To evaluate the clinical value of contrast-enhanced ultrasound (CEUS) quantitative analysis in assessing the disease activity of Crohn′s disease (CD).

From February to August 2014, 55 consecutive patients who were comprehensively confirmed to have CD by clinical, endoscopic, and pathologic evidence were prospectively evaluated. Using the concentration of high-sensitivity C-reactive protein (hs-CRP) as the reference standard, the diagnostic performance of power Doppler image (PDI) according to Limberg classification, the enhancement patterns on CEUS, and quantitative parameters including peak intensity (PI), rising time (RT), and time to peak (TTP) were analyzed and compared. Quantitative parameters between active and inactive CD patients were compared by the independent t-test. The receiver operating characteristic curve (ROC) of each parameter was analyzed, and the area under the ROC (AUROC) was compared by the χ²-test.

There were 39 patients with active and 16 with inactive CD according to the level of hs-CRP. PDI according to Limberg classification had a Youden index of 0.49, while CEUS patterns had a Youden index of 0.25. Quantitative analysis showed higher PI and shorter RT and TTP in patients with active disease than in those with inactive CD (P<0.05). ROC analysis showed that the cutoff values in assessment of disease activity were: PI>19 dB, RT≤6.2 s, and TTP≤8.7 s. By using the quantitative parameters presented above as diagnostic standard, the Youden indexes were 0.56, 0.39, and 0.45, respectively. Pairwise comparisons showed that PI had higher efficiency in assessing the inflammatory activity of CD in comparison to qualitative analysis (P<0.05).

CEUS quantitative analysis performs better than qualitative analysis in the assessment of the activity of CD. Although the performance of CEUS quantitative analysis is equal to that of PDI, the former is more objective and should be recommended in clinical practice.