Multiparametric T1, T2 and T2* MR Imaging Kate Hanneman MD Assistant Professor of Radiology Joint Department of Medical Imaging, University of Toronto
Disclosure Neither I nor my immediate family members have a financial relationship with a commercial organization that may have a direct or indirect interest in the content.
Objectives Describe the basic techniques of myocardial MR mapping Explain the role of myocardial MR mapping Identify findings of common diseases on T1, T2, and T2* maps
Cardiac MRI Important role in the assessment of anatomy, function and tissue characterization Traditionally qualitative characterization of the myocardium LGE may not identify diffuse fibrosis if contrast uptake is uniform
T1 Mapping All tissues have inherent T1 relaxation times Key source of soft tissue contrast Myocardial diseases can alter native T1 and T2 signals
T1 Mapping Techniques Different acquisition schemes to sample the T1 recovery signal: MOLLI ShMOLLI SASHA SAPPHIRE Taylor et al. T1 Mapping: Basic Techniques and Clinical Applications. J Am Coll Cardiol Img. 2016 9(1):67-81. Roujol et al. Accuracy, precision, and reproducibility of four T1 mapping sequences: a head-to-head comparison of MOLLI, ShMOLLI, SASHA, and SAPPHIRE. Radiology. 2014 272(2):683-689.
Inversion Recovery Techniques MOLLI, shmolli, variants Potential bias from T2 and magnetization transfer effects due to SSFP readout Heart rate dependence High precision T1 values tend to be lower than SR-based techniques Roujol et al. Accuracy, precision, and reproducibility of four T1 mapping sequences: a head-to-head comparison of MOLLI, ShMOLLI, SASHA, and SAPPHIRE. Radiology. 2014 272(2):683-689.
Saturation Recovery Techniques SASHA More accurate Lower precision Similar reproducibility Roujol et al. Accuracy, precision, and reproducibility of four T1 mapping sequences: a head-to-head comparison of MOLLI, ShMOLLI, SASHA, and SAPPHIRE. Radiology. 2014 272(2):683-689.
Variation in T1 Mapping Values Scanner related: Magnetic field strength Image acquisition plane Region of myocardium being sampled Type of mapping sequence Patient related: Heart rate, age, and sex Messroghli DR, et al. Radiology 2006;238(3):1004 1012. ; Hamlin SA et al. Radiographics. 2014 34(6):1594-611.
Non-Contrast (Native) T1 Mapping Normal myocardium has a T1 relaxation time of ~950-1050 ms at 1.5T and ~11001150 ms at 3T Hamlin SA1, Henry TS, Little BP, Lerakis S, Stillman AE. Mapping the future of cardiac MR imaging: case-based review of T1 and T2 mapping techniques. Radiographics. 2014 34(6):1594-611.
Post-Contrast T1 Mapping Administration of contrast shortens the T1 relaxation time of myocardium by several hundred milliseconds Hamlin SA1, Henry TS, Little BP, Lerakis S, Stillman AE. Mapping the future of cardiac MR imaging: case-based review of T1 and T2 mapping techniques. Radiographics. 2014 34(6):1594-611.
Extra-Cellular Volume Fraction (ECV) Proportion of extracellular space within the myocardium Normal myocardial ECV ~24-30% Hamlin SA1, Henry TS, Little BP, Lerakis S, Stillman AE. Mapping the future of cardiac MR imaging: case-based review of T1 and T2 mapping techniques. Radiographics. 2014 34(6):1594-611.
Extra-Cellular Volume Fraction (ECV) Calculated on the basis of non-enhanced and contrast-enhanced T1 values with hematocrit: ECV = 1/T1 MYO-POST - 1/T1 MYO-PRE 1/T1 BP-POST - 1/T1 BP-PRE x (100 - hematocrit) Moon JC, Messroghli DR, Kellman P, et al. Myocardial T1 mapping and extracellular volume quantification: a Society for Cardiovascular Magnetic Resonance (SCMR) and CMR Working Group of the European Society of Cardiology consensus statement. J Cardiovasc Magn Reson 2013;15:e92.
