Bowel Wall Vascularization in Crohn's Disease: Exploratory Comparison of Vendor-Derived Vascular Index, ImageJ-Based...

Background: Assessment of inflammatory activity in Crohn's disease (CD) remains challenging. Bowel wall vascularization is an established marker of transmural inflammation and is typically evaluated using semiquantitative ultrasound scoring systems. In contrast, quantitative vascularization analysis is not yet widely used in clinical practice. To compare these approaches, this study evaluated semiquantitative and quantitative methods in the same patient cohort. Methods: This prospective single-center study included 50 patients with CD and sonographically detectable bowel wall thickening. Bowel wall vascularization was assessed using power Doppler (PD), color-coded superb microvascular imaging (cSMI) and monochrome mode superb microvascular imaging (mSMI). Video sequences were independently evaluated by three blinded readers using the Limberg classification. Quantitative vascularization was assessed using a vendor-derived vascular index and retrospective ImageJ analysis. Crohn's Disease Activity Index (CDAI) and laboratory parameters were documented. Results: Interobserver agreement differed between imaging modalities. Krippendorff's α values were 0.735 (PD), 0.655 (cSMI) and 0.527 (mSMI), indicating higher reliability for PD than for the SMI techniques. According to Fleiss' κ (0.480 (PD), 0.376 (cSMI) and 0.367 (mSMI)), agreement was moderate for PD and fair for both SMI techniques. Complete concordance among all three readers was observed in 24 (PD), 18 (cSMI), and 22 (mSMI) patients, respectively. SMI-based techniques consistently resulted in higher Limberg grades compared to PD. Exploratory analyses showed strong correlations between different quantitative vascularization parameters (ρ up to 0.898, p < 0.001), but only moderate correlations with fecal calprotectin (FC) (ρ up to 0.389 with p = 0.017). Significant negative correlations were observed between vascular indices and body mass index (BMI) and skin-to-bowel distance (ρ up to -0.614, p < 0.001). The same trend was observed in the semiquantitative Limberg classification. Conclusions: Semiquantitative assessment of bowel wall vascularization seems to be limited by interobserver variability and Doppler technique, with SMI yielding higher Limberg grades than conventional Doppler. Standardized quantitative approaches may improve objectivity, but their reproducibility requires further validation. Patient-related factors should be considered when interpreting vascularization findings.