Even without DICOM calibration, consumer-grade color displays can perform comparably to medical-grade grayscale LCDs for reading chest radiographs, Colombian researchers reported in the June issue of the American Journal of Roentgenology.
In a study involving 76 digitized chest x-rays, six radiologists, and three displays, the researchers found no significant difference in diagnostic accuracy between interpretations performed on the three displays and with and without DICOM calibration.
"Consumer-grade color LCD or LED displays with factory calibration may be useful for radiology services," said lead author Antonio Salazar, PhD, of the University of Los Andes in Bogota. "Expensive medical displays will be rapidly replaced by consumer color displays."
Following up on previous work that detected no difference in diagnostic accuracy between LCD and LED consumer-grade and medical-grade displays that had all been calibrated to the DICOM Grayscale Standard Display Function (GSDF) standard, the team sought to compare the performance using consumer-grade displays that had only received factory calibration (AJR, June 2014, Vol. 202:6, pp. 1272-1280).
They randomly selected 76 digital chest computed radiography exams from a university hospital in Bogota that had been performed between November 2007 and June 2009. All of these patients also received chest CT exams, which served as the reference standard in the study. The sample included 20 cases of interstitial opacities, 16 cases of pneumothorax, 18 cases of nodules, and 27 healthy subjects. Cases with obvious lesions were not included.
Six hospital radiologists with experience ranging from two to 10 years were recruited to participate in the study. The chest radiographs were printed on 35 x 43-cm film using a DryStar 5503 printer (Agfa HealthCare), and were digitized with an iCR-612SL film digitizer (iCRco) at 375 dpi resolution in 8-bit grayscale. The images were stored uncompressed in DICOM format.
Images were reviewed using DICOM software developed on three different displays:
- MD213MG 3-megapixel grayscale medical-grade display (NEC Display Solutions) with a dot pitch of 0.21 mm, spatial resolution of 2048 x 1536 pixels, maximum luminance of 1450 cd/m2, 10-bit grayscale, and cost of $15,000
- UltraSharp U2711 LCD consumer-grade color display (Dell) with a dot pitch of 0.23 mm, spatial resolution of 2048 x 1536 pixels, maximum luminance of 350 cd/m2, and cost of $862
- Consumer-grade LED display of a Vostro 3750 laptop computer (Dell) with a dot pitch of 0.24 mm, 1600 x 900 pixels, maximum luminance of 220 cd/m2, and cost of $780
The radiologists interpreted all of the images on each of the displays in separate sessions over a six-month period, with results rendered as mean area under the curve (mean AUC).
| Overall accuracy, medical-grade vs. consumer-grade displays | ||
| Without DICOM calibration (mean AUC) | With DICOM calibration (mean AUC) | |
| Medical-grade LCD | 0.89 | 0.97 |
| LCD | 0.87 | 0.97 |
| Laptop LED | 0.97 | 0.90 |
Differences were not statistically significant, according to the researchers. The readers agreed strongly for each display with and without calibration. There also were no significant differences in the other observed variables, which included accuracy of condition classification, false-positive rates, false-negative rates, and image-quality perception.
"Performing or not performing display calibration according to the DICOM GSDF curve does not appear to be associated with a difference in diagnostic performance in chest radiography when interpretations are realized with both medical-grade grayscale displays and consumer-grade color LCD or LED displays," the authors wrote. "The reason may be that current monitors come with factory calibration that somewhat resembles the GSDF, and that the GSDF is designed to model human grayscale discrimination tasks rather than detection tasks."
Although medical-grade grayscale displays are available for routine radiology practice or teleradiology services, there aren't enough of these units to meet the image-viewing requirements in emergency rooms, intensive care units, and examination rooms, and for use in educational purposes, Salazar told AuntMinnie.com.
"In addition, for teleradiology diagnostics delivery by radiologists at home or in small offices, specialized medical-grade displays are not affordable for radiologists who deliver teleradiology services [outside] of hospitals," he said. "Therefore, the key point of this study is the possibility to expand the teleradiology services to the radiologist's home or office. From the point of view of capture devices, it is possible to expand radiology services to rural areas and the jungle (more than 40% of our country, including the Amazonas, for example)."
The researchers are now evaluating use of these displays for mammography interpretations, Salazar said.
