Hologic R2 ImageChecker 9.1 User manual

Understanding

R2 ImageChecker

MAN-00934 Rev 002

®

9.1

Mammography

Understanding

R2 ImageChecker

PN MAN-00934 Rev 001

®

9.1

Technical Support

For support in North America contact:

Toll Free: +1.866.243.2533 (+1.866.CHECKED)
Email: [e-mail]
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 June 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,
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7054473, 7072498, 7146031, 7174515

Hologic, the Hologic logo, Cenova, Citra, DigitalNow, EmphaSize, ImageChecker, LesionMetrics,
Malc, PeerView, Quantra, RightOn, R2, R2 Technology, SecurView
trademarks or registered trademarks of Hologic in the USA. MAMMOMAT is a registered
trademark of Siemens Medical Solutions in the USA.

, and Selenia are

DX

Hologic Inc.
35 Crosby Drive
Bedford, MA 01730-1401 USA
Tel: [phone]
Sales: +1.781.999.7453
Fax: [phone]

Asia Pacific
Room 302, Hung Kei Building
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Tel: [phone]

Hologic N.V.
Authorized Representative
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Tel: [phone]
Fax: [phone]

ii Understanding R2 ImageChecker 9.1 – PN MAN-00934 Rev 002

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

Image Acquisition Systems .............................................. 7

R2 Cenova Server ..................................................... 8

Diagnostic Review Workstations and PACS Devices ........................... 8

1.7. ImageChecker Features ................................................ 9

Input Ports .......................................................... 9

Citra Core ........................................................... 9

RightOn CAD Marks.................................................. 10

EmphaSize.......................................................... 10

PeerView Digital ..................................................... 10

LesionMetrics ....................................................... 10

Operating Points ..................................................... 11

Part 2: Data Inputs and Outputs

2.1. System Data Flows................................................... 13

......................................... 13

Digital CAD Systems .................................................. 13

Digital CAD with DICOM 6000 Overlay ................................... 15

Digital and Film-Based CAD with DigitalNow .............................. 16

2.2. CAD Inputs and Supported Views ....................................... 18

Images with Breast Implants ............................................ 18

2.3. Image and Case Processing ............................................ 19

Selecting Images for Case Processing ...................................... 19

2.4. CAD Outputs........................................................ 21

DICOM 6000 Overlays ................................................ 21

Understanding R2 ImageChecker 9.1 – PN MAN-00934 Rev 002 iii

Contents

Part 3: Algorithm Description ............................................ 23

3.1. ImageChecker CAD Algorithm .......................................... 23

3.2. RightOn CAD Marks .................................................. 24

Limiting the Number of Marks .......................................... 24

3.3. EmphaSize Marks .................................................... 25

3.4. PeerView Digital ..................................................... 26

3.5. LesionMetrics ....................................................... 27

3.6. What the Algorithm Detects............................................ 28

Calcifications........................................................ 28

Masses/Architectural Distortions......................................... 29

3.7. Detecting Calcifications ............................................... 31

Image Processing for Calcifications ....................................... 31

Case Processing for Calcifications ........................................ 32

3.8. Detecting Masses .................................................... 33

Image Processing for Masses ............................................ 33

Case Processing for Masses ............................................. 34

3.9. CAD Operating Points................................................. 35

Index .................................................................. 39

iv Understanding R2 ImageChecker 9.1 – PN MAN-00934 Rev 002

Part 1: Introduction

f 1.1. Intended Use
f

1.2. Resources Available

f

1.3. Warnings and Precautions

f

1.4. Overview of ImageChecker CAD

f

1.5. Benefits of ImageChecker CAD

f

1.6. Devices Used with ImageChecker CAD

f

1.7. ImageChecker Features

R2 ImageChecker® is a software algorithm used for analyzing mammography images.
The software was originally developed by R2 Technology, and is now available as a
licensed option with Hologic’s R2 Cenova™ digital mammography server.

The R2 Cenova server provides a second application, R2 Quantra™, which is used for
volumetric assessments of breast tissue. For more information, refer to the manual
Understanding Quantra 1.1. (Quantra is not available in the United States.)

The information in this manual is intended to serve as a reference for radiologists and
clinic personnel who need to understand how computer-aided detection (CAD) can
be integrated into their practices.

