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Understanding
R2 ImageChecker®
Software Versions 8.5–8.7
MAN-01049 Rev 001
Screen-Film Mammography
Understanding
R2 ImageChecker®
Software Versions 8.5–8.7
PN MAN-01049 Rev 001
Technical Support
For support in North America contact:
Toll Free: +1 866.243.2533 (866.CHECKED) Email: techsupport@r2tech.com
Hours: Monday – Friday, 6:00 AM – 5:00 PM, PT (GMT –8:00) Website: www.hologic.com
For support in Europe, South America, or Asia, contact your local dealer or distributor.
© 2008, Hologic, Inc. All rights reserved. Duplication or distribution without written permission is prohibited. Hologic reserves the right to revise this manual. Issued August 2008.
Protected by one or more of the following U.S. Patents: 5133020, 5452367, 5491627, 5537485, 5622171, 5657362, 5673332, 5729620, 5732697, 5740268, 5815591, 5828774, 5832103, 5917929, 6014452, 6035056, 6075879, 6078680, 6185320, 6198838, 6263092, 6266435, 6301378, 6404908, 6434262, 6477262, 6574357, 6580818, 6640001, 6628815, 6909795, 7054473, 7072498, 7146031, 7174515
Hologic, the Hologic logo, Cenova, CheckMate, DigitalNow, EmphaSize, ImageChecker, Malc, Mammolux, R2, R2 Technology, SecurViewDX, and Selenia are trademarks or registered trademarks of Hologic in the USA. MergeCOM-3 is a trademark of Merge Healthcare.
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ii Understanding R2 ImageChecker 8.5–8.7 – PN MAN-01049 Rev 001
Contents
Part 1: Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1. Intended Use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2. Resources Available . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.3. Warnings and Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.4. Overview of ImageChecker CAD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.5. Benefits of ImageChecker CAD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.6. Devices Used with ImageChecker CAD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.7. ImageChecker Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
RightOn CAD Marks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
EmphaSize. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
PeerView and PeerView Digital . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Operating Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.1. Film-Based CAD with DigitalNow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.2. CAD Inputs and Supported Views . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Selecting Images for Case Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.4. System Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Part 3: Algorithm Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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3.1. ImageChecker CAD Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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3.2. RightOn CAD Marks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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Limiting the Number of Marks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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3.3. EmphaSize Marks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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3.4. PeerView and PeerView Digital . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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3.5. What the Algorithm Detects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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Calcifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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Masses/Architectural Distortions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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Understanding R2 ImageChecker 8.5–8.7 – PN MAN-01049 Rev 001 |
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Contents
3.6. Detecting Calcifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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Image Processing for Calcifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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Case Processing for Calcifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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3.7. Detecting Masses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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Image Processing for Masses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
30 |
Case Processing for Masses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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3.8. CAD Operating Points. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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iv Understanding R2 ImageChecker 8.5–8.7 – PN MAN-01049 Rev 001
Part 1: Introduction
f1.1. Intended Use
f1.2. Resources Available
f1.3. Warnings and Precautions
f1.4. Overview of ImageChecker CAD
f1.5. Benefits of ImageChecker CAD
f1.6. Devices Used with ImageChecker CAD
f1.7. ImageChecker Features
R2 ImageChecker® is a software application used for analyzing mammography images. This manual describes R2 ImageChecker software versions 8.5, 8.6, and 8.7, which were developed to provide the ImageChecker software as a licensed option with these Hologic film scanning systems:
•R2 DMax System
•R2 LS System
•R2 DM System
These systems support a second application, R2 DigitalNow™, which the systems use to create archivable digital mammography image files from the original films.
R2 ImageChecker 8.7 is available as a software upgrade for customers that have previous versions. For customers using full-field digital mammography (FFDM) systems, the ImageChecker software is also available as a licensed option with Hologic’s R2 Cenova digital mammography server. For more information, contact your Hologic customer representative.
The information in this manual is intended to serve as a reference for radiologists and clinic personnel who need to understand how ImageChecker computer-aided detection (CAD) can be integrated into their practice.
1.1. Intended Use
ImageChecker is a software application intended to identify and mark regions of interest on routine screening and diagnostic mammograms to bring them to the attention of the radiologist after the initial reading has been completed.
ImageChecker assists the radiologist in minimizing observational oversights by identifying areas on the original mammogram that may warrant a second review.
Understanding R2 ImageChecker 8.5–8.7 – PN MAN-01049 Rev 001 |
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Part 1: Introduction
1.2. Resources Available
In addition to this manual, the following resources are available to assist you:
• R2 Member Center: This website provides quick access to electronic (pdf) versions of Hologic manuals and training materials. You can find the R2 Member Center by visiting the Hologic website (www.hologic.com). See the R2U flyer that accompanies this product for instructions on accessing the R2 Member Center.
