Spiral CT findings in active and remission phases in patients with Crohn disease

The purpose of this study was to evaluate the radiologic findings in helical CT (HCT) that can be useful to differentiate patients with active Crohn disease (CD) from those in the remission phase.

Fifty patients diagnosed with cases of CD were classified into active or remission phases (n = 37 and n = 13, respectively) according to clinical criteria and laboratory data. All of them underwent an abdominal HCT exploration. The following radiologic findings were evaluated: thickness, density and enhancement of the bowel wall, presence of "target" or "double halo," mesenteric involvement, and possible complications.

All patients in the active phase had pathologic findings on HCT. The wall thickness was 8.5 (SD 3.2) and 6.5 mm (SD 4 mm) in active and remission phases, respectively (p = 0.06). Target was present in seven patients (19%) with active disease and in five patients (38.5%) in the remission phase (p = 0.15). Density of the wall in the active phase was 95 HU and in the remission phase 65 HU (p < 0.002). Mesentery was involved in 89.2% of patients in the active phase and 38% of patients in the remission phase (p < 0.001). The complications observed in patients with active-phase disease were abscesses in nine (24%), phlegmons in two, fistulas in three, intestinal obstruction in two, and pancreatitis in one.

A normal HCT rules out that a patient with CD is in the active phase of disease. The presence of significant bowel wall enhancement and mesentery involvement assists in the differentiation of patients in the active phase from those in remission. HCT is also effective to assess the presence of complications, which are indicative of the active phase.