Abstract
Radiologists can identify the gist of a radiograph (i.e., abnormal vs. normal) better than chance in breast, lung, and prostate images presented for half a second. However, this rapid perceptual gist processing has only been demonstrated in static two-dimensional images. Standard practice in radiology is moving to three-dimensional (3D) “volumetric” modalities. In volumetric imaging, such as multiparametric MRI (mpMRI), used in prostate screening, a single case consists of a series of image slices through the body that are assembled into a virtual stack. Radiologists can acquire a 3D representation of organ structures by scrolling through stacks. Can radiologists extract perceptual gist from this more complex imaging modality? We tested 14 radiologists with prostate mpMRI experience on 56 cases, each comprising a stack of 26 T2-weighted prostate mpMRI slices. Lesions (Gleason scores 6–9) were present in 50% of cases. A trial consisted of a single movie of the stack. After each case, participants localized the cancerous lesion on a prostate sector map, then indicated whether a cancerous lesion was presented, and gave a confidence rating. Presentation duration was varied between groups. Radiologists were divided into three groups who viewed cases presented at either 48 ms/slice (20.8 Hz, n = 5), 96 ms/slice (10.4 Hz, n = 5), or 144 ms/slice (6.9 Hz, n = 4). Performance declined as slice duration increased (d’ [95% CI]: 48 ms = 0.77 [−.08 - 1.6]; 96 ms = 0.71 [0.17 - 1.24]; 144 ms = 0.47 [0.25 - 0.69]), though gist perception was not statistically significant for the 48 ms group. Localization accuracy (chance ~= 0.08) was 0.40, 0.47, and 0.48, respectively. Our data indicate that radiologists do develop gist perception for 3D modalities. Furthermore, slower presentation rates did not improve performance; there may be an optimal framerate for processing this type of 3D information.