White Paper

Study to Demonstrate Efficacy of 8MP Color Display - Mammography

CONTENTS

1．INTRODUCTION ....................................................................................................................................................................... 2
2．PURPOSE.................................................................................................................................................................................... 2
3．METHODS ................................................................................................................................................................................... 2
4．RESULTS ..................................................................................................................................................................................... 3
5．CONCLUSIONS ........................................................................................................................................................................ 5
6．REPORT FROM DR. KRUPINSKI, UNIVERSITY OF ARIZONA ........................................................................ 6

No.15-001 Revision A
July 2015
Product & Business Development Dept.
Product Technology section

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1．Introduction
EIZO proposes the RadiForce RX850, an 8MP color diagnostic display, as being equivalent to dual
5MP displays for mammography use despite its smaller matrix size (2 x 2048 x 2160 for theRadiForce RX850 vs. 2 x 2048 x 2560 for the dual 5MP displays).
In order to compare the diagnostic performance of the single 8MP display to that of the dual 5MPdisplays, we asked Elizabeth A. Krupinski, PhD, a Professor at the University of Arizona in theDepartments of Medical Imaging, Psychology and Public Health, to conduct a clinical evaluation.
One of the evaluation results was that there were significant improvements in reader efficiency withthe single 8MP display compared to the dual 5MP displays. This white paper shows the details of theclinical evaluation including the advantages of the 8MP display. For more details, please see thereport written by Dr. Krupinski.

2．Purpose
The goal of this study was to assess diagnostic accuracy and reader efficiency as a function ofdisplay and display layout. This study had 2 reading conditions: a single EIZO 8MP display (withoutcentral bezel) vs dual-5MP EIZO displays (with bezels between the two screens). There were three
aspects of reader performance that were studied: diagnostic accuracy as measured by Receiver
Operating Characteristic (ROC) analysis, reading time, and number of times the readerszoomed/panned the images.

3．Methods
The study was carried out using displays (Figure 1) that were equivalent except for the parameterof interest (8MP without bezel vs dual 5MP with bezel). They were set up by EIZO with as equivalentas possible white points, maximum/minimum luminance, and black levels, and were calibrated to theDICOM GSDF. For details, please see the report written by Dr. Krupinski.

4096 pixels
4096 pixels
2160 pixels

2560 pixels
Figure 1. The two display configurations.

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4．Results
This section shows three advantages we found of the single 8MP display. For details, please see
the report written by Dr. Krupinski.
For viewing time, there was a significant difference between the two reading conditions, with thesingle 8MP display taking less time on average than with the dual 5MP displays. The single 8MP
display is superior to the dual 5MP displays by 10 percent.

Figure 2. Average viewing time in each reading condition.

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The total number of fixations generated with the single display was also significantly fewer thanwith the dual displays. The single 8MP display is superior to the dual 5MP displays by 13 percent.

Figure 3. Average of total number of fixations.

The number of times they scanned from one image to the other was significantly fewer with thesingle display than with the dual displays. The single 8MP display is superior to the dual 5MP displaysby 17 percent.

Figure 4. Average of number of times scanned from one image to the other for each of thereaders in each reading condition.

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5．Conclusions
Our conclusion is that the single 8MP display yielded the same diagnostic accuracy as the dual
5MP displays. In addition, we found advantages in viewing time, total number of fixations and numberof times readers scanned from one image to the other. Therefore, the single 8MP display can
substitute for the dual 5MP displays.

Note: All figures are not based on the measurement result but simplified images.
All product names are trademarks or registered trademarks of their respective companies. Copyright 2015 EIZO CORPORATION. All rights reserved.

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6．Report from Dr. Krupinski, University of Arizona

Study to Demonstrate Efficacy of 8MP Color Display - Mammography
Elizabeth A. Krupinski, PhD

University of Arizona Department of Medical Imaging
Contact: krupinski@radiology.arizona.edu

1. PURPOSE
The goal of this study was to assess diagnostic accuracy and reader efficiency as a function ofdisplay and display layout. This study had 2 reading conditions: single Eizo 8MP display(without central bezel) vs dual-5MP Eizo displays (with bezels between the twoscreens). There were three aspects of reader performance that were studied: diagnostic
accuracy as measured by Receiver Operating Characteristic (ROC) analysis, readingtime, and number of times the readers zoomed/panned the images.

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2. METHODS
The study was carried out using display monitors (Figure 1) that were as equivalent except for theparameter of interest (8MP without bezel vs dual 5MP with bezel). They were set up by Eizo withas equivalent as possible white points, maximum/minimum luminance, and black levels, and werecalibrated to the DICOM GSDF.