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 9.1 – PN MAN-00934 Rev 002 1

Part 1: Introduction

1.2. Resources Available

In addition to this manual, the following resources are available to assist you when
working with ImageChecker and the R2 Cenova server.

•

R2 Member Center: This website provides quick access to electronic (pdf) versions

of Hologic | R2 manuals and training materials. You can find the R2 Member
Center by visiting the Hologic website (
accompanies this product for instructions on accessing the R2 Member Center.

•

Manuals: The manuals for the R2 Cenova server and its applications are listed

below:

– Understanding R2 ImageChecker
– Understanding R2 Quantra
– R2 Cenova User Manual
– R2 Cenova Service Manual
– R2 Cenova Release Notes
– R2 Cenova DICOM Conformance Statement

www.hologic.com). See the R2U flyer that

– R2 Cenova Cybersecurity Best Practices
– R2 Cenova IHE Integration Statement

You can obtain additional copies of printed manuals through your Hologic
Account Manager. The DICOM Conformance Statement and Cybersecurity Best
Practices documents are available at

•

Training: The Hologic Applications team is available to train your staff, should you

www.hologic.com.

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:

Email:

+1.866.243.2533 (+1.866.CHECKED)

[e-mail]

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 9.1 – PN MAN-00934 Rev 002

1.3. Warnings and Precautions

 Note: For Warnings and Cautions related to the installation, operation, and

maintenance of the R2 Cenova server, refer to the R2 Cenova User Manual.

• The radiologist should base interpretation only on 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.

1.3. Warnings and Precautions

• 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 ‘
algorithm has a lower sensitivity for masses greater than 2.5 cm in diameter.

– 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.

3.9. CAD Operating Points’. In addition to not marking all masses, the

• For images with breast implants, send only Implant Displaced views to the system.

Images with more than 2.5 cm (1 in) of the breast implant appearing on the image
may not be processed correctly.

Understanding R2 ImageChecker 9.1 – PN MAN-00934 Rev 002 3

Part 1: Introduction

• The performance of the software has not been characterized for special diagnostic

views (e.g., magnified views or spot-compressed views).

• Images of partial views of the breast that are not correctly identified as such, may

be processed by the software, although the software has not been designed for that
purpose.

• On rare occasions for a lesion on or near the pectoral muscle, the system may

report a negative value for the chest wall distance.

4 Understanding R2 ImageChecker 9.1 – PN MAN-00934 Rev 002

1.4. Overview of ImageChecker CAD

The R2 Cenova server configured with ImageChecker software analyzes digital
mammography images produced by full-field digital mammography (FFDM)
systems. The proprietary ImageChecker algorithm 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 server generates results in the form of Mammography CAD SR
(Structured Report) objects that include CAD marks and other data identifying and
characterizing the regions of interest. At the review workstation, the results are
matched with the digital mammography images produced by the FFDM system.

After making an initial interpretation from the original diagnostic-quality images, the
radiologist displays the ImageChecker results and chooses whether or not to reinspect
the marked regions on the original images. 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 is generally recognized by the radiologist upon a
second review of the original images.

1.4. Overview of ImageChecker CAD

Examination is

Performed

 Note: The appearance of the images on the workstation is dependent upon the

acquisition modality and the workstation’s display capabilities, and is not affected by the
ImageChecker software.

The R2 Cenova server and the ImageChecker algorithm are designed for sites that
process only digital mammography images; the server does not scan films or support
CAD with analog (film) mammograms. For information on systems that perform
film-screen CAD, contact your Hologic Account Manager.

For Presentation Images

For Processing Images

ImageChecker CAD

Analyzes the Images

Workflow with ImageChecker CAD

Mammography

CAD SR

Radiologist

Reviews Images

Understanding R2 ImageChecker 9.1 – PN MAN-00934 Rev 002 5

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 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.

ImageChecker CAD 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. Retrospective clinical studies using the film-based ImageChecker algorithm
have shown that 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 9.1 – PN MAN-00934 Rev 002

1.6. Devices Used with ImageChecker CAD

All systems with ImageChecker include the following devices:

• Digital mammography image acquisition system(s)

• R2 Cenova server configured with the ImageChecker option

• Diagnostic review workstation or PACS

The ImageChecker software can accept digital mammography images from a
supported Full-Field Digital Mammography (FFDM) system or a PACS (picture
archiving and communication system). Once received, the server performs the CAD
algorithm processing and sends the study results (CAD marks and related data) to
one or more devices such as Hologic’s SecurViewdx diagnostic workstation or a
PACS for storage.

