Volumetric motion quantification by 3D velocity encoded MRI
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POSTER PRESENTATION
Open Access
Volumetric motion quantification by 3D velocity encoded MRI Anja Lutz1, Jan Paul1, Axel Bornstedt1, Gerd Ulrich Nienhaus2, Patrick Etyngier3, Peter Bernhardt1, Wolfgang Rottbauer1, Volker Rasche1* From 15th Annual SCMR Scientific Sessions Orlando, FL, USA. 2-5 February 2012 Summary It is objective to show the feasibility of volumetric velocity-encoded MRI (3D-TPM) to derive velocity based motion quantification parameters. Background About 30% of patients treated with cardiac resynchronization therapy (CRT) do not benefit from the procedure. The introduction of quantitative parameters for selection of patients appears mandatory. However, parameters based on 2D imaging techniques may be less reproducible caused by rapid changes of the motion pattern along the cardiac axis. Methods 12 volunteers (26±7 years) and 2 patients (46, DCM/29, LBBB) were investigated at a 3T whole body MR scanner (Achieva, Philips) with a 32 channel cardiac coil. A 3D black blood velocity encoded navigated segmented gradient echo sequence (3D-TPM) was applied for whole heart coverage. The acquisition parameters were: FOV=3802mm2, isotropic resolution of 3x3x3mm3, FOV in through-plane direction =63mm in healthy volunteers (this FOV was increased in patients due to their enlarged heart corresponding to the distance between basis and apex), acquisition matrix =128x124, TR/ TE=7.1ms/4.9ms, flip angle =15°, SENSE =4, nominal scan duration =15:30 minutes, 3 k-lines per segment, phase interval =37.3ms and 25 cardiac phases for 60bpm. The acquisition of the whole heart data was split into 3 chunks to ensure sufficient black blood contrast.
1 University Hospital of Ulm, Ulm, Germany Full list of author information is available at the end of the article
From the 3D-TPM data, the following parameters were evaluated: longitudinal and radial standard deviation of time to peak systolic and diastolic velocities SD (TTPl,sys), SD(TTPl,dias), SD(TTPr,sys), SD(TTPr,dias)[1], the mean radial, circumferential and longitudinal asynchrony correlation coefficient over all cardiac segments (ACC)[2], the longitudinal and radial velocity range Δvl = vl,max-vl,min, Δvr = vr,max-vr,min and the new parameter temporal uniformity of velocity (TUV) in radial, longitudinal and circumferential direction, which was defined analogously to the temporal uniformity of strain defined in [3,4].
Results Figure 1 shows the 3D velocity over time curves exemplarily for one volunteer and patient 2 with proven asynchrony. A clearly modified motion pattern with reduced peak velocities can be appreciated as well as the large variation of the motion curve along the heart axes in the volunteer. Table 1 contains the motion quantification parameter evaluation based on 3D-TPM data as mean ± standard deviation for the volunteer group and the patients. The mean ACC over all segments is decreased and the velocity ranges and TUV are decreased in the patients compared to healthy volunteers. SD(TTP sys,r ) is increased in case of asynchrony. Conclusions It is feasi
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