•Manuals: The manuals for the R2 film scanning systems are listed below:
–Understanding R2 ImageChecker
–R2 DMax User Manual
–R2 DM User Manual
–R2 LS User Manual
–R2 DMax/DM/DX/LS Service Manual
–R2 DMax/DM/DX/LS Release Notes
–R2 DMax/DM/DX/LS DICOM Conformance Statement
You can obtain additional copies of printed manuals through your Hologic Account Manager. The DICOM Conformance Statement is available at www.hologic.com.
• Training: The Hologic Applications team is available to train your staff, should you feel they need additional training. To purchase additional personalized instruction, contact your Hologic Account Manager.
• Technical Support and Service: For support in North America contact:
Toll Free: +1.866.243.2533 (+1.866.CHECKED)
Email: r2support@hologic.com
Hours: Monday – Friday, 6:00 AM – 5:00 PM, PT (GMT –8:00)
Website: www.hologic.com
For support in Europe, South America, or Asia, contact your local dealer or distributor.
2 Understanding R2 ImageChecker 8.5–8.7 – PN MAN-01049 Rev 001
1.3. Warnings and Precautions
1.3.Warnings and Precautions
Note: For Warnings and Cautions related to the installation, operation, and maintenance of the R2 film scanning system, refer to the user manual accompanying the product.
•The radiologist should base interpretation only on original diagnostic-quality
images and not depend on ImageChecker CAD marks for interpretation.
•The device is a detection aid, not an interpretative aid. ImageChecker CAD marks should be activated only after the first reading.
•The device does not enhance what the user sees; rather it helps to identify regions on mammograms that should be re-examined.
•The ImageChecker software marks calcification features with triangles (Calc marks) and mass features with asterisks (Mass marks). The software marks mass and calcification features that occur at the same location on the image with pointed crosses (Malc marks). These features may not represent cancer, and the skill of the user is still required for proper interpretation of the marked areas.
•EmphaSize (variable-size) marks – Sites may choose to display prominence detail, in which case the size of a Calc, Mass, or Malc mark is proportional to the ranking of the feature by the algorithm. The marked features may not represent cancer, and the skill of the user is still required for proper interpretation of areas marked by the device.
•For proper system operation, the technical quality of the original films or images (e.g., contrast) should meet relevant MQSA standards (or the appropriate national standards) and be acceptable to the mammographer.
•The use of digitized images (scanned film images) for primary reading has not been approved by MQSA. Digitized film images retrieved from archive should be used only for the purpose of comparison with digital images meeting the current standard.
•During routine interpretation of mammograms and results produced by ImageChecker CAD, Hologic recommends use of a mammography workstation that has been FDA-approved, recently calibrated, and employs a CAD marking schema authorized by Hologic.
•ImageChecker software does not identify all areas that are suspicious for cancer.
–The software does not mark all lesions and a user should not be dissuaded from working up a finding if the software fails to mark that site.
–The software is not designed to detect changes from prior mammograms.
–The software is not designed to detect skin thickening or nipple retractions.
–Conditions of the breast that diminish mammographic sensitivity, such as density of normal tissue, also diminish the sensitivity of the software.
–The software is more sensitive for detection of calcifications than masses, and the sensitivity depends on the site-specific operating points chosen. For sensitivity values, see ‘3.8. CAD Operating Points’. In addition to not marking all masses, the algorithm has a lower sensitivity for masses greater than 2.5 cm in diameter.
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Part 1: Introduction
–Individual practice patterns may influence results obtained when using ImageChecker CAD. Therefore, each facility and radiologist should carefully monitor the results that the software has on their practice of mammography in order to optimize its effectiveness.
•The performance of the system has not been characterized for mammograms from patients with:
–Breast implants. Process only Implant-Displaced Views with less than 2.5 cm (1 in) of the breast implant appearing on the image.
–Special diagnostic views (e.g., magnified views or spot-compressed views). Process only full-view diagnostic images.
–Segmented views of the breast (e.g., ‘mosaic’ views) with no clear breast border. Process only views with breast borders.
4 Understanding R2 ImageChecker 8.5–8.7 – PN MAN-01049 Rev 001
1.4. Overview of ImageChecker CAD
1.4. Overview of ImageChecker CAD
Systems configured with R2 ImageChecker 8.5–8.7 analyze digitized film mammography images with a software algorithm that identifies regions of interest, which can include clusters of bright spots (suggestive of calcification clusters), and dense regions with or without radiating lines (suggestive of masses or architectural distortions). The systems generate results that include ImageChecker CAD marks identifying the regions of interest. The results produced are either image files, Mammography CAD SR (Structured Report) objects, or both.
After making an initial interpretation from the original mammograms, the radiologist displays the ImageChecker results and chooses whether or not to reinspect the marked regions on the original mammogram. The ImageChecker algorithm marks visually perceptible structures that have some of the generally accepted geometric characteristics of calcifications or masses. The marked areas may be something other than an actual abnormality, which the radiologist generally recognizes upon a second review of the original mammogram.
