Koutsiaris 2013_b_ΜRI BLADE_Lumbar Spine

  • Published on

  • View

  • Download

Embed Size (px)


<ul><li><p>Magnetic Resonance Imaging xxx (2013) xxxxxx</p><p>Contents lists available at SciVerse ScienceDirect</p><p>Magnetic Resonance Imaging</p><p>j ourna l homepage: www.mr i journa l .comElimination of motion, pulsatile flow and cross-talk artifacts using blade sequencesin lumbar spine MR imaging</p><p>Eleftherios Lavdas a, Panayiotis Mavroidis b,c,, Spiros Kostopoulos d, Dimitrios Glotsos d, Violeta Roka e,Aristotle G. Koutsiaris f, Georgios Batsikas g, Georgios K. Sakkas h, Antonios Tsagkalis i, Ioannis Notaras i,Sotirios Stathakis b, Nikos Papanikolaou b, Katerina Vassiou j</p><p>a Department of Medical Radiological Technologists, Technological Education Institute of Athens, Greeceb Department of Radiological Sciences, University of Texas Health Sciences Center at San Antonio, San Antonio, TX, USAc Department of Medical Radiation Physics, Karolinska Institutet &amp; Stockholm University, Stockholm, Swedend Department of Medical Instruments Technology, Technological Education Institute of Athens, Greecee Health Center of Farkadona, Trikala, Greecef Bioinformatics Laboratory, Department of Medical Laboratories, School of Health Sciences, Technological Educational Institute of Larissa, Larissa, Greeceg Department of Medical Imaging, IASO Thessalias Hospital, Larissa, Greeceh Center for Research and Technology Thessaly Trikalai Department of Orthopaedic Surgery, IASO Thessalias Hospital, Larissa, Greecej Department of Radiology, Medical School, University of Thessaly, Larissa, Greecea b s t r a c ta r t i c l e i n f o Corresponding author. Division of Medical Physics, DSciences, Cancer Therapy and Research Center, UniversCenter San Antonio, MC 7889, San Antonio TX 7822941027; fax: +1 210 478 9703.</p><p>E-mail address: mavroidis@uthscsa.edu (P. Mavroidi</p><p>0730-725X/$ see front matter 2013 Elsevier Inc. Alhttp://dx.doi.org/10.1016/j.mri.2013.03.006</p><p>Please cite this article as: Lavdas E, et al, Espine MR imaging, Magn Reson Imaging (2Article history:Received 24 October 2012Revised 28 January 2013Accepted 8 March 2013Available online xxxx</p><p>Keywords:1.5 T MRIMotionPulsatile flow and cross-talk artifactsBLADE sequencesLumbar spine examinationThe purpose of this study is to evaluate the ability of T2 turbo spin echo (TSE) axial and sagittal BLADEsequences in reducing or even eliminating motion, pulsatile flow and cross-talk artifacts in lumbar spineMRI examinations. Forty four patients, who had routinely undergone a lumbar spine examination,participated in the study. The following pairs of sequences with and without BLADE were compared: a) T2TSE Sagittal (SAG) in thirty two cases, and b) T2 TSE Axial (AX) also in thirty two cases. Both quantitativeand qualitative analyses were performed based on measurements in different normal anatomicalstructures and examination of seven characteristics, respectively. The qualitative analysis was performedby experienced radiologists. Also, the presence of image motion, pulsatile flow and cross-talk artifacts wasevaluated. Based on the results of the qualitative analysis for the different sequences and anatomicalstructures, the BLADE sequences were found to be significantly superior to the conventional ones in all thecases. The BLADE sequences eliminated the motion artifacts in all the cases. In our results, it was found thatin the examined sequences (sagittal and axial) the differences between the BLADE and conventionalsequences regarding the elimination of motion, pulsatile flow and cross-talk artifacts were statisticallysignificant. In all the comparisons, the T2 TSE BLADE sequences were significantly superior to thecorresponding conventional sequences regarding the classification of their image quality. In conclusion,this technique appears to be capable of potentially eliminating motion, pulsatile flow and cross-talkartifacts in lumbar spine MR images and producing high quality images in collaborative and non-collaborative patients.epartment of Radiologicality of Texas Health Science427, USA. Tel.: +1 210 450</p><p>s).