasons. First, it moves assessment of creeping fat from subjective interpretation toward reproducible measurement[1,3,4]. Second, it integrates mesenteric evaluation into a broader multiparametric CT assessment of CD activity[3,5,6]. Third, it provides a potential imaging link between visible peri-enteric changes and underlying histologic or molecular processes. In the study by Dong et al[1], creeping fat volume showed strong positive correlations with the CD Activity Index and the Simplified Endoscopic Score for CD. More importantly for imaging practice, it also correlated with histologic inflammation and fibrosis scores, supporting its relevance as a marker of transmural tissue remodeling rather than merely a secondary external feature[1,4,5].

The reported molecular associations are particularly important. The correlation between creeping fat volume and tumor necrosis factor α and transforming growth factor β is consistent with the inflammatory and profibrotic environment of active CD[1,7,8]. The positive association with peroxisome proliferator-activated receptor gamma 2 supports the role of adipocyte differentiation in creeping fat expansion, while the inverse relationship with occludin links mesenteric fat proliferation with epithelial barrier disruption[1,9,10]. These findings suggest that spectral CT may provide information that reflects not only morphology but also disease mechanisms[1,4,5]. Although imaging cannot replace tissue analysis, quantitative imaging markers that parallel molecular pathways could refine how radiologists report disease activity and chronicity.

DECT-derived fat volume plausibly reflects these molecular processes through a coherent, if still circumstantial, chain of evidence. Peroxisome proliferator-activated receptor gamma 2, the master regulator of adipocyte differentiation, is consistent with the hyperplastic adipogenesis that enlarges fat volume on DECT[9,10]. Tumor necrosis factor α and transforming growth factor β drive the inflammatory-to-fibrotic transition in CD, and their local activity may alter the fat’s attenuation and spectral characteristics, not just its volume[7,8]. The inverse association with occludin expression, reflecting barrier dysfunction, aligns with evidence that translocated microbiota and macrophage kynurenine metabolism promote mesenteric adipogenesis[9,10]. Together, these pathways support DECT-derived fat metrics as plausible surrogates for inflammatory, adipogenic, and barrier-related processes, rather than a purely anatomic finding.

A notable finding is the persistence of increased creeping fat volume in patients with quiescent CD compared with healthy controls[1]. Active disease showed the highest values, but quiescent disease did not return to baseline[1]. This observation is clinically relevant. It supports the concept that symptom improvement or mucosal remission may coexist with residual mesenteric abnormality[11-13]. In practice, such residual changes may represent low-grade inflammation, chronic adipose remodeling, or ongoing fibrotic remodeling. This is precisely where cross-sectional imaging can add value beyond endoscopy. Radiology can identify and quantify disease compartments that are not visible from the bowel lumen[11,14].

The potential clinical applications are substantial but should be interpreted cautiously. Dual-energy CT-based creeping fat quantification could support disease phenotyping, especially in patients at risk for fibrostenotic complications. It may also help monitor response to therapy when transmural healing is a target. In selected patients, serial quantitative assessment could complement clinical indices, biomarkers, endoscopy, and magnetic resonance enterography. However, CT-based monitoring must be balanced against radiation exposure, particularly in young patients who often require repeated imaging. For this reason, the role of dual-energy CT may be most appropriate in carefully selected clinical scenarios, such as when CT enterography is already indicated, when magnetic resonance imaging is unavailable or contraindicated, or when additional quantitative information may influence management[2].

Several barriers remain before this method can enter routine clinical practice. The study population was relatively focused, and broader validation is needed across age groups, disease phenotypes, scanner platforms, acquisition protocols, and reconstruction algorithms. Standardization of region-of-interest selection, segmentation methods, fat fraction thresholds, and reporting terminology will be essential. Interobserver reproducibility and workflow feasibility also require attention, since quantitative tools must be practical in daily radiology practice. Finally, longitudinal studies should determine whether changes in creeping fat volume predict treatment response, progression to stricturing disease, surgery, or relapse after apparent remission.

These workflow barriers have plausible technical solutions. Manual region of interest selection and segmentation, the most labor-intensive and operator-dependent steps, are also the most amenable to automation. Deep learning-based segmentation already delineates mesenteric and visceral fat on CT with near-expert accuracy in other abdominal applications; an analogous approach for creeping fat could reduce inter-observer variability, standardize fat fraction thresholds, and shorten analysis from a research task to routine reporting. Prospective validation against expert segmentation, across scanner platforms and reconstruction algorithms, would be a logical next step toward clinical practicality.

CONCLUSION

Despite the limitations, the work by Dong et al[1] is important because it reframes creeping fat as a measurable radiologic biomarker rather than a qualitative sign. It also illustrates the expanding role of spectral CT in inflammatory bowel disease. As abdominal imaging moves toward quantitative and biologically informed interpretation, dual-energy CT may help radiologists assess the mesenteric component of CD with greater precision. The future value of this approach will depend on whether creeping fat quantification can improve clinical decisions and patient outcomes. At present, it offers a promising window into the transmural and extraintestinal burden of CD, where radiology has a distinct and increasingly indispensable role.