T2 Imaging T2 relaxation time is altered by the water content in tissue
T2 Mapping T2 maps are generated on the basis of a similar principle to that used in T1 mapping Normal myocardial T2 values 45-55 ms Giri et al. JCMR 2009
T2* Imaging Clinical standard for assessment of myocardial iron T2* shorter than T2 T2* decay progresses with time Anderson LJ et al. Eur Heart J 2001; Chavan GB et al. Radiographics 2009
T2* Imaging T2* post-processing is typically performed off-line T2* maps can be generated at the scanner 60 ms 0 ms Anderson LJ et al. Eur Heart J 2001; Chavan GB et al. Radiographics 2009
Objectives Describe the basic techniques of myocardial MR mapping Explain the role of myocardial MR mapping Identify findings of common diseases on T1, T2, and T2* maps
FIBROSIS Common and final pathway in several cardiomyopathies Consistent relationship between T1 mapping indices and myocardial fibrosis on histology Non-contrast T1 values Post-contrast T1 values ECV values Hamlin SA et al. Mapping the future of cardiac MR imaging: case-based review of T1 and T2 mapping techniques. Radiographics. 2014 34(6):1594-611. Sibley CT, Noureldin RA, Gai N, et al. T1 Mapping in cardiomyopathy at cardiac MR: comparison with endomyocardial biopsy. Radiology 2012;265:724 32.
FIBROSIS Non-contrast T1 values are increased and post-contrast values are decreased in multiple cardiomyopathies Increased T1 values are associated with adverse outcomes Germain P et al. Clin Med Insights Cardiol. 2014; 8(Suppl 4): 1 11. 240 ms 1330 34% ms 369 ms 1100 ms
EDEMA Increased T1 and T2 values Typically colocalizes with LGE T2 Map T1 Map T2 LGE Hamlin SA et al. Radiographics. 2014 34(6):1594-611. Ferreira VM et al. J Cardiovasc Magn Reson. 2014;16:36.
Tako-Tsubo Cardiomyopathy Classic wall motion abnormality with apical ballooning Typically no LGE Increased non-contrast T1 and T2 values T2 map T1 map 89 ms 49 ms 1318ms Germain P et al. Clin Med Insights Cardiol. 2014; 8(Suppl 4): 1 11. Vermes E et al. JCMR 2015;17(Suppl 1):P354 1030 ms
Cardiac Sarcoid Edema and inflammation identified with T2 imaging Fibrosis identified with LGE and T1 mapping 90 0 55-60ms T1 map 1500 0 T2 map 1050ms
Amyloid 1800 T1 1443 ms Family of diseases induced by misfolded or misassembled proteins Non-contrast T1 and ECV values are elevated 0 50 ECV 34% 0 Germain P et al. Clin Med Insights Cardiol. 2014; 8(Suppl 4): 1 11. Karamitsos TD et al. JACC Cardiovasc Imaging. 2013 6(4):488-97. Fontana M et al. JACC Cardiovasc Imaging. 2014 Feb;7(2):157-65.
Amyloid Diagnostic role in patients with severe renal impairment precluding safe administration of gadolinium contrast T1 values are higher in AL compared to ATTR Non-contrast T1 1340 ms 1800 0 700 Post-contrast T1-330 ms Germain P et al. Clin Med Insights Cardiol. 2014; 8(Suppl 4): 1 11. Karamitsos TD et al. JACC Cardiovasc Imaging. 2013 6(4):488-97. Fontana M et al. JACC Cardiovasc Imaging. 2014 Feb;7(2):157-65. 0
Anderson Fabry Rare X-linked disorder of lysosomal metabolism Non-contrast T1 values are decreased Pseudo-normalization in areas of fibrosis Germain P et al. Clin Med Insights Cardiol. 2014; 8(Suppl 4): 1 11. 920 ms 1252 ms
940 ms Iron Iron is paramagnetic, causing inhomogeneity within the local magnetic field 314 ms Hanneman K et al. Radiology. 2015 Dec 10:150341. Sado DM et al. J Magn Reson Imaging. 2015 41(6):1505-11. 33 %
Iron Cardiac iron concentration is inversely related to myocardial T1 and T2* values T1 values correlate with T2*, and may be more reproducible 60 ms 0 ms 1500 ms T2* 8 ms T1 690 ms Hanneman K et al. Radiology. 2015 Dec 10:150341. Sado DM et al. J Magn Reson Imaging. 2015 41(6):1505-11. 0 ms
WHY Quantitative evaluation of diffuse myocardial changes including fibrosis and edema Diagnostic dilemma Prognostic significance
WHEN Track changes over time Detect subtle changes Inability to administer contrast Suspected Fabry disease
HOW T1, T2, and T2* sequences are available In line maps can be generated Off-line analysis possible with several vendors Values vary depending on several factors
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