www.bjorl.org
Brazilian
Journal
of
OTORHINOLARYNGOLOGY
ORIGINAL
ARTICLE
Expanding
the
limits
of
endoscopic
intraorbital
tumor
resection
using
3-dimensional
reconstruction
夽
Luciano
Lobato
Gregorio
a,b,c,∗,
Nicolas
Y.
Busaba
b,d,
Marcel
M.
Miyake
b,c,e,f,
Suzanne
K.
Freitag
f,
Benjamin
S.
Bleier
b,daUniversidadeFederaldeSãoPaulo(UNIFESP),EscolaPaulistadeMedicina,DepartamentodeOtorrinolaringologiaeCirurgiade Cabec¸aePescoc¸o,SãoPaulo,SP,Brazil
bMassachusettsEyeandEarInfirmary,DepartmentofOtolaryngology-HeadandNeckSurgery,Boston,UnitedStates cCoordenac¸ãodeAperfeic¸oamentodePessoaldeNívelSuperior(CAPES),Brasília,DF,Brazil
dHarvardMedicalSchool,DepartmentofOtologyandLaryngology,Boston,UnitedStates
eFaculdadedeCiênciasMédicasdaSantaCasadeSãoPaulo,DepartamentodeOtorrinolaringologia,SãoPaulo,SP,Brazil fHarvardMedicalSchool,MassachusettsEyeandEarInfirmary,OphthalmicPlasticSurgeryService,Boston,UnitedStates
Received18June2017;accepted13November2017 Availableonline26December2017
KEYWORDS Endoscopicendonasal approach; Orbitaltumors; Orbit; Nasalsurgical procedures; Otorhinolaryngologic surgicalprocedures Abstract
Introduction:Endoscopicorbitalsurgeryisanascentfieldandnewtoolsarerequiredtoassist withsurgicalplanningandtoascertainthelimitsofthetumorresectability.
Objective: Wepurposetoutilizethree-dimensionalradiographicreconstructiontodefinethe theoreticallaterallimitofendoscopicresectabilityofprimaryorbitaltumorsandtoapplythese boundaryconditionstosurgicalcases.
Methods:A three-dimensional orbitalmodelwas renderedin4representativepatients pre-sentingwithprimaryorbitaltumorsusingOsiriXopensourceimagingsoftware.A2-Dimensional planewaspropagatedbetweenthecontralateralnareandalinetangentialtothelongaxisof theopticnervereflectingthetrajectoryofatrans-septalapproach.Anytumorvolumefalling medialtotheopticnerveand/orwithinthespaceinferiortothisplaneofresectabilitywas consideredtheoreticallyresectableregardlessofhowfaritextendedlateraltotheopticnerve asnerveretractionwouldbeunnecessary.Actualtumorvolumeswerethensuperimposedover thisplanandcorrelatedwithsurgicaloutcomes.
夽 Pleasecitethisarticleas:GregorioLL,BusabaNY,MiyakeMM,FreitagSK,BleierBS.Expandingthelimitsofendoscopicintraorbital
tumorresectionusing3-dimensionalreconstruction.BrazJOtorhinolaryngol.2019;85:157---61.
∗Correspondingauthor.
E-mail:gregorioluciano@me.com(L.L.Gregorio).
PeerReviewundertheresponsibilityofAssociac¸ãoBrasileiradeOtorrinolaringologiaeCirurgiaCérvico-Facial. https://doi.org/10.1016/j.bjorl.2017.11.010
1808-8694/©2017Associac¸˜aoBrasileiradeOtorrinolaringologiaeCirurgiaC´ervico-Facial.PublishedbyElsevierEditoraLtda.Thisisanopen accessarticleundertheCCBYlicense(http://creativecommons.org/licenses/by/4.0/).
Results:Amongthe4lesionsanalyzed,twowerefullymedialtotheopticnerve,oneextended lateraltotheopticnervebutremainedinferiortotheplaneofresectability,andoneextended bothlateraltotheopticnerveandsuperiortotheplaneofresectability.Aspredictedbythe three-dimensionalmodeling,acompleteresectionwasachievedinalllesionsexceptonethat transgressed theplane of resectability. Nonew diplopiaor vision losswas observed inany patient.
