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Randy D Ernst 1 , Russell C Hardie 2 , Metin N Gurcan 3 , Aytekin Oto 1 , Steve K Rogers 3 , Jeffrey W Hoffmeister 3 1. Department of Radiology, The University of Texas Medical Branch, Galveston TX 2. iCAD Inc. and University of Dayton, Dayton OH 3. iCAD Inc., Beavercreek OH.

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Presentation Transcript
slide1

Randy D Ernst1, Russell C Hardie2,

Metin N Gurcan3, Aytekin Oto1,

Steve K Rogers3, Jeffrey W Hoffmeister3

1. Department of Radiology, The University of Texas Medical Branch, Galveston TX

2. iCAD Inc. and University of Dayton, Dayton OH

3. iCAD Inc., Beavercreek OH

CAD Performance Analysis for Pulmonary Nodule Detection: Comparison of Thick- and Thin-Slice Helical CT Scans
introduction
Introduction
  • This study compares the performance of a CAD (QuickCue™, iCAD, Inc.) system in detecting lung nodules from thick- and thin-slice multi-detector row CT scans, and to evaluate the potential benefit of CAD on radiologist sensitivity.
methods and materials
Methods and Materials
  • 57 reports reviewed retrospectively
  • Case selection:
    • Obtained during a 5-month period
    • Referred from multiple departments
    • Contain at least 1 pulmonary nodule but fewer than 10 nodules to localize
    • Have no significant breathing miss - registration, post surgical changes, pleural effusions & atelectasis
methods and materials1
Methods and Materials
  • 4-detector LightSpeed QX/I Scanner, GE systems
  • HQ setting with 5.0 collimation, helical pitch of 0.75/1.0
  • Standard-dose (160 - 270 mA, 120 kVp)
  • Images were reconstructed at 5 mm (thick) and 2.5 mm (thin) slice thicknesses.
methods and materials2
Methods and Materials
  • 140 nodules (3 mm - 25 mm) were identified
    • pre-CAD by radiologists
    • From thick-slice cases only.
  • Cases with multiple nodules were excluded.
  • Truth marks were mapped to the thin-slice data
  • Mean nodule size 7.3 ± 4.2 mm (3 – 25 mm)
  • Gold standard for nodule truth comes for post-CAD Radiologist review
    • One gold standard for thick-slice and one for thin-slice
cad system quickcue icad inc
CAD System(QuickCue™, iCAD Inc.)

DICOM

Images

3D Lung

Segmentation

3D Candidate

Segmentation

Calculate

Features

Classifier

Detection

Mask

review of thick slice cad results
Review of Thick-Slice CAD Results
  • CAD detected 72.1% (101/140) of the pre-CAD truth nodules
  • CAD detected 35 additional radiologist-confirmed nodules, an increase of 25% (35/140) in sensitivity
  • 5.6 (317/57) false-positives per case
    • 55 due to atelectasis
    • 18 due to scarring
venn diagram for thick
Venn Diagram for Thick

Pre-CAD Review

CAD

0

0

317

101

35

39

3

Post-CAD Review

Gold Standard

review of thin slice cad results
Review of Thin-Slice CAD Results
  • CAD detected 80.7% (113/140) of the pre-CAD truth nodules.
  • CAD detected 94 additional radiologist-confirmed nodules, an increase of 67.1% (94/140).
  • 4.6 (262/57) false-positives per case.
    • 70 due to atelectasis
    • 39 due to scarring
venn diagram for thin
Venn Diagram for Thin

Pre-CAD Review using thick-slice

with detections mapped to thin-slice

CAD using thin-slice

0

0

262

113

94

26

0

Post-CAD Review of thin-slice

Gold Standard

cad detections in thick slice
CAD detections in Thick-Slice

Additional Detections

cad detections in thin slice
CAD detections in Thin-Slice

Additional Detections

case follow up
Case Follow-up
  • 5 primary lung cancers
  • 24 cases of metastatic cancer including
    • 7 lymphomas, 4 breast, 4 head and neck, 2 colon, 2 pancreas, 1 carcinoid, 1 seminoma,  1 ovarian, 1 melanoma and 1 tracheal papillomatosis
  • 23 cases of infection, including
    • 19 granulomatous disease either calcified, stable on follow-up or biopsy proven. 4 were presumed infection that resolved with follow-up
  • 1 case proved to be a thrombosed AVM
  • 4 cases lost to follow up
example tps
Example TPs
  • Examples of nodules that are detected by both radiologist and CAD
example tps1
Example TPs
  • Examples of nodules that are initially missed by radiologists then detected after reviewing CAD
review of cad results
Review of CAD Results
  • Sources of false positives
    • Vessel intersections
    • Inaccurate lung segmentation
    • Partial volume effects
    • Other lung abnormalities (scarring, atelectasis)
review of cad results1
Review of CAD Results
  • Sources of false negatives (missed nodules)
    • Low density, irregular
    • Strong connectivity with vessels
    • Imperfect candidate segmentation
    • Inaccurate lung segmentation
conclusion s
Conclusions
  • Preliminary results indicate that both sensitivity and specificity of the CAD system increases when used with thin-slice scans versus thick-slice scans.
  • The CAD system operating on both thick- and thin-slice scans improved radiologist sensitivity
    • Improvement was greater for CAD operating on thin-slice scans