iPad nearly matches LCD monitors for interpreting brain CT

Detection of cerebral infarction was similar using LCD monitors with either gamma 2.2 calibration or gray-scale standard display function calibration, and only slightly worse performance was measured with use of an iPad, according to a study published in the June issue of the American Journal of Roentgenology.

“The present result showed that the iPad was acceptable for reading brain CT, especially when used by well-trained observers,” wrote Kumiko Yoshimura, of Nagoya University Graduate School of Medicine, Nagoya, Japan, and colleagues.

There have been a number of previous studies comparing medical-grade and low-grade LCD monitors, and the authors had previously found that a low-grade LCD with gamma 2.2 calibration had superior contrast resolution compared to a medical-grade LCD of gray-scale standard display function.

“If a low-grade LCD were available in restricted situations, the overall cost of the PACS could be reduced,” wrote Yoshimura and colleagues.

To compare performance between monitor calibrations, while also assessing performance on an iPad, Yoshimura and colleagues amassed 97 sample brain CT sets representing 47 patients with proven cerebral infarction and 50 healthy control subjects. The CTs were reviewed in random order on either an iPad or medical-grade monitors, with the monitors using either gray-scale standard display function or gamma 2.2 calibration. Reviews were conducted over 4-week intervals by nine independent radiologists.

Results showed the area under the receiver operating characteristic (ROC) curve was calculated at 0.875, 0.884 and 0.839 for the gray-scale standard display LCD, the gamma 2.2 LCD and iPad, respectively. The differences between gray-scale and gamma 2.2 were not significant, but the area under the ROC curve was statistically significantly smaller for the iPad than the gamma 2.2 LCD, according to the authors.

They noted that the evaluation was affected by the level of experience of the observers, with the difference in detectability smaller among observers with 10 or more years of experience compared with less experienced observers. “We speculated that this result showed that the experience of the observers complements the difference between the LCD monitor calibrated with γ 2.2 and that with gray-scale standard display function,” wrote Yoshimura and colleagues. “The experience of observers is considered to be an important factor for detectability.”

In speculating why the iPad came up just a bit short of the LCD monitors, the authors said the smaller screen size and unfamiliar operation of the iPad hindered performance. “The diagnostic accuracy of an iPad is certainly inferior to other LCDs; nevertheless, the tablet PC, such as an iPad, possessed great advantages in portability and applications for teleradiology.”