Early experience of novel biliary tree magnetic resonance cholangio pancreatography (MRCP) analysis Siddharth Vikal, Nassim Parvizi, Michael Brady, Rajarshi Banerjee Motivation MRCP Enhancement without contrast Need for objective quantitative measures • MRCP routinely used in evaluation of: gall bladder anatomy, stones, cholestatic diseases including PSC, choledocholithiasis, pancreatitis, hepatobiliary- pancreatic tumours, and surgical planning • Non-invasive, increases diagnostic confidence and reduces frequency of invasive follow-up procedures • Still has limitations: variable image quality, intra- hepatic bile ducts depicted poorly as compared to invasive ERCP • No standard method for interpreting MRCP data • Conventional Maximal Intensity Projections (MIP) are difficult to interpret since 2D representation suffers from occlusion problems and lack of depth information • Analysis/interpretation is qualitative, with large inter rater variation • Objective, quantitative tools/measures needed for accurate diagnosis and monitor disease progression • We propose a novel synthesis of image processing techniques for enhancement and 3D visualization of biliary tree from MRCP • Hessian based tubular structure enhancement, followed by Otsu thresholding, and interactive 3D visualization • Post processing technique, no contrast required Axial, Coronal, Sagittal views MIP Thresholded, 3D visualization Enhanced, thresholded, 3D visualization Quantitative modelling of biliary tree MRCP data Extracted biliary tree, interactive 3D visualization Computed quantitative model that shows individual duct centerlines, widths, cross- section orientations and branching topology Automatic identification and quantification of strictures and dilatations Bile duct under review in 3D • Color coded with diameter • Red arrows indicate strictures • Blue arrows indicate dilatations • Size of arrow proportional to amount of stricturing/dilatation • Unfold the convoluted bile duct and show it in 2D with diameter measurements Registration and co-viewing of MRCP with anatomical MRI in 3D Clinical impact study Case examples Healthy individual Small duct PSC patient Biliary reconstruction patient • Double blinded study to assess clinical usefulness of the tools developed • 10 original patient datasets, 10 corresponding enhanced datasets à 20 different datasets for radiologist to report findings on • Radiologist records findings • Findings combined and decoded into original (unenhanced) vs enhanced Result: Enhancement allows to see greater level of branching of intra-hepatic ducts and helps finding strictures with ease Conclusions • Analytical enhancement techniques developed help see faint intra-hepatic ducts clearly without any contrast agent • Quantitative modeling tools allow for an objective and accurate assessment • Post processing techniques allow for retrospective evaluation and prospective validation as well • Information fusion of anatomical MRI with MRCP • Robust and repeatable methods

Early experience of novel biliary tree magnetic resonance

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Page 1: Early experience of novel biliary tree magnetic resonance

Earlyexperienceofnovelbiliarytreemagneticresonancecholangiopancreatography (MRCP)analysis

SiddharthVikal,Nassim Parvizi,MichaelBrady,Rajarshi Banerjee

Motivation

MRCPEnhancementwithoutcontrast

Needforobjectivequantitativemeasures

• MRCProutinelyusedinevaluationof:gallbladderanatomy,stones,cholestatic diseasesincludingPSC,choledocholithiasis,pancreatitis,hepatobiliary-pancreatictumours,andsurgicalplanning

• Non-invasive,increasesdiagnosticconfidenceandreducesfrequencyofinvasivefollow-upprocedures

• Stillhaslimitations:variableimagequality,intra-hepaticbileductsdepictedpoorlyascomparedtoinvasiveERCP

• NostandardmethodforinterpretingMRCPdata• ConventionalMaximalIntensityProjections(MIP)aredifficulttointerpretsince2Drepresentationsuffersfromocclusionproblemsandlackofdepthinformation

• Analysis/interpretationisqualitative,withlargeinterratervariation

• Objective,quantitativetools/measuresneededforaccuratediagnosisandmonitordiseaseprogression

• Weproposeanovelsynthesisofimageprocessingtechniquesforenhancementand3DvisualizationofbiliarytreefromMRCP

• Hessianbasedtubularstructureenhancement,followedbyOtsuthresholding,andinteractive3Dvisualization

• Postprocessingtechnique,nocontrastrequired

Axial,Coronal,Sagittalviews MIP Thresholded,3Dvisualization

Enhanced,thresholded,

3Dvisualization

Quantitativemodellingofbiliarytree

MRCPdata

Extractedbiliarytree,interactive3Dvisualization

Computedquantitativemodelthatshowsindividualductcenterlines,widths,cross-sectionorientationsandbranchingtopology

AutomaticidentificationandquantificationofstricturesanddilatationsBileductunderreviewin3D• Colorcodedwithdiameter• Redarrowsindicatestrictures• Bluearrowsindicatedilatations• Sizeofarrowproportionaltoamountofstricturing/dilatation•Unfoldtheconvolutedbileductandshowitin2Dwithdiametermeasurements

Registrationandco-viewingofMRCPwithanatomicalMRIin3D

Clinicalimpactstudy Caseexamples

Healthyindividual

SmallductPSCpatient

Biliaryreconstructionpatient

• Doubleblindedstudytoassessclinicalusefulnessofthetoolsdeveloped

• 10originalpatientdatasets,10correspondingenhanceddatasetsà 20differentdatasetsforradiologisttoreportfindingson

• Radiologistrecordsfindings• Findingscombinedanddecodedintooriginal

(unenhanced)vsenhanced

Result:Enhancementallowstoseegreaterlevelofbranchingofintra-hepaticductsandhelpsfindingstrictureswithease

Conclusions

• Analyticalenhancementtechniquesdevelopedhelpseefaintintra-hepaticductsclearlywithoutanycontrastagent