Quantitative evaluation of the memory bias effect in ROC studies with PET/CT

Maria Kallergi; Nicoletta Pianou; Alexandros Georgakopoulos; Georgia Kafiri; Spiros Pavlou; Sofia Chatziioannou

doi:10.1117/12.911621

22 February 2012 Quantitative evaluation of the memory bias effect in ROC studies with PET/CT

Maria Kallergi, Nicoletta Pianou, Alexandros Georgakopoulos, Georgia Kafiri, Spiros Pavlou, Sofia Chatziioannou

Proceedings Volume 8318, Medical Imaging 2012: Image Perception, Observer Performance, and Technology Assessment; 83180D (2012) https://doi.org/10.1117/12.911621
Event: SPIE Medical Imaging, 2012, San Diego, California, United States

Abstract

PURPOSE. The purpose of the study was to evaluate the memory bias effect in ROC experiments with tomographic data and, specifically, in the evaluation of two different PET/CT protocols for the detection and diagnosis of recurrent thyroid cancer. MATERIALS AND METHODS. Two readers participated in an ROC experiment that evaluated tomographic images from 43 patients followed up for thyroid cancer recurrence. Readers evaluated first whole body PET/CT scans of the patients and then a combination of whole body and high-resolution head and neck scans of the same patients. The second set was read twice. Once within 48 hours of the first set and the second time at least a month later. The detection and diagnostic performances of the readers in the three reading sessions were assessed with the DBMMRMC and LABMRMC software using the area under the ROC curve as a performance index. Performances were also evaluated by comparing the number and the size of the detected abnormal foci among the three readings. RESULTS. There was no performance difference between first and second treatments. There were statistically significant differences between first and third, and second and third treatments showing that memory can seriously affect the outcome of ROC studies. CONCLUSION. Despite the fact that tomographic data involve numerous image slices per patient, the memory bias effect is present and substantial and should be carefully eliminated from analogous ROC experiments.

Citation Download Citation

Maria Kallergi, Nicoletta Pianou, Alexandros Georgakopoulos, Georgia Kafiri, Spiros Pavlou, and Sofia Chatziioannou "Quantitative evaluation of the memory bias effect in ROC studies with PET/CT", Proc. SPIE 8318, Medical Imaging 2012: Image Perception, Observer Performance, and Technology Assessment, 83180D (22 February 2012); https://doi.org/10.1117/12.911621

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