Films |
CAD Results |
Examination is |
ImageChecker |
Radiologist |
Reviews Films |
||
Performed |
Analyzes the Images |
and CAD Results |
ImageChecker Workflow
Understanding R2 ImageChecker 8.5–8.7 – PN MAN-01049 Rev 001 |
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Part 1: Introduction
1.5. Benefits of ImageChecker CAD
The interpretation of mammograms is challenging. Normal breast tissue varies widely among women, even for the same woman over time or at different times of the month. The radiologist also has to balance the need for accurate detection of breast cancer with the need to limit the number of unnecessary procedures. The combination of viewing a large number of cases, radiologist fatigue, the complex image of the breast structure, and the subtle nature of certain observable characteristics of the disease can result in false-negative readings. In fact, studies show that half of undetected cancers are missed due to observational oversights. The prevalence of observational oversights is not strongly related to experience and may be inevitable with human observers.
R2 ImageChecker functions like a spellchecker for medical images. It is designed to help radiologists in reducing the number of false-negative readings due to observational oversight by drawing their attention to areas that may warrant a second review. Use of ImageChecker CAD can result in earlier detection of up to 23.4% of the cancers currently detected with screening mammography in those women who had a prior screening mammogram 9–24 months earlier. Early detection is the key to higher survival rates, better prognosis, and lower treatment costs.
6 Understanding R2 ImageChecker 8.5–8.7 – PN MAN-01049 Rev 001
1.6. Devices Used with ImageChecker CAD
1.6. Devices Used with ImageChecker CAD
All systems with R2 ImageChecker 8.5–8.7 include a film scanner for scanning mammography X-ray films and a processing unit computer configured with the R2 image-processing software. There are three models:
•R2 DMax System
•R2 LS System
•R2 DM System
Facilities must also have an output device in order to review or store the CAD results. These devices may include any of the following:
•R2 CheckMate Ultra™ display unit
•Postscript printer
•Diagnostic mammography review workstation (such as Hologic’s SecurViewdx)
•PACS (Picture Archiving and Communication System)
The system devices are connected by a computer network and can be in the same room, different rooms, the same building, different buildings, or even different cities. The R2 processing unit can send results to several different output devices.
The R2 DMax, LS, and DM systems are designed to:
•Scan mammography X-ray films and convert them into digital image files
•Allow users to review the scanned images, and to reorient, label, and reprocess the images as needed.
•Analyze the images using the R2 ImageChecker algorithm to detect regions of interest.
•Transmit the study results so they can be viewed on an output device such as the R2 CheckMate Ultra display unit, printer, diagnostic review workstation (or to a PACS for archiving).
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Part 1: Introduction
1.7. ImageChecker Features
R2 ImageChecker provides the following features, which are discussed below:
fRightOn CAD Marks
fEmphaSize
fPeerView and PeerView Digital
fOperating Points
Upon installation, the Hologic field service engineer will configure the software based on the preferences of site personnel. Thereafter, your Hologic representative can help you add a new license (such as DigitalNow) and enable or disable features as needed.
For more information on ImageChecker features, see ‘Part 3: Algorithm Description’.
Important! Display of results from each ImageChecker feature depends upon several factors, in particular:
•The feature must be licensed and enabled on the R2 processing unit.
•The review workstation must be equipped with software that can interpret the output produced by the processing unit.
Some workstations can interpret only a subset of ImageChecker features. Consult with your workstation vendor concerning availability and integration of ImageChecker features with your workstation.
RightOn CAD Marks
The ImageChecker software provides three types of RightOn™ CAD marks (Mass, Calc, and Malc) that can appear in the results. You can choose to display any or all of the three types of marks. Each mark identifies a region of interest for the radiologist to review.
Calc – Marks regions suggestive of calcifications.
Mass – Marks regions suggestive of masses or architectural distortions.
Malc – Marks regions where Calc and Mass marks are coincident.
EmphaSize
The processing unit is configured by default to convert the CAD marks to EmphaSize™ marks, which can be viewed on some diagnostic review workstations, as well as the R2 output devices (R2 CheckMate Ultra and postscript printer). EmphaSize produces CAD marks of variable size that correlate to feature significance. When the algorithm determines that a region is more significant, the CAD mark appears larger, indicating that the region should receive more emphasis from the radiologist. EmphaSize marks can be disabled if clinic staff choose not to use them. For more information see ‘3.3. EmphaSize Marks’.
PeerView and PeerView Digital
PeerView™ and PeerView Digital are optional features that help radiologists better understand why a region of interest was marked. PeerView and PeerView Digital
8 Understanding R2 ImageChecker 8.5–8.7 – PN MAN-01049 Rev 001
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