Use of Full-quality DICOM Images Compared to Minimally Compressed Mammograms in JPEG Format for Radiology Training: A Study From Radiologist and Radiographer Perspectives

Running online training in mammography interpretation poses a challenge to radiologists and reporting radiographers due to the large size of digital mammograms in DICOM format and limited bandwidth capabilities of the users for image transmission. This study aims to compare image quality between the full-quality with minimal compressed JPEG and DICOM format of mammograms on a diagnostic monitor through the evaluation of radiologists and radiographers. Twelve participants including six radiologists and six radiographers participated as observers in this study. The observers viewed 60 2D digital mammography screening cases (22 cancer and 38 normal cases) in DICOM and minimal compressed JPEG formats on a 5MP diagnostic monitor. A 5-point Likert scale was provided for observers to compare the quality of mammograms between the two formats, with text anchors indicating to one image being significantly better, slightly better or of equal quality in terms of technical and diagnostic aspects. Nonparametric descriptive statistics were used to evaluate the ratings of radiologists and radiographers in different characteristics of mammograms of two image formats. The DICOM and JPEG images were statistically equivalent through ratings from radiographers in brightness, contrast, dynamic range, sharpness, no significant distortion, no significant noise, and background homogeneity in all mammograms. Similarly, most radiologists rated DICOM and JPEG images clinically and statistically equivalent with respect to difficulty of interpretation, brightness, contrast, dynamic range, sharpness, the appearance of Cooper's ligaments, visibility of subtle microcalcifications, visibility of structures at the margins of the breast. Normal cases were marginally favored by radiologists in DICOM format (ranging from 0.4% to 5.3%) while cancer cases in JPEG (ranging from 0.8% to 7.6%) received slightly higher rating. Findings showed that baseline full-quality with minimal compression JPEG was equivalent to the DICOM format of full-field digital mammograms which suggests that this type of JPEG could be used for online training and education in radiology.