An investigation of workstation image manipulation usage when examining FFDM images

Introduction

With the introduction of digital breast screening across the UK, screeners need to learn how best to inspect these images. A key advantage over mammographic film is the facility to use workstation image manipulation tools.

Methods

Forty two-view FFDM screening cases, representing malignant, normal and benign appearances, were examined by 14 radiologists and advanced practitioners from two UK screening centres. For half the cases, the mammography workstation image manipulation tools could be employed; and for the other half these were not used. Participants classified each case and indicated whether an abnormality was present. Throughout the study, the participants visual search behaviour as well as their image manipulations were recorded.

Results

Whether or not image manipulation tools were used made very little difference to overall performance (t test, P >0.05) as confirmed by JAFROC analysis figure-of-merit values of 0.816 and 0.838 (with and without tools, respectively); performance not using tools was better. However, using tools significantly increased inspection time (P <0.5) as well as participants’ confidence. Detailed examination of participants’ image inspection behaviour elicited that when imaging tools were used then they spent 17 to 77% of their time manipulating the images; with the less experienced participants spending more time using such tools. Eye movement data demonstrated that when abnormalities were missed then this was typically due to search errors.

Conclusions

For these cases, whilst using imaging tools was not necessary to identify abnormalities, their use improved confidence, especially in identifying normal appearances. With experience, less use of such tools was evident.