Gender-related differences of magnetic resonance T1 relaxation times of normal myocardium: the impact of blood correction

Transcription

1 Gender-related differences of magnetic resonance T1 relaxation times of normal myocardium: the impact of blood correction Poster No.: C-0460 Congress: ECR 2013 Type: Scientific Exhibit Authors: G. Reiter, U. Reiter, K. Dorr, A. Greiser, R. Maderthaner, M Fuchsjaeger ; Graz/AT, Erlangen/DE Keywords: Cardiac, MR, Imaging sequences, Tissue characterisation DOI: /ecr2013/C-0460 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 22

2 Purpose Quantitative T1 myocardial mapping has been rapidly becoming an applicable clinical imaging tool enabling to distinguish normal from pathologically affected myocardium. Normal myocardial T1 reference values have been defined with respect to magnetic field strength and imaging protocols [1-7], as well as patients' age and gender [8]. Cut-off values associated with myocardial injuries related to ischemic and various non-ischemic diseases have been reported [9-15], suggesting T1 mapping as robust diagnostic, observer-independent tool for myocardial tissue characterization. Besides tissue composition, T1 time of blood, varying according to differences in hematocrit and oxygen content over wide ranges with respect to gender and age [16-19], should be considered as relevant parameter in the interpretation of myocardial T1 times. Non-contrast myocardial T1 mapping blood-normalization algorithms, however, have not been introduced to date. The aim of the present study was to investigate variances of myocardial T1 values associated with T1 time of blood in healthy subjects, and to analyze the effect of bloodcorrection of myocardial T1 values. Methods and Materials Study population 40 healthy subjects (20 female, 20 male; mean age ± SD = 24 ± 3 y, age range y) with no history of cardiovascular or pulmonary disease where included in this study. To reduce influence of age related differences in myocardial T1 times associated with myocardial changes during aging, age limit of subjects was set to 35 years [8,20]. MR imaging MR examination was performed on a 1.5 Tesla MR scanner (Magnetom Espree, Siemens Healthcare, Erlangen, Germany) using a phased array 6-channel body coil. Single breath-hold ECG-gated Modified Look-Locker inversion recovery (MOLLI) sequence with balanced single-shot SSFP readout, motion correction and automatic T1 map generation [2,6] was used to acquire basal, mid-ventricular and apical short axes myocardial T1 maps in late diastole (end of data 80%-90% of the respective RR interval). Protocol parameters of the balanced SSFP readout were: repetition time TR = 2.8 ms, TE = ms, flip angle = 35, field-of-view FOV = mm, voxel size = 2.2 Page 2 of 22

3 mm. GRAPPA (generalized auto-calibrating partially parallel acquisition) with a parallel acquisition factor of 2 and partial Fourier reconstruction were employed to minimize acquisition time within each cardiac interval. Image analysis Segmental myocardial T1 times were derived from manually contouring basal, midventricular and apical automatic generated T1 maps according to the AHA segment model [21] in 16 segments, carefully excluding blood pool and epicardial structures (refer to Figure 1). Blood T1 time was measured in a region of interest drawn in the blood pool of the left ventricular cavity in mid-ventricular short axis slices. Fig. 1: Basal (A), mid-ventricular (B) and apical (C) short-axis T1 maps segmented according to the AHA segmentation scheme. Blood T1 time was measured in a region of interest b drawn in the blood pool of the left ventricular cavity the mid-ventricular short axis slices. References: Siemens AG, Healthcare Division - Graz/AT Statistical analysis Blood correction of global and segmental myocardial T1 times was performed by means of the slope of (multiple) linear regression analysis. Group means of T1 values were compared by t-test. Images for this section: Page 3 of 22

4 Fig. 1: Basal (A), mid-ventricular (B) and apical (C) short-axis T1 maps segmented according to the AHA segmentation scheme. Blood T1 time was measured in a region of interest b drawn in the blood pool of the left ventricular cavity the mid-ventricular short axis slices. Page 4 of 22

5 Results Mean global myocardial T1 time was 984 ± 28 ms and differed in male and female (1003 ± 28 ms in female and 966 ± 12 ms in male). Segmental myocardial T1 times (refer to Figure 2) were significantly higher in female than in male (refer to Figure 3). Page 5 of 22

6 Page 6 of 22

7 Fig. 2: Schematic drawing of left ventricular AHA segments (A) and color encoded representation of mean segmental myocardial T1 times of all subjects (B). Numbers in the segments indicate mean T1 times in ms. References: Siemens AG, Healthcare Division - Graz/AT Page 7 of 22