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 server can send results to several different output devices.

Image Acquisition Systems

1.6. Devices Used with ImageChecker CAD

ImageChecker processes mammography images originating from the following image
acquisition systems:

• Hologic Selenia

• GE Senographe 2000D, GE Senographe DS, and GE Senographe Essential

• Siemens Mammomat Novation

dr

In addition, ImageChecker processes mammography images originating from the
following image acquisition systems:

• Selenia Dimensions (2D Only)

• Fuji CRm

 Important! The FDA has not approved the use of ImageChecker 9.1 with images

originating from the Selenia Dimensions and Fuji CRm systems in the United States.

R2 Cenova does not process mammography images originating from the Fischer
SenoScan system.

R2 Cenova can process images originating from up to four image acquisition devices.
The DICOM header for each image includes an identifier (e.g., a serial number) that
indicates the device from which the image originated. Each image-acquisition device
is mapped to an input port on the server. For each R2 Cenova server, you can
purchase licenses for up to four ImageChecker input ports.

Understanding R2 ImageChecker 9.1 – PN MAN-00934 Rev 002 7

Part 1: Introduction

R2 Cenova Server

The ImageChecker software is supplied on the R2 Cenova server, a high-performance
computer that can be located in any non-patient environment, provided it is
connected to the mammography network. The server receives and processes digital
mammography images and supports up to four ImageChecker ports (each port
licensed to a specific detector).

R2 Cenova integrates easily into the clinical workflow. Following a mammography
examination, the FFDM system sends digital mammography images to the clinic’s
review workstation, PACS, and the R2 Cenova server. The server accepts and
processes each For Processing image and sends the results to the review workstation
and PACS.

For more information on the server, refer to the R2 Cenova Server User Manual.

Diagnostic Review Workstations and PACS Devices

Mammography CAD SR results produced by R2 Cenova can be sent to a variety of
PACS devices and diagnostic review workstations (including SecurViewdx available
from Hologic, Inc.).

For diagnostic review workstations and PACS devices that do not support
Mammography CAD SR, but do support DICOM 6000 overlays, Hologic’s DICOM
6000 Interface server can be used to convert Mammography CAD SR objects. For
more information, contact your Hologic Account Representative.

8 Understanding R2 ImageChecker 9.1 – PN MAN-00934 Rev 002

1.7. ImageChecker Features

Each R2 Cenova server with ImageChecker software is delivered with a number of
licensed features in place. Upon installation, the Hologic | R2 field service engineer
will tailor the software to enable or disable selected features based on the preferences
of site personnel. Thereafter, your Hologic | R2 representative can help you add new
licenses and enable or disable features as needed.

Input Ports

The R2 Cenova server can process images originating from up to four FFDM systems.
The DICOM header for each image includes an identifier (e.g., a serial number) that
indicates the device from which the image originated. Each image-acquisition device
is mapped to an input port on the server.

For each R2 Cenova server, you can purchase licenses for up to four ImageChecker
input ports. Similarly, you can obtain licenses for up to four Quantra input ports.

The server can also process images sent from any number of PACS devices, as long as
the images originated from one of the licensed FFDM systems.

Citra Core

1.7. ImageChecker Features

The standard set of ImageChecker features is included in the Citra™ Core license
group, which includes the following features:

• RightOn™ CAD Marks

• EmphaSize™

• PeerView Digital™

• LesionMetrics™

EmphaSize, PeerView Digital, and LesionMetrics are exclusive Hologic | R2 features
supported by some diagnostic review workstations. When these features are licensed,
the ImageChecker software includes extra CAD information in the Mammography
CAD SR output. When viewed at the workstation, the results help radiologists
understand better why a region of interest received a CAD mark.

The Citra Core features are discussed in the following pages. For additional
information, 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 Cenova server.

• The workstation must be equipped with software that can interpret the output

produced by the server.

Individual Citra Core features can be disabled either at the R2 Cenova server or, in most
cases, at the diagnostic workstation. Some workstations can interpret only a subset of
Citra Core features. Consult with your workstation vendor concerning availability and
integration of ImageChecker features with your workstation.

Understanding R2 ImageChecker 9.1 – PN MAN-00934 Rev 002 9