IMPROVING CONSPICUITY OF THE CANINE GASTROINTESTINAL WALL USING DUAL PHASE CONTRAST-ENHANCED COMPUTED TOMOGRAPHY: A RETROSPECTIVE CROSS-SECTIONAL STUDY.

Ella Fitzgerald,Randi Drees,Richard Lam

doi:10.1111/vru.12467

Abstract

Gastrointestinal (GI) disease is a common clinical complaint in small animal patients; computed tomography (CT) examinations enable a global overview of the GI tract and associated structures. Previously, the GI wall has been reportedly identified from serosa to mucosa in 77% of standard postcontrast CT studies and wall layers seen in ultrasound have not been distinguished. Inconsistent strong contrast enhancement of the inner layer of the GI mucosal surface was noted on dual phase CT studies acquired in our institution, which increased the visibility of the GI tract and disease processes. The aim of this retrospective, observational, cross-sectional study was to determine the optimal portal vein attenuation for maximizing GI wall conspicuity using dual phase contrast-enhanced CT. Patients with abdominal CT for a non-GI related disease were included. In a pilot study, 175 GI segments from 35 CT studies were graded for presence of mucosal surface enhancement (MSE). The strongest mucosal surface enhancement grade correlated with portal vein attenuation of 43-150HU; this value was used as inclusion criterion in the main study. A total of 441 GI segments were evaluated in 42 CT studies postcontrast for GI wall conspicuity. The GI wall was conspicuous in 56.7% precontrast, 84.5% at 30s, and 77.3% late postcontrast; 4.7% of segments were removed due to motion blur. At 30 s distinct mucosal surface enhancement was seen in the small intestine and gastric mucosal surface enhancement was poor. Findings supported the use of dual phase contrast-enhanced CT for improving conspicuity of the GI wall.

Highlights

Gastrointestinal disease can represent a diagnostic challenge in small animals using noninvasive techniques
The findings of this study have partially supported the first part of our hypothesis; that distinct mucosal surface enhancement occurs in early (30 s) postcontrast examinations for the majority of the evaluated gastrointestinal segments
In the pilot study mucosal surface enhancement occurred at mean portal vein attenuation values of 94, 87, and 81 HU for the duodenum, jejunum, and ileum, respectively

Summary

Introduction

Gastrointestinal disease can represent a diagnostic challenge in small animals using noninvasive techniques. First-line modalities used in patients with gastrointestinal disease commonly include conventional radiography, contrast radiography, or ultrasound (US). Pronounced enhancement of the inner layer of the gastrointestinal tract, the stomach and small intestine, was noted intermittently on the studies acquired in the 30 s and late postcontrast examinations. This enhancement subjectively aided in the depiction of the gastrointestinal wall compared to regular postcontrast studies acquired at approximately 60 s postcontrast injection. The sonographic appearance of normal gastrointestinal wall layering is well described in the literature. A similar description of normal gastrointestinal wall layering in post- contrast CT examinations has not been described in veterinary patients.[10]

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