8 Page 8 of 22

9 Fig. 3: Schematic drawing of left ventricular AHA segments. * denotes significant different segmental myocardial T1 values between female and male (A). Color encoded representation of segmental myocardial T1 times of female (B) and male (C) subjects. Numbers in the segments indicate mean T1 times in ms. References: Siemens AG, Healthcare Division - Graz/AT Similar to myocardial T1 values, mean blood T1 time in female (1667 ± 77 ms) was significantly higher than in male (1505 ± 43 ms) with p < Multiple linear regression analysis of segmental myocardial T1 values with respect to blood T1 time and myocardial 2 segments revealed high coefficients of determination (R = 0.53), however slope of regression lines did neither depend on myocardial segment nor on gender. Respective regression lines with slope of 0.22 are shown in Figure 4. Fig. 4: Scatter plot and multiple linear regression of segmental myocardial T1 times versus blood T1 value and AHA segment. Intercepts of segments differ significantly (p < 0.001). References: Siemens AG, Healthcare Division - Graz/AT Slope of regression lines were used to recalculate diastolic and systolic segmental myocardial T1 times to the mean blood T1 time of 1586 ms. Resultant blood-normalized Page 9 of 22

10 mean segmental myocardial T1 times showed decreased standard deviations in all segments, and moreover, no significant difference in gender (refer to Figure 5). Page 10 of 22

11 Page 11 of 22

12 Fig. 5: Schematic drawing of left ventricular AHA segments. The * denotes significant different segmental myocardial T1 values between female and male (A). Color encoded representation of Blood-normalized segmental myocardial T1 times of female (B) and male (C) subjects. Numbers in the segments indicate mean T1 times in ms. References: Siemens AG, Healthcare Division - Graz/AT Images for this section: Page 12 of 22

13 Page 13 of 22

14 Fig. 2: Schematic drawing of left ventricular AHA segments (A) and color encoded representation of mean segmental myocardial T1 times of all subjects (B). Numbers in the segments indicate mean T1 times in ms. Page 14 of 22

15 Page 15 of 22

16 Fig. 3: Schematic drawing of left ventricular AHA segments. * denotes significant different segmental myocardial T1 values between female and male (A). Color encoded representation of segmental myocardial T1 times of female (B) and male (C) subjects. Numbers in the segments indicate mean T1 times in ms. Page 16 of 22

17 Page 17 of 22

18 Fig. 5: Schematic drawing of left ventricular AHA segments. The * denotes significant different segmental myocardial T1 values between female and male (A). Color encoded representation of Blood-normalized segmental myocardial T1 times of female (B) and male (C) subjects. Numbers in the segments indicate mean T1 times in ms. Fig. 4: Scatter plot and multiple linear regression of segmental myocardial T1 times versus blood T1 value and AHA segment. Intercepts of segments differ significantly (p < 0.001). Page 18 of 22

19 Conclusion Gender related differences in normal myocardial T1 values disappear if corrected by T1 relaxation time of blood. Blood correction can thus facilitate the definition of myocardial T1 threshold values between normal and diseased myocardium irrespective of gender. References [1] Messroghli DR, Radjenovic A, Kozerke S, Higgins DM, Sivananthan MU, Ridgway JP. Modified Look-Locker inversion recovery (MOLLI) for high-resolution T1 mapping of the heart. Magn Reson Med. 2004;52(1): [2] Messroghli DR, Plein S, Higgins DM, Walters K, Jones TR, Ridgway JP, Sivananthan MU. Human myocardium: single-breath-hold MR T1 mapping with high spatial resolutionreproducibility study. Radiology. 2006;238(3): [3] Messroghli DR, Greiser A, Fröhlich M, Dietz R, Schulz-Menger J. Optimization and validation of a fully-integrated pulse sequence for modified look-locker inversion-recovery (MOLLI) T1 mapping of the heart. J Magn Reson Imaging. 2007;26(4): [4] Piechnik SK, Ferreira VM, Dall'Armellina E, Cochlin LE, Greiser A, Neubauer S, Robson MD. Shortened Modified Look-Locker Inversion recovery (ShMOLLI) for clinical myocardial T1-mapping at 1.5 and 3T within a 9 heartbeat breathhold. J Cardiovasc Magn Reson. 2010;12:69. [5] Nacif MS, Turkbey EB, Gai N, Nazarian S, van der Geest RJ, Noureldin RA, Sibley CT, Ugander M, Liu S, Arai AE, Lima JA, Bluemke DA. Myocardial T1 mapping with MRI: comparison of look-locker and MOLLI sequences. J Magn Reson Imaging. 2011;34(6): [6] Xue H, Shah S, Greiser A, Guetter C, Littmann A, Jolly MP, Arai AE, Zuehlsdorff S, Guehring J, Kellman P. Motion correction for myocardial T1 mapping using image registration with synthetic image estimation. Magn Reson Med. 2012;67(6): [7] Kawel N, Nacif M, Zavodni A, Jones J, Liu S, Sibley CT, Bluemke DA. T1 mapping of the myocardium: intra-individual assessment of the effect of field strength, cardiac cycle and variation by myocardial region. J Cardiovasc Magn Reson. 2012;14:27. Page 19 of 22

