Carestream RSNA 2015 Pediatric Fracture Detection Study

PRESENTED AT THE RADIOLOGICAL SOCIETY OF

AMERICA (RSNA) 2015 ANNUAL MEETING

CHICAGO IL

DECEMBER 3, 2015

Pediatric Fracture Detection Study:

A Task-Based Observer Study Evaluating Enhanced

Image Presentation and Potential Dose Reduction

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© 2015, Carestream Health

Pediatric Fracture Detection Study:

A Task-Based Observer Study Evaluating

Enhanced Image Presentation and

Potential Dose Reduction

Lynn La Pietra1, Sosamma Methratta2, Samuel Richard1

1. Carestream Health, Inc., Rochester, NY, USA

2. The Milton S. Hershey Medical Center, Hershey, PA, USA

December 3, 2015

Outline

• Background

• Study Goal and Objectives

• Study Design

• Simulated Dose Reduction

• Reader Study Description

• Evaluation and Analysis

• Results and Summary

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Background

• Pilot Study (ESPR 2012, Methratta et al)

• Image quality assessment of 5 reductions in dose using validated, simulated

noise models (Equivalent film speeds: 720, 900, 1440, 2280, 3600)

• Readers evaluated image interpretability using 4 point, RadLex Image Quality

Scale

• Pilot Study Results• Diagnostic quality images of pediatric patients may be captured with DR using

exposures as low as 900 speed

• Digital radiography coupled with multi-frequency image processing may offer the

opportunity to reduce default pediatric exposures

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Background: European Society Pediatric

Radiology (ESPR 2012)

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Today’s task-based study explores the previously

reported “Diagnostic” quality of this exposure range

New Study: Goal and Objectives

• Goal

• Reduce digital projection X-ray dose to the pediatric

population while maintaining diagnostic image quality.

• Study Objectives

Given the observer task of finding pediatric fractures:

1. Determine the impact of a simulated reduced dose

rendering on sensitivity.

2. Determine the impact of enhanced skeletal processing on

sensitivity (CARESTREAM ImageView SW, to be released

2016.)

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Standard

Processing

Enhanced Skeletal

Processing


High Level Study Design

• Retrospectively collect de-identified pediatric images

• Generate ground truth from original captures (combination clinical

findings, repeat exam findings, repeat radiologist markings 2x separated by 6

months, for each image with fracture)

• Simulate reduced dose for each study image to an

equivalent 720 film-speed

• Generate:

• Standard of care image rendering for original study and simulated reduced

dose images

• Enhanced skeletal processing for original study and reduced images

• Reader Study: 5 Radiologists mark detected fractures in

each rendering, separated by 2+ weeks, mitigating learning

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Dose Reduction Simulation Approach*+

AND REDUCE SIGNAL

Structured Noise – fixed pattern noise with

variance proportion to exposure squared

Quantum Noise – shot or Poisson noise with

variance proportional to the exposure

Electronic Noise – exposure-independent or

‘dark’ noise

Automatic Exposure Control or Phototimer

Anatomically Programmed Radiography

*Topfer et al, US 7,480,365 B1, Jan 20, 2009, Dose Reduced Digital Medical Image Simulations.

+Ellinwood et al, US 7,949,098 B2, May 24, 2011, Method for Determining Reduced Exposure Conditions

for Medical Images.

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09 June 2011

Example Original Image, 200 SpeedSimulated Dose 30% of Original, 720 Speed

READER STUDY

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Case Selection:100 cases free of fractures

50 cases with one or more fractures

• CsI or GoS DR

• Default processing for Carestream DR equipment

• 6 exam categories

• 5 age groups

• Chosen sequentially

• Each case consisted of 1, 2 or 3 projections

• 95 fractures in 50 cases

ORIGINAL

100 fx negative;

50 fx positive

< 3

mos

3 mos up

to 1 year

1 - 5

years

6 - 13

years

14 – 18

yearsTotals

Chest 8 12 8 2 1 31

Lower Extremity 8 14 9 4 5 40

Pelvis/Hip 2 2 4 2 2 12

Skull 4 9 5 1 0 19

Spine/Shoulder 3 5 2 2 4 16

Upper Extremity 1 5 7 11 8 32

Totals 26 47 35 22 20 150


Reader Demographics

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Reader # Years

experience

Specialty %Time

Reading

Pediatrics

1 20 Pediatrics 100

2 7 Pediatrics 85

3 40 Pediatrics 100

4 6 Pediatrics 90

5 16 Pediatrics 100


Study Objective #1:

Determine the impact of a simulated

reduced dose rendering on fracture

sensitivity

Experiment Design (150 Cases: Original acquisitions +

150 Simulated Reduced Dose from Same Cases )

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ORIGINAL

100 no fx;

50 with fx

< 3 mos3 mos up

to 1 year

1 -5

years

6 -13

years

14 – 18

years

Chest 8 12 8 2 1

Lower Extremity 8 14 9 4 5

Pelvis/Hip 2 2 4 2 2

Skull 4 9 5 1 0

Spine/Shoulder 3 5 2 2 4

Upper Extremity 1 5 7 11 8

720 Speed

(Same 150 cases)< 3 mos

3 mos up

to 1 year

1 -5

years

6 -13

years

14 – 18

years

Chest 8 12 8 2 1

Lower Extremity 8 14 9 4 5

Pelvis/Hip 2 2 4 2 2

Spine/Shoulder 4 9 5 1 0

Skull 3 5 2 2 4

Upper Extremity 1 5 7 11 8

+

Exam

Data Pool

300 cases

Reader Study – SW

generates a unique list

for each participant with

the same criteria• Every reader sees every case

• Original and Reduced

exposures must be read in

different sessions

Session 1

Session 2


Study Objective #2:

Determine the impact of enhanced

skeletal view on sensitivity

Experiment Design Software Control

Add Companion View: Enhanced Skeletal Rendering

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Standard

Processed Case

may include 1, 2,

or 3 projections

Enhanced

Case may

include 1, 2, or

3 projections

Presented with

Standard

Processing of

Case Y.

