TheBigPicture:WholeBodyMRISTIRanditsusesinatertiarypaediatrichospitalDrRPrasad1,DrPMenon2,DrHChaudhry2,DrCLandes2,DrSHarave2.

AlderHeyChildren’sHospitalNHSTrust,Liverpool,UK.Abstract

Purpose:Anecdotallyinourcentre,wholebodyMRISTIR(WBMS)isbecomingthepreferredimagingmodalityinassessingsystemicdiseaseinchildren,replacingtheolderimagingmodality,bonescan.Therearenocurrentguidelinesinthisarea.TheauthorsaimtoreviewtheuseofWBMS,andcomparethefindingswithtraditionalbonescans.

Methods:ThiswasaretrospectivestudyinwhichdatawascollectedaboutWBMSperformedinourcentrefrom2011-2016. WecomparedthefindingsofWBMSwithbonescanfindingsinthepatientsthathadundergoneboth.

Results: 126WBMRISTIRscanswereincludedinthestudy.Theaveragepatientagewas9years.Most(66%)patientsdidnotrequireGA.Most requestswerefortheinvestigationofrheumatological,infectiousandoncologicaldisease.Most(63%)ofthescanshadpositivefindings.20patientsunderwentabonescanwithin6weeksoftheWBMS.15ofthesehadconcurringfindingsonbothscans.Intheremaining5caseswithdiscrepantfindings,nonewereclinicallysignificant.

Conclusion:Ourstudydemonstratesthatinourpractice,mostfindingsonWBMSandbonescanareconcurring.TherewasnothingclinicallysignificantmissedInthecasesinwhichtherewerediscrepantfindings.TheauthorsproposethatWBMSisaveryusefulandeffectiveimagingmodalityforimagingmulti-focaldiseaseinchildren.Withouttheuseofionisingradiation,itsallowstheassessmentofbothosteoblasticandosteoclasticskeletalandextra- skeletallesions.FurtherrobuststudiesareneededtoinformguidelinesontheroleofWBMSinthepaediatricsetting.

Background

Traditionally,nuclearmedicinescanssuchasbonescanswerethemainstayofimagingformulti-focaldiseaseinchildren.Howeversincearound2000,advancesinMRtechnologyandsoftwarehavemadewholebodyMRSTIR(WBMS)imagingpossible1,2.STIRisaT2fatsuppressedsequence,resultinginwater-containingstructuresdemonstratinghighsignal.Thisisusefulasmostpathologicallesionscontainwater.SeeTable1fortheadvantagesanddisadvantagesofWBMS.

ResultsOutofatotal138WBMSscansperformedbetween2011-2016,126wereincluded.

Meanageofpatient:9yearsold(youngest6wks,oldest18yrs)%ofpatientsthatdidnotrequireGA:Atleast66%(83)(Yes14%(18),Unknown20%(25))Scanindication:34%(43)oncology,30%(38)rheumatology,24%(31)infection,11% (14)miscellaneous(Piechart1showsthetypesofpathologies)FindingsonWBMS:63%withsignificantfinding,32%nofindings,6%incidentalfindings(ovariancysts,non-pathologicalnodes,traceoffluid)20patientshadabonescanwithin6weeksoftheirWBMS,theresultsareshowninTable4.

StudyaimsTheuseofwholebodyMRISTIR(WBMS)inmulti-focaldiseasepaediatricdiseaseisanecdotallyincreasingtobecomethepreferredimagingmodalityovertraditionalbonescans.Intheabsenceofguidelines,theauthorsaimto:1. FormallyreviewouruseofWBMS2. ComparethefindingsofWBMSwiththefindingson

bonescans.

MethodsTable2showstheinclusionandexclusioncriteria.3radiologyregistrarscollecteddata,showninTable3,usinginformationfoundonPACS.

Discussion:Ourstudywaslimitedasitwasretrospective,andwehadarelativelysmallnumberofpatientswhohadundergonebothWBMSandbonescaninthesameclinicalpresentation.Howevertheauthorsfeelourstudydemonstratesthatinourpractice,mostfindingsonWBMSandbonescanareconcurring.TherewasnothingclinicallysignificantmissedbyeithermodalityInthecasesinwhichtherewerediscrepantfindings.TheauthorsproposethatWBMSisaveryusefulandeffectiveimagingmodalityforimagingmulti-focaldiseaseinchildren.Withouttheuseofionisingradiation,itallowstheassessmentofbothosteoblasticandosteoclasticskeletalandextra- skeletallesions.ItdoeshoweveraddtothepressuresontheMRscanner,andpoorspecificitymayleadtofalsepositives.Somecentresadddiffusionweightedand/orT1sequencestoWBMStoreducefalsepositives,thoughscantimeislengthened.Furtherrobuststudiesareneededtoinformevidence-basedguidelinesontheroleofWBMSinthepaediatricsetting.

Table4:Outofthe 20patientswhounderwentbothWBMSandbonescanswithin6weeks,15 hadthesamefindingsonbothscans.Thefollowing5caseshaddiscrepantfindings.Case 1indication :Toddlerwithtreatedmetastatic rhabdomyosarcomaWBMS: High STIRsignalintheproximallefttibiawhichcouldbenewmetastasis(Fig.1a),BONESCAN(sameday):nocorrespondinghighsignalintheleftproximaltibia,overallincreaseduptakeintheleftlegduetoincreaseduse(Fig.1b)OUTCOME:followupx-rayshowedscleroticmetaphyses(Fig.1c)- felttobeinkeepingwithbenignradiotherapychanges.

