ATLANTA - When it comes to interpreting soft-copy chest images, radiologists are just as comfortable with LCD (liquid-crystal display) monitors as with CRT (cathode-ray tube) displays -- even when they're inexperienced in flat-panel reading. In a presentation at the American Roentgen Ray Society (ARRS) meeting on Monday, Dr. Eliot Siegel from the University of Maryland discussed the results of this comparison study.
"Recent advances in active-matrix LCD monochrome displays, in addition to declining prices, make these a lot more attractive lately for both primary and secondary diagnoses," said Siegel, who also is chief of imaging at the VA Maryland Health System in Baltimore. "The use of these 3-megapixel LCD monitors (instead of) 5-megapixel CRTs requires two leaps of faith that we believe needed to be tested clinically. The first is that they are clinically comparable to CRT displays -- that LCDs can substitute for CRTs. The second is that a 3-megapixel monitor can serve as a satisfactory substitute for a 5-megapixel monitor."
For the study, 120 chest images, some normal and some with at least one nodule, were reviewed by four radiologists, all of whom had experience with soft-copy interpretation. The abnormal CR images were correlated with CT results to establish pathology.
One reader was a fourth-year resident, while another was a thoracic imaging specialist. However, no one had prior experience with LCD monitors, Siegel said. The radiologists read 40 images during each of three sessions, for a total of 480 interpretations.
"The images were stored on a Fuji Medical Systems PACS and were displayed using the standard Fuji processing for CR images," Siegel said.
The LCD and CRT monitors were calibrated according to manufacturers’ specifications, with one exception: Both were set to a brightness of 100 foot-Lamberts. "This setting was on the high end for the CRT monitors that are typically set at about 65 foot-Lamberts," Siegel explained. "The LCD monitors had to be cranked way down because their manufacturer’s recommended setting was significantly higher."
The researchers found no significant differences in the overall sensitivity and specificity of LCD versus CRT reading, Siegel said. Both measurements came in at around 80%. Interpretation time for the CRT was 35.4 seconds compared to 35.6 seconds on the LCD.
There also was no significant difference between the readers’ confidence in diagnosis. There was one discrepancy, however, involving the length of interpretation time when the window/level feature was used.
"We found that window/level was applied by the radiologists in 1/4 to 1/3 of the cases. In cases where there were one or more nodules, it was about 33 seconds without window/level adjustment and 58 seconds with window/level adjustment," he said. Siegel attributed this 25-second increase to the study setup.
"They were windowing and looking for nodules. They were looking at the upper portion of the hemidiaphragm, trying to look behind the heart. They knew their task was to find nodules so they were windowing and leveling multiple times. They weren’t just windowing and leveling once to optimize the image, they were windowing and leveling as part of a nodular search pattern," he said. If the window and level is correct at the time the case is presented to the radiologist, it can potentially increase efficiency and productivity, Siegel added.
While LCD monitors are expensive, they may be cheaper to own over the long run, especially as radiologists’ familiarity with flat-panel displays increases, Siegel said. The next phase for his group will be to test LCD versus CRT monitors for identifying and diagnosing other types of lung pathologies.
By Shalmali PalAuntMinnie.com staff writer
April 30, 2002
Related Reading
Radiology workstations need integration, automation, March 15, 2002
Bigger not necessarily better for digital chest x-ray matrix, January 15, 2002
Flat-panel combo provides less noise, lower dose, November 29, 2001
Flat-panel digital x-ray wins hands down over CR, screen-film, November 25, 2001
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