Reader indicates

fx or advances to

next view.

Once Reader

advances to

Enhanced view,

detections on

Standard view

are frozen.

Presented with

Enhanced View

of Case Y.

Reader indicates

fx or advances to

next view. Reader

can toggle to

Standard View

and use as a

reference only.

Once Reader

advances to next

case, detections

on previous case

are frozen.

Start Session 1

Reader XNext Case


Evaluation Procedure

• Images displayed on diagnostic quality monitor

• 3MP, grayscale, GSDF calibrated, reduced ambient lighting

• Presentation sequence randomized among readers

• “Reason for image” displayed on control monitor

• Reader performs fracture detection task – in software, draw

rectangle around detected fx(s). Specify if same fx in

multiple projections

• GT compared with detection – Reader centroid must fall

within GT boundaries to count as true positive

• Calculate Sensitivity and Specificity per reader and

aggregate reader

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Analysis

• Sensitivity = probability of a positive test among patients

with skeletal fracture =

• Specificity = probability of a negative test among patients

without skeletal fracture =

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Fracture exists No Fracture in

Case

Test Positive a (TP) b (FP)

Test Negative c (FN) d (TN)

ca

a

db

d


Example Femur Exam: Reduced Exposure Standard

(RES) Processing Paired with Enhanced Processing

(REE)Reduced Exposure Standard Processing

Lateral Projection PA Projection

Reduced Exposure Enhanced Processing

Lateral Projection PA Projection

Example Femur Exam: Reduced Exposure Standard

(RES) Processing Paired with Enhanced Processing

(REE)

Reduced E

xposure

Sta

ndard

(R

ES

)

Reduced E

xposure

Enhanced

(RE

E)

*

**

*

*

FN no Fx marking

TP (RES)

TP Fx found in 2nd

rendering (REE)

FP no GT Fx TP both

(RES) and

(REE)

TP (RES)

Example Chest Exam: Original Exposure Standard

(OES) Processing Paired with Enhanced Processing

(OEE)

Origin

al E

xposure

Sta

ndard

(O

ES

)

Orig

inal E

xp

osure

Enhanced

(O

EE

)

Reader#

Original Exposure Standard

(OES)

Reduced Exposure Standard

(RES)

Original Paired with Enhanced

Processing (OEE)

Reduced Paired with Enhanced

Processing (REE)

1 0.6842 0.3368 0.9684 0.8842

2 0.2105 0.2421 0.4316 0.4316

3 0.4105 0.5474 0.7368 0.7158

4 0.5053 0.3684 0.7895 0.7579

5 0.3368 0.5684 0.8211 0.7368

Average 0.4295 0.4126 0.7495 0.7053

Results: Sensitivity


Results: Specificity

Reader#

Original Exposure Standard

(OES)

Reduced Exposure Standard

(RES)

Original Paired with Enhanced

Processing (OEE)

Reduced Paired with Enhance

Processing (REE)

1 0.8426 0.8846 0.7008 0.7692

2 0.8889 0.8922 0.7706 0.8426

3 0.7615 0.7387 0.6641 0.6772

4 0.7167 0.9091 0.5745 0.7632

5 0.7232 0.7339 0.5248 0.5597

Average 0.7866 0.8317 0.6470 0.7224


Summary

• Diagnostic quality images of pediatric patients may be captured with DR

using exposures at least as low as 720 speed.

• DR coupled with the Enhanced Skeletal Processing offers the opportunity

to reduce default pediatric exposures targeting fracture detection.

• Viewing Reduced Exposure (RES) paired with the Enhanced View (REE)

may improve Sensitivity over use of the Original Exposure Standard

(OES) view only, while detecting fractures in DR images.

• Viewing Reduced Exposure paired with the Enhanced View

is comparable to use of the Original Exposure paired with the Enhanced

View, for detecting fractures in DR images.

• Viewing Reduced Exposure paired with the Enhanced View yields

slightly reduced Specificity over use of the OES view only, with

increased Sensitivity over OES.

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Summary (Continued)

The addition of some noise may increase a reader’s ability to see details.

Though, reasonable attempts were made to provide appropriate context to

the readers during the study. i.e.

• Orthogonal views were presented when available

• A “reason for exam” was provided for each exam

The Study was a challenge to perform given:

• Some information was not available to the readers during the study, such

as prior exams, previous diagnoses, and full skeletal surveys

• Learning curve to use the new SW tools

• SW behaviors differed from day to day viewing operations

For these reasons, we focused on changes to sensitivity given the four

treatment pairings.

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Carestream RSNA 2015 Pediatric Fracture Detection Study