Visualization of CAD results to the radiologist. influence of the marker type on radiologist's sensitivity for the detection of pulmonary nodules

Purpose: The efficiency of the detection of pulmonary nodules by a radiologist with the help of CAD is influenced by the user interface of the system. Marker with a visually dominant appearance may distract the radiologist from other parts of the screen. Purpose was to analyse the influence of different CAD markers on radiologist's performance. Materials and methods: 10 radiologists analysed 150 pictures of chest CT slices. Every picture contained a CAD marker; five different types of markers were used - each respectively on 30 pictures (1: thick walled square, 2: thin walled circle, 3: small arrow, 4: pixel sized point on nodule, 5: very subtle change of colour). One hundred images contained one nodule: CAD markers marked this finding in 50 cases; in 50 cases a false positive finding was marked instead. The remaining 50 images contained no nodule but a marker of a false positive finding. The radiologists had to decide for each image if there was a nodule visible and either click on the nodule or on a button "no finding". Sensitivity and specificity were calculated for each marker type. Results: Mean sensitivity was 59%, 62%, 64%, 65% and 64% for marker 1 to 5, respectively. Specificity was 50%, 51%, 64%, 45% and 67%. In the cases with false positive findings sensitivity for detection of the unmarked nodule was 41%, 58%, 59%, 49% and 54%. New work to be presented: The study shows that the marker type influences radiologist's sensitivity and distraction from other findings. Conclusion: Of the tested markers a small arrow was most efficient for the presentation of the results to the radiologist.