POSTER PRESENTATION Open Access Improved ......Cite this article as: Shao et al.: Improved...
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POSTER PRESENTATION Open Access Improved myocardial T1 mapping for patients with implanted cardiac devices Jiaxin Shao 1* , Shams Rashid 1 , Kim-Lien Nguyen 1,2 , Peng Hu 1,3 From 19th Annual SCMR Scientific Sessions Los Angeles, CA, USA. 27-30 January 2016 Background Myocardial T1 mapping holds promise for non-invasive evaluation of diffuse fibrosis. Nevertheless, the widely used cardiac T1 mapping techniques, including MOLLI and SASHA, are generally not applicable to patients with implanted cardiac devices, such as implantable cardiover- ter defibrillators (ICDs) and pacemakers, due to large off-resonance induced by the device and the associated banding artifacts when using bSSFP readouts. We sought to develop and validate an improved technique for accu- rate myocardial T1 mapping in patients with implanted cardiac devices. Methods Recent work by Rashid et al. (Radiology 2014; 270:269- 274) demonstrates the use of a wideband adiabatic inver- sion pulse in late gadolinium enhancement (LGE) MRI to remove hyper-intensity image artifacts during myocardial scar imaging of patients with cardiac devices. In this work, we incorporate a similar wideband inversion pulse to a MOLLI sequence based on FLASH readouts, using a M0- (1)-5-(1)-3-(1)-1 acquisition scheme shown in Figure 1a. Ten FLASH images were acquired over 13 heart beats during a single breath-hold with a resolution of 1.9 × 2.5 × 8.0 mm 3 . The BLESSPC fitting algorithm recently described by Shao et al. (JMRI 2015; doi: 10.1002/ jmri.24999) was applied to the reconstruction of T1 maps. Wideband FLASH-MOLLI was evaluated using 8 phantom studies and validated in 10 healthy volunteers and 5 patients with ICDs using a 1.5T MR scanner. The effects of off-resonance frequency variation, heart rate variation, and presence of ICD on T1 estimation accu- racy were investigated using phantom studies. To mimic ICD-induced image artifacts, the ICD generator was attached to the body coil and close to the left shoulder of healthy volunteers. The original FLASH-MOLLI sequence using a 3-(3)-3-(3)-5 acquisition scheme was used to image one healthy volunteer (before and after ICD attachment) and in one patient with ICD for comparison. Results Wideband FLASH-MOLLI generated consistent T1 values over a wide range of off-resonance frequencies (Figure 1b) and showed no dependence on heart rate variation. The maximum T1 estimation errors by wideband FLASH- MOLLI were less than 3% for T1 range from 212 ms - 1673 ms. Compared to original FLASH-MOLLI, wideband FLASH-MOLLI succeeded in 1) removing artifacts result- ing from ICD-induced non-uniform signal inversion of the myocardium and 2) producing more homogeneous T1 estimation over the entire myocardium (Figure 2). In all ten healthy volunteers, there was no significant myocardial T1 estimation difference by wideband FLASH-MOLLI before and after ICD attachment (1177 ± 27 ms vs. 1178 ± 27 ms, p = 0.94). Using wideband FLASH-MOLLI, myo- cardial T1 maps from 5 patients with ICDs were generated without ICD-induced artifacts. Conclusions This study demonstrates the feasibility of using wideband FLASH-MOLLI for accurate myocardial T1 mapping in patients with implanted cardiac devices through mitigation of image artifacts associated with conventional T1 mapping techniques. Authors’ details 1 Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA, USA. 2 Department of Medicine, Division of Cardiology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA. 3 Biomedical Physics Inter-Departmental Graduate Program, University of California, Los Angeles, CA, USA. 1 Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA, USA Full list of author information is available at the end of the article Shao et al. Journal of Cardiovascular Magnetic Resonance 2016, 18(Suppl 1):P25 http://www.jcmr-online.com/content/18/S1/P25 © 2016 Shao et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http:// creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/ zero/1.0/) applies to the data made available in this article, unless otherwise stated.
Transcript of POSTER PRESENTATION Open Access Improved ......Cite this article as: Shao et al.: Improved...
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POSTER PRESENTATION Open Access
Improved myocardial T1 mapping for patientswith implanted cardiac devicesJiaxin Shao1*, Shams Rashid1, Kim-Lien Nguyen1,2, Peng Hu1,3
From 19th Annual SCMR Scientific SessionsLos Angeles, CA, USA. 27-30 January 2016
BackgroundMyocardial T1 mapping holds promise for non-invasiveevaluation of diffuse fibrosis. Nevertheless, the widely usedcardiac T1 mapping techniques, including MOLLI andSASHA, are generally not applicable to patients withimplanted cardiac devices, such as implantable cardiover-ter defibrillators (ICDs) and pacemakers, due to largeoff-resonance induced by the device and the associatedbanding artifacts when using bSSFP readouts. We soughtto develop and validate an improved technique for accu-rate myocardial T1 mapping in patients with implantedcardiac devices.
