HOW SAFE IS TELERADIOLOGICAL TELEDIAGNOSI S FOR CT IMAGING

Purpose: To define the Value of teleradiographic studies, a comparison was carried out between digitised copies of CT examinations of the sk ull with the original images. Differences in image quality obtained fr om a digital scanner and a camera were quantified. Material and method : 56 CT examinations of the skull, 28 of which had discrete abnormalit ies, were chosen for ROC analysis. The original films were digitised w ith a Vidar VXR-12 scanner and Panasonic WV-160 and WV-BP 500 cameras. The images were evaluated by five radiologists after image transfer w ith Video Conference software to a personal computer. Results: For the analysis of the films the area under the ROC curve was 0.91 +/- 0.04, for the digital scanner it was 0.85 +/- 0.04, for camera WV-BP 500 0. 89 +/- 0.06 and for camera WE-160 0.87 +/- 0.09. Comparison with the f ilm findings showed a minimal p-value of 0.17 which indicated that the re was no significant reduction in diagnostic Value following digitisa tion. Conclusion: The probable reason for the slight deterioration usi ng the digital scanner was the reduction to 75 dpi compared with 134 d pi on the CT films. The cameras produce image noise comparable to CT w ith low window settings and reduced local resolution. We expect simila r results for CT with soft tissue windows or for MRT of the skull. Con ventional radiographs containing high local resolution, wide grey scal e and low image noise would presumably make higher demands on methods of digitisation.