Medical images are increasingly examined on computer monitors. In contrast to the traditional viewbox, the use of computer displays often involves a tradeoff between the number and size of images shown and the available screen space. This paper focuses on two solutions to this problem: the "thumbnail" technique and the "detail-in-context" technique.

We have examined the user interface of many current commercial medical imaging software systems. We observed one such system in use at a local hospital. Like many other commercial software packages, it utilizes the thumbnail technique, which displays small images in a thumbnail bar. These images can then be selected for magnification in a separate window.

Our earlier work indicated that a different approach may be feasible for the presentation of Magnetic Resonance Images (MRI) on a desktop monitor. The proposed technique, called detail-in-context, displays selected images in full detail and maintains context by displaying the remaining images in lesser detail around the selected ones.

We conducted a controlled experiment to evaluate the detail-in-context technique as well as the traditional thumbnail technique. Thirty-two university students were asked to perform a task that resembled radiologists' work practice during MRI examination. All interaction with the system was recorded via computer logs. Qualitative data was collected in a post-session questionnaire. We performed statistical and qualitative analyses with respect to performance, preference, and nature of interaction.

The results of this study revealed that performance was not significantly different for both techniques. In terms of preference, half the participants preferred the detail-in-context technique and half preferred the thumbnail technique. However, differences were found in the interaction patterns and comments provided by the participants. The detail-in-context technique accommodated many individual strategies and offered good capabilities for comparing different images whereas the thumbnail technique strongly encouraged sequential examination of the images and allowed for high magnification factors. Given the results of this study, our research suggests new alternatives to the presentation of medical images as well as provides an increased understanding of the feasibility of existing medical image viewing methods.