Predictors of Durability of Radiological Response in Patients With Small Bowel Crohn's Disease

Abstract

Background: The long-term significance of radiological transmural response (TR) as a treatment goal at the first follow-up scan in small bowel Crohn's disease (CD) has been previously shown. We examined the durability of a long-term strategy of treating to a target of radiological TR and the influence of baseline predictors on the maintenance of TR.

Methods: Small bowel CD patients between January 1, 2002, and December 31, 2014, were identified with serial computed tomography enterography (CTE)/magnetic resonance enterography (MRE) before and after initiation of therapy or on maintenance therapy. Overall TR (inflammatory lesions with/without strictures) w1as characterized by abdominal radiologists in up to 5 small bowel lesions per patient at each serial scan until last follow-up or small bowel resection, as response, partial response, or nonresponse. The rate of conversion between TR states and transition to surgery, including the effect of baseline patient/disease characteristics, was examined using a multistate model (mstate R-package).

Results: CD patients (n = 150, 705 CTE/MRE) with a median of 4 CTE/MRE during 4.6 years of follow-up, 49% with ileal-only distribution, had 260 examined bowel segments. Conversion from response to partial response/nonresponse was 37.4% per year of follow-up with no transitions seen directly from response to surgery. Current smoking status (hazard ratio [HR], 2.2; 95% confidence interval [CI], 1.1-4.3) and internal penetrating disease at baseline scan (HR, 2.2; 95% CI, 1.2-4.1) were associated with a 2-fold increased risk of transition from partial response/nonresponse to surgery.

Conclusions: Achievement and maintenance of radiological response is associated with avoidance of small bowel surgery. Continued follow-up with CTE/MRE is recommended to identify loss of response, especially in current smokers and patients with internal penetrating disease at baseline CTE/MRE.

FIGURE 1.

Four-state model of radiological transmural response identified on serial enterography in small bowel Crohn’s disease patients with 3 transient states (response, partial, or nonresponse) and an absorbent state (small bowel surgery).

FIGURE 2.

Seventy-five-year-old male with CT enterography that demonstrated active inflammatory Crohn’s disease involving the terminal ileum (A, white arrow) and distal ileum over a distance of approximately 30 cm, with the proximal end of the inflamed segment also shown (A, arrowhead). The subsequent 2 CT enterography exams demonstrated no change, but subsequent CT enterography obtained 7 years after index scan show a normal-appearing terminal ileum (B, arrow) and equivocal enhancement and wall thickening (B, arrowhead) that involves only approximately 15 cm of the distal ileum in a discontinuous fashion.

FIGURE 3.

Eighty-four-year-old female with CT enterography that demonstrated active inflammatory Crohn’s disease involving 25 cm of the distal ileum (A, white arrow) but without prestenotic dilation (B, arrowhead). Two years later, CT enterography demonstrates increasing ileal inflammation, as manifested by increasing wall thickness and peri-enteric stranding (C, arrows) with additional development of prestenotic dilation (D, arrowhead) indicating stricture development. Ten months later, repeat exam shows marked reduction in distal ileal inflammation (E, arrows) with persistent stricture (F, arrowhead).

FIGURE 4.

Twenty-five-year-old female underwent MR enterography demonstrating marked inflammation in the 13 cm of neoterminal ileum (arrows, A) with stricture, as manifested by dilation of the proximal ileum to greater than 4 cm (arrowhead, inset A), and generalized proximal small bowel distension. Patient had 2 subsequent MR enterography exams, each showing decrease in length and severity of inflammation. A third subsequent MR exam performed 4 years later shows only 4 cm of neoterminal inflammation, with decrease in wall thickness as well (arrow, B), with minimal dilation of the proximal small bowel immediately proximal to the stricture (arrowhead, inset B) and normalization of jejunal and proximal ileal distension.