Imaging Criteria for Differentiating Under‑Distension from True Enteritis in the Proximal Jejunum

Diagnostic Imaging Features

Segmental hyperenhancement together with wall thickening (>3–5 mm) provides moderately high sensitivity and specificity for inflammatory bowel disease – a key criterion for confirming true enteritis【1】.
Mural stratification (bi‑ or tri‑laminar pattern) indicates submucosal edema or inflammatory infiltration, supporting a diagnosis of enteritis rather than simple under‑distension【1】.
Perienteric fat stranding (increased attenuation with loss of a sharp bowel‑mesentery interface) is a supportive sign of true inflammation【3】.
Increased T2‑weighted signal on MR enterography reflects mural edema and correlates with moderate‑to‑severe inflammation【4】.
Luminal ulcerations (small focal breaks in the bowel wall surface) are specific imaging manifestations of active enteritis【5】.
Restricted diffusion on MR enterography adds supportive evidence for inflammation when other inflammatory features are present【5】.
Hyperenhancement without accompanying wall thickening is nonspecific and may represent under‑distension, contraction, or other non‑inflammatory processes【1】.

Asymmetric involvement, especially pronounced along the mesenteric border, is highly specific for Crohn’s disease and argues against simple under‑distension【6】.
Symmetric, homogeneous wall thickening in a collapsed jejunal segment favors under‑distension rather than true inflammation【2】.

Infectious enteritis accounts for roughly 25 % of proximal jejunal wall‑thickening cases【6】.
Crohn’s disease is the primary inflammatory cause in about 14 % of cases【6】.
Reactive inflammation contributes approximately 15 % of cases【6】.
Other potential etiologies include ischemia, neoplasm, medication‑related injury (e.g., NSAID enteropathy), vasculitis, and graft‑versus‑host disease【1】.

When imaging shows only mild, symmetric wall thickening in a collapsed proximal jejunal segment without hyperenhancement, fat stranding, edema, or ulcerations, the report should describe the finding as “nonspecific proximal jejunal wall thickening, likely related to under‑distension” and suggest clinical correlation【5】.
If wall thickening is accompanied by hyperenhancement, perienteric fat stranding, mural edema, or ulcerations, the report should state “findings consistent with proximal jejunal enteritis” and detail the specific features and their severity【1】【5】.
All nonspecific imaging findings require correlation with clinical symptoms, laboratory results, and endoscopic evaluation to avoid over‑diagnosis【6】.