Normal variation of magnetic resonance T1 relaxation times in the human population at 1.5 T using ShMOLLI

Journal of Cardiovascular Magnetic Resonance

Research

Merzaka Lazdam¹  Paul Leeson¹  Adam J Lewandowski¹  Rajarshi Banerjee²  Stefan K Piechnik²  Matthew D Robson²  Stefan Neubauer²  Theodoros Karamitsos²  Cameron Holloway²  Ntobeko AB Ntusi²  Vanessa M Ferreira³  Mark BM Hofman⁴  James C Moon⁵  Viviana Maestrini⁵  Steven K White⁵  Daniel M Sado⁵ 

[1] Department of Cardiovascular Medicine, Oxford Cardiovascular Clinical Research Facility, University of Oxford, Oxford, UK;Department of Cardiovascular Medicine, Oxford Centre for Clinical Magnetic Resonance Research, University of Oxford, Oxford, UK;Department of Cardiovascular Medicine, Oxford Centre for Clinical Magnetic Resonance Research, University of Oxford, Oxford, UK;Stephenson Cardiovascular MR Centre, Libin Cardiovascular Institute of Alberta, Calgary, AL, Canada;Department of Physics & Medical Technology, ICaR-VU, VU, University Medical Center, Amsterdam, the Netherlands;The Heart Hospital Imaging Centre, The Heart Hospital, London and University College, London, UK;

关键词: Cardiovascular Magnetic Resonance;    Partial Volume Effect;    Myocardial Thickness;    Myocardial Wall Thickness;    Myocardial Contour;   

DOI  :  10.1186/1532-429X-15-13

 received in 2012-07-23, accepted in 2013-01-14,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundQuantitative T1-mapping is rapidly becoming a clinical tool in cardiovascular magnetic resonance (CMR) to objectively distinguish normal from diseased myocardium. The usefulness of any quantitative technique to identify disease lies in its ability to detect significant differences from an established range of normal values. We aimed to assess the variability of myocardial T1 relaxation times in the normal human population estimated with recently proposed Shortened Modified Look-Locker Inversion recovery (ShMOLLI) T1 mapping technique.MethodsA large cohort of healthy volunteers (n = 342, 50% females, age 11–69 years) from 3 clinical centres across two countries underwent CMR at 1.5T. Each examination provided a single average myocardial ShMOLLI T1 estimate using manually drawn myocardial contours on typically 3 short axis slices (average 3.4 ± 1.4), taking care not to include any blood pool in the myocardial contours. We established the normal reference range of myocardial and blood T1 values, and assessed the effect of potential confounding factors, including artefacts, partial volume, repeated measurements, age, gender, body size, hematocrit and heart rate.ResultsNative myocardial ShMOLLI T1 was 962 ± 25 ms. We identify the partial volume as primary source of potential error in the analysis of respective T1 maps and use 1 pixel erosion to represent “midwall myocardial” T1, resulting in a 0.9% decrease to 953 ± 23 ms. Midwall myocardial ShMOLLI T1 was reproducible with an intra-individual, intra- and inter-scanner variability of ≤2%. The principle biological parameter influencing myocardial ShMOLLI T1 was the female gender, with female T1 longer by 24 ms up to the age of 45 years, after which there was no significant difference from males. After correction for age and gender dependencies, heart rate was the only other physiologic factor with a small effect on myocardial ShMOLLI T1 (6ms/10bpm). Left and right ventricular blood ShMOLLI T1 correlated strongly with each other and also with myocardial T1 with the slope of 0.1 that is justifiable by the resting partition of blood volume in myocardial tissue. Overall, the effect of all variables on myocardial ShMOLLI T1 was within 2% of relative changes from the average.ConclusionNative T1-mapping using ShMOLLI generates reproducible and consistent results in normal individuals within 2% of relative changes from the average, well below the effects of most acute forms of myocardial disease. The main potential confounder is the partial volume effect arising from over-inclusion of neighbouring tissue at the manual stages of image analysis. In the study of cardiac conditions such as diffuse fibrosis or small focal changes, the use of “myocardial midwall” T1, age and gender matching, and compensation for heart rate differences may all help to improve the method sensitivity in detecting subtle changes. As the accuracy of current T1 measurement methods remains to be established, this study does not claim to report an accurate measure of T1, but that ShMOLLI is a stable and reproducible method for T1-mapping.

【 授权许可】

CC BY   
© Piechnik et al.; licensee BioMed Central Ltd. 2013