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This project aims to combine machine learning and physician knowledge to improve the accuracy of breast biopsies, reducing inconclusive results and unnecessary procedures. The study analyzes data from over 1,300 image-guided core biopsies to learn characteristics of inconclusive cases and enhance the classifier with expert rules.
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Integrating Machine Learning and Physician Knowledge to Improve the Accuracy of Breast Biopsy Inês Dutra Universityof Porto, CRACS & INESC-Porto LA HoussamNassif, David Page, JudeShavlik, Roberta Strigel, YirongWu, MaiElezabiandElizabethBurnside UW-Madison
IntroandMotivation • USA: • 1 woman dies of breast cancer every 13 minutes • In 2011: • estimated 230,480 newcases ofinvasivecancer • 39,520 women are expected to die • Source: U.S. Breast Cancer Statistics, 2011 AMIA 2011
IntroandMotivation • Portugal: • Per year: • 4,500 new cases • 1,500 deaths (33%) • Source: Liga Portuguesa Contra o Cancro - September 2011 AMIA 2011
IntroandMotivation • Mammography • MRI • Ultrasound • Biopsies AMIA 2011
IntroandMotivation • Image-guidedpercutaneous core needlebiopsy • standard for thediagnosisofsuspiciousfindings • Over 700,000 womenundergobreast core biopsyinthe US • Imperfect: biopsiescanbeinconclusivein5-15% of cases • ≈ 35,000-105,000 oftheabovewillrequireadditionalbiopsies AMIA 2011
IntroandMotivation • Breastbiopsies: • Fine needlebreastbiopsy • Stereotacticbreastbiopsy • Ultrasound-guided core biopsy • Excisionalbiopsy • MRI-guided AMIA 2011
Objectives • Hypotheses • Canwelearncharacteristicsofinconclusivebiopsies? • Canweimprovetheclassiferbyaddingexpertknowledge? AMIA 2011
Terminology • Inconclusivebiopsies: “non-definitive”: • Discordantbiopsies • Highrisklesions • Atypicalductalhyperplasia • Lobular carcinoma insitu • Radial scar • etc. • Insufficientsampling AMIA 2011
MaterialsandMethods • Data collected • Oct1st, 2005 to Dec 31st, 2008 • Tools • WEKA • Aleph • Validation: leave-one-outcrossvalidation • Resultstested for statisticalsignificance AMIA 2011
Data source 1384 imageguided core biopsies 349 M 1035 B 925 (C) 110 (NC) 43 (D) 51 (ARS) 16 (I) Aftereliminatingredundancies 94 AMIA 2011
Data distribution • 94 non-concordant cases wentthroughadditionalprocedures (e.g., excision) • 15 were “upgraded” frombenign to malignant • Ourpopulation: 15+/79- • Task: find a distinctionbetween upgrades andnon-upgrades AMIA 2011
Data Features AMIA 2011
WEKA andAleph • Data cleaning, singletable • 15-fold stratifiedcross-validation (leave-one-out) • WEKA (BayesTAN) andAleph • Withoutexpertknowledge • Withexpertknowledge AMIA 2011
WEKA andAleph • Waikato Environment for KnowledgeAnalysis • Collectionofmachinelearningalgorithmsand data miningtasks • use “propositionalized” data (flattable) • ALearningEngine for ProposingHypotheses • InductiveLogicProgramming (ILP) system • Knowledgerepresentation: firstorderrules AMIA 2011
Method Learnrulesabouthowandwhynon-definitive cases are “upgraded” Otherrules (simple) providedby a specialist Combine Newrules AMIA 2011
Modelling upgrades withoutexpertknowledge • Alephlearningonthe 94 cases (15+/79-) • Exampleofrulelearned upgrade(A) IF bxneedlegauge(A,9) AND abndisappeared10(A,0) AND mass01(A,1) AND anotherlesionbxatsametime01(A,0). [4+/0-] AMIA 2011
ExamplesofExpertrules (1) Upgrade increases on stereo if calcifications and ADH are present upgrade(A) IF pathdx(A,atypical_ductal_hyperplasia) AND calcifications(A,’a,f’) AND biopsyprocedure(A, stereo). (2) Upgrade increases on US(Ultra-Sound) if high BIRADS category upgrade(A) IF concordance(A,d) AND mammobirads(A,4B/4C/5). AMIA 2011
Modelling upgrades withexpertknowledge • Exampleofrulelearned upgrade(A) IF numOfSpecimens(A,gt6) AND rule1_2(A) AND rule1_3(A). [3+/1-] rule1_2(A) IF pathdxabbr(A,adh) AND calcifications(A,f). [3+/4-] rule1_3(A) IF pathdxabbr(A,adh) AND calcification_distribution(A,g). [3+/6-] AMIA 2011
Results AMIA 2011
Results AMIA 2011
Results:WEKA versus Alephandhumanrules AMIA 2011
Conclusions • Both WEKA andAlephcanimproveresultswhencombining original data withexpertknowledge (withouttuning) • WEKA improvesonfalse positives andcanbeadjusted to achieveRecallof 100% withtheneed to re-examinearound60 women (outof 79) • Alephimprovesonfalse negatives andproduces a betterclassifierwiththeadvantageofusing a languagethatiseasilyunderstandablebythespecialist AMIA 2011
FutureWork • NLM projectstartedthismonth AMIA 2011
FutureWork • NLM projectstartedthismonth • Shorttermtasks: • Augmentthecurrentdataset • Reviewconsistentlymisclassifiedexamples • Possibily use associationrules to produce a firstsubsetofrules AMIA 2011
FutureWork • NLM projectstartedthismonth • Shorttermtasks: • Augmentthecurrentdataset • Reviewconsistentlymisclassifiedexamples • Possibily use associationrules to produce a firstsubsetofrules • Mediumtermtasks: • learnfromthe cases thatwerenotupgraded • Developtheiterativecycleoflearningandexpertrulerevision AMIA 2011
FutureWork • NLM projectstartedthismonth • Shorttermtasks: • Augmentthecurrentdataset • Reviewconsistentlymisclassifiedexamples • Possibily use associationrules to produce a firstsubsetofrules • Mediumtermtasks: • learnfromthe cases thatwerenotupgraded • Developtheiterativecycleoflearningandexpertrulerevision • Longtermtasks: • Use more sophisticatedlearningmethods to producebetterrules • To integratebiopsyattributesandtheclassifiersobtained to MammoClass (http://cracs.fc.up.pt/pt/mammoclass/) AMIA 2011
Acknowledgments • UW-MadisonMedicalSchool • FCT-PortugalandHorusandDigiScopeprojects • AMIA reviewersandorganizers • Specialack to theUW-MadisonMedicalSchoolpeoplethatwerenever “scared” ofcomputertechnologyandhavebeenalwaysveryenthusiasticaboutusingcomputationalmethodologies to helptheirwork AMIA 2011
CONTACT: ines@dcc.fc.up.pt THANK YOU! AMIA 2011
Experiment 1Significancetests - p-values AMIA 2011
Experiment 2tuning • 5x4 stratifiedcrossvalidation • Parameterstuned: • Minacc: 0.05 and 0.1 • Minpos: 1, 2, 3 • Noise: 0, 1, 2 AMIA 2011
Experiment 2 - Results p= 0.1 0.3 0.03 AMIA 2011
Summary AMIA 2011
UW upgrades data • 94 benign cases afterbiopsieswerediscussed • 15 considered to be, infact, malignant upgrades • Tasks: • learncharacteristicsof upgrades that do notappearinnon-upgrades interpretablerules • Canweimprovetheclassiferbyaddingexpertknowledge? AMIA 2011