How important is mammographic image manipulation when examining digital screening cases?

Introduction

A group of screeners was presented with recent digital screening cases on a mammographic workstation and asked to examine these images either with or without using any image manipulation functions. Their performance and visual search behaviour was measured to determine how using these functions affected their case reading behaviour and performance.

Methods

Two sets of 20 cases were matched for abnormality presence and mammographic appearances as closely as possible. Seven radiologists and advanced practitioners then examined these cases on a GE digital mammography workstation whilst their eye movements were recorded using a head-mounted eye tracker. For 20 cases they were not allowed to manipulate the images and for the other 20 they could manipulate the images (that is, pan, zoom and adjust contrast and window level) if they wanted to. Case viewing order was randomised. For each case they rated their confidence in abnormality presence, its location, case density and their screening decisions. Their performance and search behaviour were also compared to those of an experienced radiologist who was very familiar with the case set.

Results

The data demonstrated that participants were as able to identify abnormalities without the need of using image enhancement manipulations as they were with them (P > 0.05). However, using these tools increased their rated confidence in their case decisions as well as resulted in overall slower examination times compared to the experienced radiologist.

Conclusion

Whilst image post-processing manipulations are not necessary for reporting screening cases appropriately, they do affect reporting confidence and mammographic case visual examination.