Aims and objectives
In recent years,
technological developments of MRI scanners have allowed the mapping sequences to become clinically feasible: these sequences generate parametric maps able to display tissue magnetic properties [1,
2].
Qualitative and quantitative information of tissues [3] should be obtained through the appropriate image acquisition and analysis of the body physical properties,
like spin-lattice relaxation times (T1) and spin-spin relaxation times (T2).
A new approach to the evaluation of standardization will be necessary in order to take in to account the possibility of finding T1...
Methods and materials
Six vials (ID 2,
4,
11,
13,
14 and 15) of an Eurospin phantom (Diagnostic Sonar,
Livingston,
UK),
filled with agarose gels doped with gadolinium,
were used to compare relaxation times results obtained from measurements performed with different scanners.
Standard reference values of ID inserts were needed to be established with NMR methodology.
First,
the vials were scanned with Tecmag Apollo NMR spectrometer (Tecmag,
Houston,
TX,
USA) at University Physics Department’s laboratories using standard sequences in order to restate reference T1 and T2 relaxation times...
Results
The NMR spectrometer results at 23°C are listed in Tab.
1.
Tab.
1. Relaxation times values of the Eurospin phantom inserts measured with the NMR spectrometer at 23°C.
Insert ID
SR - T1 (ms)
IR - T1 (ms)
SE - T2 (ms)
CPMG - T2 (ms)
2
348 ± 6
294 ± 10
20 ± 1
50 ± 2
4
507 ± 9
427 ± 12
18 ± 1
33 ± 1
11
1039 ± 20
886 ± 44
17 ± 1
71 ± 1...
Conclusion
A good agreement was observed between IR values,
obtained with the three different scanners (NMR spectrometer at Pavia University,
Siemens Aera and General Electric Signa MRI scanners in our Hospital),
and between CPMG and SE values,
obtained respectively with the NMR spectrometer and with the MRI scanners: the expected linear dependence of relaxation times with temperature is observed considering the experimental errors (± 3% for T1 and ± 10% for T2,
limits of agreement,
Fig.3).
The correspondence between CPMG (NMR spectrometer) and SE (MRI scanners)...
References
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Carneiro AAO.
MRI Relaxometry: Methods and Applications.
Braz J Phys 2006;36(1A):9-15.
http://dx.doi.org/10.1590/S0103-97332006000100005.
2.
Salerno M.
Advances in parametric mapping with cardiac magnetic resonance imaging.
JACC Cardiovasc Imaging 2013;6(7):806-822.
https://doi.org/10.1016/j.jcmg.2013.05.005.
3.
Cheng H-LM.
Practical medical applications of quantitative MR relaxometry,
J Magn Reson Imaging 2012;36:805-824.
https://doi.org/10.1002/jmri.23718.
4.
Stanisz GJ.
T1,
T2 relaxation and magnetization transfer in tissue at 3 T.
Magn Reson Med 2005;54:507-512.
https://doi.org/10.1002/mrm.20605.
5.
Heiberg E.
Design and validation of Segment – freely available software for cardiovascular image analysis.
BMC Med Imaging 2010;10:1....