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The Yellow Scale Is Superior to the Gray Scale for Detecting Acute Ischemic Stroke on a Monitor Display in Computed Tomography

Posted Aug 31, 2018 Updated Apr 10, 2023
By Akio Ogura PhD , Katsumi Hayakawa MD , Yoshito Tsushima MD , Fumie Maeda RT , Aoi Kamakura RT , Kunihiko Katagiri MS
7 min read

Rationale and Objectives

The purpose of this study was to compare the efficacy of the color scale with regard to focal detection with computed tomography in acute ischemic stroke.

Materials and Methods

Computed tomography images of the brain of 19 patients diagnosed with acute stroke, based on magnetic resonance diffusion-weighted images obtained within an onset of 24 hours, and the images of five normal patients were displayed in each color look-up table on a monitor. The detection of acute stroke was compared among 15 radiologists. The images were compared in the gray, green, yellow, red, and blue scales of the look-up tables. The observers recorded acute ischemic stroke as “present” or “absent.” They also located the position of the stroke lesion and described the degree of their conviction as to whether a lesion existed. Detection was evaluated by receiver operating characteristic analysis. The area under the receiver operating characteristic curves was compared. In addition, reduced fatigue and the ease in image observation were compared.

Results

Compared to the other scales, the yellow scale had a significantly higher area under the receiver operating characteristic curve, which indicated that this scale allowed better detection of acute ischemic stroke. The gray scale produced the least fatigue in image observation.

Conclusions

The detection of acute ischemic stroke is improved by changing the display monitor from the gray scale to the yellow scale. From the perspective of color psychology, yellow is associated with higher arousal, cheerfulness, confidence, creativity, and excitement. Therefore, the yellow scale may be suitable for a medical imaging display.

Introduction

Stroke is the second leading cause of death worldwide, and many researchers have analyzed the developmental mechanism and the defense against stroke . If cerebral infarction is detected early and a patient receives appropriate treatment such as thrombolytic therapy, then the survival rate and convalescence are improved. In particular, adaptation to ischemic cerebrovascular disorder of recombinant tissue-type plasminogen activator is an epoch-making therapy . Patients can expect a good outcome after stroke onset if these treatments are administered early (ie, within 4.5 hours) . Computed tomography (CT) of the brain is generally performed as an emergency study when a stroke is suspected. CT of the brain provides cerebral infarction views such as early CT sign without bleeding, and the aforementioned treatments can be applied. Therefore, early diagnosis is necessary. However, interpreting cerebral infarction with few contrast changes is difficult, even for expert radiology physicians.

In recent years, an image monitor has often been used for the interpretation of a radiograph image. On an image monitor, the gray scale display (which was initially used for backlight and film diagnosis) is commonly used, although a color display can be used to determine a monitor diagnosis. However, in one report , the detectability of a low-contrast image was improved more by a color scale than by the gray scale. Changing the color scale of the monitor may improve the detectability of an acute cerebral infarction. In this study, we investigated whether the detectability of an acute cerebral infarction would be improved by using a color scale on the imaging monitor.

Materials and Methods

Image Evaluation

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Figure 1, The look-up table of gray, yellow, red, green, and blue.

Figure 2, The computed tomography image of the brain, which is displayed in each color scale.

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Observation Evaluation

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Analysis of the Evaluation

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Results

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Figure 3, The average receiver operating characteristic curves of the 15 observers for each color scale.

Figure 4, Box-and-whiskers plot of the area under the receiver operating characteristic curves (AUCs) corresponding to the 15 observers. The AUC is an index indicating the sensitivity and the specificity of lesion detection. The AUC is significantly higher in the yellow scale than in the other color scales, including the gray scale ( P < .05). (Color version available online.)

Figure 5, Reduced fatigue of the eyes arising from continuous observation among 15 observers. Reduced fatigue is an index indicating the degree to which an individual does not have fatigue of the eyes when interpreting images. The observers reported that the gray scale reduced eye fatigue more significantly than the other color scales. (Color version available online.)

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Figure 6, Ease in viewing per evaluation, as reported by the 15 observers. Ease in viewing is the degree to which an observer has ease in viewing an image. In the evaluation of ease of viewing, the yellow scale and the gray scale are not significantly different from each other, and both scales are more significantly different from the other color scales with regard to ease of viewing. (Color version available online.)

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Discussion

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Conclusions

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Acknowledgments

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Academic Radiology, Volume 25, Issue 9
Journals General Radiology
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