Conclusion:Three-dimensionalreconstructionenhancespreoperativeplanningforendoscopic orbitalsurgery.Tumorsthatextendlateraltotheopticnervemaystillbecandidatesforapurely endoscopicresectionaslongastheydonotextendabovetheplaneofresectabilitydescribed herein.
© 2017 Associac¸˜ao Brasileira de Otorrinolaringologia e Cirurgia C´ervico-Facial. Published by Elsevier Editora Ltda. This is an open access article under the CC BY license (http://
creativecommons.org/licenses/by/4.0/). PALAVRAS-CHAVE Abordagemendonasal endoscópica; Tumoresorbitais; Órbita; Procedimentos cirúrgicosnasais; Procedimentos cirúrgicos otorrinolaringológicos
Expandindooslimitesdaressecc¸ãoendoscópicadetumorintraorbitalutilizando reconstruc¸ãotridimensional
Resumo
Introduc¸ão: A cirurgia orbitalendoscópica éum campo emergentee sãonecessárias novas ferramentasparaauxiliarnoplanejamentocirúrgicoedeterminaroslimitesdaressecabilidade tumoral.
Objetivo:Usarareconstruc¸ãoradiográficatridimensionalparadefinirolimitelateralteóricode ressecabilidadeendoscópicadetumoresorbitaisprimárioseaplicaressascondic¸õesdelimites acasoscirúrgicos.
Método: Ummodeloorbitaltridimensionalfoiaplicadoaquatropacientesrepresentativoscom tumoresorbitaisprimáriosutilizandoosoftwaredeimagemdefonteabertaOsiriX.Umplano bidimensionalfoipropagadoentreanarinacontralateraleumalinhatangencialaoeixolongo donervoópticoquerefleteatrajetóriadeumaabordagemtranseptal.Qualquervolumede tumorsituadomedialmenteaoonervoópticoe/oudentrodoespac¸oinferioraesseplanode ressecabilidadefoiteoricamenteconsiderado ressecável,independentementedequãolonge eleseestendiaatéonervoóptico,poisaretrac¸ãodonervoseriadesnecessária.Osvolumes reaisdotumorforamentãosobrepostossobreesseplanoecorrelacionadoscomosresultados cirúrgicos.
Resultados: Entreasquatrolesõesanalisadas,duaseramtotalmentemediaisaonervoóptico, umaseestendialateralmenteaonervoóptico,maspermaneceuinferioraoplanode ressecabil-idadeeumaseestendialateralmenteaonervoópticoesuperioraoplanoderessecabilidade. Conformeprevistopelomodelotridimensional,umaressecc¸ãocompletafoiobtidaemtodas aslesões,excetouma,quetransgrediuoplanoderessecabilidade.Nenhumanovadiplopiaou perdadevisãofoiobservadaemqualquerpaciente.
Conclusão:Areconstruc¸ãotridimensionalmelhoraoplanejamentopré-operatórioparaa cirur-giaorbitalendoscópica.Ostumoresqueseestendemlateralmenteaonervoópticopodemainda sercandidatosàressecc¸ãopuramenteendoscópica,desdequenãoseestendamalémdoplano deressecabilidadeaquidescrito.
© 2017 Associac¸˜ao Brasileira de Otorrinolaringologia e Cirurgia C´ervico-Facial. Publicado por Elsevier Editora Ltda. Este ´e um artigo Open Access sob uma licenc¸a CC BY (http://
creativecommons.org/licenses/by/4.0/).
Introduction
Endoscopic orbital surgery is a rapidly growing field and
many studies have proven the efficacy of the exclusive
endoscopicapproachformanagementofbenignand
malig-nantintraorbitaltumors.1---4 Aswithanynascentfield,new
tools are required to assistwith surgical planning and to
ascertainthelimitsoftumorresectability.Whilealgorithms
have been proposed toassist in thechoice of approach,5
these studies have relied on traditional tri-planar
imag-ingtodeterminetumormorphology andlateralextension.
