ParametersforCharacterizingDiastolicFunctionwithCardiacMagneticResonanceImagingOGrebe,MLehn,*HNeumann,*FSchwenker,JWöhrle,MHöher,VHombach,*HAKestlerDept.ofCardiologyand*Dept.ofNeuralInformationProcessing,UniversityofUlm,Ulm,GermanyAbstract23healthysubjectsand23patients withisolateddia-stolic dysfunction were examined with cine magneticresonance imagingto find newmarkers forthediastolicheartfunction.Asinglemid-ventricularshortaxissliceinthetruecardiacaxiswasusedandendo-andepicardialborderswerehanddrawn.Fivefeatureswereappliedtocharacterize isolated diastolic function: Irregularitymarkerofcontractioncalculatedasthesumof thestan-darddeviationsofcorrespondingpointsacrossallframes(IRREG);slopeofalinearfittothediastolicareachange(SLOPE); slopeoftheminimalandmean wallthickness(MINWTH/MEANWTH); shift parameter of the least-squares fit of the sigmoid Fermi-function (SHIFT). Theparameters were corrected for through-plane motion.MINWTH,MEANWTH,andSHIFTdifferedsignificantlyin both groups. These features represent promisingobjective parameters to discriminate patients withdiastolicdysfunctionfromhealthysubjects.1. IntroductionThe full heart cycle is characterized by contraction(systole)andrelaxation(diastole).Relaxationisasimpor-tantforglobalventricularperformanceassystolic func-tion but more difficult to assess. Relaxation speed anddurationforexamplemeasuredbyechocardiographyareacceptedparametersforthediastolicfunctionoftheleftventricle [1]. Primary diastolic heart failure can be ob-servedinpatientswithleft ventricularhypertrophy(duetopressureoverloadasitoccurswithhypertensionorob-struction of the outflow tract) and restrictive cardio-myopathy.Impairmentofthediastolicfunctionisalsoanearlysignofmyocardialischemia.Allcurrentmethodsforthedetectionofdiastolicdys-functionhavemajordrawbacks[2]andthereisnorobustparameterliketheejectionfractionforthesystolicfunc-tion.Theevaluationoftheheartfunctionbymagneticreso-nanceimaging(MRI)asanon-invasivetoolwithagoodspatialandtemporalresolutionhasbecomefeasibleinthelast years. Current dedicated cardiovascular MRI scan-ners provide excellent demarcation of the endocardialborder in nearly all patients. There are different ap-proches to determine diastolic function by MRI. Flowvelocity and volume measurements across the mitralvalvearepossible[3]buthamperedbyasystematicerrorduetothemovementofthevalveplaneduringtheheartcycle.Inanearlierfeasibilitystudy[4]wefoundpromisingnew markersin a patient group withboth diastolic andsystolicdysfunction.Aimofthisstudywastheexamina-tion of the previously described andnew parameters inpatientswithisolateddiastolicdysfunction.2. Methods2.1. SubjectdataTwenty-three healthy subjects (control) and 23 con-secutivepatientswithisolateddiastolicdysfunction(dia-dys) were examined with magnetic resonance imaging.Allofthediadyspatientshadanelevatedleftventricularend-diastolicpressure(>16mmHg), measured invasivelyby cardiac catheterization. Hypertension treated withdrugswaspresentin14patients,theremaininghadval-vulardiseaseorotherconditionsleadingtodiastolicdys-function.2.2. ImagingImagingwasperformedona1.5Twholebodyscanner(InteraCV,PhilipsMedicalSystems)withMasterGradi-ents(slewrate150T/m/s,amplitude30mT/m)andsoft-wareRelease8.1.A5-elementphased-arraycardiaccoilwas used. Three short survey scans were performed todefinethepositionandtrueaxisoftheleftventricle.Af-terwards,wallmotionwasimagedduringbreathholdingwithlong and short-axis slicesusing a steady-state freeprecession (balanced fast-field echo) sequence, whichprovidesanexcellentendocardialcontrast.Cardiac syn-chronization was achieved by prospective gating. Thecine images were recorded with 23 heart phases (23framesperheartcycle).Septalwallthicknesswasmeas-uredinabasalshortaxisslice.0276−6547/02 $17.00 © 2002 IEEE 185 Computers in Cardiology 2002;29:185−188.2.3. ImageanalysisA single mid-ventricular short axis slice was chosenfortheanalysis.Shortaxisslicesaremorerepresentativefor the cardiac function than long axis views and plani-metryresultsinanearlycirculararea.Inaddition,partial-volume-effectsarelowerinshort-axis-slicescomparedtothe long axis. Endocardial and epicardial contours foreach of the 23 heart phases were hand-drawn on a SunUltra60workstationusingtheEasyVisionSoftwareRe-lease5.1 (Philips, Best, The Netherlands).The papillarymuscleswereassignedtotheventricularcavum(Fig.1).Movie sequences of the contours
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