</p><p>l rights reserved.</p><p>limination of motion, pulsatile flow and cros013), http://dx.doi.org/10.1016/j.mri.2013.03 2013 Elsevier Inc. All rights reserved.1. Introduction</p><p>Magnetic resonance imaging (MRI) is the imaging technique ofchoice for the investigation of patients with documented primarytumours and suspected malignant infiltration of the spine [1].s</p><p>Extradural compression of the spinal cord or cauda equina fromvertebral metastases has been widely reported in the literature[24]. Intradural extramedullary metastases are uncommon [5]although their incidence is felt to be increasing, possibly as a result ofthe longer survival times in patients with systemic metastaticdiseases [6]. Degenerative disc disease of the spine is one of the mostcommon clinical entities and the lumbar spine region is among themost commonly involved sites in severe primary spinal degenerativechanges [7].</p><p>In all the above clinical cases, especially when the diseases are ina more advanced stage (primary tumor, matastasis, degenerations-talk artifacts using blade sequences in lumbar.006</p><p>http://dx.doi.org/10.1016/j.mri.2013.03.006mailto:mavroidis@uthscsa.eduhttp://dx.doi.org/10.1016/j.mri.2013.03.006http://www.sciencedirect.com/science/journal/0730725Xhttp://dx.doi.org/10.1016/j.mri.2013.03.006</p></li><li><p>Table 1Summary of the sequences that were applied for lumbar spine MR examination.</p><p>Sequences T2-TSE-SAG T2-TSE-SAGBLADE</p><p>T2 TSE-AX T2 TSE-AXBLADE</p><p>TR (ms) 3500 6000 3610 6000TE (ms) 92 103 108 103Matrix (Freq/Phase) 384/288 256/256 384/288 256/256BW (Hz/pixel) 161 383 171 383Acquisition time (min) 4:03 3:08 4:25 3:08Thickness (mm) 4 4 4 4Space (%) 10 10 10 10ETL 34 35 24 30FOV (mm) 280/280 280/280 240/240 280/280Echo spacing (ms) 11.05 5.74 12 5.74Proportion of coverage - 130.4 - 130.4Number of signalaverages (NSA)</p><p>2.0 1.0 3.0 1.0</p><p>2 E. Lavdas et al. / Magnetic Resonance Imaging xxx (2013) xxxxxxetc.) the patient may often undergo MR examination under pain,which may result in lack of patient collaboration and undesirablepatient movements during the course of the examination. The use ofsagittal T2-weighted and axial T2-weighted sequences is a basicstarting point in the imaging of spinal discogenic diseases [8]. MR ofthe spine based on T2-weighted images can be performed withconventional spin echo (SE) or, preferably with fast spin echo (FSE)techniques [912]. FSE MR imaging sequences have a shorteracquisition time than the conventional SE imaging sequences.</p><p>MR imaging with BLADE, which is a PROPELLER-equivalentimplementation of the Siemens Medical System (Erlangen, Germa-ny), have been shown to effectively reducemotion and pulsatile flowartifacts [1217]. The term BLADE is the product name of a brandsTSE sequence that uses the PROPELLER (periodically rotated over-lapping parallel lines with enhanced reconstruction) k-spacetrajectory. The BLADE method acquires N blades (N number ofblades) that are rotated around the center of the k space. Each bladeconsists of L lowest phase encoding lines (i.e., echo train length[ETL]) of a conventional rectilinear k-space trajectory that areacquired after a single radiofrequency excitation. In brain MRimaging, it has been reported that the BLADE sequences reducemotion artifacts and improve image quality [1822]. Recently, theBLADE technique was also used in examinations of the cervical spine,neck, upper abdomen, knee, kidneys and breast [2329]. The BLADEtechnique has the advantage of central k-space oversampling, so thatimage artifacts are greatly reduced [18,2330]. On the other hand, itis not yet confirmed how much motion and streak artifacts[21,23,31], which appear in radial scans [32], are reduced whendifferent BLADE parameters are employed [33].