However,thecompact,conalstructureoftheorbitalapex
often obscurestheprecise relationship betweentheoptic
nerveand thetumor masswhich,in turn,has ledto
con-servativerecommendationsregardingthelateralextentof
tumor resectability. Furthermore, the complex shape of
the tumor asit insinuates throughthe apical
neurovascu-lar structures can lead to significant errorsin estimation
of tumor volume by tri-planar measurement. This
fea-turebecomesparticularlyimportantwhentryingtoassess
whether a lesion has been fully resected based on gross
3-Dimensional reconstruction and analysis of planar
imageshasbecomeincreasinglyusefulthankstothe
prolif-erationof thirdpartyDigitalImagingandCommunications
inMedicine(DICOM)viewingsoftwaresuchasOsiriX(Pixmeo
Geneva, Switzerland). These reconstructions are able to
overcome the described limitations of planar imaging of
theorbital apexastheintimaterelationship between the
opticnerveandthelesioncanbevisualizedfromtheoptic
chiasm and the globe. The purpose of this study was to
thereforedeterminewhether3-dimensionalreconstruction
could be used to create a precise boundary to describe
the laterallimit of endoscopictumor resectability and to
accuratelycharacterizethevolumeofrepresentativeorbital lesions.
Methods
Approval of this study was obtained through the Human
Studies Committee --- Institutional Review Board
(Proto-col n◦ 754915-8 (15-068H)). Four patients with primary
orbitaltumorsrepresentative ofdistinct tumorepicenters
who underwent endoscopic intraorbital surgery between
January 2014 and May 2015 were selected. Computed
tomography (CT)scans(100kVtube voltage,600---800mAs
intensity without modulation, and temporal resolution
125---625ms)wereacquired foreach patientandimported
in OsiriX Software x6.5.2 32-bit. The region-of-interest
(ROI) tool was used to identify the optic nerve (ON),
extraocular muscles and tumor in successive axial cuts.
Three-dimensional volume rendering was used to create
a reconstruction of the relationship between the bony
orbit, tumor and ON and also to calculate the tumor
volume.
Anobliqueparasagittalline wasappliedalong thelong
axisoftheONdividingitintomedialandlateralhalvesalong
itsentire length. A 2-dimensional plane was then
propa-gatedbetweenthecontralateralnareandthelinedescribing
thelong axis of the ON.This plane, termedthe plane of
resectability(POR),reflectsthetrajectoryofatrans-septal
approachtotheorbit.Accordingtoourcriteria,anytumor
volumefallingmedialtotheONand/orinferiortothePOR
wasconsideredtheoreticallyresectableregardlessofits lat-eralextent.Thisisduetothefactthatthedissectioncan
proceedinferiortheONwithoutrequiringnerveretraction.
Actualtumorvolumesfromtherepresentativepatientswere
thensuperimposedoverthisplaneandcorrelatedwith
sur-gicaloutcomes.
Results
Of the four patients studied, the relationship between
theopticnerveand tumorvolumecould beclearly
delin-Figure1 ComparisonofT1-weightedMRI(A,D,G)withCTscan(B,E,H)andwith3Drendered(C,F,I)ofPatient1withamassive orbitaltumor.Notehowthethree-dimensionalrenderinggivesdepthtotheimageandimprovesthedistinctionbetweentheON (N)andorbitalTumor(T)whichcannotbefullydistinguishedoneitherCTorMRI.
Table1 Comparisonofpredictedtumorvolumeby3Drenderingtofinalpathology. Patient Location Pathology
volume CTvolume CTdiscrepancy frompathology (%) 3Dvolume 3D discrepancy from pathology (%) Tumor volume lateralto theON Tumor volume superiorto POR 1 Opticcanal 0.03 0.17 496.94 0.05 151.94 0 0 2 Extraconal 3.7 7.74 206.45 4.02 107.44 0.77 0 3 Intraconal 0.39 1.43 362.63 0.48 121.69 0.1 0 4 Intraconal --- 7.79 --- 4.61 --- 3.9 0.17
Allvolumesarecalculatedincm3.