Figure 1. The two display configurations.
The study protocol was approved by the University of Arizona’s Human Subjects office for IRB
approval prior to the start of the study. Six mammographers were recruited as observers – four
Board-Certified mammographers, 1 mammography Fellow, and one senior resident about to enter amammography Fellowship.
Each observer viewed a set of 60 mammographic cases, once on each reading condition using acounterbalanced design in which half of the observers viewed the cases in one condition first andthe other half viewed them on the alternative condition first. At least 3 weeks passed between
sessions to promote forgetting of the cases. Forty of the cases contained a single malignant lesion(20 masses and 20 microcalcification clusters) and 20 were lesion free. All cases with lesions had
been verified by biopsy regarding lesion status, and the lesion-free cases had at least 2-years
follow-up without change in status. Lesions ranged from subtle to moderately subtle and werelocated throughout the breast.
The images were displayed using specialized display software (ImprocRAD) for image presentation
and recording of observer response data. The software was originally developed by Bill Dallas, PhD
and was modified under the contract for use in this study to incorporate the specific needs of thedesign and reporting procedures. Standard observer performance study protocols were observed,
such as having the ambient room lights set to 40 lux and noise levels were minimized.
The task of the readers was to determine for each case if a lesion was present or absent. They thenreported their confidence in that decision using a 6-point scale: lesion present definite; lesion
present probable; lesion present possible; lesion absent possible; lesion absent probable; lesion
absent definite. They indicated the location using the mouse and a cursor. Reading time (time fromwhen the images first appear until a decision is rendered) was recorded as was the number of times
they zoomed/panned per case presentation.
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The confidence data were analyzed for statistically significant differences in reader accuracy using
the Multi-Reader Multi-Case (MRMC) Receiver Operating Characteristic (ROC) technique andsoftware from the University of Iowaz(http://perception.radiology.uiowa.edu/Software/ReceiverOperatingCharacteristicROC/MRMCAnalysis/tabid/116/Default.aspx). The timing and zoom/pan use data were analyzed using a repeatedmeasures Analysis of Variance with time (sec) and zoom/pan use as the dependent variables anddisplay condition and lesion type as independent variables.
An additional study with eye-position recording, using a sub-set of 15 cases (5 mass, 5calcification,
5 normal), was also conducted. The ASL SU4000 Eye-Tracker system (Applied Science Labs,Bedford, MA) was used to record eye-position. The eye-position data were analyzed using standard
methods. Parameters analyzed were: total viewing time, number of fixations generated, time to first
hit lesion (in either image), total time on lesion (sum for both views, MLO and CC), and number oftimes scanned from one image to the other.

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3. RESULTS
Diagnostic Accuracy
The MRMC ROC analysis revealed no statistically significant difference in diagnostic accuracy
between the two display conditions (F = 4.43, p = 0.0891). The average and individual area under
the curve (Az) results are shown in Table 1.
Reader123456
Mean

Dual 5MP
0.869
0.819
0.816
0.817
0.894
0.876
0.849

Single 8MP
0.840
0.779
0.767
0.825
0.849
0.890
0.823

Table 1. ROC Az values for each of the readers in each reading condition with means for theconditions at the bottom.

Viewing TimeFor viewing time, there was a significant difference (F = 13.901, p = 0.0002) between the tworeading conditions, with the single 8MP display taking less time on average than with the dual 5MPdisplays. On average, viewing time with the single display was 62.04 sec (sd = 24.09) and that withthe dual displays was 68.99 (sd = 25.87). There were no significant differences as a function of typeof lesion (F = 0.144, p = 0.8657). Figure 2 shows the average reading time for each of the 6readers in the two reading conditions.

Figure 2. Viewing times for each of the readers in each reading condition.
Zoom/Pan UseThere was no significant difference (F = 0.254, p = 0.6145) in the number of times zoom/pan wasused by the readers as a function of single display vs dual displays. On average, frequency ofzoom/pan use with the single display was 1.94 times per case (sd = 1.40) and that with the dual
format was 1.89 times per case (sd = 1.38). There was no significant difference as a function oflesion type (F = 0.292, p = 0.7467). Figure 3 shows the average zoom/pan use for each of the 6
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readers in the two reading conditions.
3.0

Zoom/Pan (f)2.5
readerfive
fourone
six
three
two

2.0
1.5
1.0
0.5
0.0
SingleDoubleModality

Figure 3. Frequency of use of zoom/pan for each of the readers in each reading condition.
Eye-Position Study
As in the main study, the total viewing time was significantly shorter (F = 4.372, p = 0.0394) withthe single display (mean = 54.65, sd = 24.09) than with the dual displays (mean = 62.86, sd =27.58). The total number of fixations generated with the single display was also significantly (F =4.073, p = 0.0466) shorter (mean = 134.47, sd = 65.14) than with the dual displays (mean = 154.29,sd = 65.09). The number of times they scanned from one image to the other (Figure 4) was
significantly fewer (F = 10.305, p = 0.0018) with the single display (mean = 6.83, sd = 2.58) thanwith the dual displays (mean = 8.22, sd = 2.99).
1210Reader
FiveFourOne
Six
ThreeTwoXOvers

864
20
DualSingle
Modality

Figure 4. Number of times scanned from one image to the other for each of the readers in eachreading condition.
The time to first fixate the lesion (in either image) did not differ significantly (F = 0.126, p =0.7240) between the single display (mean = 6.83, sd = 3.47) and dual displays (mean = 6.63, sd =3.64). In other words, it did not take any longer to detect the lesion as a function of the display
configuration. The total time spent on the lesion (in both views) did not differ significantly (F =0.097, p = 0.7567) between the single display (mean = 8.59, sd = 4.43) and dual displays (mean =8.39, sd = 4.18).

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4. CONCLUSIONS
Overall the single 8MP display yielded the same diagnostic accuracy as the dual 5MP displays. Thelower resolution did not appear to influence the readers’ ability to detect and view the lesion details,
as the eye-position study showed no significant differences in time to first fixate or in total time on
the lesions. Nor did the lower resolution result in significant differences in the number of times thereaders zoomed/panned the images while viewing the cases.
There were however significant improvements in reader efficiency with the single 8MP display
compared to the dual 5MP displays. This was seen in terms of reduced overall time spent viewing
the images in both the main and eye-position studies. From the eye-position study it appears that thegain in efficiency is not due to detecting or spending any different time on the lesions, but in termsof not scanning back-and-forth from image to image as much. The reason for this may be thepresence of the bezels between the two screens of the dual 5MP displays – creating a physicalseparation between the two images, while the single 8MP display has the two images abutting eachother without anything between them.

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