MethodsRecent work by Rashid et al. (Radiology 2014; 270:269-274) demonstrates the use of a wideband adiabatic inver-sion pulse in late gadolinium enhancement (LGE) MRI toremove hyper-intensity image artifacts during myocardialscar imaging of patients with cardiac devices. In this work,we incorporate a similar wideband inversion pulse to aMOLLI sequence based on FLASH readouts, using a M0-(1)-5-(1)-3-(1)-1 acquisition scheme shown in Figure 1a.Ten FLASH images were acquired over 13 heart beatsduring a single breath-hold with a resolution of 1.9 × 2.5 ×8.0 mm3. The BLESSPC fitting algorithm recentlydescribed by Shao et al. (JMRI 2015; doi: 10.1002/jmri.24999) was applied to the reconstruction of T1 maps.Wideband FLASH-MOLLI was evaluated using 8
phantom studies and validated in 10 healthy volunteersand 5 patients with ICDs using a 1.5T MR scanner. Theeffects of off-resonance frequency variation, heart ratevariation, and presence of ICD on T1 estimation accu-racy were investigated using phantom studies. To mimicICD-induced image artifacts, the ICD generator was
attached to the body coil and close to the left shoulderof healthy volunteers. The original FLASH-MOLLIsequence using a 3-(3)-3-(3)-5 acquisition scheme wasused to image one healthy volunteer (before and afterICD attachment) and in one patient with ICD forcomparison.
ResultsWideband FLASH-MOLLI generated consistent T1 valuesover a wide range of off-resonance frequencies (Figure 1b)and showed no dependence on heart rate variation. Themaximum T1 estimation errors by wideband FLASH-MOLLI were less than 3% for T1 range from 212 ms -1673 ms. Compared to original FLASH-MOLLI, widebandFLASH-MOLLI succeeded in 1) removing artifacts result-ing from ICD-induced non-uniform signal inversion of themyocardium and 2) producing more homogeneous T1estimation over the entire myocardium (Figure 2). In allten healthy volunteers, there was no significant myocardialT1 estimation difference by wideband FLASH-MOLLIbefore and after ICD attachment (1177 ± 27 ms vs. 1178 ±27 ms, p = 0.94). Using wideband FLASH-MOLLI, myo-cardial T1 maps from 5 patients with ICDs were generatedwithout ICD-induced artifacts.
ConclusionsThis study demonstrates the feasibility of using widebandFLASH-MOLLI for accurate myocardial T1 mapping inpatients with implanted cardiac devices through mitigationof image artifacts associated with conventional T1mapping techniques.
Authors’ details1Department of Radiological Sciences, David Geffen School of Medicine,University of California, Los Angeles, CA, USA. 2Department of Medicine,Division of Cardiology, David Geffen School of Medicine, University ofCalifornia, Los Angeles, CA, USA. 3Biomedical Physics Inter-DepartmentalGraduate Program, University of California, Los Angeles, CA, USA.
1Department of Radiological Sciences, David Geffen School of Medicine,University of California, Los Angeles, CA, USAFull list of author information is available at the end of the article
Shao et al. Journal of Cardiovascular MagneticResonance 2016, 18(Suppl 1):P25http://www.jcmr-online.com/content/18/S1/P25
© 2016 Shao et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided theoriginal work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
http://creativecommons.org/licenses/by/4.0http://creativecommons.org/licenses/by/4.0http://creativecommons.org/publicdomain/zero/1.0/http://creativecommons.org/publicdomain/zero/1.0/
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Figure 1 (a) Illustration of the wideband FLASH-MOLLI acquisition scheme. The FLASH images were acquired over 13 heart beats during asingle breath-hold. (b) Plots of measured T1 using the wideband FLASH-MOLLI as a function of off-resonance in phantom experiments.Wideband FLASH-MOLLI produced consistent T1 estimation over 3.4 KHz. Reference T1 values (Ref T1) were determined using a standardinversion recovery spin-echo sequence.
Figure 2 Example of raw images and corresponding T1 maps acquired in the mid left ventricular short axis plane of a healthyvolunteer without (row a) and with (row b) an ICD taped near the left shoulder and of a patient (row c) with an ICD, using theoriginal FLASH-MOLLI (columns 1 and 3) and the wideband FLASH-MOLLI (columns 2 and 4). T1 values of pixels where the data did notfit well (R2 < 0.95) were set to zero. The raw images acquired using FLASH-MOLLI showed severe dark band artifacts within the myocardium(blue arrow, column 1), which occur at the boundary of inverted and non-inverted regions despite using a FLASH readout. In contrast, the rawimages acquired using wideband FLASH-MOLLI (column 2) are without dark band artifacts, resulting in more accurate and homogenous T1estimation (column 4).
Shao et al. Journal of Cardiovascular MagneticResonance 2016, 18(Suppl 1):P25http://www.jcmr-online.com/content/18/S1/P25
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Published: 27 January 2016
doi:10.1186/1532-429X-18-S1-P25Cite this article as: Shao et al.: Improved myocardial T1 mapping forpatients with implanted cardiac devices. Journal of CardiovascularMagnetic Resonance 2016 18(Suppl 1):P25.
Shao et al. Journal of Cardiovascular MagneticResonance 2016, 18(Suppl 1):P25http://www.jcmr-online.com/content/18/S1/P25
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BackgroundMethodsResultsConclusionsAuthors’ details