</p><p>In this study, T2 TSE AX and T2 TSE SAG BLADE sequences wereemployed in order to assess their ability to significantly reduce oreven eliminatemotion artifacts and improve image quality in lumbarspine MRI examinations.</p><p>2. Materials and methods</p><p>2.1. Patients</p><p>From March 2010 to April 2012, forty four patients (19 females,25 males; mean age 41 years, range 1681 years), who had beenroutinely scanned for lumbar spine examination using four differentimage acquisition techniques, participated in the study. Morespecifically, the following pairs of sequences with and withoutBLADE were applied: a) T2 TSE SAG in thirty two patients, and b) T2TSE AXIAL in thirty two patients. This study was approved by thelocal institutional review board and written informed consent wasobtained from all the subjects participating in the study protocol.Due to practical limitations, both pairs of sequences were acquired in20 of the patients. Of the remaining group of 24 patients, one halfwas scanned using the TSE SAG BLADE sequence, whereas the otherhalf was scanned using the TSE AXIAL BLADE sequence.</p><p>2.2. MR imaging techniques</p><p>On all the patients, the lumbar spine MRI examinations wereperformed using a 1.5 T scanner (Magneton Avanto, SiemensHealthcare Sector, Erlangen, Germany) and a synergy bodyphased-array surface coil. The parameters of the different sequencesare presented in Table 1.</p><p>2.3. Quantitative analysis</p><p>A quantitative analysis was performed for the examined foursequences. In the quantitative analysis the following items werePlease cite this article as: Lavdas E, et al, Elimination of motion, pulsatile flow and cross-talk artifacts using blade sequences in lumbarspine MR imaging, Magn Reson Imaging (2013), http://dx.doi.org/10.1016/j.mri.2013.03.006analyzed: (a) the signal-to-noise ratio (SNR) in spinal cord (SC),normal bone marrow (BM), neural root (NR), fatty tissue (FT),cerebrospinal fluid (CSF) and vertebral disk (VD) (b) the contrast-to-noise ratio (CNR) between the CSF and spinal cord, normal bonemarrow and vertebral disc, neural root and its surrounding fattytissue, CSF and normal bone marrow, CSF and vertebral disc,vertebral disk and neural root, and finally vertebral disk and fattytissue. For calculating these values, the signal intensity (SI) of thespinal cord, CSF, normal bone marrow, vertebral disc, neural root,fatty tissue and standard deviation (SD) of background noise weremeasured by placing regions of interest (ROIs). For each patient, theROIs were identical and were place in the same position in the twosequences under comparison. The SD of the background noise wasmeasured in the largest possible ROI positioned in the phase-encoding direction outside the abdominal wall (air) to account forany motion artifacts. When in some cases the positions of the ROIs ofone sequence were shifted due to patient motion, the ROIs weremanually placed based on their relative position to adjacent tissues.</p><p>The SNR was calculated as:</p><p>SNRA SIAN</p><p>1</p><p>where A represents the tissue of interest, the SIA is the signalintensity of A measured by an elliptical region-of-interest (ROI) onthe system console. SI is taken as themean value throughout the ROI.N is the background noise, which was defined as the standarddeviation of a measurement.</p><p>The CNR was calculated as:</p><p>CNRAB SIASI B</p><p>N2</p><p>where SIA and SIB define the SI of the tissues A and B, respectively.A fundamental requirement for any comparison of SNR or CNR</p><p>between two different sequences is that the resolution should bemade equivalent between the two methods. For this reason, the SNRand CNR values of the examined sequences were normalized by thecorresponding voxel sizes in order to account for the differences invoxel size.