Case2indication:Teenagerwithpreviouslyresectedspinaltumourabroad,baselineimagingneeded.WBMS:Highsignalinrightiliacwingwhichcouldbenewmetastasis(Fig.2a).BONESCAN(6weeksprior):normal(Fig.2b)OUTCOME:followupWBMS6monthslaterwasnormal(Fig.2c)– initialWBMSfindingwasfelttohavebeenartefactual.

Case3indication :TeenagerwithrelapsedEwing’stumour(Fig.3a)BONE SCAN: Ewing’stumourinthedistalleftfemur.Twohotspotsabovetherightiliaccrest(Fig.3b),couldbenewmetastases.WBMS(sameday):(Fig.3c)Nometastasis.OUTCOME:On balancebonescanfindingwasfelttobeanartefactualfinding.

Case4indication:TeenagerwithmultiplejointpainsandswellingBONESCAN:uptakeinrightindexfinger- dactylitis(Fig.4a),WBMS (2weekslater):normal(Fig.4b)OUTCOME:DactylitishadprobablyresolvedbythetimetheWBMSwasperformed.

Case5indication: Teenagerwithjuvenile idiopathicarthritispresentingwithlegpainsBONESCAN:bilateraltibialshaftuptakewhichcouldbeshinsplints(Fig.5a)WBMS (sameday):normal(Fig.5b)OUTCOME:X-ray6monthslater(Fig.5c)foundsubtlediffusecorticalthickening- possiblemelorheostosis

Table3

AgeofpatientDidthepatienthaveGAduringWBMS?%(No.)

IndicationtodoWBMS%(No.)

Findings onWBMS(%)

No. ofpatientswhoalsohad

bonescaninthesameepisode

WBMSandbonescanfindings

Table1WBMS advantagesoverbonescan WBMSdisadvantages

- Noionisingradiation.Bonescans caninvolveupto4.4mSV.1- TheliteraturesuggeststhatMRISTIRismoresensitiveatdetectinglesionsthanbonescans.1,2

- Detectsbothosteoblasticandosteoclasticskeletalandextra-skeletallesions. Bonescansonlydetectskeletalosteoblasticlesions.

- Takeslesstime.WBMS isa15minutescanvs >4hrstotaltimeneededforabonescanappointment(radio-isotopeisinjected4hourspriortothescan)

- Poorspecificityforpathologicallesionsandsusceptibletoartifact.Benignlesionscanmay alsodemonstratehighsignalonWBMS3- Youngerpatientsrequiregeneralanaesthetic(usually4m- 4yrolds,similarbonescans)- Noisyandclaustrophobic- IncreasestheburdenofdemandoftheMRslots.

Table2InclusionCriteria ExclusionCriteria

-WBMS onAlderHeyPACS(studycodeMSKES)-Performedbetween2011-December2016

- IfothersequencesbesidesSTIRwereused- Iftheradiologyreportwasunavailable(usuallybecausescanwasfromanothertrust)

- Ifitwasdoneasapost-mortemscan.

References

1.MentzelHJ,KentoucheK,SaunerD,etal.Comparisonofwhole-bodySTIR-MRIand99mTcmethylene-diphosphonatescintigraphyinchildrenwithsuspectedmultifocalbonelesions. EurRadiol. 2004;14:2297–2302.doi:10.1007/s00330-004-2390-5.2.Whole-BodyMRImagingforDetectionofBoneMetastasesinChildrenandYoungAdul,HeikeE.Daldrup-Link, ChristianeFranzius, ThomasM.Link, DanielaLaukamp, JoachimSciuk, HeribertJürgens, OtmarSchober,and ErnstJ.Rummeny,AmericanJournalofRoentgenology 2001 177:1, 229-2363.FastSTIRWhole-BodyMRImaginginChildren,ChristianJ.Kellenberger, MonicaEpelman, StephenF.Miller,and PaulS.Babyn,RadioGraphics 2004 24:5, 1317-13304.SmetsAM,DeurlooEE,SlagerTJE,StokerJ,BipatS.Whole-bodymagneticresonanceimagingfordetectionofskeletalmetastasesinchildrenandyoungpeoplewithprimarysolidtumors- systematicreview. PediatricRadiology.2018;48(2):241-252.doi:10.1007/s00247-017-4013-8.

Oncology 34%(43)

Rheumatology =30%(38)

Infection24%(31)

11%Miscellaneous• Hemihypertrophy• Complexidiopathicosteolytic

syndrome,• LCH

• 30%Rhuematology• DiagnosisorfollowupofJIA,• SAPHO• Jointpain/jointswelling• Sarcoidosis, Vasculitis

• 24%Infection:• DiagnosisandfollowupofCRMO• Diagnosisandfollowupofosteomyelitis• Pyrexiaofunknownorigin

• 34%Oncology• Bonytumours,softtissuetumours,

neuroblastoma,rhabdomyosarcoma(diagnosis,stagingandfollow–up)

PIECHART1

Fig.1b Fig.1c

Fig.2a Fig.2b Fig.2c

Fig.3a

Fig.1a

Fig3b Fig.3c

Fig.4a Fig.4b

Fig.5a Fig.5b Fig.5c