Predicting Risk of Surgery in Patients With Small Bowel Crohn's Disease Strictures Using Computed Tomography and Magnetic Resonance Enterography

Abstract

Background: We aimed to determine if patient symptoms and computed tomography enterography (CTE) and magnetic resonance enterography (MRE) imaging findings can be used to predict near-term risk of surgery in patients with small bowel Crohn's disease (CD).

Methods: CD patients with small bowel strictures undergoing serial CTE or MRE were retrospectively identified. Strictures were defined by luminal narrowing, bowel wall thickening, and unequivocal proximal small bowel dilation. Harvey-Bradshaw index (HBI) was recorded. Stricture observations and measurements were performed on baseline CTE or MRE and compared to with prior and subsequent scans. Patients were divided into those who underwent surgery within 2 years and those who did not. LASSO (least absolute shrinkage and selection operator) regression models were trained and validated using 5-fold cross-validation.

Results: Eighty-five patients (43.7 ± 15.3 years of age at baseline scan, majority male [57.6%]) had 137 small bowel strictures. Surgery was performed in 26 patients within 2 years from baseline CTE or MRE. In univariate analysis of patients with prior exams, development of stricture on the baseline exam was associated with near-term surgery (P = .006). A mathematical model using baseline features predicting surgery within 2 years included an HBI of 5 to 7 (odds ratio [OR], 1.7 × 105; P = .057), an HBI of 8 to 16 (OR, 3.1 × 105; P = .054), anastomotic stricture (OR, 0.002; P = .091), bowel wall thickness (OR, 4.7; P = .064), penetrating behavior (OR, 3.1 × 103; P = .096), and newly developed stricture (OR: 7.2 × 107; P = .062). This model demonstrated sensitivity of 67% and specificity of 73% (area under the curve, 0.62).

Conclusions: CTE or MRE imaging findings in combination with HBI can potentially predict which patients will require surgery within 2 years.

Keywords: Crohn disease; computed tomography enterography; magnetic resonance enterography; predictive model; surgical intervention.

Figure 1.

An example of imaging measurements. A-D, Each reader measured the maximum bowel wall thickness (A: circle), narrowest luminal diameter (B: circle), diameter of the proximal small bowel greatest dilation (C: broken arrow), and stricture length (D: broken arrow).

Figure 2.

Stricture morphology. A, Stricture with a short segment inflammation <10 cm (with proximal and distal ends marked by the bracket). B, Stricture with a long segment inflammation more than 10 cm (circle). C, Single stricture without inflammation (arrow). D, Multifocal short segment strictures (arrows). E, Complex fistula (arrow) with inflammation without upstream dilation. F, Complex fistula (arrow) with inflammation and upstream dilation.

Figure 3.

Examples of imaging features that predict near-term surgery within 2 years in multivariate analysis. A and B, Predominantly inflammatory stricture: a 27-year-old male patient with ileal wall thickening with mural hyperenhancement (black arrow in A) associated with 54 mm of the proximal small bowel dilation (white arrows in A and B). The wall thickening is observed in the appendix (white arrowhead in A). This patient underwent ileal resection 282 days after the baseline computed tomography enterography (CTE). C and D, Penetrating disease: a 33-year-old male patient with inflamed small bowel segments tethered to each other and connected through a complex fistula (arrows). This patient underwent ileal resection 329 days after the baseline CTE. E and F, Newly developed stricture: a 38-year-old female patient with the terminal ileal bowel wall thickening and mural hyperenhancement, indicating active inflammatory Crohn’s disease on a CTE 64 months before baseline CTE (arrow in E). The same terminal ileal segment developed a stricture with 32 mm of proximal small bowel dilation on the baseline CTE (arrows in F). This patient underwent ileocolonic resection 105 days after the baseline CTE.