</p><p>The quantitative evaluation was performed by means of theKolmogorov-Smirnov non parametric test.</p><p>2.4. Qualitative analysis</p><p>All the images of the examined four MR sequences with andwithout BLADE were visually evaluated and compared indepen-dently at two separate examination sessions with 3 weeks interval</p><p>http://dx.doi.org/10.1016/j.mri.2013.03.006</p></li><li><p>Table 2Summary of the results of the quantitative comparison between the BLADE and conventional sequences.</p><p>SNR T2-TSE-SAG T2-TSE-SAG BLADE p T2 TSE-AX T2 TSE-AX BLADE p</p><p>BM 55.7 19.4 203.5 57.5 b0.01 43.2 18.1 235.8 75.5 b0.01VD 29.1 16.5 130.9 82.2 b0.01 13.0 5.6 86.2 34.4 b0.01NR 53.3 20.1 181.4 59.0 b0.01 38.5 43.9 177.1 121.0 b0.01SC 63.8 15.2 155.8 33.4 b0.01 - - -CSF 133.8 39.2 436.6 113.3 b0.01 85.9 36.4 406.0 109.8 b0.01FT 55.7 19.4 203.5 57.5 b0.01 43.2 18.1 235.8 75.5 b0.01NS 166.1 50.8 424.6 113.2 b0.01 118.9 43.4 441.7 154.9 b0.01</p><p>CNR T2-TSE-SAG T2-TSE-SAG BLADE p T2 TSE-AX T2 TSE-AX BLADE p</p><p>BM/VD 29.2 18.8 85.6 47.1 b0.01 30.3 17.3 151.7 76.4 b0.01CSF/SC 102.3 38.1 268.8 87.6 b0.01 - - -NR/FT 80.6 28.5 255.2 91.8 b0.01 54.7 26.6 229.2 120.4 b0.01CSF/BM 110.4 34.3 221.1 85.9 b0.01 75.7 35.4 205.9 101.3 b0.01CSF/VD 137.0 47.5 293.7 111.2 b0.01 106.0 41.1 355.5 148.5 b0.01VD/NR 26.9 18.7 81.3 45.3 b0.01 25.8 44.1 93.3 123.7 b0.01VD/FT 104.7 37.3 305.7 108.7 b0.01 73.0 34.1 319.8 98.5 b0.01</p><p>The analysis of the signal to noise ratio (SNR) and contrast to noise ratio (CNR) results was performed using the Kolmogorov-Smirnov non parametric test.BM: bone marrow, VD: vertebral disc, NR: neural root, SC: spinal cord, NS: noise, CSF: cerebrospinal fluid, FT: fatty tissue.</p><p>3E. Lavdas et al. / Magnetic Resonance Imaging xxx (2013) xxxxxxby two experienced onMR imaging radiologists and the results of theblinded evaluations were used in the analysis.</p><p>The images from the corresponding sequences were filmed atoptimal window and level settings. It should be stated that windowFig. 1. Sagittal T2 TSE (upper left), Sagittal T2 TSE BLADE (upper right), Axial T2 TSE (lower left) and Axial T2 TSE BLADE (lower right) images of the spine. It is shown that themotion artifacts that are seen in the T2 TSE sequences are eliminated in the T2 TSE BLADE sequences improving significantly the overall image quality.</p><p>Please cite this article as: Lavdas E, et al, Elimination of motion, pulsatile flow and cross-talk artifacts using blade sequences in lumbarspine MR imaging, Magn Reson Imaging (2013), http://dx.doi.org/10.1016/j.mri.2013.03.006settings have a dynamic width in MRI examinations and thosewindow and level settings are decided by the system itself. Theradiologists graded on a 5-point scale (0: non-visualization; 1: poor;2: average; 3: good; 4: excellent) each of the following image</p><p>http://dx.doi.org/10.1016/j.mri.2013.03.006</p></li><li><p>Fig. 2. Sagittal T2 TSE (left) and sagittal T2 TSE BLADE (right) images of the lumbar spine. It is shown that the motion artifacts that are seen in the T2 TSE sequence are eliminatedthe T2 TSE BLADE sequence improving significantly the overall image quality.</p><p>ig. 3. Axial T2 TSE (upper left), Axial T2 TSE BLADE (upper right), Axial T2 TSE (lower left) and Axial T2 TSE BLADE (lower right) images of the spine. It is shown that the BLADEequences manage to minimize or even eliminate the initially observed cross-talk (lateral arrows) and pulsatile flow (central arrows) artifacts.</p><p>4 E. Lavdas et al. / Magnetic Resonance Imaging xxx (2013) xxxxxxin</p><p>Fs</p><p>Please cite this article as: Lavdas E, et al, Elimination of motion, pulsatile flow and cross-talk artifacts usin...</p></li></ul>