POOR QUALITY OF CAPSULE ENDOSCOPY IMAGES HAS A SIGNIFICANT NEGATIVE EFFECT ON THE DIAGNOSIS OF SMALL BOWEL MALIGNANCY

Aims:

Capsule endoscopy (CE) diagnosis relies on image quality, commonly affected by poor preparation. Currently, there is no widely-accepted method for quantifying visualisation quality. We examined the contribution of image parameters to visualisation quality and their effect on diagnostic certainty of small bowel (SB) lesions.

Methods:

Five clear CE images of SB pathology were processed for 3 parameters to simulate increasingly poor SB preparation:

• opacity (colour-matched to luminal content; 10 – 90%, 10% increments),

• blurriness (radius 1 – 10px; 1px increments), and

• contrast (-50 – 50%; 10% increments).

9 experts evaluated whether images were adequate for diagnosis. Points where perception of image quality changed significantly were determined for each parameter. Three further sets of SBCE images (vascular, inflammatory and malignant lesions) were processed for 4 points per parameter. 20 experienced-expert CE readers reviewed the resulting images.

Results:

In vascular and inflammatory lesions, diagnostic certainty was least affected by increasing image opacity, requiring opacities > 90% before most readers considered images inadequate for diagnosis. The greatest negative effects of image opacity were seen in malignancies where significantly fewer readers found images adequate at > 50% opacity. Similar results were obtained with increasing blur radius, simulating motion blur and poor focus. The proportions of readers finding vascular and inflammatory images adequate did not drop significantly at wider blur radii, while the proportion who found images of malignancies diagnostically adequate dropped at blur radius 6px. Decreasing contrast had greater negative effect than raised contrast, most obvious in malignant lesions.

Conclusions:

Poor visualisation quality in all parameters had the greatest effect on images of malignant lesions. Software to increase contrast and sharpen images can improve visualisation quality; smart frame rate adaptation could also improve the number of high-quality frames obtained. Furthermore, our results suggest that thoroughness in SB cleansing is most important when there is suspicion of malignancy, so as to improve diagnostic certainty from the images obtained.