20 [8] Piechnik SK, Ferreira VM, Lewandowski AJ, Ntusi N, Sado D, Maestrini V, White SK, Lazdam M, Banerjee R, Hofman MB, Moon J, Neubauer S, Leeson P, Robson MD. Age and gender dependence of pre-contrast T1-relaxation times in normal human myocardium at 1.5T using ShMOLLI. Journal of Cardiovascular Magnetic Resonance 2012;14(Suppl 1):P221. [9] Sparrow P, Messroghli DR, Reid S, Ridgway JP, Bainbridge G, Sivananthan MU. Myocardial T1 mapping for detection of left ventricular myocardial fibrosis in chronic aortic regurgitation: pilot study. AJR Am J Roentgenol. 2006;187(6):W [10] Messroghli DR, Walters K, Plein S, Sparrow P, Friedrich MG, Ridgway JP, Sivananthan MU. Myocardial T1 mapping: application to patients with acute and chronic myocardial infarction. Magn Reson Med. 2007;58(1): [11] Dass S, Suttie JJ, Piechnik SK, Ferreira VM, Holloway CJ, Banerjee R, Mahmod M, Cochlin L, Karamitsos TD, Robson MD, Watkins H, Neubauer S. Myocardial tissue characterization using magnetic resonance noncontrast t1 mapping in hypertrophic and dilated cardiomyopathy. Circ Cardiovasc Imaging. 2012;5(6): [12] Ferreira VM, Piechnik SK, Dall'Armellina E, Karamitsos TD, Francis JM, Choudhury RP, Friedrich MG, Robson MD, Neubauer S. Non-contrast T1-mapping detects acute myocardial edema with high diagnostic accuracy: a comparison to T2-weighted cardiovascular magnetic resonance. J Cardiovasc Magn Reson. 2012;14:42. [13] Dall'Armellina E, Piechnik SK, Ferreira VM, Si QL, Robson MD, Francis JM, Cuculi F, Kharbanda RK, Banning AP, Choudhury RP, Karamitsos TD, Neubauer S. Cardiovascular magnetic resonance by non contrast T1-mapping allows assessment of severity of injury in acute myocardial infarction. J Cardiovasc Magn Reson. 2012;14:15. [14] Ellims AH, Iles LM, Ling LH, Hare JL, Kaye DM, Taylor AJ. Diffuse myocardial fibrosis in hypertrophic cardiomyopathy can be identified by cardiovascular magnetic resonance, and is associated with left ventricular diastolic dysfunction. J Cardiovasc Magn Reson. 2012;14:76. [15] Karamitsos T, Banypersad SM, Sado D, Maestrini V, Ferreira V, Piechnik SK, Robson MD, Hawkins PN, Neubauer S, Moon J. Pre-contrast ShMOLLI T1 mapping in cardiac AL amyloidosis. J Cardiovasc Magn Reson. 2012; 14(Suppl 1): O76. Page 20 of 22

21 [16] Tadamura E, Hatabu H, Li W, Prasad PV, Edelman RR. Effect of oxygen inhalation on relaxation times in various tissues. J Magn Reson Imaging. 1997;7(1): [17] Varela M, Hajnal JV, Petersen ET, Golay X, Merchant N, Larkman DJ. A method for rapid in vivo measurement of blood T1. NMR Biomed. 2011;24(1): [18] Geaghan S. Normal blood values: selected reference values for neonatal, pediatric and adult populations. In Hematology, Basic Principles and Practice, 4th edn., Hoffman R, Benz EJ, Shttil SJ, Furie B, Cohen HJ, Silberstein LE, McGlave P (eds). ElsevierChurchill Livingstone: Philadelphia, PA, 2005; [19] Lu H, Clingman C, Golay X, van Zijl PC. Determining the longitudinal relaxation time (T1) of blood at 3.0 Tesla. Magn Reson Med. 2004;52(3): [20] Bernhard D, Laufer G. The aging cardiomyocyte: a mini-review. Gerontology. 2008;54(1): [21] Cerqueira MD, Weissman NJ, Dilsizian V, Jacobs AK, Kaul S, Laskey WK, Pennell DJ, Rumberger JA, Ryan T, Verani MS; American Heart Association Writing Group on Myocardial Segmentation and Registration for Cardiac Imaging. Standardized myocardial segmentation and nomenclature for tomographic imaging of the heart: a statement for healthcare professionals from the Cardiac Imaging Committee of the Council on Clinical Cardiology of the American Heart Association. Circulation Jan 29;105(4): Personal Information Gert Reiter, PhD; Siemens AG, Healthcare Sector, Graz, Austria; gert.reiter@siemens.com. Ursula Reiter, PhD; Division of General Radiology, Department of Radiology, Medical University of Graz, Austria; ursula.reiter@klinikum-graz.at. Katrin Dorr, MD; Department of Radiology, Feldbach Regional Hospital, Austria; katrin.dorr@medunigraz.at. Page 21 of 22

22 Andreas Greiser, PhD; Siemens AG, Healthcare Sector, Erlangen, Germany; Ralph Maderthaner, MD; Division of General Radiology, Department of Radiology, Medical University of Graz, Austria; Michael Fuchsjäger, MD; Division of General Radiology, Department of Radiology, Medical University of Graz, Austria; Page 22 of 22