A Novel Diagnostic Aid for Detection of Intra-Abdominal Adhesions to the Anterior Abdominal Wall Using Dynamic Magnetic Resonance Imaging

Abstract

Introduction. Abdominal adhesions can cause serious morbidity and complicate subsequent operations. Their diagnosis is often one of exclusion due to a lack of a reliable, non-invasive diagnostic technique. Development and testing of a candidate technique are described below. Method. During respiration, smooth visceral sliding motion occurs between the abdominal contents and the walls of the abdominal cavity. We describe a technique involving image segmentation and registration to calculate shear as an analogue for visceral slide based on the tracking of structures throughout the respiratory cycle. The presence of an adhesion is attributed to a resistance to visceral slide resulting in a discernible reduction in shear. The abdominal movement due to respiration is captured in sagittal dynamic MR images. Results. Clinical images were selected for analysis, including a patient with a surgically confirmed adhesion. Discernible reduction in shear was observed at the location of the adhesion while a consistent, gradually changing shear was observed in the healthy volunteers. Conclusion. The technique and its validation show encouraging results for adhesion detection but a larger study is now required to confirm its potential.

Figures

Figure 1

Schematic of the motion discontinuity in the abdomen during respiration. The horizontal green arrow indicates the predominant motion of the abdominal wall whilst the mostly vertical arrow represents the predominant motion of the abdominal contents. The dotted red line indicates the approximate location of the motion discontinuity.

Figure 2

Flow chart describing the methodology. Step  1: typical region drawn to separate (segment) the two regions of different motion; step 2: depiction of the mathematically quantified movement; step 3: depiction of the shear taking place along the boundary in a “sheargram”.

Figure 3

Comparison of the sheargrams from (a) a patient with an adhesion (arrow) and (b) and (c) two healthy volunteers.

Figure 4

Validation experiment 1 with an idealised stretch of the portion of a MR image shown in (a) and shear results compared to actual shear in the system in (b).

Figure 5

Syringe test object displaying (a) uncompressed sponge, (b) compressed sponge, (c) shear result without adhesive tape, and (d) shear result with adhesive tape (indicated by red block).