The effects of the conversion and enlargement of digital radiological image from DICOM to JPEG image format on distance measurement

Introduction: Conversion of images from DICOM format to other image formats affects measuring distances in images. Materials: and methods. Distances in DICOM or JPEG images were measured with different zoom using 1.5T MRI scanning of human diaphragm during spontaneous breathing and during low and high lung volumes. Results: . Correlation between distance measurements in mm and pixels at all zoom factors on DICOM and JPEG images ranged from r=0.9981-1.00 and 95% CI for r of 0.9972 - 0.9986 to 1.00 - 1.00 and the p-value in all correlations was <0.001. Results of comparing the difference in measured dimensions on DICOM and JPEG images in mm for F1.0 indicate that differences in measurements are small (0.1 mm average). Image zooming in JPEG for F1.8 compared to the idealized pixel size values with that zoom on average increases the number of pixels for 1 (range from 5 pixels increase to 4 pixels loss). Conclusions: . The values of linear regression equation for all zoom factors (F1.0 - F1.8) indicate that distance measurement on the zoomed JPEG image is not suitable for obtaining accurate results of distance measurements. The distance measurements in JPEG images without zoom are entirely in accordance with distance measurements in DICOM images. In the zoomed images distance measurements differ from the results of distance measurements in DICOM format and for the possible use of the results it is necessary to provide data on zoom factor, physical size of the pixel spacing and the values of the linear regression equation.