Figure2 3DrenderedorbitaltumorsofPatients3(A,B,C)and4(D,E,F).Line1representsthelongaxisoftheOpticNerve(N) whileLine2representstheplaneofresectability.Notehowtheselinesdividethetumorinto3zones(T1)easilyresectable,(T2) resectableand(T3)unresectable.
eatedfollowing3-dimensionalreconstruction(Fig.1).Three
patients were deemed resectable according toour
imag-ing criteria and underwent successful endoscopic gross
total resection intraoperative (Table 1). Patients 2 and 3
had tumor volumes, which extended lateral to the optic
nerve but remained inferior to the POR. Patient 4 was
found to have a tumor volume which extended both
lat-eral to the ON and superior to the POR (Fig. 2). This
patientwasdeemed unresectable andunderwent
debulk-ingandbiopsywhichwasconsistentwithasolitaryfibrous
tumor.
The 3-dimensional reconstruction software was
signifi-cantlymoreaccurateinpredictingthegrosstumorvolume
than traditional triplanar calculations (Fig.3). The mean
(±standarddeviation) percenttriplanaroverestimation of
thetumorvolumewas355.34±145.38%vs.127.02±22.72%
(p=0.03,Student’st-test)using3-dimensionalrendering.
Discussion
Thechoiceofsurgicalapproachwhenaddressingan
intraor-bitallesiondependsonmanyfactorsincludinganticipated
pathology,size,morphology,andlocation.Traditional
teach-inghasheldthatendoscopicapproachestotheorbitmust
berestrictedtolesions,which remainmedialtotheoptic
nerve.As thefieldof endoscopicorbital surgeryexpands,
these restrictionscontinue tobechallenged asnew
diag-nosticandsurgicalapproachesaredeveloped.6
Compartmentalizationoftheintraconalspacebasedon
itsfixedneurovascularstructuresmayhelp thesurgeonto
safely removeintraorbitallesions.7 However,preoperative
visualizationofthediscreetrelationshipbetweenthetumor
and theopticnerve along itsentire length isexceedingly
difficult due to thecompact neuroanatomy of the orbital
Figure3 Comparisonbetweenresectedorbitaltumorandthe3-dimensionalrenderedtumorinPatient2demonstratingaclose concordanceintumorsizeandmorphology.NoteinpanelBthatthedifferentzonesofthetumorwereidentified:(T1-green)easily resectedtumor,(T2-purple)resectabletumor.
enablestheend usertoeasily importtraditionaltriplanar
imaging studies and create an accurate reconstructionof
therelationshipbetweenthelesion,theON,andanyother
relevantbonyandmuscularorbitalstructures.
Ourfindingsdemonstratethatthesereconstructionsmay
also be used to more precisely define the lateral limits
of endoscopic approaches.5,8 By taking into account the
oblique pathway of the optic nerve and the trajectory
of a transseptal approach, we have defined a novel safe
planeofresection.Consequently,thecriteriaforendoscopic
resectionmaybeexpandedtoincludeanytumormedialto
theopticnerveand/orinferiortothePOR,regardlessofits lateralextent.
Furthermore, the reconstructive software described
herein maybeusedtofaithfully reconstructthe
morphol-ogyandvolumeoftheorbitaltumor.Thisfeaturebecomes
significantlyimportantwhenassessingthecompletenessof
theresectionofthegrossspecimen.Bycomparingthe
intra-operativespecimentothepreoperativereconstruction,the
surgeon may more readily beable to determine whether
thetumorwascompletelyresected.Thisisextremely
valu-ableinpreventingtheneedforfurthersurgicalexploration
thereby reducing the operative time, the potential for
furtherneurovascularinjury,andtherequirementof
intra-operativeorperioperativeimaging.
Conclusion
Preoperative3-dimensionalreconstructionoforbitaltumors
representsavaluablediagnostictechniquetoevaluatethe
relationshipbetweenthetumorandtheopticnerveaswell
as accurately determine the tumor volume and
morphol-ogy. Using thistechnique, we have defineda novel plane
ofresectability,termedthe ‘‘POR’’,whichchallenges the
conventionalteachingthattumorslateraltotheopticnerve
shouldnotbeapproachedendoscopically.Basedonour
find-ings,thecriteriaforanendoscopicapproachtotheorbitcan
beexpandedtolesions,whichliemedialtotheopticnerve
and/orareinferiortotheplaneofresectabilityregardless oftheirlateralextent.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
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